2.1. Grade Resistance and Assistance

Try these first

1. 1.

   Calculate the rolling resistance for a machine weighing 30 tons with a rolling resistance of 25 kg per ton.

   Hint

   Use the formula: Total Rolling Resistance = Gross Weight × Rolling Resistance Value.

2. 2.

   What is grade resistance for a slope of 3% for a machine weighing 10 tons?

   Hint

   Remember, 1% of grade equals 10 kg per ton.

3. 3.

   What is the formula to calculate total rolling resistance?

   • Total Rolling Resistance = Weight × Resistance Value
   • Total Rolling Resistance = Weight + Resistance Value
   • Total Rolling Resistance = Weight - Resistance Value

   Hint

   Identify which operation reflects the relationship between weight and resistance.

4. 4.

   True or False: Grade assistance increases the tractive effort required.

   • True
   • False

   Hint

   Consider the effects of gravity on moving machines.

5. 5.

   A construction site requires a bulldozer that weighs 40 tons with a rolling resistance of 50 kg per ton. It needs to operate on a slope of 8%. Calculate the total resistance and how much power will be available if the maximum tractive effort is 6000 kg.

   Hint

   Follow the steps for calculating rolling and grade resistance and subtract from total power.

6. 6.

   Evaluate how operating at a high altitude affects the usable power of a machine with otherwise specified ratings. What considerations should be made when specifying equipment for such conditions?

   Hint

   Reflect on how altitude could influence machine efficiency.