Skid Loader Seeks Zero Leaks

How Gates Helped One Company Eliminate Hydraulic Leaks

Problem: Hydraulic Hose Line Leaks 

A skid loader manufacturer had been experiencing some leaking issues in the hydraulic lines on their equipment. They formed a “zero-leak” team to track down and eliminate the causes of leakage.

The Gates sales representative was called in to conduct a production line audit to uncover the source of the leaks. With a Gates engineer, they walked the production line to examine the hydraulic hose assemblies on each hydraulic sub-system, and how they were put together.

The audit revealed that the equipment maker was using hose and tubing assemblies from six different manufacturers. Combining terminations and platings with different tolerances from multiple manufacturers could create leak paths. The Gates team also noted the use of some old-style male boss swivels, which were prone to leaking, and recommended replacing them with newer terminations for better performance.

The plumbing of the drive motor presented another potential source of leaks. Four hoses originated from the drive motor, all of the same type and length. Four identical hoses for this hydraulic sub-assembly helped simplify the bill of materials and made economic sense. However, one of the hoses was too short for the application.

As the skid loader went about its work, this hose was stretched and flexed excessively, stressing both the hose and the terminations on either end. The Gates team recommended a longer hose for the application, and a different type of coupling to eliminate this leak source.

On one of the larger skid loaders the Gates team discovered a non-Gates hose that was routed too tightly for its bend radius. In the field, the hose cover began cracking prematurely. This problem was attributed to hose quality. The original hose had been a Gates product with a tighter minimum bend radius that could handle the application. In an effort to cut costs, the manufacturer had switched to a lesser quality hose, which was the source of the problem.

Hose routing was another problem that came to the team’s attention. These skid loaders carried both 3/4″ and 5/8” diameter high pressure, spiral wire hose assemblies. On one assembly the hose wrapped 90° under the hydrostat to connect to a port. The bend radius was too tight for a hose subjected to pressure spikes of 5,000 psi or more. The team recommended rerouting to fix the potential leak point.

While looking for leaks, the Gates team discovered a hydraulic sub-system that was over-designed for the application. The skid loader’s two joysticks, which are used to maneuver the machine, were hydraulically connected to a hydrostat. The connecting pilot lines use low pressure, yet they were plumbed with Gates Megasys® M3K (SAE 100R17) hoses with a rated working pressure of 3,000 psi, much more than needed. The Gates team recommended switching to Gates M500 wire braid hoses, whose 500 psi rating was more than enough for the application. Eliminating the overkill saved about $10 to $12 per machine.

Solution: Production Audit and Recommendations Eliminate Leaks 

The result of the production audit was a number of recommendations that included:

  • Lengthening hoses that were too short
  • Swapping out old-style, leak-prone terminations for newer, leak-free designs
  • Swapping out a high-end termination for a less expensive one that included an adapter to accomplish the same task
  • Swapping out Gates M3K 3,000 psi hoses for less expensive Gates M500 hoses for pilot lines

The manufacturer has implemented all these recommendations, and is now generating monthly and quarterly warranty reports to track hose leaks. With this data, the zero-leak team and Gates will continue to monitor the leak situation to identify which hoses are leaking the most, what they are attached to, and what needs to change to completely eliminate the leak problem.

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