Field diagnosis
Final drive noise and metal in the gear oil: travel reduction gears
Noise from a travel reduction gear, or metal on the drain plug, has three usual sources. Check them before the spline fails and takes the motor with it.
Check these in order
| Check | What it looks like | What it tells you |
|---|---|---|
| Gear oil condition | Metal paste on the magnet, or a metallic shimmer in the oil, is the earliest warning available. | Drain and inspect at the specified interval and keep a sample. |
| Gear oil level and leaks | A low level from a weeping seal destroys a planetary set quickly. | Check for leaks at the seals and housing joints. |
| Backlash and bearing play | Excess play is heard as knocking when the machine stops or changes direction. | Check play at the output against the service data. |
| Spline and coupling wear | A worn coupling spline makes one side travel weak and can strip without warning. | Open the coupling cover and inspect the spline. |
| Brake drag | A travel brake that does not release fully heats the gear oil and loads the motor. | Measure brake release pressure at the port. |
| Contamination from the brake | Brake friction material ends up in the gear oil as the brake wears. | Flush the gearbox and renew the oil after any brake repair. |
Units and parts this usually leads to
FTD26
13–16 t excavator / drilling rig / crawler crane →
FTD45
18–22 t excavator / drilling rig / crawler crane →
FTD48
22–26 t excavator / drilling rig / crawler crane →
FDNB12
8–10 t excavator →
Field notes on this complaint
The notes our own team works to on this symptom. Each one is a principle you can check on the machine, a step from the case-drain and cleanliness procedure we follow, or a figure transcribed from our catalogue - not advice copied from a video or a forum. Anything we could not check against a catalogue, a manufacturer document or a working machine is left out.
- Oil and bearing play first. Final-drive noise is usually gear-oil condition or bearing play. Check the oil level and what is in the oil before assuming motor wear. (circuit principle, checkable on the machine)
- The same case-drain test applies. Travel motors are tested the way we test pumps: case-drain flow at working temperature, compared against the value the manual gives for that unit. (our own case-drain and cleanliness procedure)
- Clean the housing before the new drive goes in. If the differential or final-drive housing is not properly cleaned when a new or rebuilt drive is installed, the contamination left inside keeps circulating through the new unit - which is how a rebuild fails early. Flush and wipe the housing, then check the oil after the first hours of running. (circuit principle, checkable on the machine)
- Bearing life is a function of pressure, speed, load, viscosity and cleanliness Parker's documentation sets out what the B10 (L10) bearing life figure depends on: system pressure, working speed, external shaft load, the fluid viscosity in the case and the contamination level of the oil - and notes that 50 percent of bearings statistically last at least five times the B10 figure. The practical reading for a noisy final drive or motor: bearing life is not a single number to compare between sizes, it is what your duty cycle and your oil are doing to the bearings, and cleanliness is one of the five inputs you can actually change. (manufacturer service or operator manual we hold (title on request))
Common questions
Is a humming final drive always failing?
No. Check the oil: clean oil with normal backlash and only light humming is usually normal running noise. Metal in the oil changes the picture immediately.
How do I tell a motor fault from a gearbox fault?
Compare the two sides at the same temperature. Case drain flow and relief pressure test the motor; gear oil condition and backlash test the gearbox. A worn spline affects both.
What is available for travel assemblies?
Complete travel assemblies as well as internal parts supplied as catalogue lines. Send the unit nameplate and we confirm the correct line before dispatch.
Why it happens
The mechanism behind this symptom, from our technical articles: reading the principle first usually shortens the checklist.
Travel and swing drives: three numbers that decide whether a hydrostatic drive lasts
Systems and control
Charge pressure, case drain flow and control response - measured hot - tell you whether a pump-controlled drive is healthy. How to...
Closed-circuit hydrostatic drives: why travel and swing use pump control
Systems and control
How a closed-circuit hydrostatic drive works: variable pump, motor, relief valves and charge pump; why it wastes less energy than ...
Hydraulic noise: what the sound tells you, and the order to check it
Field diagnosis and maintenance
Fluid noise and mechanical noise sound different. Pick the frequency band, then work the checks in order: suction, settings, mount...
More in Swing, travel and drive assemblies: Swing slow, weak or drifting to one side · Tracks weak, one side not moving · all areas