Metric Ball Screw Jacks include integral safety device.

Press Release Summary:

Available in capacity ratings from 10-300 kN, Metric Ball Screw Jacks provide extra safety in case of ball failure or excessive wear in screw jack. In event of excessive wear in ball screw drive, safety device will contact screw shaft and act as ACME thread, providing drive and offering early warning of any possible ball screw failure. Safety device also allows ball nut on screw jack to sustain load in event of catastrophic ball failure.

Original Press Release:

Metric Ball Screw Jack with Integral Safety Device as Standard

Power Jacks new range of Metric Ball Screw Jacks is designed with an integral safety device as standard. This provides extra safety for the customer in case of ball failure or excessive wear in the screw jack. Current ball screw jacks only meet the demands of customers to have a more efficient screw jack over machine screw types. The need to improve safety was identified during application work with customers who requested extra safety features on screw jack systems due to their working environments including operations with human cargo, fragile or high value industrial cargo or work in hazardous areas. To provide the best solution for these requirements it was decided to review the screw jack design with a view to improving design rather than adding more equipment to the whole screw jack system, which increases costs and the working envelope. Working in close partnership with one of the leading ball screw manufacturers Power Jacks designed a new ball screw arrangement for the Metric actuator and Sym-metric actuator ranges that maintained a compact housing. These ball screw jacks now accommodate a special ball nut that incorporates a safety device as well as integral wipers. The addition of the integral safety device to Power Jacks screw jacks provides the customer with the two advantageous safety features of load sustaining and wear indication:-

1. In the unlikely event of excessive wear in the ball screw drive, the safety device will contact the screw shaft, and act as an "ACME" Thread. This will provide early warning of any possible ball screw failure, and is capable of providing drive in the event of any such failure. It also allows a company's control system to alert an operator to wear of this kind by monitoring the increase in motor current required to drive the system due to the increased friction generated by the device.

2. It allows the ball nut on the screw jack to sustain a load in the event of catastrophic ball failure. The safety of industrial and human cargo is therefore improved. Ball screw systems without this device could collapse under load or drop the carried load.

The ball screw unit used in Power Jacks actuators is designed and manufactured to Power Jacks own specification from certified materials, in an ISO9000 environment. The ball screw drive is custom manufactured with high precision, close conformity raceways. These have been tested and proven as having amongst the highest load carrying capacities.

A further and important benefit to customers is that the safety device is now a standard feature available on Metric ball screw jacks at no extra cost. The ball screw jacks are available in capacity ratings from 10kN up to 300kN as standard with up to 1000kN available on special request. The ability to maintain screw jack cost levels was achieved by the new design allowing improved methods of manufacture and assembly.

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