Question

Which of the following is an indicator of efficiency with which the traction device transforms the torque acting on axle into linear drawbar pull ?

• A. Net traction coefficient
• B. Tractive efficiency
• C. Motion resistance ratio
• D. Traction force

Hint:

Any metric assessing output power (drawbar) compared to input power (axle) is a measure of thermodynamic or mechanical efficiency.
Hence, "Tractive efficiency" is the direct power efficiency parameter.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The conversion of rotational power at the tractor axle into linear draft power at the drawbar involves losses due to wheel slip, soil compaction, and motion resistance.

Step 3: Detailed Explanation:
Let us examine the traction parameters:
1.

Net traction coefficient: The ratio of pull to the dynamic vertical load on the traction device.
2.

Tractive efficiency: Defined as the ratio of drawbar power to the axle power:
\[ \eta_{\text{tractive}} = \frac{P_{\text{drawbar}}}{P_{\text{axle}}} = \frac{\text{Drawbar Pull} \times \text{Travel Speed}}{\text{Axle Torque} \times \text{Axle Angular Velocity}} \] Thus, tractive efficiency is the direct indicator of how effectively torque is transformed into linear drawbar pull.
3.

Motion resistance ratio: The ratio of soil resistance opposing motion to the vertical load.
4.

Traction force: The gross pull developed at the wheel-soil interface.

Step 4: Final Answer:
The correct option is 2, which corresponds to Tractive efficiency.