Rebuilding and Replacing the Equalizer Bar on the Caterpillar D5H Dozer

[MikePhua]

The Role of the Equalizer Bar in Crawler Dozer Suspension
The equalizer bar is a critical component in the undercarriage of Caterpillar’s track-type tractors, particularly in the D5H series. It connects the left and right track frames and allows limited oscillation, enabling the machine to maintain ground contact and stability across uneven terrain. This bar pivots at the center and is supported by bearings at both ends, mounted to the A-frames. Its function is mechanical but essential for traction, grading accuracy, and operator comfort.
Caterpillar introduced the D5H in the late 1980s as a mid-size dozer with hydrostatic drive and improved blade control. The equalizer bar design was carried over from earlier models like the D6H, with some refinements in bearing placement and lubrication access. However, many early units lacked grease fittings on the center pin, leading to premature wear and eventual failure.
Terminology Annotation

• Equalizer Bar: A pivoting steel beam that connects the track frames and allows vertical movement for terrain adaptation.
  
• A-Frame Mounts: Structural brackets on each side of the dozer that house the end bearings of the equalizer bar.
  
• Center Pin: The pivot point of the bar, located beneath the engine, often subject to wear due to poor lubrication.
  
• Reboring: A machining process that restores worn bearing seats by enlarging and re-machining them to fit oversized bushings or bearings.
  

Symptoms of Wear and Damage
When the end bearings fail, the equalizer bar begins to wear into its own housing. This results in:

• Excessive play in the track frames
  
• Uneven blade response during grading
  
• Audible clunking or vibration during travel
  
• Accelerated wear on the center pin and mounts
  

In severe cases, the bar may eat into the steel itself, requiring welding and reboring to restore structural integrity. If left unchecked, the damage can compromise the dozer’s alignment and cause stress fractures in the frame.
Repair Options and Field Techniques
There are several approaches to restoring a damaged equalizer bar:

• Weld and rebore: A common method where the worn ends and center are built up with weld and then machined to accept new bearings. This is often done in the field using portable boring equipment.
  
• Replacement: If the bar is beyond repair, a rebuilt or remanufactured unit can be sourced from dealers or salvage yards. Prices vary, but rebuilt bars with new seals and bearings typically cost around $1,950.
  
• Retrofit grease fittings: For older models lacking lubrication access, technicians often install hoses or zerk fittings to allow regular greasing of the center pin.
  

One technician described removing the bar by driving the dozer onto rail sleepers, lifting the blade, and using timber blocks to relieve pressure on the pins. The center pin was removed first, followed by the outer pins, allowing the bar to be tipped out from the rear. Reinstallation involved using pull lifts hooked over the tracks to align the mounts and insert the pins.
A Story from the Field
In Iowa, a contractor operating a D6H noticed excessive sway in the track frames. Upon inspection, the center mount had worn through due to lack of grease. The Cat technician advised installing a hose to allow greasing from outside the belly pan. After welding and reboring the mount, the bar was stamped as certified and returned to service. The operator later retrofitted grease fittings to the outer pins as well, preventing future failures.
Preventative Maintenance and Recommendations
To extend the life of the equalizer bar:

• Grease all pivot points every 100 hours, especially the center pin
  
• Inspect for play or movement during undercarriage service
  
• Replace seals and bearings at the first sign of wear
  
• Avoid operating with failed bearings, as this accelerates structural damage
  
• Keep spare bushings and seals in the service kit
  

For machines used in wet or abrasive environments, consider sealing the mounts with high-quality grease and installing protective covers over the fittings.
Industry Trends and Legacy Support
Caterpillar continues to support legacy models like the D5H through its dealer network and remanufacturing programs. Equalizer bars are available as new, rebuilt, or reman units, and many independent shops offer welding and reboring services. In 2024, several aftermarket suppliers began offering upgraded bars with improved metallurgy and pre-installed grease fittings.
The equalizer bar remains a vital but often overlooked component. Its failure can mimic track frame issues or blade instability, leading to misdiagnosis. Technicians and operators who understand its function and maintenance requirements can prevent costly downtime and extend the life of their machines.
Conclusion
The equalizer bar on the Caterpillar D5H is more than a passive connector—it’s a dynamic suspension element that directly affects performance and longevity. Whether rebuilding a worn unit or sourcing a replacement, attention to lubrication, alignment, and bearing integrity is essential. With proper care and field-tested techniques, this component can continue supporting the dozer’s work across rugged terrain and demanding conditions.