How It Works - Torque Reaction Theory
+Torque Arm Calculator
Calculate reaction forces at torque arm anchor points and mounting bolt loads for motors and gearboxes.
Torque Input
kW
rpm
N-m (overrides power/speed)
✓
Calculated
Reaction forces determined
Reaction Force Results
Design Torque
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Running Torque
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Reaction Force (per arm)
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Bolt Shear Load (max)
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Bolt Tension (max)
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Enter motor parameters and geometry.
Recommended Bolt Sizes
Min Bolt for Shear
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Based on
Grade 8.8, SF=2
Motor Starting Torque Multipliers
| Motor Type | Starting/Full Load |
|---|---|
| NEMA B (standard) | 1.5 - 2.0x |
| NEMA C (high torque) | 2.0 - 2.5x |
| NEMA D (high slip) | 2.5 - 3.0x |
| VFD controlled | 1.0 - 1.5x |
| Locked rotor | 3.0 - 4.0x |
Torque Arm Guidelines
- Arm length should be at least 1.5x shaft center height
- Use spherical rod ends to allow misalignment
- Include rubber bushing for vibration isolation
- Design for both directions if motor is reversing
- Factor of safety: 3-4 for general industrial