When a vehicle moves down a grade, the force of gravity that assists vehicle movement is also called grade assistance.

An advantage of a crawler dozer as compared with a wheel-type dozer is higher speed.

Using Fig. 17.13, select the minimum-length boom required to hoist a load of 80,000 lb from a truck at ground level and place it on a platform 76 ft above the ground. The minimum allowable vertical distance from the bottom of the load to the boom point of the crane is 42 ft. The maximum horizontal distance from the center of rotation of the crane to the hoist line of the crane when lifting the load is 40 ft.

Which of the following equipment is a clamshell that is especially suited for lifting material vertically?

A fully loaded wheeled scraper (Model #: 615C) must travel down a 3% slope on an unmaintained hard road (tire penetration is 5 inches and the coefficient of traction is estimated to be 0.45), and then return to the same location. Only the front tires of this scraper are powered, and you can obtain the following information from the manufacturer’s data. Empty vehicle weight: 97,000 lbFully loaded vehicle weight: 172,000 lbWhen empty, 37% of the weight on the rear tires, 63% on the front tiresWhen fully loaded, 50% of the weight on the rear tires, 50% on the front tiresPlease estimate what is the total resistance force when traveling down the slope with full load?

A contractor plans to excavate 4,000 bank cubic yards from a site. He needs to have 1,000 compacted cubic yards for the backfill of excavations. The soil test shows that the soil has a bank density of 2,500 pounds per cubic yard, a loose density of 2,000 pounds per cubic yard, and a compacted density of 3,000 pounds per cubic yard. He plans to use a truck that can haul 25 loose cubic yard per load. How many full truckloads of loose excess material should be hauled off the site?

Continue with the previous question, what is the total effective grade when returning?

A contractor wants to investigate the production and cost differences of using a 4S blade on a crawler-type dozer (D4H-4S). The material is dry clay and is to be moved a distance of 150 ft from the beginning of the cut. The dozing is uphill on a 20% grade. The operator will have average skill. The site conditions will be dark for visibility. The material weighs 108 pcf in the bank state. Job efficiency is assumed to be equivalent to a 50-min hour. What is the grade correction factor? Please choose a range from the following where your reading will be within.

The decision process for matching the best possible machine to the project task requires the engineer to take into account both the properties of the material to be handled and the mechanical capabilities of the machine.

A contractor wants to investigate the production and cost differences of using a 4S blade on a crawler-type dozer (D4H-4S). The material is dry clay and is to be moved a distance of 150 ft from the beginning of the cut. The dozing is uphill on a 20% grade. The operator will have average skill. The site conditions will be dark for visibility. The material weighs 108 pcf in the bank state. Job efficiency is assumed to be equivalent to a 50-min hour. What is the work efficiency correction factor?