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A Gehl DL-6H telehandler exhibited a dramatic failure when hydraulic oil sprayed from the axle breather upon releasing the parking brake. This symptom pointed to a breach in the internal seal system, allowing pressurized fluid to escape into the axle housing. Wet brake systems, which use hydraulic pressure to engage and disengage internal brake discs submerged in oil, are particularly vulnerable to seal degradation and component fatigue.

Understanding Wet Brake Systems and Seal Function

Wet brakes operate within a sealed environment filled with hydraulic fluid. Key components include:

  • Brake discs and plates submerged in oil
  • Hydraulic piston actuators
  • Inner and outer seals to contain fluid
  • Axle breathers to relieve pressure

When seals fail, fluid can migrate into unintended areas—such as the axle housing—and escape through breathers. In this case, the failure was not just a seal leak but a catastrophic breakdown of the parking brake assembly.

Teardown Findings: Metal Debris and Retaining Ring Fragments

Upon disassembly of the left side axle, technicians found:

  • Metal fragments consistent with brake disc or piston damage
  • A retaining ring believed to belong to the parking brake assembly
  • No damage on the left side, suggesting the failure originated on the right

This indicated that the parking brake mechanism had self-destructed, possibly due to:

  • Overpressure during brake release
  • Fatigue or misalignment of retaining components
  • Improper fluid type or contamination

One technician described the failure as “exploratory surgery,” highlighting the uncertainty and complexity of diagnosing internal brake failures without full teardown.

Parts Sourcing and Vendor Strategy

Finding replacement parts for the Gehl DL-6H proved challenging. The original manufacturer’s support was limited, but technicians identified two viable sources:

  • Alta Forklift: A regional Gehl vendor able to supply OEM components
  • Joseph Industries: A specialized supplier with a strong inventory of Carraro axle parts, which are used in many Gehl machines

Joseph Industries became the preferred source due to their responsiveness and catalog depth. They stock:

  • Brake discs and friction plates
  • Seal kits for wet brake systems
  • Retaining rings and piston assemblies
  • Axle housing components for Carraro-manufactured axles

This sourcing strategy reflects a broader trend in legacy equipment repair—where third-party vendors often outperform OEM channels in availability and support.

Field Anecdote: Brake Failure in Cold Weather

A technician in Wisconsin recalled a similar failure on a telehandler during sub-zero conditions. The hydraulic fluid thickened, increasing pressure during brake release. A brittle retaining ring snapped, sending fragments into the brake cavity and jamming the piston. The machine locked up mid-operation, requiring a full axle teardown in freezing temperatures.

Preventive Measures and Inspection Tips

To avoid similar failures, operators and mechanics should:

  • Use manufacturer-recommended hydraulic fluid with correct viscosity
  • Inspect axle breathers for signs of oil mist or pressure buildup
  • Monitor brake engagement behavior—delayed release or noise may signal internal wear
  • Replace seals and retaining rings during scheduled maintenance, not just when failure occurs
  • Avoid prolonged brake engagement under load, which increases internal pressure

Final Thoughts

The Gehl DL-6H wet brake failure illustrates the complexity of hydraulic brake systems and the importance of proactive maintenance. When seals fail or retaining rings fracture, the result can be explosive—literally. With careful teardown, accurate diagnosis, and strategic parts sourcing, even catastrophic failures can be resolved. For legacy machines, building relationships with specialized vendors like Joseph Industries may be the key to keeping equipment operational and safe.

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