GATE 2024 AG – Question 50
A rotary mower has 1.2 m swath at 5 km/hour. Friction losses are1.5 kW per metre swath and cutting energy2 kJ/m². Tractor plus mower weighs25 kN and propulsion resistance is 6% of weight. Engine-to-drawbar/PTO efficiencies are75%/87%. Find total engine power in kW, to two decimals.
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Correct answer: 8.60 to 8.80
Explanation
Ground speed is 1.388889 m/s. Drawbar power is $.06(25)(1.388889)=2.083333$ kW, requiring2.777778 kW at the engine. Cutting power is $2(1.2)(1.388889)=3.333333$ kW and mower friction is $1.5(1.2)=1.8$ kW. PTO demand5.133333 kW requires $5.133333/.87=5.900383$ engine kW. Total is **8.68 kW**.