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The Case 850C and Its Undercarriage Design
The Case 850C crawler dozer, introduced in the early 1980s, was part of Case Corporation’s mid-size dozer lineup aimed at contractors, municipalities, and land-clearing operations. Powered by a naturally aspirated Case 4-390 diesel engine producing around 80 horsepower, the 850C featured a torque converter transmission, power shuttle, and a robust undercarriage built for moderate grading and pushing tasks.
Case Corporation, founded in 1842, had already established a strong presence in the construction equipment market. By the time the 850C was released, Case had sold tens of thousands of dozers globally. The 850C’s undercarriage was designed for durability, with sealed and lubricated track chains, bolt-on track pads, and a spring-loaded recoil system.
Common Track Issues and Their Symptoms
Operators of the 850C often encounter track-related problems that affect performance, safety, and wear. Typical symptoms include:
Key Components to Inspect
When diagnosing track issues, focus on the following areas:
Depending on the issue, repairs may include:
Field Anecdotes and Lessons Learned
A contractor in Montana shared a story of an 850C that repeatedly threw its right track during snow clearing. After replacing the recoil spring and installing a new idler, the problem disappeared. The operator noted that the old spring had lost nearly 30% of its preload force, allowing the track to slacken under load.
Another operator in Georgia rebuilt his track rollers using aftermarket seals and bushings. The cost was half that of OEM replacements, and the machine ran another 1,200 hours without issue.
Terminology Notes
Track issues on the Case 850C are often the result of wear, misalignment, or neglected tension systems. With methodical inspection and targeted repairs, most problems can be resolved without full undercarriage replacement. The 850C remains a capable machine, and with proper care, its tracks will stay on course—literally and figuratively—for thousands of productive hours. In the world of dozers, keeping the chain tight and the rollers turning is the key to forward motion.
The Case 850C crawler dozer, introduced in the early 1980s, was part of Case Corporation’s mid-size dozer lineup aimed at contractors, municipalities, and land-clearing operations. Powered by a naturally aspirated Case 4-390 diesel engine producing around 80 horsepower, the 850C featured a torque converter transmission, power shuttle, and a robust undercarriage built for moderate grading and pushing tasks.
Case Corporation, founded in 1842, had already established a strong presence in the construction equipment market. By the time the 850C was released, Case had sold tens of thousands of dozers globally. The 850C’s undercarriage was designed for durability, with sealed and lubricated track chains, bolt-on track pads, and a spring-loaded recoil system.
Common Track Issues and Their Symptoms
Operators of the 850C often encounter track-related problems that affect performance, safety, and wear. Typical symptoms include:
- Track popping off during turns or reverse
- Excessive slack or sag in the chain
- Uneven wear on pads or sprockets
- Binding or resistance during travel
- Loud clanking or grinding noises from the undercarriage
Key Components to Inspect
When diagnosing track issues, focus on the following areas:
- Track Tension System
The 850C uses a grease-filled recoil cylinder to maintain track tension. If the cylinder leaks or the spring weakens, the track may become loose and derail.
- Front Idler and Rear Sprocket
Check for bearing play, misalignment, and wear. A tilted idler or worn sprocket teeth can cause the chain to ride improperly.
- Track Rollers and Carrier Rollers
Inspect for flat spots, seized bearings, or missing seals. Rollers must rotate freely and support the chain evenly.
- Track Chain and Links
Measure pitch and inspect for stretch. Excessive wear can cause the chain to elongate and skip over sprocket teeth.
- Track Frame and Guides
Look for bent or cracked guides that fail to keep the chain centered. Frame distortion can result from impact or long-term stress.
Depending on the issue, repairs may include:
- Replacing or rebuilding the recoil spring and tension cylinder
- Installing new idler bearings or complete idler assemblies
- Replacing worn sprockets and track chains
- Reboring and sleeving roller mounts
- Straightening or reinforcing track guides
- Grease the tension cylinder monthly and monitor for leaks
- Check track sag weekly and adjust to factory spec (typically 1–1.5 inches of sag between carrier roller and track)
- Clean debris from the undercarriage daily to prevent binding
- Rotate track pads periodically to even out wear
- Avoid sharp turns at high speed, especially on slopes
Field Anecdotes and Lessons Learned
A contractor in Montana shared a story of an 850C that repeatedly threw its right track during snow clearing. After replacing the recoil spring and installing a new idler, the problem disappeared. The operator noted that the old spring had lost nearly 30% of its preload force, allowing the track to slacken under load.
Another operator in Georgia rebuilt his track rollers using aftermarket seals and bushings. The cost was half that of OEM replacements, and the machine ran another 1,200 hours without issue.
Terminology Notes
- Recoil Spring: A heavy-duty spring that maintains track tension and absorbs shock.
- Idler: A wheel that guides the track at the front of the undercarriage.
- Carrier Roller: A roller mounted above the track frame to support the top of the chain.
- Track Pitch: The distance between pin centers in the track chain.
- Derailment: When the track chain slips off the sprockets or rollers.
Track issues on the Case 850C are often the result of wear, misalignment, or neglected tension systems. With methodical inspection and targeted repairs, most problems can be resolved without full undercarriage replacement. The 850C remains a capable machine, and with proper care, its tracks will stay on course—literally and figuratively—for thousands of productive hours. In the world of dozers, keeping the chain tight and the rollers turning is the key to forward motion.
