Inspection and repair on FLENDER SDN 450 gearbox

This client from Belgium came to us with this FLENDER SDN 450. We inspected the gearbox and performed a repair. After a succesful testrun we shipped the gearbox back to the client.

GBS was invited to assess the state of the interior of the gearbox in addition to the periodic vibration measurements.

A videoscope was used for the inspection of the toothing, as well as the bearings of the gearbox. With a videoscope, hard-to-access locations of the gearbox can be clearly displayed.

The two gearboxes have been successfully inspected, the Flender KLN 250 is in reasonable condition and the Flender SDN 450 is in good condition. This difference has its basis in the state of the bearings of the Flender KLN 250.

During the inspection, the following details were noted on the Flender KLN 250:

- The flexible coupling that connects the fluid coupling to the gearbox has 18 mm clearance. This is too much, it is recommended to keep 5 mm
- There is no filter element in the oil system, this can explain the large amount of traces of rotating dirt in the bearings
- The ingoing, outgoing and oil pump lid have traces of oil leakage.

During the inspection, a few bolt holes of the aluminum oil cooler have been rotated. This was solved on the spot by providing all four bolt holes with Helicoils. The oil cooler was then tested by raising the water pressure again, no leakages were observed.

We advise:

- Continue the vibration measurements and visual inspections at the same interval
- If a change in vibration levels, or error frequencies is detected, perform a visual inspection again
- At a subsequent revision, install a filter element in the lubrication system of the Flender KLN 250
- Adjust the axial clearance of the flexible coupling correctly.