Pulley with integral clutch

Slightly off topic but we have a 3 cylinder lister air cooled at work, it's

20hp and runs a wood chipper (american and originally petrol powered but converted by the importer). As it has become a bit old it's slow to start but performs well and doesn't burn oil.

One of the reasons it is slow to start is that it is permanently coupled to the wood chipping disc via a twin vee belt, with the vee belts removed it strats within 10 seconds on the colder days.

Apart from a more powerful starter motor it looks like the best option is to fit a clutch. The obvious thing is to have an idler roller tensioning the belts but this would involve extra levers and pivots. The other would be a clutch on the chipping disc which driven via a taperloc on a ~40mm (or imperial equivalent) shaft. There is about a 2:1 reduction in the belt drive at present. So is it possible to have a ~150mm twin groove pulley taperloc with an integral dog clutch? Then the engine can be started with no load, warmed up (OK not ideal from a wear point of view) and then restarted once the clutch is engaged?

Andrew Heggie

Reply to
andrew
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It might be more starightforward to fit a clutch to the engine, Listers did supply engines with clutches fitted. Unfortunately I threw out a TwinDisc clutch from a Lister SR2 just a few months ago, after tripping over it for over 15 years and occasionally offering it on various forums. There must be other examples kicking around somewhere.

Tim

Reply to
Tim L

I think the answer is to rebuild the engine, not mask the problem with a clutch...

Tim.

Reply to
Tim..

You may find that wear is reduced starting the engine under no load. If you start it under load, the forces on the bearing surfaces will be greater, and those bearings will be short of oil for a few seconds until oil from the pump arrives.

If it used to work fine, you might be better off rebuilding the engine as opposed to trying to fit a clutch. Otherwise you might fit a clutch and find out that soon you have to rebuild the engine anyway.

Does it have a "cold start" button which causes extra diesel to be injected when starting to increase the compression ratio and reduce the blow-by around the rings? Those things are pretty effective at improving cold starting.

Best wishes,

Chris

Reply to
Christopher Tidy

Can you fit a centrifugal clutch? That would allow starting off load and be fully automatic. Don't worry too much about the power as it will be starting the machine before any load is applied. Google for centrifugal clutch to read more. They're fitted to a number of smaller motorcycles, scooters and go carts.

John

Reply to
John

I have a spare one here, removed from a Douglas SV54. Probably not what the OP is looking for, it has a chaindrive cog and sits on a 1 1/2 inch shaft.

Reply to
crn

And before he does that I think the starter could do with a lock torque test to check its power - it maybe a stuck or worn brush and oiling the starter bearings. Over time the sintered bearings do dry out and a drop of oil works wonders for starting.

Reply to
Tony Brooks

You might consider a centrifugal clutch. That allows the engine to start off load but would automatically connect the drive as the speed rose. The power needn't be too big an issue as the chipper would be starting off load. Mind you, the chipper's I worked on had a large flywheel effect in their rotors requiring a high torque to accelerate them.

John

Reply to
John

This is an lpa3 and if a bellhousing with clutch and outrigger bearing were available that would be just the ticket.

I've read all the replies and we are considering refurbishing the engine (just rings and valve seats I hope), we have 2 donors for bits but the engine starts readily when not belted up. The engine is a retrofit by the importer as the chipper was designed to run with a petrol engine. As it has always been slow to start I think it a mismatch and should have been provided with a clutch, 14 years ago!

The centrifugal clutch is interesting if it would stand the power but it may mean the flywheel freewheeling for a long while after the engine has stopped. We do have a little 16hp machine that has a magnetic clutch but I worry about the robustness. Hence I thought a simple dog clutch built into the pulley looked reasonable if such things were available ( I have less than fond memories of such a device on a Suffolk Punch lawn mower but this was built into the centrifugal clutch).

Andrew Heggie

Reply to
andrew

Have you considered using a thinner oil in the winter? Modern engine oils are much thinner at low temperatures than their older equivalents and still seem to lubricate better.

John

Reply to
John

Reply to
Charles Hamilton

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