Question

A traction wheel having 600 mm diameter was tested in a soil bin and following data was obtained, angular speed=10rpm, input torque to wheel angle=60 Nm, drawbar pull=150 N, normal load on wheel axle=500 N, wheel forward speed=0.25 ms^-1. What will be the tractive efficiency?

(a) 69.96%

(b) 59.67%

(c) 24.48%

(d) 51.49%

I had been asked this question during an internship interview.

This interesting question is from Traction and Traction Theory in division Farm Tractor of Farm Machinery

Answer 1

Right choice is (b) 59.67%

To elaborate: μ = P/R2 = 150/500 = 0.3

Vt = \(\frac{0.6}{2}*\frac{2π*10}{60*10}\) c = 0.3142 ms^-1

Slippage = \(\frac{0.3142-0.25}{0.3142}\)*100 = 20.43%

Tractive efficiency = \(\frac{drawbar \, power}{axle \, power} = \frac{pull*Va}{F*Vt} = \frac{150*0.25}{\frac{60}{0.3}*0.3142}\)  = 59.67%