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The Hitachi EX60-2 and Its Undercarriage Design
The Hitachi EX60-2 is a compact hydraulic excavator introduced in the early 1990s, part of Hitachi’s second-generation EX series. Known for its reliability and smooth hydraulic response, the EX60-2 is powered by an Isuzu 4-cylinder diesel engine and weighs approximately 13,000 pounds. It features a rubber or steel track undercarriage with a grease-adjusted track tensioning system, a common design in compact and mid-size excavators.
The track tensioning system uses a grease-filled hydraulic cylinder behind the front idler. When grease is pumped into the cylinder via a zerk fitting, the piston extends, pushing the idler forward and tightening the track. A leaking seal or damaged cylinder can cause the track to lose tension rapidly, leading to derailment or accelerated wear.
Symptoms of a Failing Track Adjuster
In one case, a newly purchased EX60-2 exhibited a recurring issue where the left rubber track would slacken within 15–20 minutes of operation, despite being freshly greased. No visible grease leakage was observed at the zerk fitting, suggesting an internal failure—most likely a blown rod seal inside the adjuster cylinder.
To confirm the diagnosis, the operator removed the track using a simple method: inserting a shovel between the front idler and the track, rotating the track until the shovel reached the 9 o’clock position, and prying the track off with a 2x4. This allowed access to the adjuster assembly.
Disassembly and Component Damage
Upon removing the adjuster cylinder, it was discovered that the end cap bolts had loosened, allowing the piston rod to cock sideways and bend. This deformation rendered the rod unusable. Fortunately, the operator had prior experience in hydraulic repair and fabricated a new rod from scratch. This highlights the importance of torque-checking fasteners during routine maintenance.
Track Tension Guidelines for Rubber Tracks
Unlike steel tracks, which have specific sag measurements, rubber tracks require a more flexible approach. A general rule is to allow 2–3 inches of sag between the track and the center roller when the machine is lifted off the ground. Over-tightening rubber tracks can lead to premature wear and increased stress on the final drives.
Common Causes of Track Loosening
Track tension issues on the Hitachi EX60-2 are often rooted in hydraulic adjuster failure or undercarriage wear. With a methodical approach—removing the track, inspecting the adjuster, and replacing or fabricating damaged components—operators can restore proper tension and extend the life of their tracks. For machines with over 6,000 hours, proactive undercarriage inspection is essential. In compact excavators, the undercarriage is not just a support system—it’s the foundation of productivity.
The Hitachi EX60-2 is a compact hydraulic excavator introduced in the early 1990s, part of Hitachi’s second-generation EX series. Known for its reliability and smooth hydraulic response, the EX60-2 is powered by an Isuzu 4-cylinder diesel engine and weighs approximately 13,000 pounds. It features a rubber or steel track undercarriage with a grease-adjusted track tensioning system, a common design in compact and mid-size excavators.
The track tensioning system uses a grease-filled hydraulic cylinder behind the front idler. When grease is pumped into the cylinder via a zerk fitting, the piston extends, pushing the idler forward and tightening the track. A leaking seal or damaged cylinder can cause the track to lose tension rapidly, leading to derailment or accelerated wear.
Symptoms of a Failing Track Adjuster
In one case, a newly purchased EX60-2 exhibited a recurring issue where the left rubber track would slacken within 15–20 minutes of operation, despite being freshly greased. No visible grease leakage was observed at the zerk fitting, suggesting an internal failure—most likely a blown rod seal inside the adjuster cylinder.
To confirm the diagnosis, the operator removed the track using a simple method: inserting a shovel between the front idler and the track, rotating the track until the shovel reached the 9 o’clock position, and prying the track off with a 2x4. This allowed access to the adjuster assembly.
Disassembly and Component Damage
Upon removing the adjuster cylinder, it was discovered that the end cap bolts had loosened, allowing the piston rod to cock sideways and bend. This deformation rendered the rod unusable. Fortunately, the operator had prior experience in hydraulic repair and fabricated a new rod from scratch. This highlights the importance of torque-checking fasteners during routine maintenance.
Track Tension Guidelines for Rubber Tracks
Unlike steel tracks, which have specific sag measurements, rubber tracks require a more flexible approach. A general rule is to allow 2–3 inches of sag between the track and the center roller when the machine is lifted off the ground. Over-tightening rubber tracks can lead to premature wear and increased stress on the final drives.
Common Causes of Track Loosening
- Blown rod seal in the adjuster cylinder
- Bent or scored piston rod
- Worn idler guide rails or bushings
- Cracked cylinder housing
- Loose or missing end cap bolts
- Grease fitting not sealing properly
- Replace both track adjuster seals if one side fails, as the other is likely close to failure
- Inspect the cylinder bore for scoring; if damaged, consider machining and installing a polypack seal
- Use anti-seize on end cap bolts and torque to spec to prevent loosening
- Check for excessive wear in the idler slide frame; if the idler reaches full extension and the track is still loose, the undercarriage may be worn beyond service limits
- Avoid makeshift solutions like welding extensions to the idler—removing a track link is a more reliable fix if the track is stretched
Track tension issues on the Hitachi EX60-2 are often rooted in hydraulic adjuster failure or undercarriage wear. With a methodical approach—removing the track, inspecting the adjuster, and replacing or fabricating damaged components—operators can restore proper tension and extend the life of their tracks. For machines with over 6,000 hours, proactive undercarriage inspection is essential. In compact excavators, the undercarriage is not just a support system—it’s the foundation of productivity.
