Inspection and overhaul on WGW AA-SCZ-600/2/S gearbox

This client from THE NETHERLANDS came to us with this WGW AA-SCZ-600/2/S. We inspected the gearbox and performed a repair. After a succesful testrun we shipped the gearbox back to the client.

We were invited by the client to perform a visual inspection on a gearbox.

The state of the gearbox can be considered unacceptable.

This conclusion based on powder with the color of bronze on the bottom of the gearbox, this grit was not available for sampling. Furthermore, slight traces of co-rotating particles have been observed on a number of the bearings (in particular the first two stages). This can come from the observed grit. Images of the videoscopy have found a possible source of the grit, the contact surfaces between bearing cages and the roller elements are damaged.

In addition, there was a lot of dark deposits in the gearbox, an indication of possible rotating bearings. A process that produces powdered iron oxide which is deposited in the gearbox as a dark attack.

The toothing of the 5th and 6th pinion shafts shows traces of micropitting in several places. Micropitting is a phenomenon that occurs on hardened gears. Several factors influence this, including surface roughness, lubrication and tooth maturation. The damage is characterized by a matt and gray discolouration of the surface due to surface weakening. Micropitting can be stabilized or progressive, in the latter case it can develop into pitting, peeling and peeling.

We recommended:
- In the short term, carry out an extensive inspection of the gearbox to determine the origin of the grit (by removing the top cover)
- Regardless of the result of the extensive inspection, the gearbox must be cleaned
- To refresh or filter the oil for reuse in order to remove any metal particles
- Perform a visual inspection and oil analysis annually.