| What is the delivery time of standard screw jacks? | Normally 3/4 weeks from receipt of order |
| What are the determining factors in selecting the correct screw jack? | There are many. Please complete the application questionnaire which can be found in the Support area on this site to list operating details. The diagramatic checklist will identify the stroke and the stroke starting point as well as assist in selecting accessories. |
| What corrosion resisting options are available for screw jacks? |
Electroless nickel plated housings.
Standard and offshore paint finishes.
Stainless steel spindles with or without bellows protection.
Stainless steel spindle cover tubes and bearing housings. |
| What's the difference between rotating or translating screw jacks spindle designs? |
With the rotating spindle design, a nut fixed to the load climbs the spindle.
Feature - there is zero protrusion below the jack.
With the translating spindle design, the spindle rises and falls through the gearbox
Feature - there is no permanent protrusion above the jack. |
| What is the Euler figure often quoted with screw jacks installations? | Euler is a spindle buckling reference. For our own calculations, a figure of 6 is required as a minimum. Values below this indicate a tendency to buckling when the spindle is under load. It relates to spindle length, spindle diameter and the applied force or load. |
| Trapezoidal/ball screw/worm gear….which combination should I use for my screw jack? |
Nominally, use a standard worm gear jack with trapezoidal spindle for stroke speeds up to 1.5 m/min and intermittent duty.
For higher speed operation, it is possible to use a worm gear jack with a ball spindle or a bevel gear jack with a trapezoidal spindle.
For demanding/continuous duty cycle, it might be better to use the bevel gear jack with the ball spindle.
We have a mathematical model which will quickly resolve which combination is the best for your particular application.. |
| Are CAD files available for your screw jacks? | Yes, in dwg, dxf and pdf format. |
| How should motors be sized for a screw jack system? | Preferably, refer the application to our technical office to calculate the power requirement.
Alternatively use the formula in our catalogue.
Be generous when selecting the motor. Temperature, stiction and imperfect assemblies can cause greater than calculated loads to be encountered.
This is particularly true for multi jack installations.
Size the motor based on the dynamic load. Obvious but often missed. |
| What does a screw jack self sustaining mean? | The ability for a screw jack spindle to hold position without a brake.
Trapezoidal spindles normally will be self sustaining.
Vibration will cause them to tend toward not being so.
Ball screw spindles are not self sustaining and must be braked if used vertically.
Always refer to relevant health and safety requirements when planning screw jack systems. |
| Why is spindle rotation prevention offered on screw jacks with non rotating spindles? | Under "no load" conditions, translating spindles will rotate due to drag between the spindle and the worm gear. This can be prevented by the used of a keyed lifting screw.
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| Why is a spindle travel limit option offered for screw jacks? |
Translating spindles can be easily wound out of the gearbox. A mechanical stop, bolted to the base of the spindle prevents this. It is particularly recommended for manually operated jacks.
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| Are screw jacks backlash free? | No. The very nature of the screw jack system means that some clearances must exist to prevent binding.
This nominally creates backlash of 0.13 to 0.28mm as measured at the spindle.
Backlash reduction options are available for critical applications where the stroke encompasses both
compressive and tensile load cycles.
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| Can I achieve a stroke speed higher than 1.5 m/min with worm gear screw jacks? | Yes, by using a 2 start thread or a high lead ball screw. Be aware that the motor power will increase.
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| Can screw jacks be maintained and refurbished by users? | Yes they can and full maintenance instructions are published on our web site.
In the interests of health and safety however, the supply of some parts for refurbishment may be refused.
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