Swing. The house turns, but late and weak. Under a load it creeps back. Nine out of ten times the swing circuit is losing pressure somewhere between the pump and the motor — and the motor's case drain tells you where.
Tee a 0–60 MPa gauge into the swing relief port, hold against a stall, compare with the rated 34.3 MPa.
Measure case-drain flow with the motor at relief: over 8–10 L/min at 1,800 min⁻¹ means the piston group is done.
Check pilot pressure at the brake release port — it must reach the value in the catalogue, and the brake must open within 0.5 s.
Compare motor inlet pressure with pump outlet pressure at the same moment; a gap that grows with oil temperature points at the joint.
Tee into the swing relief port at the valve block. Record: stall pressure, pressure at first movement, and pressure after 10 minutes of work.
Run the motor at relief for 60 s with the drain hose into a measuring container. Flow, not pressure, is the wear signal.
Listen and feel: a brake that drags heats the housing to 70 °C+ within 15 minutes of work.
Three points that settle the argument about the cause: pump pressure, motor inlet pressure, and case drain.
| Reading | Where | Expected | Recorded |
|---|---|---|---|
| Pump pressure | TP1 | catalogue | |
| Motor inlet pressure | TP2 | catalogue | |
| Case drain | TP3 | ≤ 8–10 L/min |
A seal kit, a sub-assembly and a complete unit are three different prices for three different amounts of work. Ask for all three on the same sheet and decide with the downtime cost in front of you.
A seal kit restores a dry motor. A worn piston group is a motor or a sub-assembly, not a kit — ask for both numbers on one quote and compare against a day of downtime.
Ask for the price
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