Graders

Mansoor Azam Qureshi NUST

Islamabad

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Grader

Graders are multipurpose machines used for finishing and shaping. This is a long tractor driven piece of equipment with a blade mounted underneath

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FunctionsGraders are used

for Grading Shaping Bank sloping Ditching

They are also used for MixingSpreadingSide casting Leveling CrowningGeneral constructionRoad and runway

maintenance

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Graders Vs DozersA grader can make a shallow cut in medium

to hard materials where dozer can perform heavy works.

Location and structural strength of grader blade does allow for heavy work.

Graders are capable of progressively cutting ditches upto 3 ft.

Graders can cut slope of 3:1 which can be done by a dozer.

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Graders- EquipmentStd Equipment is Moldboard or Blade.

Mounted on rotating circle. It can be placed into many positions, either

under the grader or to the side or it can be side-shifted horizontally for increased reach outside of the tires.

Aux equipments are:Scarifier is placed between front wheel and

bladeRippers are placed at rear of graderLaser blade control

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Blade OperationCan be angled

(positioned) at almost any angle to the line of‘ travel, parallel to the direction of travel, shifted to either side, or raised into vertical position.

The top of the blade can be pitched (leaned) forward or backward.

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Estimating ProductionNo of Passes(P)Distance traveled in

each pass(D)Efficiency of grader(E)Grader speed(S)Effective blade width(W)

Proper gear ranges for grader operations

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Example Maintenance of 5 miles of haul road requires

cleaning the ditches, and leveling and reshaping the roadway. Use an efficiency factor of 0.60. Cleaning the ditches requires two passes in first gear (2.3 mph); leveling the road requires two passes in second gear (3.7 mph); and final shaping of the road requires three passes in fourth gear (9.7 mph).

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Example A haul road of 1,500 ft requires leveling and

reshaping. Use an efficiency factor of 0.60. The work requires two passes in second gear (3.7 mph) and three passes in third gear (5.9 mph).

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ExampleIt is required to fine grade the subgrade of a roadway

before proceeding to construct the subbase. Use an efficiency factor of 0.60. The grader will be operated in second gear· (3.5 mph) for this work. The effective blade width per pass is 9 ft. Estimate the production rate for these conditions.

Note: Typically, multiple passes are required to meet the specified grade tolerance, which can accordingly reduce production.

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A grader has a large blade used to create a flat surface.

Typical models have three axles, with the

engine and cab situated above the rear axles at one end of the vehicle and a third axle at the front end of the vehicle, with the blade in between.

The grader's purpose is to "finish grade" (refine, set precisely) the "rough grading" performed by heavier vehicles such as bulldozers.

Graders can produce inclined surfaces and cambered cross-sections for roads