In composite construction, steel beams and a concrete slab are connected so that they act together to resist the load on the beam. The slab, in effect, serves as a cover plate. As a result, a lighter steel section may be used.
Construction In Buildings
There are two basic methods of composite construction.
Method 1. The steel beam is entirely encased in the concrete. Composite action in this case depends on the steel-concrete bond alone. Because the beam is completely braced laterally, the allowable stress in the flanges is 0.66F y , where F y is the yield strength, ksi (MPa), of the steel. Assuming the steel to carry the full dead load and the composite section to carry the live load, the maximum unit stress, ksi (MPa), in the steel is
F s = ( M D / S S ) + ( M L / S t r ) ? 0.66F y
where M D = dead-load moment, in-kip (kN-mm)
M L = live-load moment, in-kip (kN-mm)
S s = section modulus of steel beam, in 3 (mm 3 )
S t r = section modulus of transformed composite section, in 3 (mm 3 )
An alternative, shortcut method is permitted by the AISC specification. It assumes that the steel beam carries both live and dead loads and compensates for this by permitting
a higher stress in the steel:
f s = M D + M L / S s ? 0.76 F y
Method 2. The steel beam is connected to the concrete slab by shear connectors. Design is based on ultimate load and is independent of the use of temporary shores to support the steel until the concrete hardens. The maximum stress in the bottom flange is
F s = M D + M L / S t r £ 0.66 F y
To obtain the transformed composite section, treat the concrete above the neutral axis as an equivalent steel area by dividing the concrete area by n, the ratio of modulus of elasticity of steel to that of the concrete. In determination of the transformed section, only a portion of the concrete slab over the beam may be considered effective in resisting compressive flexural stresses (positive-moment regions). The width of slab on either side of the beam centerline that may be considered effective should not exceed any of the following:
1. One-eighth of the beam span between centers of sup- ports
2. Half the distance to the centerline of the adjacent beam
3. The distance from beam centerline to edge of slab
Saturday, July 4, 2009
NUMBER OF CONNECTORS REQUIRED FOR BUILDING CONSTRUCTION
The total number of connectors to resist V h is computed from V h / q, where q is the allowable shear for one connector, kip (kN). Values of q for connectors in buildings are given in structural design guides.
The required number of shear connectors may be spaced uniformly between the sections of maximum and zero moment. Shear connectors should have at least 1 in (25.4 mm) of concrete cover in all directions; and unless studs are located directly over the web, stud diameters may not exceed 2.5 times the beam-flange thickness.
With heavy concentrated loads, the uniform spacing of shear connectors may not be sufficient between a concentrated load and the nearest point of zero moment. The number of shear connectors in this region should be at least
N 2 = N 1 [ ( M b / M m a x ) - 1] / ( b - 1 )
where M = moment at concentrated load, ft kip (kN-m)
M max = maximum moment in span, ft kip (kN-m)
N 1 = number of shear connectors required between M m a x and zero moment
b = S t r / S s or S e f f / S s , as applicable
S e f f = effective section modulus for partial composite action, in 3 (mm 3 )
Shear on Connectors
The total horizontal shear to be resisted by the shear connectors in building construction is taken as the smaller of the values given by the following two equations:
V h = 0.85 f ‘ c A c / 2
V h = A s F y / 2
where V h = total horizontal shear, kip (kN), between maximum positive moment and each end of steel beams (or between point of maximum positive moment and point of contraflexure in continuous beam)
f ‘ c = specified compressive strength of concrete at 28 days, ksi (MPa)
A c = actual area of effective concrete flange, in 2 (mm 2 )
A s = area of steel beam, in 2 (mm 2 )
In continuous composite construction, longitudinal reinforcing steel may be considered to act compositely with the steel beam in negative-moment regions. In this case, the total horizontal shear, kip (kN), between an interior support and each adjacent point of contraflexure should be taken as
V h = A s r F y r / 2
where A s r = area of longitudinal reinforcement at support within effective area, in 2 (mm 2 ); and F y r = specified minimum yield stress of longitudinal reinforcement, ksi (MPa).
The required number of shear connectors may be spaced uniformly between the sections of maximum and zero moment. Shear connectors should have at least 1 in (25.4 mm) of concrete cover in all directions; and unless studs are located directly over the web, stud diameters may not exceed 2.5 times the beam-flange thickness.
With heavy concentrated loads, the uniform spacing of shear connectors may not be sufficient between a concentrated load and the nearest point of zero moment. The number of shear connectors in this region should be at least
N 2 = N 1 [ ( M b / M m a x ) - 1] / ( b - 1 )
where M = moment at concentrated load, ft kip (kN-m)
M max = maximum moment in span, ft kip (kN-m)
N 1 = number of shear connectors required between M m a x and zero moment
b = S t r / S s or S e f f / S s , as applicable
S e f f = effective section modulus for partial composite action, in 3 (mm 3 )
Shear on Connectors
The total horizontal shear to be resisted by the shear connectors in building construction is taken as the smaller of the values given by the following two equations:
V h = 0.85 f ‘ c A c / 2
V h = A s F y / 2
where V h = total horizontal shear, kip (kN), between maximum positive moment and each end of steel beams (or between point of maximum positive moment and point of contraflexure in continuous beam)
f ‘ c = specified compressive strength of concrete at 28 days, ksi (MPa)
A c = actual area of effective concrete flange, in 2 (mm 2 )
A s = area of steel beam, in 2 (mm 2 )
In continuous composite construction, longitudinal reinforcing steel may be considered to act compositely with the steel beam in negative-moment regions. In this case, the total horizontal shear, kip (kN), between an interior support and each adjacent point of contraflexure should be taken as
V h = A s r F y r / 2
where A s r = area of longitudinal reinforcement at support within effective area, in 2 (mm 2 ); and F y r = specified minimum yield stress of longitudinal reinforcement, ksi (MPa).
PONDING CONSIDERATIONS IN BUILDINGS
Flat roofs on which water may accumulate may require analysis to ensure that they are stable under ponding conditions. A flat roof may be considered stable and an analysis does not need to be made if both of the following two equations are satisfied:
C p + 0.9 C s £ 0.25
I d ³ 25S 4 / 10 6
Where C p = 32 L s L 4 p / 10 7 I p
C s = 32 SL 4 s / 10 7 s
L p = length, ft (m), of primary member or girder
L s = length, ft (m), of secondary member or purlin
S = spacing, ft (m), of secondary members
I p = moment of inertia of primary member, in 4
(mm 4 )
I s = moment of inertia of secondary member, in 4
(mm 4 )
I d = moment of inertia of steel deck supported on secondary members, in 4 /ft (mm 4 /m)
For trusses and other open-web members, I s should be decreased 15 percent. The total bending stress due to dead loads, gravity live loads, and ponding should not exceed 0.80F y , where F y is the minimum specified yield stress for the steel.
C p + 0.9 C s £ 0.25
I d ³ 25S 4 / 10 6
Where C p = 32 L s L 4 p / 10 7 I p
C s = 32 SL 4 s / 10 7 s
L p = length, ft (m), of primary member or girder
L s = length, ft (m), of secondary member or purlin
S = spacing, ft (m), of secondary members
I p = moment of inertia of primary member, in 4
(mm 4 )
I s = moment of inertia of secondary member, in 4
(mm 4 )
I d = moment of inertia of steel deck supported on secondary members, in 4 /ft (mm 4 /m)
For trusses and other open-web members, I s should be decreased 15 percent. The total bending stress due to dead loads, gravity live loads, and ponding should not exceed 0.80F y , where F y is the minimum specified yield stress for the steel.
LOW COST HOUSING
Low Cost Housing is a new concept which deals with effective budgeting and following of techniques which help in reducing the cost construction through the use of locally available materials along with improved skills and technology without sacrificing the strength, performance and life of the structure.There is huge misconception that low cost housing is suitable for only sub standard works and they are constructed by utilizing cheap building materials of low quality.The fact is that Low cost housing is done by proper management of resources.Economy is also achieved by postponing finishing works or implementing them in phases.
Building Cost
The building construction cost can be divided into two parts namely:
Building material cost : 65 to 70 %
Labour cost : 65 to 70 %
Now in low cost housing, building material cost is less because we make use of the locally available materials and also the labour cost can be reduced by properly making the time schedule of our work. Cost of reduction is achieved by selection of more efficient material or by an improved design.
Areas from where cost can be reduced are:-
1) Reduce plinth area by using thinner wall concept.Ex.15 cms thick solid concrete block wall.
2) Use locally available material in an innovative form like soil cement blocks in place of burnt brick.
3) Use energy efficiency materials which consumes less energy like concrete block in place of burnt brick.
4) Use environmentally friendly materials which are substitute for conventional building components like use R.C.C. Door and window frames in place of wooden frames.
5) Preplan every component of a house and rationalize the design procedure for reducing the size of the component in the building.
6) By planning each and every component of a house the wastage of materials due to demolition of the unplanned component of the house can be avoided.
7) Each component of the house shall be checked whether if it’s necessary, if it is not necessary, then that component should not be used.
Cost reduction through adhoc methods
Foundation
Normally the foundation cost comes to about 10 to 15% of the total building and usually foundation depth of 3 to 4 ft. is adopted for single or double store building and also the concrete bed of 6″(15 Cms.) is used for the foundation which could be avoided.
It is recommended to adopt a foundation depth of 2 ft.(0.6m) for normal soil like gravely soil, red soils etc., and use the uncoursed rubble masonry with the bond stones and good packing. Similarly the foundation width is rationalized to 2 ft.(0.6m).To avoid cracks formation in foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.
It is further suggested adopt arch foundation in ordinary soil for effecting reduction in construction cost up to 40%.This kind of foundation will help in bridging the loose pockets of soil which occurs along the foundation.
In the case black cotton and other soft soils it is recommend to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.
Plinth
It is suggested to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.It is necessary to take precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface and crack formation.
Walling
Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building and 41/2 ” for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls
Rat - trap bond wall
It is a cavity wall construction with added advantage of thermal comfort and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce in the material cost of bricks by 25% and about 10to 15% in the masonry cost. By adopting rat-trap bond method one can create aesthetically pleasing wall surface and plastering can be avoided.
Concrete block walling
In view of high energy consumption by burnt brick it is suggested to use concrete block (block hollow and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of wall resulting in higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.
Soil cement block technology
It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy efficient method of construction where soil mixed with 5% and above cement and pressed in hand operated machine and cured well and then used in the masonry. This masonry doesn’t require plastering on both sides of the wall. The overall economy that could be achieved with the soil cement technology is about 15 to 20% compared to conventional method of construction.
Doors and windows
It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%.Similiarly for shutters commercially available block boards, fibre or wooden practical boards etc., shall be used for reducing the cost by about 25%.By adopting brick jelly work and precast components effective ventilation could be provided to the building and also the construction cost could be saved up to 50% over the window components.
Lintals and Chajjas
The traditional R.C.C. lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30 to 40% over the traditional method of construction. By adopting arches of different shapes a good architectural pleasing appearance can be given to the external wall surfaces of the brick masonry.
Roofing
Normally 5″(12.5 cms) thick R.C.C. slabs is used for roofing of residential buildings. By adopting rationally designed insitu construction practices like filler slab and precast elements the construction cost of roofing can be reduced by about 20 to 25%.
Filler slabs
They are normal RCC slabs where bottom half (tension) concrete portions are replaced by filler materials such as bricks, tiles, cellular concrete blocks, etc.These filler materials are so placed as not to compromise structural strength, result in replacing unwanted and nonfunctional tension concrete, thus resulting in economy. These are safe, sound and provide aesthetically pleasing pattern ceilings and also need no plaster.
For more on filler materials check Filler Materials Used in Concrete
Jack arch roof/floor
They are easy to construct, save on cement and steel, are more appropriate in hot climates. These can be constructed using compressed earth blocks also as alternative to bricks for further economy.
Ferrocement channel/shell unit
Provide an economic solution to RCC slab by providing 30 to 40% cost reduction on floor/roof unit over RCC slabs without compromising the strength. These being precast, construction is speedy, economical due to avoidance of shuttering and facilitate quality control.
Finishing Work
The cost of finishing items like sanitary, electricity, painting etc., varies depending upon the type and quality of products used in the building and its cost reduction is left to the individual choice and liking.
Conclusion
The above list of suggestion for reducing construction cost is of general nature and it varies depending upon the nature of the building to be constructed, budget of the owner, geographical location where the house is to be constructed, availability of the building material, good construction management practices etc. However it is necessary that good planning and design methods shall be adopted by utilizing the services of an experienced engineer or an architect for supervising the work, thereby achieving overall cost effectiveness to the extent of 25% in actual practice.
Building Cost
The building construction cost can be divided into two parts namely:
Building material cost : 65 to 70 %
Labour cost : 65 to 70 %
Now in low cost housing, building material cost is less because we make use of the locally available materials and also the labour cost can be reduced by properly making the time schedule of our work. Cost of reduction is achieved by selection of more efficient material or by an improved design.
Areas from where cost can be reduced are:-
1) Reduce plinth area by using thinner wall concept.Ex.15 cms thick solid concrete block wall.
2) Use locally available material in an innovative form like soil cement blocks in place of burnt brick.
3) Use energy efficiency materials which consumes less energy like concrete block in place of burnt brick.
4) Use environmentally friendly materials which are substitute for conventional building components like use R.C.C. Door and window frames in place of wooden frames.
5) Preplan every component of a house and rationalize the design procedure for reducing the size of the component in the building.
6) By planning each and every component of a house the wastage of materials due to demolition of the unplanned component of the house can be avoided.
7) Each component of the house shall be checked whether if it’s necessary, if it is not necessary, then that component should not be used.
Cost reduction through adhoc methods
Foundation
Normally the foundation cost comes to about 10 to 15% of the total building and usually foundation depth of 3 to 4 ft. is adopted for single or double store building and also the concrete bed of 6″(15 Cms.) is used for the foundation which could be avoided.
It is recommended to adopt a foundation depth of 2 ft.(0.6m) for normal soil like gravely soil, red soils etc., and use the uncoursed rubble masonry with the bond stones and good packing. Similarly the foundation width is rationalized to 2 ft.(0.6m).To avoid cracks formation in foundation the masonry shall be thoroughly packed with cement mortar of 1:8 boulders and bond stones at regular intervals.
It is further suggested adopt arch foundation in ordinary soil for effecting reduction in construction cost up to 40%.This kind of foundation will help in bridging the loose pockets of soil which occurs along the foundation.
In the case black cotton and other soft soils it is recommend to use under ream pile foundation which saves about 20 to 25% in cost over the conventional method of construction.
Plinth
It is suggested to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6″ which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.It is necessary to take precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface and crack formation.
Walling
Wall thickness of 6 to 9″ is recommended for adoption in the construction of walls all-round the building and 41/2 ” for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls
Rat - trap bond wall
It is a cavity wall construction with added advantage of thermal comfort and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce in the material cost of bricks by 25% and about 10to 15% in the masonry cost. By adopting rat-trap bond method one can create aesthetically pleasing wall surface and plastering can be avoided.
Concrete block walling
In view of high energy consumption by burnt brick it is suggested to use concrete block (block hollow and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of wall resulting in higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.
Soil cement block technology
It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy efficient method of construction where soil mixed with 5% and above cement and pressed in hand operated machine and cured well and then used in the masonry. This masonry doesn’t require plastering on both sides of the wall. The overall economy that could be achieved with the soil cement technology is about 15 to 20% compared to conventional method of construction.
Doors and windows
It is suggested not to use wood for doors and windows and in its place concrete or steel section frames shall be used for achieving saving in cost up to 30 to 40%.Similiarly for shutters commercially available block boards, fibre or wooden practical boards etc., shall be used for reducing the cost by about 25%.By adopting brick jelly work and precast components effective ventilation could be provided to the building and also the construction cost could be saved up to 50% over the window components.
Lintals and Chajjas
The traditional R.C.C. lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 30 to 40% over the traditional method of construction. By adopting arches of different shapes a good architectural pleasing appearance can be given to the external wall surfaces of the brick masonry.
Roofing
Normally 5″(12.5 cms) thick R.C.C. slabs is used for roofing of residential buildings. By adopting rationally designed insitu construction practices like filler slab and precast elements the construction cost of roofing can be reduced by about 20 to 25%.
Filler slabs
They are normal RCC slabs where bottom half (tension) concrete portions are replaced by filler materials such as bricks, tiles, cellular concrete blocks, etc.These filler materials are so placed as not to compromise structural strength, result in replacing unwanted and nonfunctional tension concrete, thus resulting in economy. These are safe, sound and provide aesthetically pleasing pattern ceilings and also need no plaster.
For more on filler materials check Filler Materials Used in Concrete
Jack arch roof/floor
They are easy to construct, save on cement and steel, are more appropriate in hot climates. These can be constructed using compressed earth blocks also as alternative to bricks for further economy.
Ferrocement channel/shell unit
Provide an economic solution to RCC slab by providing 30 to 40% cost reduction on floor/roof unit over RCC slabs without compromising the strength. These being precast, construction is speedy, economical due to avoidance of shuttering and facilitate quality control.
Finishing Work
The cost of finishing items like sanitary, electricity, painting etc., varies depending upon the type and quality of products used in the building and its cost reduction is left to the individual choice and liking.
Conclusion
The above list of suggestion for reducing construction cost is of general nature and it varies depending upon the nature of the building to be constructed, budget of the owner, geographical location where the house is to be constructed, availability of the building material, good construction management practices etc. However it is necessary that good planning and design methods shall be adopted by utilizing the services of an experienced engineer or an architect for supervising the work, thereby achieving overall cost effectiveness to the extent of 25% in actual practice.
ABOUT CIVIL ENGINEERING
Engineering is a term applied to the profession in which a knowledge of the mathematical and natural sciences, gained by study, experience, and practice, is applied to the efficient use of the materials and forces of nature. Engineers are the ones who have received professional training in pure and applied science.Before the middle of the 18th century, large-scale construction work was usually placed in the hands of military engineers. Military engineering involved such work as the preparation of topographical maps, the location, design, and construction of roads and bridges; and the building of forts and docks; see Military Engineering below. In the 18th century, however, the term civil engineering came into use to describe engineering work that was performed by civilians for nonmilitary purposes.
Civil engineering is the broadest of the engineering fields. Civil engineering focuses on the infrastructure of the world which include Water works, Sewers, Dams, Power Plants, Transmission Towers/Lines, Railroads, Highways, Bridges, Tunnels, Irrigation Canals, River Navigation, Shipping Canals, Traffic Control, Mass Transit, Airport Runways, Terminals, Industrial Plant Buildings, Skyscrapers, etc. Among the important subdivisions of the field are construction engineering, irrigation engineering, transportation engineering, soils and foundation engineering, geodetic engineering, hydraulic engineering, and coastal and ocean engineering.
Civil engineers build the world’s infrastructure. In doing so, they quietly shape the history of nations around the world. Most people can not imagine life without the many contributions of civil engineers to the public’s health, safety and standard of living. Only by exploring civil engineering’s influence in shaping the world we know today, can we creatively envision the progress of our tomorrows.
Civil engineering is the broadest of the engineering fields. Civil engineering focuses on the infrastructure of the world which include Water works, Sewers, Dams, Power Plants, Transmission Towers/Lines, Railroads, Highways, Bridges, Tunnels, Irrigation Canals, River Navigation, Shipping Canals, Traffic Control, Mass Transit, Airport Runways, Terminals, Industrial Plant Buildings, Skyscrapers, etc. Among the important subdivisions of the field are construction engineering, irrigation engineering, transportation engineering, soils and foundation engineering, geodetic engineering, hydraulic engineering, and coastal and ocean engineering.
Civil engineers build the world’s infrastructure. In doing so, they quietly shape the history of nations around the world. Most people can not imagine life without the many contributions of civil engineers to the public’s health, safety and standard of living. Only by exploring civil engineering’s influence in shaping the world we know today, can we creatively envision the progress of our tomorrows.
Friday, July 3, 2009
Construction Equipment
DUMP TRUCK
Dump trucks or production trucks are those that are used for transporting loose material such as sand, dirt, and gravel for construction. The typical dump truck is equipped with a hydraulically operated open box bed hinged at the rear, with the front being able to be lifted up to allow the contents to fall out on the ground at the site of delivery.Dump trucks come in many different configurations with each one specified to accomplish a specific task in the construction chain.
Standard dump truck
The standard dump truck is a full truck chassis with the dump body mounted onto the frame. The dump body is raised by a hydraulic ram lift that is mounted forward of the front bulkhead, normally between the truck cab and the dump body. The standard dump truck also has one front axle, and one or more rear axles which normally has dual wheels on each side. The common configurations for standard dump trucks include the six wheeler and ten wheeler.
Transfer dump truck
For the amount of noise made when transferring, the transfer dump truck is easy to recognize. It’s a standard dump truck that pulls a separate trailer which can be loaded with sand, asphalt, gravel, dirt, etc. The B box or aggregate container on the trailer is
powered by an electric motor and rides on wheels and rolls off of the trailer and into the main dump box. The biggest advantage with this configuration is to maximize payload capacity without having to sacrifice the maneuverability of the short and nimble dump truck standards.
Semi trailer end dump truck
The semi end dump truck is a tractor trailer combination where the trailer itself contains the hydraulic hoist. The average semi end dump truck has a 3 axle tractor that pulls a 2 axle semi trailer. The advantage to having a semi end dump truck is rapid unloading.
Semi trailer bottom dump truck
A bottom dump truck is a 3 axle tractor that pulls a 2 axle trailer with a clam shell type dump gate in the belly of the trailer. The biggest advantage of a semi bottom dump truck is the ability to lay material in a wind row. This type of truck is also maneuverable in reverse as well, unlike the double and triple trailer configurations.
Double and triple trailer
The double and triple bottom dump trucks consist of a 2 axle tractor pulling a semi axle semi trailer and an additional trailer. These types of dump trucks allow the driver to lay material in wind rows without having to leave the cab or stop the truck. The biggest disadvantage is the difficulty in going in reverse.
Side dump trucks
Side dump trucks consist of a 3 axle trailer pulling a 2 axle semi trailer. It offers hydraulic rams that tilt the dump body onto the side, which spills the material to the left or right side of the trailer. The biggest advantages with these types of dump trucks are that they allow rapid unloading and carry more weight than other dump trucks.
In addition to this, side dump trucks are almost impossible to tip over while dumping, unlike the semi end dump trucks which are very prone to being upset or tipped over. The length of these trucks impede maneuverability and limit versatility.
Off road dump trucks
Off road trucks resemble heavy construction equipment more than they do highway dump trucks. They are used strictly for off road mining and heavy dirt hauling jobs, such as excavation work. They are very big in size, and perfect for those time when you need to dig out roads and need something to haul the massive amounts of dirt to another location.
FRONT LOADER
Also known as a front end loader, bucket loader, scoop loader, or shovel, the front loader is a type of tractor that is normally wheeled and uses a wide square tilting bucket on the end of movable arms to lift and move material around.The loader assembly may be a removable attachment or permanently mounted on the vehicle. Often times, the bucket can be replaced with other devices or tools, such as forks or a hydraulically operated bucket.
Larger style front loaders, such as the Caterpillar 950G or the Volvo L120E, normally have only a front bucket and are known as front loaders, where the small front loaders are often times equipped with a small backhoe as well and called backhoe loaders or loader backhoes.Loaders are primarily used for loading materials into trucks, laying pipe, clearing rubble, and also digging. Loaders aren’t the most efficient machines for digging, as they can’t dig very deep below the level of their wheels, like the backhoe can.
The deep bucket on the front loader can normally store around 3 - 6 cubic meters of dirt, as the bucket capacity of the loader is much bigger than the bucket capacity of a backhoe loader. Loaders aren’t classified as excavating machinery, as their primary purpose is other than moving dirt.In construction areas, mainly when fixing roads in the middle of the city, front loaders are used to transport building materials such as pipe, bricks, metal bars, and digging tools. Front loaders are also very useful for snow removal as well, as you can use their bucket or as a snow plow. They can clear snow from the streets and highways, even parking lots.They will sometimes load the snow into dump trucks which will then haul it away.
Unlike the bulldozer, most loaders are wheeled and not tracked. The wheels will provide better mobility and speed and won’t damage paved roads near as much as tracks, although this will come at the cost of reduced traction. Unlike backhoes or tractors fitted with a steel bucket, large loaders don’t use automotive steering mechanisms, as they instead steer by a hydraulically actuated pivot point set exactly between the front and rear axles.This is known as articulated steering and will allow the front axle to be solid, therefore allowing it to carry a heavier weight.
Articulated steering will also give a reduced turn in radius for a given wheelbase. With the
front wheels and attachment rotating on the same axis, the operator is able to steer his load in an arc after positioning the machine, which can come in quite handy. The problem is that when the machine is twisted to one side and a heavy load is lifted high in the air, it has a bigger risk of turning over.
FORKLIFT
Sometimes called a forklift truck, the forklift is a powerful industrial truck that is used to lift and transport material by steel forks that are inserted under the load. Forklifts are commonly used to move loads and equipment that is stored on pallets. The forklift was developed in 1920, and has since become a valuable piece of equipment in many manufacturing and warehousing operations.
Types of Forklifts
The most common type of design with forklifts is the counter balance. Other types of designs include the reach truck and side loader, both of which are used in environments where the space is at a minimum.
Control and capability
Forklifts are available in many types and different load capacities. In the average warehouse setting,most forklifts have load capacities of around five tons. Along with the control to raise and lower the forks, you can also tilt the mast to compensate for the tendency of the load to angle the blades towards the ground and risk slipping it off the forks. The tilt will also provide a limited ability to operate on ground that isn’t level.There are some variations that allow you to move the forks and backrest laterally, which allows easier placement of a load. In addition to this, there are some machines that offer hydraulic control to move the forks together or further apart, which removes the need for you to get out of the cab to manually adjust for a different size load.
Another forklift variation that is sometimes used in manufacturing facilities, will utilize forklifts with a clamp attachment that you can open and close around a load, instead of having to use forks. Products such as boxes, cartons, etc., can be moved with the clamp attachment.
Safety
Forklifts are rated for loads at a specified maximum weight and a specified forward type center of gravity. All of this information is located on a nameplate that is provided by the manufacturer and the loads cannot exceed these specifications. One of the most important aspects of operating a forklift is the rear wheel steering. Even though this helps to increase maneuverability in tight cornering situations, it differs from the traditional experience of a driver with other wheeled vehicles as there is no caster action. Another critical aspect of the forklift is the instability. Both the forklift and the load must be considered a unit, with a varying center of gravity with every movement of the load.You must never negotiate a turn with a forklift at full speed with a raised load, as this can easily tip the forklift over.
VARIOUS TYPES OF CRANES:
A crane is a tower or derrick that is equipped with cables and pulleys that are used to lift and lower material. They are commonly used in the construction industry and in the manufacturing of heavy equipment. Cranes for construction are normally temporary
structures, either fixed to the ground or mounted on a purpose built vehicle.
They can either be controlled from an operator in a cab that travels along with the crane, by a push button pendant control station, or by radio type controls. The crane operator is ultimately responsible for the safety of the crews and the crane.
Mobile Cranes
The most basic type of crane consists of a steel truss or telescopic boom mounted on a mobile platform, which could be a rail, wheeled, or even on a cat truck. The boom is hinged at the bottom and can be either raised or lowered by cables or hydraulic cylinders.
Telescopic Crane
This type of crane offers a boom that consists of a number of tubes fitted one inside of the other. A hydraulic mechanism extends or retracts the tubes to increase or decrease the length of the boom.
Tower Crane
The tower crane is a modern form of a balance crane. When fixed to the ground, tower cranes will often give the best combination of height and lifting capacity and are also used when constructing tall buildings.
Truck Mounted Crane
Cranes mounted on a rubber tire truck will provide great mobility. Outriggers that extend vertically or horizontally are used to level and stabilize the crane during hoisting.
Rough Terrain Crane
A crane that is mounted on an undercarriage with four rubber tires, designed for operations off road. The outriggers extend vertically and horizontally to level and stabilize the crane when hoisting. These types of cranes are single engine machines where the same engine is used for powering the undercarriage as it is for powering the crane. In these types of cranes, the engine is normally mounted in the undercarriage rather than
in the upper portion.
Loader Crane
A loader crane is a hydraulically powered articulated arm fitted to a trailer, used to load equipment onto a trailer. The numerous sections can be folded into a small space when the crane isn’t in use.
Overhead Crane
Also refered to as a suspended crane, this type is normally used in a factory, with some of them being able to lift very heavy loads. The hoist is set on a trolley which will move in one direction along one or two beams, which move at angles to that direction along elevated or ground level tracks, often mounted along the side of an assembly area.
In the excavation world, cranes are used to move equipment or machinery. Cranes can quickly and easily move machinery into trenches or down steep hills, or even pipe. There are many types of cranes available, serving everything from excavation to road work.
Cranes are also beneficial to building bridges or construction. For many years, cranes have proven to be an asset to the industry of construction and excavating. Crane operators make really good money, no matter what type of crane they are operating.
COMPACT EXCAVATOR:
The compact hydraulic excavator can be a tracked or wheeled vehicle with an approximate operating weight of 13,300 pounds.Normally, it includes a standard backfill blade and features an independent boom swing. The compact hydraulic excavator is also known as a mini excavator.
A compact hydraulic excavator is different from other types of heavy machinery in the sense that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid.The work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders.The rotation and travel functions are also activated by hydraulic fluid powering hydraulic motors.
Most types of compact hydraulic excavators have three assemblies - house, undercarriage, and the work group
House
The house structure contains the compartment for the operator, engine compartment, hydraulic pump and also the distribution components. The house structure is attached to the top of the undercarriage via swing bearing. Along with the work group, them house is able to rotate upon the undercarriage without limit due to a hydraulic distribution valve that supplies oil to the undercarriage components.
Undercarriage
The undercarriage of compact excavators consists of rubber or steel tracks, drive sprockets, rollers,idlers, and associated components and structures.The undercarriage is also home to the house structure and the work group.
Work group
The work group consists of the boom, dipper or arm, and attachment. It is connected to the front of the house structure via a swinging frame that allows the work group to be hydraulically pivoted left or right in order to achieve offset digging for trenching parallel with the tracks.
Independent boom swing
The purpose of the boom swing is for offset digging around obstacles or along foundations,
walls, and forms. Another use is for cycling in areas that are too narrow for cab rotation. Another major advantage of the compact excavator is the independent boom swing.
Backfill blade
The backfill blade on compact excavators are used for grading, leveling, backfilling, trenching, and general dozer work. The blade can also be used to increase the dumping height and digging depth depending on it’s position in relation to the workgroup.
The most common place you’ll find compact excavators is in residential dwellings. When digging phone lines or other things, these pieces of equipment are very common for getting between houses. Due to their small size, they can fit almost anywhere.Over the years, the capabilities for compact excavators have expanded far beyond the tasks of excavation. With hydraulic powered attachments such as breakers, clamps, compactors and augers, the compact excavator is used with many other applications and serves as an effective attachment tool as well. Serving many purposes, the compact excavator is a great addition to any job that requires the use of machinery.
BULLDOZER:
The bulldozer is a very powerful crawler that is equipped with a blade. The term bulldozer is often used to mean any type of heavy machinery, although the term actually refers to a tractor that is fitted with a dozer blade. Often times, bulldozers are large and extremely powerful tracked vehicles. The tracks give them amazing ground mobility and hold through very rough terrain. Wide tracks on the other hand, help to distribute the weight of the dozer over large areas, therefore preventing it from sinking into sandy or muddy ground.
Bulldozers have great ground hold and a torque divider that’s designed to convert the power of the engine into dragging ability, which allows it to use its own weight to push heavy objects and even remove things from the ground. Take the Caterpillar D9 for example, it can easily tow tanks that weight more than 70 tons. Due to these attributes,bulldozers are used to clear obstacles, shrubbery and remains of structures and buildings.
The blade on a bulldozer is the heavy piece of metal plate that is installed on the front. The
blade pushes things around. Normally, the blade comes in 3 varieties:
1. A straight blade that is short and has no lateral curve, no side wings, and can be used
only for fine grading.
2. A universal blade, or U blade, which is tall and very curved, and features large side wings to carry more material around.
3. A combination blade that is shorter,offers less curvature, and smaller side wings.
Modifications
Over time, bulldozers have been modified to evolve into new machines that are capable of things the original bulldozers weren’t. A good example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which will raise and lower the bucket, therefore making it useful for scooping up the earth and loading it into trucks.Other modifications to the original bulldozer include making it smaller to where it can operate in small working areas where movement is very limited, such as mining caves and tunnels. Very small bulldozers are known as calfdozers.
History
The first types of bulldozers were adapted from farm tractors that were used to plough fields. In order to dig canals, raise earth dams, and partake in earthmoving jobs, the tractors were equipped with a thick metal plate in the front. Later on, this thick metal plate earned the name blade.
The blade of the bulldozer peels layers of soil and pushes it forward as the tractor advances.The blade is the heart and soul of the bulldozer, as it was the first accessory to make full use for excavation type jobs. As the years went by, when engineers needed equipment to complete larger jobs, companies such as CAT, Komatsu, John Deere, Case, and JCB started to manufacture large tracked earthmoving equipment.They were very loud, very large, and very powerful and therefore earned the nickname “bulldozer”.Over the years, the bulldozers got bigger, more powerful, and even more sophisticated. The important improvements include better engines,more reliable drive trains, better tracks, and even hydraulic arms that will enable more precise manipulation of the blade and automated controls.As an added option, bulldozers can come equipped with a rear ripping claw to break up pavement or loosen rocky soil.The best known manufacturer of bulldozer is CAT,which has earned a vast reputation for making
tough and durable, yet reliable machines.Even though the bulldozer started off a modified farmtractor, it rapidly became one of the most useful pieces of equipment with excavating and construction.
BACKHOE LOADER
Also referred to as a loader backhoe, the backhoe loader is an engineering and excavation vehicle that consists of a tractor, front shovel and bucket and a small backhoe in the rear end. Due to the small size and versatility, backhoe loaders are common with small construction projects and excavation type work.Originally invented in Burlington Iowa back in 1857, the backhoe loader is the most common variation of the classic farm tractor.As the name implies, it has a loader assembly on the front and a backhoe attachment on the back.
Anytime the loader and backhoe are attached it is never referred to as a tractor, as it is not normally used for towing and doesn’t normally have a PTO.When the backhoe is permanently attached, the machine will normally have a seat that can swivel to the rear to face the backhoe controls.Any type of removable backhoe attachments will normally have a seperate seat on the attachment itself.Backhoe loaders are common and can be used for many tasks, which include construction, light transportation of materials, powering building equipment, digging holes and excavating, breaking asphalt, and even paving roads.You can often replace the backhoe bucket with other tools such as a breaker for breaking and smashing concrete and rock. There are some loader buckets that offer a retractable bottom, which enable it to empty the load more quickly and efficiently.
The retractable bottom loader buckets are often times used for grading and scratching off sand.The front assembly on a backhoe may be either removable or permanently attached. Often times,the bucket can be replaced with other tools or devices. In order to mount different attachments to the loader, it must be equipped with a tool coupler. The coupler consists of two hydraulic cylinders on the end of the arm assembly, which can expand and retract to allow different tools to be attached to the unit. There are several types of backhoe loader brands,including New Holland, John Deere, and Case. Some will offer you cabs, while others won’t. The newer types of backhoe loaders even offer you air conditioning, radios, and other accessories that make you feel like you are working with luxury.Common with excavating jobs, the backhoe can serve many purposes. It can haul equipment and supplies in the loader bucket.Another great use is to cover up dirt when filling in trench lines or covering up pipe that was just put in the ground.The backhoe attachment at the rear is ideal for digging water pipes and sewer pipes.The best thing about the backhoe loader is the fact that they are easy to operate. You don’t need to be a rocket scientist to fully operate this nifty piece of equipment.
Dump trucks or production trucks are those that are used for transporting loose material such as sand, dirt, and gravel for construction. The typical dump truck is equipped with a hydraulically operated open box bed hinged at the rear, with the front being able to be lifted up to allow the contents to fall out on the ground at the site of delivery.Dump trucks come in many different configurations with each one specified to accomplish a specific task in the construction chain.
Standard dump truck
The standard dump truck is a full truck chassis with the dump body mounted onto the frame. The dump body is raised by a hydraulic ram lift that is mounted forward of the front bulkhead, normally between the truck cab and the dump body. The standard dump truck also has one front axle, and one or more rear axles which normally has dual wheels on each side. The common configurations for standard dump trucks include the six wheeler and ten wheeler.
Transfer dump truck
For the amount of noise made when transferring, the transfer dump truck is easy to recognize. It’s a standard dump truck that pulls a separate trailer which can be loaded with sand, asphalt, gravel, dirt, etc. The B box or aggregate container on the trailer is
powered by an electric motor and rides on wheels and rolls off of the trailer and into the main dump box. The biggest advantage with this configuration is to maximize payload capacity without having to sacrifice the maneuverability of the short and nimble dump truck standards.
Semi trailer end dump truck
The semi end dump truck is a tractor trailer combination where the trailer itself contains the hydraulic hoist. The average semi end dump truck has a 3 axle tractor that pulls a 2 axle semi trailer. The advantage to having a semi end dump truck is rapid unloading.
Semi trailer bottom dump truck
A bottom dump truck is a 3 axle tractor that pulls a 2 axle trailer with a clam shell type dump gate in the belly of the trailer. The biggest advantage of a semi bottom dump truck is the ability to lay material in a wind row. This type of truck is also maneuverable in reverse as well, unlike the double and triple trailer configurations.
Double and triple trailer
The double and triple bottom dump trucks consist of a 2 axle tractor pulling a semi axle semi trailer and an additional trailer. These types of dump trucks allow the driver to lay material in wind rows without having to leave the cab or stop the truck. The biggest disadvantage is the difficulty in going in reverse.
Side dump trucks
Side dump trucks consist of a 3 axle trailer pulling a 2 axle semi trailer. It offers hydraulic rams that tilt the dump body onto the side, which spills the material to the left or right side of the trailer. The biggest advantages with these types of dump trucks are that they allow rapid unloading and carry more weight than other dump trucks.
In addition to this, side dump trucks are almost impossible to tip over while dumping, unlike the semi end dump trucks which are very prone to being upset or tipped over. The length of these trucks impede maneuverability and limit versatility.
Off road dump trucks
Off road trucks resemble heavy construction equipment more than they do highway dump trucks. They are used strictly for off road mining and heavy dirt hauling jobs, such as excavation work. They are very big in size, and perfect for those time when you need to dig out roads and need something to haul the massive amounts of dirt to another location.
FRONT LOADER
Also known as a front end loader, bucket loader, scoop loader, or shovel, the front loader is a type of tractor that is normally wheeled and uses a wide square tilting bucket on the end of movable arms to lift and move material around.The loader assembly may be a removable attachment or permanently mounted on the vehicle. Often times, the bucket can be replaced with other devices or tools, such as forks or a hydraulically operated bucket.
Larger style front loaders, such as the Caterpillar 950G or the Volvo L120E, normally have only a front bucket and are known as front loaders, where the small front loaders are often times equipped with a small backhoe as well and called backhoe loaders or loader backhoes.Loaders are primarily used for loading materials into trucks, laying pipe, clearing rubble, and also digging. Loaders aren’t the most efficient machines for digging, as they can’t dig very deep below the level of their wheels, like the backhoe can.
The deep bucket on the front loader can normally store around 3 - 6 cubic meters of dirt, as the bucket capacity of the loader is much bigger than the bucket capacity of a backhoe loader. Loaders aren’t classified as excavating machinery, as their primary purpose is other than moving dirt.In construction areas, mainly when fixing roads in the middle of the city, front loaders are used to transport building materials such as pipe, bricks, metal bars, and digging tools. Front loaders are also very useful for snow removal as well, as you can use their bucket or as a snow plow. They can clear snow from the streets and highways, even parking lots.They will sometimes load the snow into dump trucks which will then haul it away.
Unlike the bulldozer, most loaders are wheeled and not tracked. The wheels will provide better mobility and speed and won’t damage paved roads near as much as tracks, although this will come at the cost of reduced traction. Unlike backhoes or tractors fitted with a steel bucket, large loaders don’t use automotive steering mechanisms, as they instead steer by a hydraulically actuated pivot point set exactly between the front and rear axles.This is known as articulated steering and will allow the front axle to be solid, therefore allowing it to carry a heavier weight.
Articulated steering will also give a reduced turn in radius for a given wheelbase. With the
front wheels and attachment rotating on the same axis, the operator is able to steer his load in an arc after positioning the machine, which can come in quite handy. The problem is that when the machine is twisted to one side and a heavy load is lifted high in the air, it has a bigger risk of turning over.
FORKLIFT
Sometimes called a forklift truck, the forklift is a powerful industrial truck that is used to lift and transport material by steel forks that are inserted under the load. Forklifts are commonly used to move loads and equipment that is stored on pallets. The forklift was developed in 1920, and has since become a valuable piece of equipment in many manufacturing and warehousing operations.
Types of Forklifts
The most common type of design with forklifts is the counter balance. Other types of designs include the reach truck and side loader, both of which are used in environments where the space is at a minimum.
Control and capability
Forklifts are available in many types and different load capacities. In the average warehouse setting,most forklifts have load capacities of around five tons. Along with the control to raise and lower the forks, you can also tilt the mast to compensate for the tendency of the load to angle the blades towards the ground and risk slipping it off the forks. The tilt will also provide a limited ability to operate on ground that isn’t level.There are some variations that allow you to move the forks and backrest laterally, which allows easier placement of a load. In addition to this, there are some machines that offer hydraulic control to move the forks together or further apart, which removes the need for you to get out of the cab to manually adjust for a different size load.
Another forklift variation that is sometimes used in manufacturing facilities, will utilize forklifts with a clamp attachment that you can open and close around a load, instead of having to use forks. Products such as boxes, cartons, etc., can be moved with the clamp attachment.
Safety
Forklifts are rated for loads at a specified maximum weight and a specified forward type center of gravity. All of this information is located on a nameplate that is provided by the manufacturer and the loads cannot exceed these specifications. One of the most important aspects of operating a forklift is the rear wheel steering. Even though this helps to increase maneuverability in tight cornering situations, it differs from the traditional experience of a driver with other wheeled vehicles as there is no caster action. Another critical aspect of the forklift is the instability. Both the forklift and the load must be considered a unit, with a varying center of gravity with every movement of the load.You must never negotiate a turn with a forklift at full speed with a raised load, as this can easily tip the forklift over.
VARIOUS TYPES OF CRANES:
A crane is a tower or derrick that is equipped with cables and pulleys that are used to lift and lower material. They are commonly used in the construction industry and in the manufacturing of heavy equipment. Cranes for construction are normally temporary
structures, either fixed to the ground or mounted on a purpose built vehicle.
They can either be controlled from an operator in a cab that travels along with the crane, by a push button pendant control station, or by radio type controls. The crane operator is ultimately responsible for the safety of the crews and the crane.
Mobile Cranes
The most basic type of crane consists of a steel truss or telescopic boom mounted on a mobile platform, which could be a rail, wheeled, or even on a cat truck. The boom is hinged at the bottom and can be either raised or lowered by cables or hydraulic cylinders.
Telescopic Crane
This type of crane offers a boom that consists of a number of tubes fitted one inside of the other. A hydraulic mechanism extends or retracts the tubes to increase or decrease the length of the boom.
Tower Crane
The tower crane is a modern form of a balance crane. When fixed to the ground, tower cranes will often give the best combination of height and lifting capacity and are also used when constructing tall buildings.
Truck Mounted Crane
Cranes mounted on a rubber tire truck will provide great mobility. Outriggers that extend vertically or horizontally are used to level and stabilize the crane during hoisting.
Rough Terrain Crane
A crane that is mounted on an undercarriage with four rubber tires, designed for operations off road. The outriggers extend vertically and horizontally to level and stabilize the crane when hoisting. These types of cranes are single engine machines where the same engine is used for powering the undercarriage as it is for powering the crane. In these types of cranes, the engine is normally mounted in the undercarriage rather than
in the upper portion.
Loader Crane
A loader crane is a hydraulically powered articulated arm fitted to a trailer, used to load equipment onto a trailer. The numerous sections can be folded into a small space when the crane isn’t in use.
Overhead Crane
Also refered to as a suspended crane, this type is normally used in a factory, with some of them being able to lift very heavy loads. The hoist is set on a trolley which will move in one direction along one or two beams, which move at angles to that direction along elevated or ground level tracks, often mounted along the side of an assembly area.
In the excavation world, cranes are used to move equipment or machinery. Cranes can quickly and easily move machinery into trenches or down steep hills, or even pipe. There are many types of cranes available, serving everything from excavation to road work.
Cranes are also beneficial to building bridges or construction. For many years, cranes have proven to be an asset to the industry of construction and excavating. Crane operators make really good money, no matter what type of crane they are operating.
COMPACT EXCAVATOR:
The compact hydraulic excavator can be a tracked or wheeled vehicle with an approximate operating weight of 13,300 pounds.Normally, it includes a standard backfill blade and features an independent boom swing. The compact hydraulic excavator is also known as a mini excavator.
A compact hydraulic excavator is different from other types of heavy machinery in the sense that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid.The work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders.The rotation and travel functions are also activated by hydraulic fluid powering hydraulic motors.
Most types of compact hydraulic excavators have three assemblies - house, undercarriage, and the work group
House
The house structure contains the compartment for the operator, engine compartment, hydraulic pump and also the distribution components. The house structure is attached to the top of the undercarriage via swing bearing. Along with the work group, them house is able to rotate upon the undercarriage without limit due to a hydraulic distribution valve that supplies oil to the undercarriage components.
Undercarriage
The undercarriage of compact excavators consists of rubber or steel tracks, drive sprockets, rollers,idlers, and associated components and structures.The undercarriage is also home to the house structure and the work group.
Work group
The work group consists of the boom, dipper or arm, and attachment. It is connected to the front of the house structure via a swinging frame that allows the work group to be hydraulically pivoted left or right in order to achieve offset digging for trenching parallel with the tracks.
Independent boom swing
The purpose of the boom swing is for offset digging around obstacles or along foundations,
walls, and forms. Another use is for cycling in areas that are too narrow for cab rotation. Another major advantage of the compact excavator is the independent boom swing.
Backfill blade
The backfill blade on compact excavators are used for grading, leveling, backfilling, trenching, and general dozer work. The blade can also be used to increase the dumping height and digging depth depending on it’s position in relation to the workgroup.
The most common place you’ll find compact excavators is in residential dwellings. When digging phone lines or other things, these pieces of equipment are very common for getting between houses. Due to their small size, they can fit almost anywhere.Over the years, the capabilities for compact excavators have expanded far beyond the tasks of excavation. With hydraulic powered attachments such as breakers, clamps, compactors and augers, the compact excavator is used with many other applications and serves as an effective attachment tool as well. Serving many purposes, the compact excavator is a great addition to any job that requires the use of machinery.
BULLDOZER:
The bulldozer is a very powerful crawler that is equipped with a blade. The term bulldozer is often used to mean any type of heavy machinery, although the term actually refers to a tractor that is fitted with a dozer blade. Often times, bulldozers are large and extremely powerful tracked vehicles. The tracks give them amazing ground mobility and hold through very rough terrain. Wide tracks on the other hand, help to distribute the weight of the dozer over large areas, therefore preventing it from sinking into sandy or muddy ground.
Bulldozers have great ground hold and a torque divider that’s designed to convert the power of the engine into dragging ability, which allows it to use its own weight to push heavy objects and even remove things from the ground. Take the Caterpillar D9 for example, it can easily tow tanks that weight more than 70 tons. Due to these attributes,bulldozers are used to clear obstacles, shrubbery and remains of structures and buildings.
The blade on a bulldozer is the heavy piece of metal plate that is installed on the front. The
blade pushes things around. Normally, the blade comes in 3 varieties:
1. A straight blade that is short and has no lateral curve, no side wings, and can be used
only for fine grading.
2. A universal blade, or U blade, which is tall and very curved, and features large side wings to carry more material around.
3. A combination blade that is shorter,offers less curvature, and smaller side wings.
Modifications
Over time, bulldozers have been modified to evolve into new machines that are capable of things the original bulldozers weren’t. A good example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which will raise and lower the bucket, therefore making it useful for scooping up the earth and loading it into trucks.Other modifications to the original bulldozer include making it smaller to where it can operate in small working areas where movement is very limited, such as mining caves and tunnels. Very small bulldozers are known as calfdozers.
History
The first types of bulldozers were adapted from farm tractors that were used to plough fields. In order to dig canals, raise earth dams, and partake in earthmoving jobs, the tractors were equipped with a thick metal plate in the front. Later on, this thick metal plate earned the name blade.
The blade of the bulldozer peels layers of soil and pushes it forward as the tractor advances.The blade is the heart and soul of the bulldozer, as it was the first accessory to make full use for excavation type jobs. As the years went by, when engineers needed equipment to complete larger jobs, companies such as CAT, Komatsu, John Deere, Case, and JCB started to manufacture large tracked earthmoving equipment.They were very loud, very large, and very powerful and therefore earned the nickname “bulldozer”.Over the years, the bulldozers got bigger, more powerful, and even more sophisticated. The important improvements include better engines,more reliable drive trains, better tracks, and even hydraulic arms that will enable more precise manipulation of the blade and automated controls.As an added option, bulldozers can come equipped with a rear ripping claw to break up pavement or loosen rocky soil.The best known manufacturer of bulldozer is CAT,which has earned a vast reputation for making
tough and durable, yet reliable machines.Even though the bulldozer started off a modified farmtractor, it rapidly became one of the most useful pieces of equipment with excavating and construction.
BACKHOE LOADER
Also referred to as a loader backhoe, the backhoe loader is an engineering and excavation vehicle that consists of a tractor, front shovel and bucket and a small backhoe in the rear end. Due to the small size and versatility, backhoe loaders are common with small construction projects and excavation type work.Originally invented in Burlington Iowa back in 1857, the backhoe loader is the most common variation of the classic farm tractor.As the name implies, it has a loader assembly on the front and a backhoe attachment on the back.
Anytime the loader and backhoe are attached it is never referred to as a tractor, as it is not normally used for towing and doesn’t normally have a PTO.When the backhoe is permanently attached, the machine will normally have a seat that can swivel to the rear to face the backhoe controls.Any type of removable backhoe attachments will normally have a seperate seat on the attachment itself.Backhoe loaders are common and can be used for many tasks, which include construction, light transportation of materials, powering building equipment, digging holes and excavating, breaking asphalt, and even paving roads.You can often replace the backhoe bucket with other tools such as a breaker for breaking and smashing concrete and rock. There are some loader buckets that offer a retractable bottom, which enable it to empty the load more quickly and efficiently.
The retractable bottom loader buckets are often times used for grading and scratching off sand.The front assembly on a backhoe may be either removable or permanently attached. Often times,the bucket can be replaced with other tools or devices. In order to mount different attachments to the loader, it must be equipped with a tool coupler. The coupler consists of two hydraulic cylinders on the end of the arm assembly, which can expand and retract to allow different tools to be attached to the unit. There are several types of backhoe loader brands,including New Holland, John Deere, and Case. Some will offer you cabs, while others won’t. The newer types of backhoe loaders even offer you air conditioning, radios, and other accessories that make you feel like you are working with luxury.Common with excavating jobs, the backhoe can serve many purposes. It can haul equipment and supplies in the loader bucket.Another great use is to cover up dirt when filling in trench lines or covering up pipe that was just put in the ground.The backhoe attachment at the rear is ideal for digging water pipes and sewer pipes.The best thing about the backhoe loader is the fact that they are easy to operate. You don’t need to be a rocket scientist to fully operate this nifty piece of equipment.
Monday, June 22, 2009
CIRCULAR CURVES
Circular curves are the most common type of horizontal curve used to connect intersecting tangent (or straight) sections of highways or railroads. In most countries, two methods of defining circular curves are in use: the first, in general use in railroad work, defines the degree of curve as the central angle subtended by a chord of 100 ft (30.48 m) in length; the second, used in highway work, defines the degree of curve as the central angle subtended by an arc of 100 ft (30.48 m) in length.
The terms and symbols generally used in reference to circular curves are listed next and shown in Figs. 11.1 and 11.2.
PC = point of curvature, beginning of curve
PI = point of intersection of tangents
PT = point of tangency, end of curve
R = radius of curve, ft (m)
D = degree of curve (see previous text)
I = deflection angle between tangents at PI, also
central angle of curve
T = tangent distance, distance from PI to PC or PT,
ft (m)
L = length of curve from PC to PT measured on 100-ft
(30.48-m) chord for chord definition, on arc for
arc definition, ft (m)
C = length of long chord from PC to PT, ft (m)
E = external distance, distance from PI to midpoint
of curve, ft (m)
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