Screw Worm Gear Gear Axial Force Equation and Calculator

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This calculator will determine the axial thrust or load applied on a screw (worm gear) thread. Reference: Schaum's Outline Machine Design. Enter desired data within the boxes, calculations should be automatic.

See bottom of webpage for: Calculate, Reset or Print (Screen).

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Applied Torque

T =

Nmm

Major Thread Radius (Major Diameter/2)

ro =

mm

Thread Depth

h =

mm

Minor Thread Radius

ri =

Mean Thread Radius (Pitch Diameter)

rm =

Effective Radial Area Contact Surface (Load Bearing)

rc =

Coefficient of Friction Screw Thread and Mating (Nut) Thread

f =

Coefficient of Friction at Collar

fc =

Thread Pitch (equals thread pitch for single thread screws)

L =

mm

Angle of Thread at Mean Radius

a =

Thread Angle at Bearing Surface (Thread Included Angle)

q =

Angle Between Tangent to Tooth Profile (on the Loaded Side) and a Radial Line

qn =

Thread Constant

Rc =

Load Parallel to Screw Thread Axis

W =

Efficiency of the Screw Thread Mechanism (ratio of work out to work in)

Escrew=

Torque required to advance the nut (if negative then torque needs to be applied to hold nut still)

Tad =