Travel circuit · High
The machine tracks off to one side
It was straight last month. Now any run longer than ten metres needs steering. This is a comparison test, not a diagnosis: two identical circuits, one of them is wrong, and swapping hoses tells you which side in twenty minutes.
What it usually is
| Share of cases | Cause and how to check it |
|---|---|
| 38% | One travel motor is worn Swap left and right travel hoses at the swivel. If the drift follows the hose, the fault is in the valve; if it stays with the machine side, the motor is worn. |
| 24% | Counterbalance or relief valve out of adjustment Compare relief settings left vs right with a gauge at the motor ports. More than 1 MPa difference is a fault, not a tolerance. |
| 22% | Centre joint internal leak on one circuit Run both tracks against a stall and watch for oil temperature rise on one side only. |
| 16% | Travel straight spool / pilot pressure Check pilot pressure at both travel pilot ports; a 0.5 MPa difference explains a slow drift at low speed. |
Field tests
1. The swap test
Mark the hoses before you touch them. Swap, run 20 m straight, then judge. This one test eliminates half the suspect list.
2. Track and undercarriage
Seized rollers and uneven track tension mimic hydraulic drift. Check them before quoting a motor.
3. Case drain, both sides
Measure both motors the same way. The side with 2–3× the flow is the worn one.
What actually fixes it
Two travel motors are not a matching pair once one is replaced — a new motor beside a worn one will drift again. Price the pair against the lost hours.
Send the plate, get the variant in writing.
One photo of the nameplate and one of the pump from the side. We confirm the variant, then quote — the price holds for seven days.