Morooka MST2000 Undercarriage Maintenance and Idler Compatibility

[MikePhua]

The Morooka MST2000 and Its Role in Soft Terrain Transport
The Morooka MST2000 crawler carrier is a mid-sized rubber-tracked hauler designed for off-road transport in environments where wheeled vehicles struggle. Manufactured by Morooka Co., Ltd., a Japanese company founded in 1958, the MST2000 was part of a broader lineup that included smaller MST800 units and larger MST2200 models. These machines are widely used in pipeline construction, forestry, and wetland restoration due to their low ground pressure and ability to traverse mud, snow, and sand without rutting or sinking.
The MST2000 features a payload capacity of approximately 11,000 kg, hydrostatic drive, and a rotating dump bed in some configurations. Its rubber tracks allow for minimal surface disturbance, making it ideal for environmentally sensitive projects. However, like all tracked machines, its undercarriage components—especially idlers and trunnion shafts—require regular inspection and replacement.
Rear Idler Replacement and Cross-Model Compatibility
One common maintenance task on the MST2000 is replacing the rear idlers, which guide and tension the rubber tracks. These idlers are mounted at the rear of the track frame and absorb significant stress during forward motion and turning. Over time, bearings wear out, mounting holes elongate, and the idler wheels themselves may crack or deform.
A frequently asked question is whether rear idlers from the larger MST2200 model can be used on the MST2000. While both machines share similar design principles, their idlers differ in mounting dimensions and bearing size. The MST2200 idlers are typically wider and heavier, designed to support greater payloads and track tension. Installing them on an MST2000 without modification may result in misalignment or bearing overload.
Key differences include:

• Bolt pattern: MST2000 idlers may have five-hole or six-hole configurations depending on production year
  
• Bearing size: MST2200 uses larger bearings with higher load ratings
  
• Mounting width: MST2200 idlers are wider, requiring frame modification to fit MST2000
  

Operators should verify the bolt pattern and bearing dimensions before attempting a swap. Matching the hole count—five or six—is critical, as early MST2000 units used narrower mounts incompatible with newer idlers.
Terminology Annotation

• Idler: A wheel that guides the track and maintains tension, not powered directly
  
• Trunnion Shaft: A pivot shaft that supports the bottom roller triangle assembly
  
• Rubber Track: A continuous belt made of reinforced rubber and steel cords, used for traction
  
• Hydrostatic Drive: A propulsion system using hydraulic fluid to power track motors
  

Trunnion Shaft Wear and Structural Risk
Another common failure point on Morooka carriers is the trunnion pivot shaft. This shaft sits atop the triangular plate that supports the bottom rollers and allows limited articulation. When the bearings inside the trunnion housing fail, operators often continue using the machine, unaware of the internal damage. Over time, the shaft wears into the welded tube housing, leading to ovalization, cracking, and eventual structural failure.
Repairing a damaged trunnion housing requires:

• Cutting and rewelding the tube
  
• Machining new bushings or sleeves
  
• Replacing the shaft and bearings
  
• Realigning the roller triangle to prevent track misalignment
  

Preventative inspection should include checking for play in the roller assembly, listening for grinding noises, and inspecting for metal shavings near the pivot point.
Rubber Track Pricing and Market Trends
Interestingly, rubber tracks for the MST2000 are often more expensive than those for the MST2200, despite the latter being a larger machine. This pricing discrepancy may be due to lower production volumes, specialized sizing, or regional demand. Operators should compare prices across multiple suppliers and consider aftermarket options with reinforced steel cores and abrasion-resistant compounds.
Recommended track specifications:

• Width: Approximately 700 mm
  
• Pitch: 140 mm
  
• Steel cord count: Minimum 4 layers
  
• Tread pattern: Chevron or block depending on terrain
  

Some operators report better longevity with block-style treads in rocky terrain, while chevron patterns perform better in mud and snow.
Field Anecdotes and Practical Advice
One contractor in British Columbia shared that his MST2000’s rear idlers failed during a winter reclamation job. After sourcing MST2200 idlers, he discovered the bolt pattern didn’t match. Rather than modifying the frame, he located a salvage yard with original MST2000 idlers and rebuilt them with new bearings.
Another operator emphasized the importance of inspecting trunnion shafts every 500 hours. He had ignored early signs of bearing failure and ended up replacing the entire roller assembly—costing over $4,000 in parts and labor.
Tips for long-term reliability:

• Grease all pivot points monthly
  
• Replace idler bearings every 1,000 hours
  
• Use OEM or high-grade aftermarket tracks
  
• Avoid sharp turns on hard surfaces to reduce side loading
  

Conclusion
Maintaining the Morooka MST2000 requires attention to undercarriage integrity, especially rear idlers and trunnion shafts. While parts from larger models like the MST2200 may appear compatible, differences in mounting and load capacity can lead to costly mistakes. By verifying bolt patterns, inspecting pivot shafts, and sourcing quality tracks, operators can extend the life of their crawler carrier and avoid unexpected downtime. In the world of soft terrain hauling, the MST2000 remains a dependable workhorse—provided its undercarriage is treated with the respect it deserves.