Reference no: EM133257433
Assignment - CONSTRUCTION SITEWORK & EQUIPMENT Questions
Q1. In your project, you have decided to use dump trucks to excavate and haul the fill material. The empty weight of a truck is 38 tons. The distance between the borrow and the construction sites is 4 miles, and the road has an average uphill grade of 2.5% when travelling from the borrow site to the construction site. When fully loaded, the truck can carry 20 tons of fill material (LCY). You have investigated that the average tire penetration when the truck is loaded is 1.5 inches.
a. What is the grade resistance force against a fully loaded truck?
b. What is the rolling resistance force against a fully loaded truck?
c. What is the effective grade (%) against a fully loaded truck?
d. What is the total resistance force against the truck when returning from the construction site to the borrow site?
Q2. You decided to use a loader and 15-cubic-yard dump trucks (manufacturer's performance data is shown in the Table 1) to haul the material from the borrow to the construction sites. The trucks are powered with 185-horsepower, four cycle naturally respirated engines, and the gear train efficiency is estimated to be 0.8. The road has an average uphill grade of 2.5% when travelling from the borrow site to the construction site. The project site is at the elevation of 2,000 feet. The gross weight of the fully loaded truck is 35 tons and 60% of the loaded weight is carried by the rear driving wheels. Tire penetration is estimated to be 1.5 inches and the coefficient of traction is estimated to be 0.6. The trucks are not equipped with radial tires.
a. What is the maximum speed of a fully loaded truck traveling from the borrow site to the construction site?
b. What would be the answer for part a, if you use the trucks with turbocharged diesel engines?
Table 1. Manufacturer's performance data
Gear
|
Speed
|
1
|
3
|
2
|
9
|
3
|
14
|
4
|
21
|