Under Pressure

System Seals Tackles Extreme Loading

One of the world’s top manufacturers of gripper cylinders used for large-scale skidders and moving platforms experienced severe oil leaks under extreme loads. Over uneven terrain, the skids tilted, and the weight shifted off-center. In some cases, 3,800 metric tons of heavy sideload in the cylinders caused the seals to leak.

The problem would likely worsen, as the company started making larger cylinders capable of heavier loads. They realized a permanent solution was needed, and they began testing the existing seals. The existing polyurethane designs failed tests after the very first cycle in simulated side loading.

The company asked System Seals to seek an alternative solution for the 4- and 12-inch diameter pistons. Using finite element analysis, System Seals reworked the seal geometry. They incorporated a backup ring and upgraded the polyurethane material to an advanced formula. Engineers then recommended replacing the bronze overlay guidance with a proprietary composite bearing.

System Seals put prototypes to work in its research facility to test their effectiveness. Under extreme weight, in an off-center position, the new system worked flawlessly for more than 2,000 cycles. It significantly outperformed the existing seals, which failed the same test on the very first cycle.

The company quickly moved to the System Seals’ design with renewed confidence that their cylinders would perform better under extreme weight and side-load tilt. The new composite guide bands reduced manufacturing and maintenance costs and eliminated the expensive bronze overlay. Warranty claims dropped significantly, as the new seals hit the market.