Seals Are Everything

A few years ago most potato harvesting machinery was equipped with rubber or plastic rollers running on cast iron spindles. With higher speeds, heavier loads and the advent of belted digger chain came sealed ball bearing rollers.

The American market has opted for "lifetime sealed" ball bearing rollers. These rollers are designed to exclude dirt, sand and water for many years of operation. The basic principle of sealing a ball bearing is that no matter how small the space between the rotating part and the stationary part, there is a rock small enough to be forced into the opening. Once inside the opening, the rock rotates and erodes bearing parts. The challenge, then, is to keep everything out.

The ball bearing is the most expensive component of most rollers and usually the first thing to fail. For that reason, we concentrate our attention on designing and testing effective seals. It sometimes appears that the rubber tire is the first component to fail, but actually the sequence of failure began with the ball bearing seizing up due to contamination between the balls and the races. Once the roller stops turning, all the rubber will be worn off one side of the roller in a matter of hours.

What can cause a roller to stop turning? (1) Rocks wedging in between the roller and the side of the machine. (2) Small rocks (for our purposes, a "rock" can be anything from a tiny grain of sand on up) or dirt finding their way to the inside of a ball bearing. (3) Rollers which are installed too close to the side wall of the harvester allowing mud, clay, rocks and plant material to jam against the roller. We recommend using a longer standoff (spacer) to help alleviate this problem.

At AgParts, we select ball bearings with the best seals available, then where feasible, we add one or more specially designed seals to keep out the dirt and small rocks. Our number one goal is to keep your harvesters moving without your having to spend an arm and a leg.