Inspection and repair on RENK Aws 315 So gearbox

This client from The Netherlands came to us with this RENK Aws 315 So. We inspected the gearbox and performed a repair. After a succesful testrun we shipped the gearbox back to the client.

This page describes the findings of the inspection of the Renk AWS 315 propulsion gearbox, on board the GY127. The inspection took place in Boulogne-sur-mer, France. The client authorised GBS to conduct the inspection, and find the cause of a fault in the hydraulic system of the gearbox.

For the description of the problem with the hydraulic system of the gearbox, Diagram 1 of Chapter 2 will be used as reference.

During the inspection, following observations were made:

- While using either the electric standby oil-pump or the mechanical oil-pump, lubrication oilpressure in pos. 43 is relatively low (0,4-0,8 [bar] respectively)
- The clutch control pressure in pos. 20 seems normal; circa 10,0-12,0 [bar] while both clutches are in disengaged (neutral) and 23,0-25,0 [bar] with either the forward or reverse clutch engaged.
- However, the clutch control pressure increases to 35,0 to 40,0 [bar] when both oil-pumps (standby and mechanical) are run simultaneously.
- The accumulating valve (pos. 30) was leaking oil, this was solved by replacing the o-rings inside the valve.
- The pressure gauge located directly after the accumulating valve (pos. 32) is broken.

It is of great importance to the overall condition of the gearbox , to solve the hydraulic problem.

The problem of insufficient lubrication pressure is believed to be caused by a defect in the overflow valve (pos. 35) and/or the accumulating valve ( pos. 30).

The high clutch control pressure - when running both pumps simultaneously - is most likely caused by a malfunction of the accumulating valve.

A faulty pressure gauge (pos. 32) prevents the lubricating oil pressure from being measured immediately after the pumps. But it also prevents the monitoring of the oil-pressure difference before and after the oil-filter and the oil-cooler.

Recommendations

To be able to solver the problem and avoid any consequential damage to the gearbox. It is recommended that the following steps are taken on short notice.

- The disassembly and overhaul of the overflow valve (pos. 35 )
- The disassembly, overhaul and recalibration of the accumulating valve (pos. 30 )
- Replacing the faulty pressure gauge (pos. 32 )