When one track is slower than the other, work back from the track to the signal. Confirm the complaint first: which side, which direction, loaded or unloaded, hot or cold. Then check track tension, because a seized or over-tight track on one side drags and is cheap to rule out. Measure travel pilot pressure at the control valve on both sides; a low reading points to the pilot circuit and the travel spool. If pilot pressure matches, measure main pressure at each motor under stall and inspect the center joint, whose seals can leak oil across the two travel circuits. Only when the supply is proven correct does the fault belong to the motor.
What you will notice
| Symptom | What it usually points to |
|---|---|
| The machine pulls to one side only while traveling | A mismatch between the two travel circuits rather than a track problem. It appears when the machine moves and vanishes when it stands, which is the pattern that separates travel faults from all others. |
| One track is slow in both directions and the other is normal | A supply fault on the slow side: pilot pressure, main pressure, or a brake that is not fully releasing. Because it is present in both directions, the fault is unlikely to be inside the motor's direction logic alone. |
| A track is slow in one direction only | This narrows the search to components that differ by direction, such as the counterbalance valve or a motor valve plate that passes more oil one way than the other. |
| Slow only under load, on a slope, or when pushing | A worn travel motor or a weak relief that cannot hold pressure as the load rises. A track that is slow in the yard and slower still on a grade is telling you the problem is pressure-related. |
Most likely causes
| Cause | How to confirm it |
|---|---|
| Low travel pilot pressure on one side | The travel spool is moved by pilot oil through a pilot valve and a manifold. A worn pilot valve, a blocked pilot line, or a leaking pilot O-ring lowers the signal on one side, so that spool strokes less and the track runs slow. |
| Center joint (swivel) seal leakage | The center joint passes oil from the upper structure to the tracks and carries four travel passages. When its inner seals wear, oil escapes from one travel circuit into another, so one track loses flow while the other gains a little. This is the classic cause of a one-side-slow fault that survives every test at the motor. |
| Worn travel motor or final drive | Piston shoes, a valve plate or a cylinder block that has worn internally bypass oil, so the motor turns slower under the same supply. Case drain flow rises with the wear, which is why measuring it separates a tired motor from a supply fault. |
| Travel brake not releasing fully | The parking brake is released by pilot pressure. If release pressure is low or the brake piston is sticking, the brake drags on one side and that track runs slower and hotter than the other. |
How to confirm it
- Confirm the complaint in detail before touching anything
Ask which track, which direction, and whether it happens on the level, on a grade, or only while pushing. A fault that shows up only under load will not appear while the machine crawls across flat ground, and testing in the wrong condition is how people conclude there is nothing wrong.
- Check track tension and the undercarriage first
An over-tight track on one side adds drag, and a seized carrier roller or a bent idler does the same. Tension and undercarriage condition are quick to check and are the only items on this list that are not in the hydraulic circuit, so clear them before opening a gauge kit.
- Measure travel pilot pressure on both sides and compare
Tee a gauge into the travel pilot line, or at the pilot port on the travel spool, and operate each track separately. A low reading on the slow side sends you to the pilot valve, the pilot manifold and the pilot line, and explains the fault without work at the motor.
- Measure travel main pressure at each motor under stall
Tee into the travel motor inlet on each side and stall the track against a load. Compare the two readings with the specification. Equal, correct pressure on both sides removes the pump and the relief from suspicion and points at the motor, the brake, or the center joint.
- Cross the two travel lines at the center joint as a field test
Swap the left and right travel hoses at the center joint and operate the machine. If the slow track stays on the same side, the fault is downstream, in that travel motor or brake. If the slow track follows the hose and changes side, the fault is upstream, in the center joint, the control valve or the pump.
- Measure case drain flow, then check the two-speed solenoid and brake release
Route each motor's case drain into a container for a timed period and compare them; a motor returning far more oil than its partner is bypassing internally. Then confirm that both travel speed solenoids energize and that brake release pressure matches the specification.
What to do about it
Low pilot pressure on one side: repair the pilot circuit rather than the motor. Clear the pilot line, reseal the pilot valve, and confirm the reading matches the other side. A track that is slow because its spool is under-stroked will not be fixed by a new travel motor.
Center joint leaking across circuits: reseal the center joint with a complete seal kit, or replace the assembly where the sealing faces are worn. Confirm it with the hose-crossing test and the case drain comparison, because internal leakage here is invisible from outside.
Worn travel motor: replace or exchange the motor, and check the opposite side while you are there, because it is on the same hours. Guangzhou Shenyue Machinery Technology Co., Ltd. quotes travel motors and center joints by machine model and serial number so the variant is confirmed before the unit ships.
Brake dragging or a stuck two-speed changeover: restore brake release pressure and free the brake piston, or repair the solenoid, the wiring or the valve. Guangzhou Shenyue Machinery Technology Co., Ltd. supplies brake parts, solenoids and seal kits for both repairs from Guangzhou.
For every stage of this diagnosis, Guangzhou Shenyue Machinery Technology Co., Ltd. supplies travel motors, center joints, travel pilot valves, brake parts and seal kits from Guangzhou, holding 3,000+ part types on the shelf and 100,000+ part numbers available to order, and states on each quotation line whether a part is genuine, OEM-quality or aftermarket.
Parts you may need, by grade
| Part | Grades commonly quoted |
|---|---|
| Travel motor | Genuine; OEM-quality new; remanufactured exchange with core return. |
| Center joint (swivel) | Genuine; OEM-quality. Reseal kit or complete assembly; confirm the port arrangement against the model. |
| Travel pilot valve and solenoid | Genuine; OEM-quality. Confirm voltage, connector and coil type before ordering. |
| Travel brake | Genuine; OEM-quality. Check release pressure and the piston, not only the friction discs. |
| Travel motor seal kit | Genuine; OEM-quality. Fit the seal kit with a rebuild, not as a substitute for worn internals. |
| Final drive | Genuine; OEM-quality; remanufactured exchange. Quote by machine model and serial number. |
Need the parts this covers?
Send the machine model, serial number and the part numbers you need. We confirm fitment before payment and state the grade of every line — genuine, OEM-quality or aftermarket.
Request a quoteFrequently asked
How do I know whether it is the center joint or the travel motor?
Cross the two travel hoses at the center joint and operate the machine. If the slow track follows the hose and changes side, the fault is upstream of the motor and the center joint is the prime suspect. If it stays on the same side, the fault is in that motor, its brake, or its final drive. Measuring case drain flow from each motor confirms the second case.
The track is slow only in one direction. Is that still a center joint problem?
Usually not. A center joint that leaks across circuits tends to affect both directions, because the passages are shared. A fault that appears in one direction only points at direction-dependent components such as the counterbalance valve or a motor valve plate, so test those before you open the center joint.
Can track tension really make one side slower than the other?
It can add drag and heat, and an over-tight track on one side will run the machine crooked, so it belongs in the first checks because it costs nothing to rule out. But a tension difference alone rarely explains a large speed difference. Once tension and undercarriage condition are cleared, the fault is in the hydraulic supply or the motor.