DB 1200 Selectamatic 1969

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Dspillett
Posts: 40
Joined: Sun Sep 03, 2017 2:13 pm
Location: Ireland

DB 1200 Selectamatic 1969

Post by Dspillett » Sat Jun 12, 2021 9:10 am

Hi folks,

I have a 1969 DB 1200 Selectamatic, and gear changes seem a bit tough to engage at times with plenty of grinding / crashing going on , other times it can be ok, is it normal or any ideas what could be the issue ? Further checks I could do etc, thanks guys

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ollek
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Location: South West Finland

Re: DB 1200 Selectamatic 1969

Post by ollek » Sat Jun 12, 2021 9:15 am

Reduce the engine speed, then press the clutch pedal fully down and wait for a further 2 to 3 seconds before you move the gear lever. It takes time for the heavy flywheel and gear box gears to stop.

Dspillett
Posts: 40
Joined: Sun Sep 03, 2017 2:13 pm
Location: Ireland

Re: DB 1200 Selectamatic 1969

Post by Dspillett » Sat Jun 12, 2021 9:32 am

Thanks Ollek

Working with her today will try to be more managed today on the gear changes and see how she goes, thanks again

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db2d
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Location: Monmouthshire

Re: DB 1200 Selectamatic 1969

Post by db2d » Sat Jun 12, 2021 9:48 am

These non-synchromesh gearboxes are not designed for on the move changes. It can be done only by experienced drivers. In the best interest for the gearbox it is advisable not to change on the move.

Dspillett
Posts: 40
Joined: Sun Sep 03, 2017 2:13 pm
Location: Ireland

Re: DB 1200 Selectamatic 1969

Post by Dspillett » Sat Jun 12, 2021 8:04 pm

Thanks db2d,

Had it on a bale handler all day today and tried the changing when stopped but still plenty of grinding , on the odd occasion it slipped in nice and clean but mostly it was grinding,

So tried a few experiments, on a very slight incline, with clutch pedal fully down, it was holding on the incline, if I knocked lever into neutral, tractor immediately rolled back freely, so that to me tells me that the clutch is not fully disengaging the drive between engine and gearbox, so what’s next steps guys?, try adjusting and then if not successful , split the tractor ? Any help / advice greatly appreciated

Tractor Tom
Posts: 51
Joined: Sun May 02, 2021 7:15 pm
Location: Suffolk

Re: DB 1200 Selectamatic 1969

Post by Tractor Tom » Sat Jun 12, 2021 10:41 pm

Does it have a hydraulic clutch? Is the master cylinder leaking internally? Have you checked the fluid level?

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ollek
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Location: South West Finland

Re: DB 1200 Selectamatic 1969

Post by ollek » Sun Jun 13, 2021 6:05 am

The problem can be faulty adjustments, oil on clutch plate or worn clutch lever pin holes in the pressure plate lugs. The problem is NOT with the fluid level as the clutch (and brakes) did not have hydraulic control for clutch and brakes in a 1200. The hydraulic control started to be used when the Q-cab and the Sekuras S 74 cab started to be fitted at the asembly line in 1976.You will have to split the tractor if the external adjustments do not work.

Tractor Tom
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Location: Suffolk

Re: DB 1200 Selectamatic 1969

Post by Tractor Tom » Sun Jun 13, 2021 2:51 pm

I see, Dspillett did say any help appreciated :wink:

Dspillett
Posts: 40
Joined: Sun Sep 03, 2017 2:13 pm
Location: Ireland

Re: DB 1200 Selectamatic 1969

Post by Dspillett » Sun Jun 13, 2021 9:48 pm

Thanks all, was talking to an old DB mechanic today and he said it could be the flywheel bearing, so it looks like a split is on the cards :( , but will check those adjustments as well Ollek, thanks all

Rex
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Joined: Mon Jun 14, 2021 4:25 pm
Location: Cornwall

Re: DB 1200 Selectamatic 1969

Post by Rex » Wed Jun 16, 2021 5:20 pm

As db2d said and on page10 of the 1200 owners manual,
"the transmission is of the sliding gear type and gear shifting while in motion, must only be undertaken by an experienced driver"
The best I can manage is changing up between 2nd and 3rd on my 1200, even then it's 50/50, without grinding etc.
I only do a few weeks a year of topping with mine, so gear changing is not really an issue, I guess it depends if the tractor does what you want..
Certainly if the clutch is dragging, that needs to be addressed.
Ollek made the point about waiting a couple of seconds after depressing the clutch before trying to engage another gear, so you could check the adjustment of the 'clutch stop' (p65). I'm not sure if my clutch stop works either, but I try not to worry about it. I definitely won't be splitting the tractor to fix it.
Hope this helps,
Rex

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rid54
Posts: 278
Joined: Mon Oct 13, 2014 8:20 am
Location: Vallentuna, Sweden

Re: DB 1200 Selectamatic 1969

Post by rid54 » Wed Jun 16, 2021 9:11 pm

Doesn't this model have the clutch brake? This unit brakes the gearbox input shaft if I understand correctly, when you press the clutch pedal. This is to facilitate the engagement of gears from a standstill - you don't have to wait for the spindown of the driven plate etc. It does, however, have side effects, including difficult gear change with a moving tractor, and the fact that the tractor will "hang" on the clutch brake with a gear engaged, making it difficult to disengage the gear, even at standstill sometimes. If your tractor has this feature, I suppose there are adjustment instructions in the manual.

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ollek
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Re: DB 1200 Selectamatic 1969

Post by ollek » Thu Jun 17, 2021 11:09 am

Yes, David Brown 1200 had a clutch brake when the tractor left the factory some 50 years ago. Unfortunately near all of the brakes are worn or broken and not working any more and new parts are not availabe. I recomend to contact David Brown Parts and ask them if they can help if a clutch brake is needed. Please see "Clutch stop" on page 24 in the following link https://drive.google.com/drive/folders/ ... qaUCZbGaJA

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rid54
Posts: 278
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Location: Vallentuna, Sweden

Re: DB 1200 Selectamatic 1969

Post by rid54 » Thu Jun 17, 2021 5:01 pm

Dspillett wrote:
Sat Jun 12, 2021 8:04 pm
Thanks db2d,

Had it on a bale handler all day today and tried the changing when stopped but still plenty of grinding , on the odd occasion it slipped in nice and clean but mostly it was grinding,

So tried a few experiments, on a very slight incline, with clutch pedal fully down, it was holding on the incline, if I knocked lever into neutral, tractor immediately rolled back freely, so that to me tells me that the clutch is not fully disengaging the drive between engine and gearbox, so what’s next steps guys?, try adjusting and then if not successful , split the tractor ? Any help / advice greatly appreciated
As has been mentioned by ollek, things wear out with time, but the situation you describe can be the effect of the clutch brake. With clutch pedal down, the engine should be disengaged from the drive train, but the gearbox input shaft is held by the clutch brake. The tractor will not roll in a slight incline/decline, if a gear is engaged because the input shaft brakes the gearbox (and the tractor). If the box is knocked out of gear, the tractor will be freed.

The clutch brake has an adjustment. The idea is that when the pedal is down enough to free the engine, the brake should engage the input shaft. If you only depress the pedal slightly, the brake may not engage enough to do its job, and the gears will crash when putting the tractor into gear from standstill.

You could try this:
At standstill and engine running, depress the clutch and try to engage a gear. If the input shaft hasn't stopped, you'll notice. Wait a bit, try again. If there is still crashing, try to depress the clutch pedal a bit more, see if that helps the situtation, i.e. it becomes easier to engage gears.

Another test: Drive in low gear in a very slight decline. Depress clutch and try to note if the tractor seems to want to stop. If the clutch brake is operational, there will be a slight braking noticeable, while the engine still is running freely. If the clutch is not releasing properly, the tractor will move on at constant speed, if the clutch is releasing and the clutch brake is not operating, the tractor will gain speed in the decline, with engine at constant speed.

These are rough tests that may say something about your clutch and/or clutch brake. I just tried them myself with an 880 selectamatic livedrive that luckily has been well kept by its previous owner and functions as it should.

Dspillett
Posts: 40
Joined: Sun Sep 03, 2017 2:13 pm
Location: Ireland

Re: DB 1200 Selectamatic 1969

Post by Dspillett » Wed Jul 07, 2021 10:15 pm

Thanks very much for those suggestions , will try those few rough tests, and let you know how it goes

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