Lister Marine Gearbox settings

Hi there!

I have just rebuilt a small boat which has a Lister SL1 single cylinder air cooled diesel for motive power. The engine is coupled to a Lister SL3 gearbox (Forward / Neutral / Reverse) and then direct drive to the prop. The gearbox has been rebuilt using only the exploded parts diagram as a reference. My problem is that engaging reverse causes deadful granching noises, a few reverse revs of the prop but quickly drags down the engine and would stall it if allowed.

The gearbox is fairly simple and is, I'm fairly sure, reassembled in the right order.

My question to the group is, does anyone out there have knowledge, or a manual to refer to, to check the setting of the large nut on the final output flange?????

At the moment its done up tight. One suggestion has been made to back this nut off and use it to set a clearance setting on the ahead clutch. My fear is that this would introduce some end float into the shaft which may cause damage to the bearings. Before I go ahead to giving it a try it would be helpful if I could get confirmation of what my advisor admits is a faint recollection of a distant memory?

Any help would be appreciated, or if you don't know, but could refer me to a man that might, I will follow up on any leads.

Regards to all Stu Knowles Doncaster

Should perhaps say that vintage engines are not my subject so don't hesitate to suggest the obvious, it's probably news to me!

Reply to
stuart knowles
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hi stu you have got something wrong in the box. the flange nut should be tight. the sun and planet gear wheels are always engaged but reverse only operates when the outside body is stopped by the brake band. it sounds like there is something wrongly assembled. regards keith

Reply to
Keith Temple

Hello Keith, Thank you for your reply. I was actually hoping that you would say the opposite, but what you have said confirms that it is unlikely to be a good idea to back the nut off and use it as an adjuster. As you rightly say, the gears are in mesh all the time, as gearboxes go its about as simple as could be but its also clearly very unhappy at the moment and I am at a loss to identify exactly where the problem lies. I have had it all out again once and double checked everything.

The only thing that makes me lean towards the 'clearance' idea is that the adjuster for the 'ahead clutch' is, at the moment, right at the extreme end of its threads. When the nut is backed off, it works correctly in the mid range of its adjustment, which sort of attracted me to think that there was something in it.

I'm going to take an other look at it tomorrow. For the sake of trying it I think that I will have to test out the theory of using the nit to adjust a clearance setting and cautiously try it.

Thanks for taking the time to reply regards, Stu k

Reply to
stuart knowles

You talk about an SL3 gearbox. is this a box from an SL3 engine, or is that a lister gearbox designation (which I don't know)?

The usual Lister mechanical box for small engines was the LM100.

If it's off an SL3, I'm just wondering if the rotation of the two engines is the same? I can't see any reason for the LM100 boxes being 'handed', but you never know?

Is it definitely a mechanical box? If it's a so-called 'hydraulic' LH150 box from a different engine, then engine rotation i very likely the problem. Lister marine engines were usually the opposite rotation to industrial versions, and if you've taken a box from a marine SL3 & put it on an industrial SL1, the oil pump will be turning the wrong way and so won't work :-( AFAIR ahead gear is a cone clutch engaged by springs in both the LM100 and LH150, the different mechanisms serve to *withdraw* the clutches against the springs. If you're trying to engage reverse whilst the ahead clutch is still engaged, then the engine and box will complain !! :-(



That sounds like a recipe for early failure of something :-(

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Reply to

Hello Tim Thanks for the reply

The engine is an SL1 single a/c diesel. The designation SL3 is taken from the brass plate on top of the gearbox which tells how to adjust the rollers inside for ahead & astern

I have seen part of a manual for the LM100 and it does appear to be very similar if not identical, I couldn't see any obvious differences. The engine runs clockwise when standing at the stern and looking forward

Definately all mechanical, Had it all to bits more than once. Oil circulation doesn't seen to be a problem

I think that the problem lies, not with the clutches as I first thought but with the sun / planet gears binding. Pulling the g/stick into neutral definately frees up the ahead clutch and disconnects the drive. Moving the lever into reverse should apply a brake band to the outside of the clutch drum and 'force' the drive via the sun / planet gears into reverse.

I have been taking another look at it today. Almost against my better judgement I have backed off the flange nut and it has freed up the gears and it seems to work OK albeit the gears are noisy. They are straight cut gears so I guess that they always will be.

I have taken one short test run and then left it until I get further info from somewhere(?!) don't know where.

The boat is an 18 ft 'double ender / header' brought back from a ruin. The main problem is that I have never seen it running until after the rebuild, so it hard to know whats 'normal' and whats not. I am trying to track down a former owner from several years back who might be able to say what it was like then.

I appeciate you taking the time and interest to reply, kind regards, Stu Knowles Doncaster

Reply to
stuart knowles

I am an ex Lister marine designer, although I have no direct experience of the lister boxes (before my time). I suggest you speak to Peter Thompson at Marine Engine Services Uxbridge, (sorry I don't have his number to hand).

Peter is just about the last person on the cut who has any spares or expertise regarding the lister boxes.



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-- Peter A Forbes Prepair Ltd, Luton, UK

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