Inspection and repair on LOHMANN+STOLTERFOHT GWS 60.66 gearbox

This client from U.S.A. came to us with this LOHMANN+STOLTERFOHT GWS 60.66. We inspected the gearbox and performed a repair. After a succesful testrun we shipped the gearbox back to the client.

This report provides an overview of the work carried out onboard the Cape Elizabeth III in Manzanillo, Mexico. GBS International was invited to carry out an inspection and repair of the Propulsion gearbox.

During inspection the seals from the haudraulic clutch were found broken, this might caused the clutch to slip and vibrate.

The input pinion and the output gearwheel showed micro pitting on the gear teeth. Micro pitting is a phenomenon that can be found on (hardened) gears. Multiple factors can affect the development of micro pitting, most important factors are surface roughness and the quality of the lubrication. The damage shows itself by a matted grey colour of the teeth. This as outcome of surface fatigue. The development of the micro pitting can be stabilized or progressive. A progressive development can eventually cause more severe pitting, and scaling.

The pitting on the gear theeth is most likely caused by corrosion.

Recommendations

- It is recommended to perform an annual visual inspection of the gearbox to define the progres-sivity of the micro pitting.
- A routine oil change is advised every 2000 serice hours, however, not longer than 12 months.