Brake Adjustment Procedure for the Caterpillar 955L Loader

[MikePhua]

The 955L and Its Role in Earthmoving History
The Caterpillar 955L track loader was introduced in the mid-1970s as part of Caterpillar’s evolution in crawler loader design. Built to replace the earlier 955K, the 955L featured a more powerful engine, improved hydraulic response, and a refined operator station. Powered by the Cat 3304 four-cylinder diesel engine, it delivered around 100 horsepower and was equipped with a torque converter and powershift transmission. Its operating weight hovered near 32,000 lbs, making it suitable for heavy-duty excavation, demolition, and material handling.
Caterpillar, founded in 1925, had by then become the global leader in tracked equipment. The 955L was produced during a time when mechanical simplicity and field serviceability were paramount. Thousands of units were sold worldwide, and many remain in operation today, especially in forestry, mining, and rural construction sectors.
Understanding the Brake System on the 955L
The braking system on the 955L is integrated with the steering clutches and consists of dry disc brakes located within the bevel gear compartment. These brakes are actuated by foot pedals that also serve as steering inputs. Over time, brake pedal travel can increase due to wear or misadjustment, leading to delayed response or reduced stopping power.
Terminology:

• Bevel Gear Compartment: A housing that contains the differential and steering clutches, accessible from the top deck of the machine.
  
• Dry Disc Brake: A braking system that uses friction between metal discs without hydraulic fluid, relying on mechanical linkage.
  

Operators often notice excessive pedal travel before braking engages, which can compromise control—especially on slopes or during tight maneuvering.
Accessing the Brake Adjustment Points
To adjust the brakes, technicians must remove the small inspection plates located on top of the bevel gear compartment. These plates provide limited access to the adjustment bolts, which are difficult to see and even harder to reach by feel alone.
Adjustment steps:

• Park the machine on level ground and engage the parking brake
  
• Remove the top plates using a 9/16" socket
  
• Locate the adjustment bolts on each brake assembly
  
• Turn the bolts clockwise to reduce pedal travel
  
• Test pedal resistance and brake engagement after each adjustment
  

Terminology:

• Pedal Travel: The distance a pedal moves before engaging its function; excessive travel indicates wear or misadjustment.
  
• Adjustment Bolt: A threaded fastener used to fine-tune brake engagement by altering spring tension or disc spacing.
  

A technician in Ontario reported that after adjusting the brakes on a 955L with over 8,000 hours, the machine regained precise steering control and reduced stopping distance by nearly 30%.
Common Challenges and Workarounds
Visibility into the bevel gear compartment is limited, and the adjustment bolts are often obscured by dust, grease, or structural framing. Mechanics sometimes use mirrors or borescopes to locate the bolts. In extreme cases, the seat and floor panels may need to be removed for better access.
Troubleshooting tips:

• Use a flexible inspection mirror to locate bolts
  
• Clean the compartment with compressed air before adjustment
  
• Mark bolt positions before turning to track changes
  
• If bolts are seized, apply penetrating oil and wait 24 hours
  

Terminology:

• Borescope: A flexible optical device used to inspect hard-to-reach areas.
  
• Penetrating Oil: A lubricant designed to loosen rusted or stuck fasteners.
  

In 2021, a forestry crew in Oregon used a borescope and custom-fabricated wrench to adjust brakes on a 955L that hadn’t been serviced in over a decade. The job took six hours but restored full braking function.
Preventive Maintenance and Brake Longevity
To extend the life of the braking system, regular inspection and adjustment are essential. Brake discs wear slowly but unevenly, and spring tension can degrade over time. Operators should monitor pedal feel and responsiveness monthly.
Maintenance schedule:

• Inspect pedal travel every 250 hours
  
• Adjust brakes every 500 hours or as needed
  
• Clean bevel gear compartment annually
  
• Replace worn discs and springs every 2,000 hours
  

Recommendations:

• Avoid aggressive braking on slopes
  
• Use steering clutches smoothly to reduce brake wear
  
• Keep compartment dry to prevent rust and corrosion
  

Terminology:

• Steering Clutch: A clutch that disengages one track to allow turning; often paired with brake application.
  
• Brake Disc Wear: The gradual thinning of friction surfaces due to repeated use.
  

A contractor in Texas implemented a quarterly brake inspection protocol across his fleet of older Cat loaders and reported a 40% reduction in brake-related downtime.
Conclusion
Adjusting the brakes on a Caterpillar 955L may be a physically awkward task, but it’s essential for maintaining control and safety. With the right tools, patience, and understanding of the system’s layout, operators can restore precise pedal response and extend the life of critical components. In machines like the 955L, where mechanical systems reign supreme, a well-adjusted brake isn’t just a convenience—it’s a cornerstone of performance.