Author Topic: gearbox layout  (Read 363 times)

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Offline saluki42

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gearbox layout
« on: 04 Aug 2020 at 11:20 »
Hi there I was wondering if anybody has any pictures of the internal layout of a 1934 600cc gearbox as the one that came as part of my jigsaw seems to have the internals of nearly two complete sets of gears and damaged shafts making it difficult to see what goes where. Also the cast in bronze bush like structure is this to act as plain bearings or should it house missing roller bearing units?

regards
Chris
aka mystified of Somerset

Offline Doug

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Re: gearbox layout
« Reply #1 on: 04 Aug 2020 at 14:35 »
Some pics here of the very similar Aero 4-speed:

https://www.douglasmotorcycles.net/index.php?topic=5595.msg20286#msg20286

-Doug

Offline saluki42

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Re: dismantling 1930's four speed gearbox - advice appreciated
« Reply #2 on: 04 Aug 2020 at 17:13 »
Thanks for that it makes things a lot clearer. Looks like I'll be ordering some bearings and other bits but the big problem is the main / lay shaft one end is for the sleeve gear and input the other, and I have two in my set, in one case terminates after a threaded section and the other continues on for about an inch and ends in a finer thread. any idea which is correct?

Chris

Offline Doug

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Re: gearbox layout
« Reply #3 on: 04 Aug 2020 at 17:53 »
Chris,

On the Aero the mainshaft pokes through the bearing, end wall, and then terminates with a thread for the kickstart ratchet (nut).

1936 Aero 600 4-speed:



My 1934 OW1 (ohv) is the same way; same gears in a different sheel turned 90 degrees and mounted up under the saddle).

There were some minor developmental variations to the 4-speed since it was introduced c1932. Perhaps the earlier version extended the shaft further? I would suspect that the ratchet pinion was then on the end of the layshaft, held off by a light spring, and capped by a nut. The earlier 3-speed had a kick start ratchet like that. The 4-speed as on my OW1 and Aero have a kickstart quadrant that is in constant mesh with the ratchet pinion. So the pinion is not on (and rotating with) the mainshaft, but floats co-axially on a idler post attached to the gearbox cover. The nut for securing this post can be seen externally on the end cover.

I do have a 4-speed trans for my 1932 Greyhound project, but not sure if the cover is loose that I could readily have a look. I'll have to dig it out first!

-Doug
« Last Edit: 04 Aug 2020 at 20:33 by Doug »

Offline saluki42

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Re: gearbox layout
« Reply #4 on: 04 Aug 2020 at 18:24 »
Hi Doug
That photograph looks like the end of the better of the two layshafts I have which is a relief unfortunately though I'm missing the outer cover, kick start ratchet and gear selector drum pinion. But on the bright side I now apparently have two complete sets of gears including 2 sleeve gears, 2 mainshafts and  2 selector drum assemblies.

Any other info would be greatly appreciated

Chris

Offline Doug

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Re: gearbox layout
« Reply #5 on: 04 Aug 2020 at 20:31 »
I found a incomplete trans I bought to fix the one for my 1932 Greyhound (GB/ prefix). It has the longer mainshaft.

1932, 4-speed:





If you had a hand-change model I think you would be able to use an outer cover and kickstart mechanism from a more common 4-speed 1936-38 Aero model. But the foot-change end cover is a different kettle of fish. That is going to be a bit of a challenge to locate. You might have to consider converting to hand-change. The foot-change was not cataloged after 1935.

-Doug






Offline saluki42

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Re: gearbox layout
« Reply #6 on: 05 Aug 2020 at 16:41 »
Hi thanks again for all of the help you mention if I had a hand change gearbox well that is what the machine came with as it is a 1934 model Z and not the 1935 model Z 'Wessex' which had a foot change. I have attached a picture of the only other 34 Model Z I have found which clearly has the hand change, all of the brackets and fitting on both tank and frame are for a hand change on my machine so that is me target for a long expensive rebuild.

Offline Doug

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Re: gearbox layout
« Reply #7 on: 05 Aug 2020 at 17:16 »
Chris,

Both the Z and Z1 of 1934 or 1935 could be had in either hand or foot change transmission. I recalled you mentioning in another post that your 'box was stamped for 1935 foot-change option (6Q/220), but forgot that you did mention that despite this it was configured in the hand-change guise. Just as well, the hand-change version will be slightly (!) easier to find, and the foot-change positive stop mechanism was not considered to be very good.

-Doug