Calculation of a Motor’s Max. Torque

Maximum torque is calculated by motor’s rotational speed(rpm), output power and reduction ratio etc. The safety factor (in the below table) has to be considered by all means in case motor’s torque information is not available.

Load Conditions		Safety Factor (SF)
Low Inertia	At 60% (or less) of motor’s rated torque	1.5~2.0
Medium Inertia	Longer acceleration/deceleration time, limited reverse motion and small impact	2.0~3.0
High Inertia	Shorter acceleration/deceleration time, frequent reverse motion and large impact	3.0~5.0

Thrust Load

P (Max. Thrust Load) < Pt (Max. Permissible Thrust Load of A.P. Lock)

The thrust load on A.P. Lock’s fastening area must be lower than max. permissible thrust load of A.P. Lock.

Combined Torque and Thrust Load

If torque and thrust load occur simultaneously, please refer to the below formula for load calculation.

Permissible Torque Variation

1. Permissible Torque Increase
   When several A.P. Locks are used together, permissible torque and thrust load gets increased.
   ※ Make sure all foreign substances must be removed from surface of the both shaft and inner part of A.P. Lock.
2. Permissible Torque Decrease
   When the shaft has an additional keyway, permissible torque would be decreased by appx. 20% due to reduced contact area.

Shaft Design Guide

1. Please refer to each overview pages for shaft tolerance.
2. Check the strength of shaft’s raw material.
   ${\sigma }_s>1.2\times P_i$

   • σ_s : Yield stress of shaft’s raw material [Mpa]
   • P_i : Surface pressure onto shaft by A.P. Lock [Mpa]
3. Determine max. inner diameter of hollow shaft.
   High surface pressure is delivered on the shaft. Thus, make sure the below formula is referred when the hollow shaft is designed.
   $d_i\le d\times \sqrt{\frac{{\sigma }_s-2\times 0.8\times P_i}{{\sigma }_s}}$

   • d_i : Inner dia. of hollow shaft
   • d : Outer dia. of hollow shaft
   • σ_s : Yield stress of shaft’s raw material [Mpa]
   • P_i : Surface Pressure onto Shaft by A.P. Lock [Mpa]

Hub Design Guide

1. Please refer to each overview pages for hub tolerance.
2. Check the strength of hub’s raw material.
   ${\sigma }_h>1.2\times P_o$

   • σ_h : Yield stress of hub’s raw material [Mpa]
   • P_o : Surface pressure onto hub by A.P. Lock [Mpa]
3. Check the min. hub outer diameter.
   You may refer to the below formula in case the material information is not available.
   $D_O\ge D_i\times \sqrt{\frac{{\sigma }_h+0.8\times P_O}{{\sigma }_h-0.8\times P_O}}$

   • D_o : Outer dia. of hub [mm]
   • D_i : Inner dia. of hub [mm]
   • σ_h : Yield stress of hub’s raw material [Mpa]
   • P_o : Surface pressure onto hub by A.P. Lock [Mpa]