Assembling A Cubic Screw Jack

By Kelston Actuation | Mar 16 2022 12:00AM | Company, Screw Jacks

A Kelston Actuation cubic screw jack can comprise over 20 individual pieces, depending on the model specification. Each of these must be made to exact standards to ensure the reliability of the product. Because our cubic screw jacks are designed to work in modular arrangements, one faulty unit can disrupt the effective functioning of an entire system, making quality control crucial.

We manufacture the majority of the required parts ourselves, so we can maintain control over component standards. We use enterprise-class equipment to machine and finish each part but also place trust in the expertise of our production technicians.

So, how are individual screw jack units assembled?

We begin at the assembly table where all the individual components have been kitted from their relative production departments.

Whilst there are many intricate, individual pieces, the key components of our cubic screw jacks are the body (or casing), the worm wheel, the drive worm shaft and the lead screw.

The first stage of assembly is to attach two bearings to either end of the worm shaft and insert it through an allocated space in the jack casing. Two circlips are used to hold the shaft and bearings in position whilst it is checked to ensure it can rotate freely. The drive shaft is then temporarily removed from the body casing.

Next, a worm wheel (with attached bearings) is placed into the body of the casing box. The worm shaft can now once again be placed in the box, forming a connection with the worm wheel. The circlips are re-attached and the worm shaft is shimmed to the correct tolerance.

With the worm wheel and drive worm shaft components in place, a top cap is screwed into the body worm wheel and sits outside the exterior of the body casing to pre-load the thrust bearings. Two dog points are drilled into the casing using a guide screw, stopping the top cap from rotating and holding the attached components in place. A grease nipple is then added to the allow the screw jack to be lubricated.

With the bulk of the assembly complete, the lead screw is then threaded through the casing, connecting with the worm wheel. A stop is attached to one end and tightened down with another dog point.

A flange or mounting attachment is fixed to the top end of the lead screw - once again secured with a dog point - before the lead screw itself is greased to ensure smooth translation through the worm wheel.

A lead screw cover is then attached onto the bottom of the casing body, providing protection for the lead screw as it translates into and out of the assembly.

Finally, a key is stamped into both exposed ends of the drive shaft to provide a locking mechanism for further drive shaft attachments.

The assembly team then tests the smooth function of each completed screw jack unit before it is cleaned down with panel wipe and then packaged up for ready for customer delivery.