KEVOS® MAKEOS · Mechanics
Scissor Lift Screw Drive Check (Actuator Force Through the Lift, Screw Torque, Lift Time, Power)
For a single-stage scissor lift table raised by a horizontal lead screw, what force does the screw push with at the bottom of the lift, what torque and power does it need, and how long does the lift take?
Check of a scissor lift table driven by a horizontal screw between the bottom pivots: the platform height range from the arm length and angles, the horizontal actuator force from the load (largest at the lowest angle), the screw travel, the torque to drive the screw at the largest force (as the power screw torque tool), the lift time at the screw speed and the drive power, against the torque available and the time allowed.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Load including the platform | N | Load on the platform plus the platform itself (arm weight left out). |
| Scissor arm length (pivot to pivot) | mm | Length of each scissor arm between its end pivots. |
| Lowest arm angle from horizontal | ° | Arm angle from horizontal with the table lowered. |
| Highest arm angle from horizontal | ° | Arm angle with the table raised. |
| Screw | ||
| Mean (pitch) diameter of thread | mm | Mean diameter of the screw thread. |
| Lead | mm | Lead of the screw. |
| Thread form | choice | Thread form. |
| Thread friction coefficient | Thread friction (a ball screw has far less). | |
| Mean collar diameter (0 = rolling thrust bearing) | mm | Mean diameter of a plain thrust collar (0 for a rolling thrust bearing). |
| Collar friction coefficient | Collar friction. | |
| Drive | ||
| Screw speed | rpm | Speed of the screw. |
| Torque available at the screw | N·m | Torque the motor and gearing can give at the screw. |
| Longest lift time | s | Longest time allowed for a full lift. |
Method and formulas
- Height = L sin θ; base length = L cos θ; screw travel = L (cos θ_min − cos θ_max).
- Virtual work: W dh = F dx gives F = W ÷ tan θ, largest at the lowest angle.
- Torque to raise the largest force (as the power screw torque tool); lift time = travel ÷ (lead × speed); power = torque × ω.
- Example: 28,356 N at the bottom of the lift needs 59.654 N·m; the lift takes 16.417 s.
Limitations
- Single stage with the load centred and arm weight and pivot friction left out.
- Screw buckling and nut wear not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size the screw and motor for a scissor table
- See why scissor lifts start hard at the bottom
- Check a lift table for a heavier load
Who it is for
- Machine designers
- Design engineers
- Materials handling engineers
What you get
- Height range and screw travel
- Largest actuator force and screw torque
- Lift time and power
Interpreting the result
- The force at the bottom of the lift is several times the load; starting a little higher (a larger lowest angle) cuts it sharply.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 153–163, 1921–1928. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
