Student gearbox problem

This topic has 9 replies, 4 voices, and was last updated 19 July 2017 at 16:22 by Nick_G.

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18 July 2017 at 15:52 #307748
Nick_G
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@nick_g
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Has anyone here actually stripped the gearbox of a Colchester student.?

There is an issue with it where one of the selector levers is stuck in position 1. – The owner says it was always stiff but gradually got stiffer until it is now jammed. It's an old machine that was used very little and had been left for considerable time in storage before he owned it.

Got the manual. But what I don't want to do is take the levers off, split the front of the gearbox (1st photo) and end up with a puddle of shafts, spacers, bushes and gears all over the floor.

So has anyone stripped one.? And is this a common issue at all with the Student.

Lever stuck at selection 1

Nick

Edited By Nick_G on 18/07/2017 16:13:02
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18 July 2017 at 15:52 #18589
Nick_G
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@nick_g
18 July 2017 at 15:56 #307749
NJH
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@njh
No pictures Nick – just some outlines where they should be.

N
18 July 2017 at 16:14 #307752
Nick_G
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@nick_g
Posted by NJH on 18/07/2017 15:56:47:

No pictures Nick – just some outlines where they should be.

N

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Okies. – Can you see them now.?

Nick
18 July 2017 at 16:29 #307754
NJH
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@njh
Hi Nick

That's fine now. I'm not able to help with your question I'm afraid – I did use one briefly! Hopefully someone in the know will respond now.

Norman
18 July 2017 at 18:28 #307780
JasonB
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@jasonb
Quite possible that the levers should stay on the shafts then when you pull the front off all the links and forks come away with the front panel
19 July 2017 at 09:31 #307833
Nick_G
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@nick_g
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Cheers Jason,

I bet that John Stevenson bloke has had one to pieces.

Nick
19 July 2017 at 09:36 #307834
JasonB
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@jasonb
Does not matter what he has had to pieces, it's if he got it back together without resorting to a welder that really matters
19 July 2017 at 10:53 #307848
KWIL
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@kwil
So it is Gear Bar 76714-0 and the gear it moves that is sticking. The Gear Selector shaft is ball mounted and the inboard end moves vertically between the various bars and slides horizontally to change the gear. eg 1 -> 2 etc. There appears to be one fork per bar, each fork slides the matching gear from left to right via central neutral point. The various "gear bars" are retained in position with the vertical plates but beware the right hand plate has balls and springs which act as detents to hold the selected gear in place. All that seems independent from the Gear Selector shaft and is fixed separately. The three levers [ABC], [RST], [VWXYZ] are retained to the casting shown in your second photo. All this is standard Colchester, my own M300 is very similar (except that the 1-8 gear selactor is a rotary input on the M300). If you take the front casting off, expect a lot of oil! Drain is on the left hand lower side.

If you think about how it would be built, each stage will be able to be set up so nothing should come away with the front as the shafts are clearly attached to the second casting.

OK for starters?
19 July 2017 at 16:22 #307875
Nick_G
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@nick_g
Posted by KWIL on 19/07/2017 10:53:09:

OK for starters?

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That's plenty for starters. Thank you.

Nick
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