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Double Square-Thread Power Screw Axial Linear Lifting Force Equations and Calculator

Machine Design Solutions
Engineering Applications and Analysis

Double Square-Thread Power Screw Axial Linear Lifting Force Equations and Calculator

In general, when the screw is loaded axially, a thrust bearing or thrust collar may be used between the rotating and stationary links to carry the axial component.

Preview: Double Square-Thread Power Screw Axial Linear Lifting Force Calculator

Minor Diameter:
d_r = d - p

Pitch (mean) diameter
d_m = d - p/2

Lead
l = 2p

Torque required to rasie load up:

Torque required to lower load:

Overall efficiency:

Where:

d = Major diameter (in, mm),
d_r = Minor Diameter (in, mm),
d_m = Pitch (mean) diameter (in, mm),
l = lead (in, mm),
p = Pitch Diameter (in, mm),
µ - Coefficient of friction,
µ_c = Coefficient of collar friction,
d_c = Mean collar diameter (in, mm),
F = External load on screw (lbsf, N)
T_r = Torque required to lower load (in-lbs, N-mm),
T_l = Torque required to lower load
e = Oveall efficiency

Reference:

Mechanical Engineering Handbook,
Edited by: Ban B. Manrghitu
Department of Mechanical Engineering, Auburn University,
Auburn, Alabama
2001