A four-wheel tractor weighing 12000 kg is towed up a 2% slope at constant speed. With a grade resistance factor of 10 kg/tonne and a tow cable tension of 720 kg, the rolling resistance of the road is___________________?
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Answer: C. 40 kg/tonne
Explanation
Subtracting grade resistance and cable tension forces from total tractive effort isolates rolling resistance. Dividing the resulting force by the tractor weight in tonnes yields the rolling resistance value. Executing this calculation for the given slope and tow tension produces forty kilograms per tonne. Earthmoving equipment performance depends on balancing tractive effort, grade resistance, and rolling resistance. Grade resistance is the force required to pull a vehicle up an inclined slope against gravity. Rolling resistance accounts for tire flexing and road surface deformation encountered by moving vehicles.
Construction estimators calculate equipment cycle times and hauling productivity using vehicle resistance formulas. Accurate rolling resistance values help determine proper tractor power requirements on site haul roads. Understanding machine performance mechanics optimizes fleet selection for large earthmoving projects. A rolling resistance of twenty kg/tonne underestimates the frictional losses for the specified road conditions. Option B provides thirty kg/tonne, which fails to balance the exact force equilibrium equations. Option D of fifty kg/tonne overestimates the rolling resistance for the given cable tension and slope.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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