This time it is a 2023 Sennebogen 730E material handler. The customer removed the damaged hydraulic pump and delivered it to us for repair. In this episode we bring it back to the machine: we install the pumps, change the filters, clean the tank, start the machine and measure the pressure. The load test, however, revealed another problem.
Installing the pumps
The pump came to us as a set of two pumps bolted together. On site we separated them to make it easier to fit the long, heavy main pump. The sequence:
- flange with coupling – bolts secured with thread locker,
- main pump, carefully aligned,
- slewing pump with a new O-ring and adapter,
- hydraulic lines and control solenoids.
Filters and tank cleaning
After a pump failure, replacing the components alone is not enough. We removed all return filter elements together with their housings, because contamination collects at the bottom, and cleaned the tank thoroughly. Then we replaced the suction filter – first blowing the area around the cover clean with compressed air so no dirt could fall in.
Bleeding, start-up and pressure measurement
The most important step of the whole job is bleeding the pump before the first start – only then do we fit the shaft. After filling with oil we connected a pressure gauge to monitor the pump pressure from the first seconds. The machine started, idled for a while to draw in oil and bleed the system, and then we checked the working pressure: approx. 365 bar, peaking at 375 bar. The pump works correctly.
Test with the operator: another fault
We tested the machine ourselves first, then the operator checked it under load in normal working conditions. That is when it turned out that the grapple cylinders were leaking internally. The customer asked us to fix them straight away so as not to extend the downtime. We removed the cylinders on site and took them to our workshop for reconditioning – more on that in the next episode.
Takeaways
- After a pump replacement we always change the return and suction filters and clean the tank – debris from the failure would destroy the new pump.
- Bleeding the pump before start-up and measuring pressure are the basis of a correct commissioning.
- A load test with the operator catches faults that are invisible when the machine is standing.
- Fixing several faults in one visit reduces total machine downtime.
Every pump is inspected free of charge on the day it arrives. See: hydraulic pump and motor repairs and construction machinery service.
Watch the repair video: A Hydraulic Pump Repair Revealed Another Problem... Sennebogen 730E Service
