A 2017 Wacker Neuson ET18 mini excavator came into our workshop. The customer had noticed a large amount of metal particles on the hydraulic filter. It turned out that one final drive had recently been replaced with a new one because the rotating group of its hydraulic motor had disintegrated – but the system had not been cleaned. The video shows the consequences of that shortcut.
Removal: final drive and pump
We raised one side of the machine, drained the oil and released the track tension via the tensioner valve so the final drive could be removed. Plenty of particles were already visible on the filter element. At the rear of the machine we removed the hydraulic pump and took everything to the workshop.
Inspection: what destroyed the new travel motor?
First we opened the old final drive supplied by the customer. The culprit was obvious: the rotating group retainer had cracked, the pistons started running loose and damaged the plate, and pieces of the retainer went into the system. Then we opened the new final drive, which had run for just a few weeks on unfiltered oil. Unfortunately, the same picture inside: particles, a damaged retainer, pistons, ball and base, and a score on the shaft. The contaminated system had killed a second, brand-new final drive.
To be sure, we also removed the final drive from the other side. Its hydraulic section was clean and the retainer intact. On the gearbox side (planet gears), however, the shaft splines were badly worn – from constant left–right operation and jerking the tracks in mud or in winter. The shafts needed replacing.
Repair and system cleaning
- Hydraulic pump – dismantled, running surfaces lapped, new seals; the controller was removed first to avoid damaging the solenoids.
- Final drives – one rebuilt (new rotating group, seals, gearbox inspection), the other replaced with a new unit after comparing the cost of parts with the price of a new drive.
- Hydraulic tank – cleaned of larger and smaller debris.
- Hydraulic oil cooler – removed and cleaned.
- New hydraulic filter and fresh oil.
After installation we bled the pump at its highest point, tensioned the tracks and topped up the oil after the first movements – an empty system always draws in a lot of it. The tests were successful.
Takeaways
- After a hydraulic pump or motor disintegrates, the entire system must always be cleaned: tank, cooler, lines, filter and oil. Otherwise the particles will destroy the new parts.
- Particles on the filter are a warning sign – the sooner the machine is serviced, the lower the repair cost.
- It is worth checking the final drive gearboxes as well: worn splines will sooner or later stop transmitting drive.
We help with hydraulic failures: hydraulic pump and motor repairs, hydraulic oil filtration and construction machinery service.
Watch the repair video: New Travel Motor and Another Failure? Here's Why – Wacker Neuson ET18
