There are many reasons that proscribe the use of re-circulating balls or rollers in a linear bearing application. For example even small amounts of dust, swarf, water or other liquids can fatally flaw the running of balls or rollers on square or round guideways, by braking the balls or rollers or introducing corrosion which will have the same anti-friction effect.
One way of avoiding this is to use a plain sliding bush. Plain bushes have no moving elements and rely on a low friction material for the bearing surface. These are available from Euro-Bearings Ltd as a "drop- in" replacement for any standard re-circulating ball bushing.
In addition, Euro-Bearings stocks a whole range of aluminum housings into which these plain sliding bushes can be fitted. Shafts and shaft support rails and end blocks complete the package.
Tested at the top most of a 5 meter wind sock set in the middle of an unprotected field during a typical wet (yes it was!) English winter the combined assembly of aluminum housing, plain bush and stainless steel hardened shaft are showing no signs of corrosion. For further protection the aluminum can, of course, be anodised to suit customers' requirements.