Question

Clutch of a tractor is designed on the basis of

• A. Constant torque
• B. Constant pressure
• C. Constant power
• D. Constant speed

Hint:

New clutch design basis $\implies$ Constant/Uniform Pressure ($p = \text{constant}$).
Worn clutch operating basis $\implies$ Uniform Wear ($p \cdot r = \text{constant}$).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Friction clutch torque capacity is evaluated using two fundamental mechanical theories: Uniform/Constant Pressure Theory (for new clutches) and Uniform/Constant Wear Theory (for old/worn clutches).
Key Formula or Approach:
\[ T = \frac{2}{3} \mu W \left( \frac{r_1^3 - r_2^3}{r_1^2 - r_2^2} \right) \quad \text{(Uniform Pressure Theory)} \]

Step 2: Detailed Explanation:
When designing a brand-new tractor clutch with newly machined, perfectly flat friction lining surfaces, the spring clamping force is distributed uniformly over the entire contact area.
Therefore, the initial design calculations for new tractor clutches are conducted on the basis of Constant Uniform Pressure Theory.
(After running in, wear is assumed uniform, where \(p \cdot r = \text{constant}\)).

Step 3: Final Answer:
Hence, the clutch of a tractor is designed on the basis of Constant pressure, matching option (B).