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Screw Jacks – Imperial 1/4 Ton – 250 Ton

Screw Jacks  – Imperial Machine Screw Key Features & Benefits

Duff-Norton offers a complete line of both standard and custom engineered machine screw actuators for applications up to 350 tons. Duff-Norton machine screw mechanical actuators are produced in many
standard models with a wide range of capacities, there is a standard
model for almost any requirement.

Machine screw jacks offer positive mechanical action, precise positioning, and uniform lifting speeds. Standard configurations include upright or inverted units with translating or rotating lifting screws, and top plate, threaded, or clevis ends.


Screw Jacks can be used to push, pull, apply pressure as linear
actuators. They are furnished with standard raises in increments of 1
inch. Depending upon size and type of load, models are available with
raises up to 20 feet.

Precise Positioning

Precise positioning can be controlled accurately within thousandths of one inch.

Self Locking

Duff-Norton machine screw actuator models with higher ratios are inherently
self-locking and will hold heavy loads without
creep as long as the actuator is not subject to vibration.

Manual or Motorised Screw Jacks

Operated manually or by means of gear motors, machine screw actuator
models can be used singularly, in tandem or in multiple arrangements. Since
most capacities have a uniform lifting speed, added economy can be
realized in raising unevenly distributed loads by operating the
different capacities in unison.

Uniform Lifting Speeds

Since many actuators feature the same gear ratios different capacities can be used in the same application to lift unevenly distributed loads with uniform speeds

Positive Reliable Operation

All actuators are designed and built to be positive acting, for accurate response to motive power