Square Thread Screw Jack Calculator
Calculate ideal square-thread raising/lowering torque and thread-only efficiency from entered load and friction.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use lead=pitch×starts and a square-thread friction model without collar losses.
tanλ=lead/(πdm); raise torque=F dm/2×(μ+tanλ)/(1−μ tanλ)
Worked example
At zero friction, raising torque is F×lead/(2π), and the nonzero-load thread efficiency is one.
Assumptions and input details
Ideal square threads, constant Coulomb friction, no collar/bearing torque, trapezoidal thread correction, strength, buckling or allowable load. Negative lowering torque means the ideal load can overhaul; no safe holding claim.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
Relate axial thread pitch, starts and mean diameter to lead, helix angle, travel speed and entered-efficiency torque.
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