LM100 or SL4 slipping in forwards

Here is something simple you can check on your LM100 or SL4 gearbox if it seems to be slipping in forwards.

Firstly, it shouldn’t slip. The gearbox has a pack of springs that hold the forward clutch in in the event of any failures, so a slipping box has to be one of two things – adjustment or clutch failure

With the top of the box off, you can check if it needs adjustment. I’m using my ex QEII lifeboat demonstrator as it’s easier to see:

 

 

 

On top is the operating shaft with the two adjustable rollers:

The forward roller pulls the forward clutch out of engagement against the springs, the reverse roller pushes the reverse band against the drum

With the operating lever forwards, check that there is clearance between the roller and the cam lever:

If there isn’t the roller needs adjusting until there is 1″ of free movement at the end of the operating lever when the gearbox is in forward (one inch of slop after the box goes into gear)

If there is clearance, and the box still slips, either the forward clutch has failed or is somehow not getting into engagement. Either way, the gearbox needs to come apart

We can supply parts for you to repair your gearbox yourself, or we would be happy to quote you for repairing it

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