Last week we were sent a couple of Woodward PSG governors in need of an overhaul.
They’ve been in constant use on a ferry for the last 16 years without ever leaving the engines and the whole exercise has highlighted what can happen if these vital assemblies do not have any routine maintenance.
Knowing the importance of effectively performing governors, the vessel owners had fitted new units but wanted the old units overhauled, so they could be kept as swing set units, ready to install when the others need overhauling.
On arrival to our governor bay, they were set up on our test rig to determine current readings before dismantling and inspection.
During these processes, internal damage was discovered; damage that was affecting the performance of the units and putting the engines at risk.
These are the types of issues found by our Woodward trained engineer:
- Both units had a different minimum speed and maximum speed when using the same degree of terminal shaft movement
- When run at full speed with no load both governors had too much movement in the output shafts, which decreased as load was added
- Extensive play in both vertical and horizontal directions indicating internal wear
- A wear step in each shaft and in the associated bush
- Wear in both pivot bushes and pins
- Wear on the droop pivot and on the floating lever
- Wear on the flyweight contact toes, altering the centralisation of the pilot valve and therefore the responsiveness
- Idler gear for running in one continuous rotation had worn on one side and there was also wear to the idler peg
- The main bushing is worn on the drive splines
- Wear step on the internal control port
- Speed adjusting internal lever fretted
These governors suffer from internal wear as they were supplied with engine oil containing small particles of carbon which act like lapping paste, wearing items quickly.
