Hydraulic Pump
Excluder Seal

Fluid Power

Recently, a Zatkoff Seals & Packings customer was in the process of creating a new hydraulic pump design. They came to the experts at Zatkoff to assist in thorough analysis of the application. After analysis, Zatkoff recommended an oil seal design made of HNBR material for wear resistance under high surface speed.

Using a test bench, the customer tested the oil seal in their pump, where it passed initial testing with flying colors. However, these test benches don’t always accurately reflect what happens in real-world applications. When they went in for the second level of testing, actually using their pump in the field, they noticed oil leakage, and the application failed prematurely.

In a collaborative effort, the customer and Zatkoff team analyzed the failure mode and determined that ingression of exterior contamination under the sealing lip was causing leak paths. In other words, external particles were wearing out the sealing lip and allowing the lubricant to pass through. This contamination was not anticipated or simulated in the lab setting. Since the pump casting was predetermined, a new sealing solution needed to be devised. There was enough room within the pump housing to press a secondary wiping oil seal on the outboard side of the unit. Zatkoff representatives proposed a “belt and suspenders” attack, utilizing an excluder type oil seal to keep the contaminants away from the primary seal.

Zatkoff provided quick prototype seals out of the same HNBR material for further field testing, where it successfully prevented external particles — mainly dirt — from touching the oil seal. As a result, the seal was able to keep the lubricant inside the pump. The field testing passed all lifecycle testing and the new pump is currently in the market. The customer was so satisfied with the performance of this new sealing system that this solution has now become a design standard on all new pump models.

Zatkoff Seals & Packings is one of the largest independent seal suppliers in North America. With eight locations throughout the United States and a network of over 400 vendors, Zatkoff’s inventory contains hundreds of thousands of sealing, EMI shielding and thermal management products.