Machine Screw Jacks - Notes

  1. The recommended maximum speed is 1,800 rpm provided that the recommended horsepower and temperature are not exceeded.
  2. Input torque is shown as torque to lift one pound of load. Starting Torque is 100% greater than torque shown. For loads less than 25% of rated loads add tare drag torque.
  3. Maximum allowable horsepower ratings are based on a 25% duty cycle. For operation at higher duty cycles or repeated use over any segment of the total travel, temperature must be monitored and remain less than 200°F.
  4. Overload capacity of the Machine Screw Jack is as follows: 10% for dynamic loads, 30% for static loads.
  5. Machine Screw Jacks having gear ratios between 20:1 and 32:1 are self-locking and will hold loads without backdriving in the absence of vibrations. All other ratios may require a brake to prevent backdriving.
  6. All units are suitable for intermittent operation providing that the housing temperature including ambient is not lower than -20°F or higher than +200°F. Factory supplied grease in standard units will operate in this range. For higher or lower operating temperature ranges consult Nook Industries, Inc.
  7. Accessories such as boots, limit switches, top plates and clevises are available.
  8. Catalog dimensions are representative only and are subject to change without notice. For construction, use only certified prints.
  9. Units are not to be used as personnel support or movement.
  10. End-of-travel stops are not provided.
  11. Tare drag torque need only be added if operating under 25% rated load.
  12. Starting Torque is 100% greater than torque shown.
  13. Measurements listed are for non-keyed jacks. See individual jack pages for keyed jack info.
Horsepower per jack = Torque to raise 1 pound × Number of pounds to be raised × rpm
Figure 1