There are certain competitors advertising that their "innovative roller carriage design" is the new benchmark of the industry. These same competitors (who always seem to be out of stock of everything they advertise) would have the potential customer believe that rollers are a better alternative to slider blocks in a two post above ground lift.
That is simply not true!
Rollers have a line of contact which results in very high stress concentrations to both the surface of the roller and the surface that is being rolled. Rollers were state of the art technology for many of the original two post lifts manufactured and sold in the 1970's. Within a few years of normal commercial use, the rollers would "wear grooves" into the inside of the columns causing an unsafe lifting condition. When metal is rolling on metal there will be an effect on one of the metal components (Common Sense 101). Most of the US and foreign manufacturers changed from the rollers to the slider blocks in the 1980s.
The slider block design requires a more efficient (and therefore more expensive) power unit than two post lifts equipped with rollers on their carriage. The cylinders in the two post lifts that utilize slide blocks are manufactured to stricter tolerances than roller carriage designed two post hoists. The slider blocks contact a much larger surface of the column and therefore afford a greater stability to the carriage as it travels inside the column. The larger contact area created by the slider block requires better quality cylinders and a more efficient power unit than those provided in a roller carriage two post lift design. Our competitors are actually paying LESS for a two post lift with carriage rollers because the power unit and cylinders provided with these lifts are less efficient.
The majority of world-class manufacturers use slider blocks in all of their commercial two post lifts.
The slider blocks are made from an Ultra High Molecular Weight Polyethylene material.
The bushings located in the roller assemblies are also of poor quality. The average "life" of these bushings is about two years.