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**Torque required to lower load calculator** - step by step calculation, formula & solved example problem to find the torque required during raising the load by using the square thread (power screw) in power transmission. Load in Newton F, mean diameter d_{m}, mean collar diameter d_{c}, square thread pitch distance l, coefficient of friction for thread μ & coefficient of friction for collar &mu_{c} are the key terms of this calculation.

In mechanical engineering, the below mathematical formula is used to calculate the minimum torque required to lower load (T_{L}) for square thread power transmission.

The below step by step solved example problem may helpful for users to understand how the input values are being used in such calculations to calculate the torque required to lower the load or horizontally move against the force using the square threaded screw (power screw) in power transmission.

**Example Problem**

A vice using the square thread having the nominal screw diameter d = 14 mm, pitch width p = l = 3 mm, square thread frictional coefficient μ = 0.35, coefficient of friction for collar &mu_{c} = 0.25, mean diameter d_{m} = 12.5 mm, mean collar diameter d_{c} = 45 mm & the capacity of the vice clamp is 850 Newton. Calculate the torque required to release load of the vice.

**Solution**

The given data

load in Newton F = 850 N

mean diameter d_{m} = 12.5 mm

mean collar diameter d_{c} = 45 mm

square thread pitch distance l = 3 mm

coefficient of friction for thread μ = 0.35

coefficient of friction for collar &mu_{c} = 0.25

__Step by step calculation__

Formula to find T_{R} = {[(F x d_{m})/2] x [(π x μ x d_{m}) - l]/[(π x d_{m}) - (μ x l)] + [(F x μ_{c} x d_{c})/2]}

If only nominal diameter & pitch of power screw given

mean diameter d_{m} = d_{n} - (p/2)

substitute the values in the above formula

= [850 x 12.5/2] x [((π x 0.35 x 12.5) - 3)/((π x 12.5) - (0.35 x 3))]+ [(850 x 0.25 x 45)/2]

= 6.27

T_{L} = 6.27 N-mm

divide it by 1000 to convert it N-mm to N-m

T_{L} = 6.27/1000

**T _{L} = 0.00627 N-m**

In the field of power transmission by using square thread or power screw in