Ball screw safety device 1

Use motors with fail-safe brakes.


Mike Halloran
Pembroke Pines, FL, USA

Thanks for your suggestion Mike,

But I am afraid we already have one installed.

The point is between the gearbox and the begining of the ball screw there are:
one rigid coupling
one universal coupling (double cardan)
one bevel gearbox and
one elstic coupling

We would like to ensure that, if something fails, the ball screw will never un-screw itself
leaving the load go down

A common solution is to use a safety system that is independent of the drive.

For example, a linear one-way rack and pawl that engages in a fail-safe way and is released when the motor is active.

Don't use a ball screw. Use a non-reversible drive screw that requires power to go up and to go down.

Anti-backdrive or spring set brake on driven part ball screw. to stop it revolving without power.

However without knowledge of your system a more reliable coupling between screw and brake would seem to be tne simplest and most reliable solution. Taking out out sources of failure is better than adding more equipment that may fail themselves. No system is 100% fail safe. You can only add extra decimal places to chances of failure.