That means that the bearings put a significant “bite” on the shaft. Anything you do in your set up to interfere with that “bite” will cause problems for you.

You can’t lessen or increase the pressure of the bearings against the shaft.

If you use oil or silicone and lessen the friction, the drive will slip.

If you attach a load improperly so that overturning moments of force are being created, the drive will slip or seize.

When there is a heavy or cantilevered payload, Amacoil often uses a load carrier to make sure all forces (weight and overturning moments) are directed away form the Uhing drive. See this http://www.amacoil.com/news07.html 

If these four conditions are met, your Uhing linear drive is going to last 10 years or longer:

1) the load is attached properly

2) you are using Amacoil-Uhing approved lubricants

3) you’re not using the drive in a manner for which it was not intended (like underwater or in a highly caustic work environment)

4) the drive was properly sized to begin with

That’s all there is to it.