Subtopic: Overload safety devices used in farm machinery
Question Statement:
A multi-plate friction slip clutch in a round baler driveline has 3 driving plates and 2 driven plates, providing $n = 4$ active pairs of contacting friction surfaces. The outer and inner radii of the friction linings are $r_1 = 120\text{ mm}$ and $r_2 = 80\text{ mm}$, respectively. The coefficient of friction is $\mu = 0.35$. If the total axial clamping force exerted by the compression springs is $W = 3500\text{ N}$, assuming uniform wear theory, the torque capacity of the clutch in $\text{N}\cdot\text{m}$ is ________ (round off to 1 decimal place).
Answer Key:
490.0
Step-by-Step Solution & Explanation
1. Mean radius under uniform wear theory ($R_m$):
$R_m = \frac{r_1 + r_2}{2} = \frac{120 + 80}{2} = 100\text{ mm} = 0.10\text{ m}$
2. Frictional torque capacity for $n = 4$ active friction surfaces:
$T = n \cdot \mu \cdot W \cdot R_m$
$T = 4 \times 0.35 \times 3500\text{ N} \times 0.10\text{ m} = 490.0\text{ N}\cdot\text{m}$