In setting out to make the perfect roller, he increased the number of ball bearings in the roller to 11, to increase its longevity and quiet operation. The high-quality hardball bearings are self-contained in a hardened steel race. He then packed those bearings in synthetic grease that adapts itself to the severity of climate changes without any change inconsistency. All of these passed Martin's strict 100,000 cycle door test.
Then he went to work on the shaft of that roller. The shaft on the Martin Door roller is made of galvanized steel. The rust-resistant covering is a yellow zinc coating often affectionately referred to by some dealers as a "gold zinc finish."
The coating on the roller is a testament too to an on-going quest for excellence at Martin Door. The tire on the roller is made of Delrin, a polymer substance made by DuPont.
Initially the tires would only last about five years before showing signs of cracking. Unhappy with that result, Martin officials tried other consistencies in the resin before finding the right combination.
The innovation hardly stopped there. David Martin also lengthened the bottom roller on his doors. The significance of that move is noticeable in earthquake areas where the slightest tremor will normally knock the rollers off most garage doors, making them inoperable. Not a Martin Door. The longer roller shaft also makes the door harder to sabotage.
The most noticeable difference between a conventional roller and that of a Martin Door is the patented roller shield. The roller with roller shield must only be used on Martin doors with hemmed vertical tracks. The oversized shield makes it difficult to actually see the roller on an installed Martin Door----thus providing a barrier as well from hands getting into the track and potential jeopardy. The roller shield actually helps push little hands out of harm's way, or hands away from danger. Again Dave Martin spent endless hours and tried different things, before coming to the right size and dimension for his shield.
Dave Martin went with a larger-than-industry standard tire, which increases its safety value, and also made the rollers more difficult to dislodge. His invention made the standard roller nearly ¼" larger in diameter than rollers made by other manufacturers.
For some it's safe to assume that "parts is parts" but not with a Martin roller. It's no coincidence that the roller has a lifetime warranty.