Question

The torque required to drive a 40 mm diameter power screw having double square threads with a pitch of 6 mm is 1.0 kN-m. The friction for the thread is 0.10. Is the condition self-locking? Show your calculation.

Answer 1

Answer:

This is self locking.

Explanation:

Given that

Diameter d= 40 mm

Pitch (P)= 6 mm

Torque T= 1 KN.m

Friction(μ) = 0.1

Thread is double square.

Condition for self locking

$\mu >tan\theta$

$tan\theta=\dfrac{L} {\pi d}$

L= n x P

N= number of start

Here given that double start so n=2

L=2 x 6 = 12 mm

$tan\theta=\dfrac{L} {\pi d}$

$tan\theta=\dfrac{12} {\pi \times 40}$

$tan\theta=0.095$            (μ = 0.1)

$\mu >tan\theta$

So from we can that this is self locking.