1950s Atco sprocket removal advice.

[hortiman]

Can anyone tell me if there is a secret to removing the drive sprocket from the roller drive on a 1950s 14″ Atco 2stroke lawnmower. All other chains, sprockets etc removed with ease, but cannot shift the nut which appears to hold the sprocket on the shaft. All nice and clean and oily so no rust. Do I use brute force or is there a magic solution ?

[andyfrost]

Chris , memory isn’t what it was , but I seem to recall that you simply undo the nut (left hand thread) and the sprocket pulls away by hand.

Andy.

[hortiman]

Thank you Andy, perhaps an extra weetabix and a longer bar !

[wristpin]

Chris , memory isn’t what it was , but I seem to recall that you simply undo the nut (left hand thread) and the sprocket pulls away by hand.

If anyone has an illustrated parts list and the end of the cutting cylinder looks to be splined or keyed it is likely that the above is correct.

[hortiman]

This is the little joker I have been trying to remove . I just cannot believe how much effort, heat and bashing this has put up with and not let go.. Tried left hand thread followed by right hand. Looking at the ratchet teeth on the drive release, you would think that it needed to be right hand thread, otherwise the nut would be loosened by the roller turning, or am I wrong? will have to use an impact driver in desperation.

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[wristpin]

NO don’t attack it with an impact driver, damage it and there’s no going back.
Am I right in thinking that as it is shown in your image the sprocket is free to turn ( not connected to the roller) and that the ratchet is part of, or fixed to the sprocket ?
If that is so, please post an image of the parts that you have already removed from that area. Preferably a better quality image.
I believe that the hexagonal sleeve is splined to the roller shaft and will draw off , possibly with some gentle levering from behind the sprocket. Any levering should be done from as near to the centre as possible to avoid distorting it, but a look at what you have removed will help to establish if that is so.

[wristpin]

I’m now looking at your image on the PC which is a lot clearer than on the ipad when I did my last post. By the looks of it the ratchet is part of the sprocket – or at least fixed to it. It certainly leads me to believe that the hex component will be either keyed of splined to the roller shaft and will draw off. Unfortunately the only parts books that I can find for that era show a slightly different design of ratchet and as far as I can see the OLC archive does not show your design either.
I suggest getting a couple of pry bars behind the sprocket and try levering it away from the side plate / roller. However if it doesn’t show signs of moving before the sprocket starts to distort, STOP.
Do post an image of the parts that you have removed – presumably the “other half” of the ratchet / dog clutch and what ever holds it on.

[hortiman]

Thank you for your input Angus, I will take some better shots as you have recommended when in the barn, but have family down at the moment, I understand what you are saying about the possibility of drawing it off the roller shaft, that method escaped me, yes you are correct the big sprocket is free along with the ratchet that releases the drive to the roller. I will check and report back. Thanks again for your help.
Chris.

[wristpin]

Fairly certain that pulling the sleeve and sprocket off is the way to go. Atco used a similar system on cutting cylinder drives right through to “modern” Atco 24s. Unless one knows, that hex sleeve just invites the application of the biggest ring spanner in in the box and I’ve seen them actually twisted. I’ve got a few damaged ones that I use for driving cylinders on the grinder.

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[hortiman]

Thank you for your wise words Angus, I will post the result very soon.
Chris

[hortiman]

Thank you Angus saving the day ( and the sleeve) 5 minutes and a pair of tyre levers and the job was done. Thinking ahead, does anyone know which green would have been used in the 50s ? is it mid Brunswick or a special Atco mix ?

[wristpin]

That question crops up quite often but I’ve yet to see a definitive answer. One issue is that back in the day when Atco service branches offered a full winter service it included a strip and repaint. That repaint would, I suspect, be the green that was in use at the time; not necessarily the one that it left the factory with.
If you are happy with the unfazed green from inside the chain case or under a handle bar grip, get an automotive paint supplier to scan it and make some up.

[wristpin]

Re my earlier post on paint – please read un-faded, not unfazed !!!

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