How It Works - Power Screw Theory
+Screw Jack Calculator
Calculate power screw torque, efficiency, and self-locking for Acme, square, and trapezoidal threads.
mm
mm
degrees
Loading & Friction
N
mm (0 = no collar)
✓
Self-Locking
Screw will hold load without brake
Screw Jack Results
Lifting Torque (total)
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Lowering Torque
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Thread Torque Only
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Collar Torque
--
Screw Efficiency
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Lead Angle
--
Mean Diameter
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Enter screw parameters to calculate torque.
Power & Speed
Linear Speed at 100 rpm
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Power at 100 rpm
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Friction Coefficients
| Material Pair | mu (dry) | mu (lubed) |
|---|---|---|
| Steel/Steel | 0.15-0.25 | 0.10-0.15 |
| Steel/Bronze | 0.10-0.20 | 0.08-0.12 |
| Steel/Cast Iron | 0.15-0.20 | 0.10-0.15 |
| Steel/Plastic | 0.15-0.35 | 0.10-0.20 |
Common Acme Thread Sizes
| Size | d (mm) | p (mm) |
|---|---|---|
| 1/2-10 | 12.7 | 2.54 |
| 3/4-6 | 19.05 | 4.23 |
| 1-5 | 25.4 | 5.08 |
| 1-1/2-4 | 38.1 | 6.35 |
| 2-4 | 50.8 | 6.35 |