Case Study

Caterpillar Seeks Improved Performance With DSTI

Case Study: Caterpillar Seeks Improved Performance With DSTI


Caterpillar's (CAT) high volume production facility for manufacturing diesel engine components was experiencing significant downtime due to performance issues regarding the OEM rotary unions supplied on their grinding equipment. The specialized equipment is designed to grind crankshaft journals which incorporated a high pressure rotary union to provide consistent clamping force while the crankshafts rotated during the process.

The rotary unions supplied with the equipment provided inconsistent performance and short seal life due to the demanding pressures and high rotational speeds. To compensate for the issues, CAT was required to operate the machine at reduced speeds which significantly impacted their production schedule.

CAT needed a rotary union design that would fit into the existing space envelope while offering improved performance. Additionally, excessive heat generation was a significant challenge due to seal friction from high pressures and constant rotation.


DSTI's engineering team worked directly with CAT to develop a solution that utilized special seals with a small contact point to minimize friction while still sealing under high pressure. The seals in DSTI's design had a low profile allowing them to fit into the available space. Additionally, the outlet ports on the design were staggered to allow minimal space between fluid channels.


DSTI was able to provide CAT with a direct replacement that exceeded all expectations for seal life and performance - lasting 150% longer than the original design while allowing for higher rotational speeds. CAT was able to achieve higher production output and significantly minimize machine downtime.

Results Overview

  • Lower investment costs
  • Less machine downtime due to longer seal life
  • Less machine wear due to reduced heat generation
  • Lower repair cost with the ability to rebuild the units with seal kits
  • Lower replacement cost if the units should ever need replacement
Your quick response and willingness to work with us on the issue we were having with our rotary unions was greatly appreciated. The rotary unions we were using were very expensive and had an extremely short life expectancy. Additionally, there was no option to rebuild the union after the seals were worn out. As a Maintenance Planner for one of the world's largest manufacturer of diesel engines, I need hydraulic equipment like DSTI's rotary unions that I can rely on to keep my facility running at its peak performance. We are exceptionally satisfied with your rotary union products and have recently ordered new equipment insisting that all must be fitted with DSTI rotary unions. Larry Back Caterpillar Inc.

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