index - Screw Jacks

A proper wind up............
I'm always on the lookout for a a discarded item that can be given another useful life........ It seems it's a trait of many a Model Engineer.
Whilst swapping some seats in a Jaguar XJ 40 (XJ6) of 1992 vintage, a flush of recycling fever came upon me!
What a lovely bunch of motor driven screw jacks move the seats in these cars - Up and down, forward and back, tilt and level. They have small but powerful 12 Volt DC motors and deliver the desire of many, a linear push / pull motion. Fascinating!
I spent a while thinking of all the things that could be done with them.

Part of the seat subframe, showing one side of the
fore / aft mechanism with its motor, gearbox and
leadscrew.

The XJ40 was cleverly designed to use seat 'subframes' which may be manual or electric. They are easily removed from the bottom of redundant seats (in my case, at a friendly local Breaker's Yard). The electric subframe is of course the most interesting to us. Buy the whole thing (its about 0.5 M2 by 300mm) and take it back to the workshop for disassembly.
The seat motors are connected to 90 degree angle drive gearboxes by a square flexible drive cable. Final linear motion is provided by a leadscrew and nut, rigged to move the seat in the desired direction and limited by microswitches set to the end of permissible travel. The arrangement is compact yet powerful, designed to move the seat with the occupant in it!
Very little (if any) wear is found in any of these components because the seats are seldom moved, sometimes only after a change in the car's ownership.

More goodies on the other side.........

Depending on their task, some motors will drive gearboxes that are 'geared down' more than others, thus delivering far less travel but a lot more torque.
Shorter travel rise / fall motor in the centre of this picture

The arrangement for moving the seat fore and aft utilises a double ended motor driving twin gearboxes and leadscrews which are usefully synchronised.
This arrangement may help someone motorise a machine table or similar?

Another view of the fore /aft mechanism

Dismantling the seat subframe takes some time and thought, some parts being a very interesting puzzle. Disassembly not only gives us these drive units but provides the hoarder with lots of lovely nuts and bolts that are certain to bring a slighty piteous look to the eyes of She who must be obeyed.... It's OK, you have an excuse......Don't discard the subframe parts until you have finished your project, the brackets and bits that mount the motors and attach the leadscrews may well be very useful!
At first, I thought these units would make a good clutch / idler wheel actuator arrangement for some machine or model, or perhaps a cheap power feed unit for a machine tool. It was later realised that they are just perfect for Railway point switching. The motors / gearboxes / leadscrews must also be useful in their own right.
Perhaps the motor could be replaced with a stepper motor to achive accuracy in positioning?
Anyhow, enough of my ideas, I bet you resourceful folk have far more - What miracles can you get these little gems to perform? I look forward to reading what you did with them!

From left to right, double ended motor with flexible drive
cables, single ended motor with gearbox and leadscrew,
longer leadscrew from double ended motor and finally,
another useful item, a central locking solenoid which could do a lot of useful work (Signal actuator?)!

A proper wind up............ I'm always on the lookout for a a discarded item that can be given another useful life........ It seems it's a trait of many a Model Engineer. Whilst swapping some seats in a Jaguar XJ 40 (XJ6) of 1992 vintage, a flush of recycling fever came upon me! What a lovely bunch of motor driven screw jacks move the seats in these cars - Up and down, forward and back, tilt and level. They have small but powerful 12 Volt DC motors and deliver the desire of many, a linear push / pull motion. Fascinating! I spent a while thinking of all the things that could be done with them.	Part of the seat subframe, showing one side of the fore / aft mechanism with its motor, gearbox and leadscrew.
The XJ40 was cleverly designed to use seat 'subframes' which may be manual or electric. They are easily removed from the bottom of redundant seats (in my case, at a friendly local Breaker's Yard). The electric subframe is of course the most interesting to us. Buy the whole thing (its about 0.5 M2 by 300mm) and take it back to the workshop for disassembly. The seat motors are connected to 90 degree angle drive gearboxes by a square flexible drive cable. Final linear motion is provided by a leadscrew and nut, rigged to move the seat in the desired direction and limited by microswitches set to the end of permissible travel. The arrangement is compact yet powerful, designed to move the seat with the occupant in it! Very little (if any) wear is found in any of these components because the seats are seldom moved, sometimes only after a change in the car's ownership.	More goodies on the other side.........
Depending on their task, some motors will drive gearboxes that are 'geared down' more than others, thus delivering far less travel but a lot more torque.	Shorter travel rise / fall motor in the centre of this picture
The arrangement for moving the seat fore and aft utilises a double ended motor driving twin gearboxes and leadscrews which are usefully synchronised. This arrangement may help someone motorise a machine table or similar?	Another view of the fore /aft mechanism
Dismantling the seat subframe takes some time and thought, some parts being a very interesting puzzle. Disassembly not only gives us these drive units but provides the hoarder with lots of lovely nuts and bolts that are certain to bring a slighty piteous look to the eyes of She who must be obeyed.... It's OK, you have an excuse......Don't discard the subframe parts until you have finished your project, the brackets and bits that mount the motors and attach the leadscrews may well be very useful! At first, I thought these units would make a good clutch / idler wheel actuator arrangement for some machine or model, or perhaps a cheap power feed unit for a machine tool. It was later realised that they are just perfect for Railway point switching. The motors / gearboxes / leadscrews must also be useful in their own right. Perhaps the motor could be replaced with a stepper motor to achive accuracy in positioning? Anyhow, enough of my ideas, I bet you resourceful folk have far more - What miracles can you get these little gems to perform? I look forward to reading what you did with them!	From left to right, double ended motor with flexible drive cables, single ended motor with gearbox and leadscrew, longer leadscrew from double ended motor and finally, another useful item, a central locking solenoid which could do a lot of useful work (Signal actuator?)!