governor: no rpm adjustment when TEF20 engine loaded

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governor: no rpm adjustment when TEF20 engine loaded

Message par stephenk » 24 Avr 2011, 09:01

Hi John,

I read we could ask you when a problem seems "hard" to fix. So I would like to talk about mine and see if ever you had ideas about how to solve it?

I have a 1952 TEF tractor whose engine seems to work fine: good power, very little leaks, no overheating, great idling, fast engine speed response when I move the throttle lever. But apart from that, the engine speed drops under load (as any engine would do) but doesn't go back to it preset level automatically, which I guess should be the case under the governor action. The load doen't need to be heavy, if I drive in second or third gear, the engine speed drops compared to what it was set in neutral (1500 rpm for instance). Same thing when ploughing or whatever.

If I manually pull the throttle lever down, the engine revs up with no hesitation. And when I get to push the clutch pedal down, and as the load is taken of, the engine roars until I move the throttle lever up. It is not conveniant to use the tractor this way.

The governor membrane looks good, the vacuum pipe isn't blocked up (I guess the engine speed wouldn't vary well if not).


Image
Image

I don't know what else I could check (by the way, the "little stick" inside the governor, in the middle of the spring, moves towards the back of the tractor when the linkage moves to accelerate, is that the right way?)

Do you have any suggestion to help me?

Many thanks :) !

Stephenk
TEF 20 modifié étroit en restauration
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Message par john » 24 Avr 2011, 12:21

Hi Stephenk,
It does seem to be Governor related and there is possibly an air leak or air restriction and just to make sure you will need to check out the Governor as follows:-

To check the Injection Pump diaphragm for leaks without pulling it apart, first remove the side plate from the Injection Pump and also detach the vacuum pipe from the Diaphragm housing on the Injection Pump, pull back the Fuel cut-off (the engine stop) now put your finger over the vacuum pipe adapter into the Pump and release the Engine Stop control which should remain stationary, you can also check the Rack in the Fuel pump (just above the four springs you can see when you remove the side cover), any movement will indicate a leak at the Diaphragm or diaphragm housing. You can then test the vacuum pipe by having it connected at the Fuel Injection Pump end and disconnecting it at the Venturi which is at the inlet manifold end. Apply a finger to block the Venturi end of the pipe and release the Stop Control as before, if the Stop Control or the Rack in the fuel Pump moves then there is a leak in the pipe. When I say "release" the Stop Control I mean just lift it up off the catch position that holds it in the STOP position, do not push the Stop Control in as you need to be able to see it move in the test.
If there is no movement in either of these tests, just lift your finger off the pipe or the adaptor and it should then move if the vacuum is good. To reset the Rack in the Pump each time you want to carry out the test, simply pull out the engine stop control.
Any movement caused by wear at the cross-shaft through the Governor Housing on the Injector Pump can cause a loss of vacuum, usually there is enough Vacuum created to withstand a lot of wear at this point, but if the housing is visibly worn then it needs replacing, don’t attempt to run the engine in work until this is repaired because there will be no maximum engine speed governing and it may rev at a dangerous speed and if allowed to run unchecked it could explode as it will be running at far higher speeds than it was designed to do.
Before you re-attach the adjustable rod to the Fuel Pump Governor control lever, you need to adjust it to prevent any “surging” in the engine revs. Start the engine and set the throttle lever to idle, at this point the engine may be “surging” but take the lever on the pump lightly in your left hand and push it rearwards until the “surging” JUST stops, at this point you need to attach the adjustable rod to this lever, altering the length so that you can re-attach it without moving the lever from the point at which the “surging” JUST stops.
Before you refit the side cover to the Fuel Pump, with an oil can, squirt some clean Diesel engine oil onto the springs and rack, open the tap on the side at the bottom of the Pump and allow the fuel/oil mixture to drain until there is just clean oil running out, then close the tap and replace the side cover. This should be done every month.
If the Diaphragm does require changing then the vacuum chamber requires removal, this is held on by four small screws, one at each corner. Once the cover is removed you can easily get at the Diaphragm to detach it from the Injection Pump. When re-fitting the vacuum chamber, do be careful to get it sitting squarely onto the Injection Pump and tighten the screws slowly and evenly, failure to do this may allow an air leak.
The Diaphragm is CAV part number 7034-19A
**You can also check the Breather on top of the Diaphragm housing as this can block up over a period of time and we have had a couple of these recently, so maybe that is worth looking at as well. (this is the domed cup toward the rear of the Pump on the top) You may find that when you remove the Side Plate, the Governor will start to work, this confirms that it is the Breather that is blocked or restricted. You should also make sure that the throttle link is attached to the Pump as this controls the Governor too.

If you check this and then let me know if it is OK, there is usually very little goes wrong with these governors apart from air leaks, but the tests will show them up. You can email me direct on fergusontractors@hotmail.com as a lot of information is too long to send on here and some of it has pictures as well to help describe it ....John

Hi John,

I read we could ask you when a problem seems "hard" to fix. So I would like to talk about mine and see if ever you had ideas about how to solve it?

I have a 1952 TEF tractor whose engine seems to work fine: good power, very little leaks, no overheating, great idling, fast engine speed response when I move the throttle lever. But apart from that, the engine speed drops under load (as any engine would do) but doesn't go back to it preset level automatically, which I guess should be the case under the governor action. The load doen't need to be heavy, if I drive in second or third gear, the engine speed drops compared to what it was set in neutral (1500 rpm for instance). Same thing when ploughing or whatever.

If I manually pull the throttle lever down, the engine revs up with no hesitation. And when I get to push the clutch pedal down, and as the load is taken of, the engine roars until I move the throttle lever up. It is not conveniant to use the tractor this way.

The governor membrane looks good, the vacuum pipe isn't blocked up (I guess the engine speed wouldn't vary well if not).





I don't know what else I could check (by the way, the "little stick" inside the governor, in the middle of the spring, moves towards the back of the tractor when the linkage moves to accelerate, is that the right way?)

Do you have any suggestion to help me?
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Message par stephenk » 24 Avr 2011, 13:05

Thanks John for your prompt answer. Up to now I thought air leaks could only cause the engine to run too fast, for a weak vacuum. I will check all that again and send you an email.

Have a nice afternoon,

Stephenk
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Message par stephenk » 05 Mai 2011, 08:40

Bonjour à tous,

Je vous donne des nouvelles de mon soucis, et en plus ça pourra peut-être servir à l'avenir même si ce cas ne semble pas fréquent:

Mon problème a été réglé avec l'aide précieuse de John. La membrane, la tuyauterie, la dépression étaient bonnes, alors que longueur de la tringlerie, le réglage du ralenti et du régime maximum étaient à revoir. La position du levier sur le corps du régulateur était bien trop en arrière, ce qui comprimait le ressort et faisait sortir le poussoir de stabilisation du ralenti bien au-delà de ce qui était nécessaire, empêchant le libre mouvement de la membrane une fois le moteur hors ralenti. Mes conclusions quant à la mécanique du problème:

- the governor lever was set too much rearwards by the previous owner
(le levier du régulateur avait été positionné trop en arrière par le précédent propriétaire)

- this made the spring loaded plunger stick out frontwards and exert too much pressure on the diaphragm.
(cela a comprimé le ressort faisant sortir le poussoir de stabilisation du ralenti, ce dernier exerçant alors trop de pression sur la membrane)

- this action injects more diesel and accelerates the engine > the idling speed was high > a higher vacuum was necessary to pull the diaphragm + spring loaded plunger rearwards to lower the idling speed > the throttle stop was completely shut to create this high vacuum
(cela augmente l'injection de diesel et accélère le moteur, c'est pourquoi les réglages de ralenti et de régime maximum ont dû être modifiés pour pallier le mauvais réglage du levier du régulateur)

- the governor couldn't maintain a constant engine speed as the plunger was certainly in constant contact with the diaphragm and it was not designed for that
(le régulateur ne pouvait pas jouer son rôle de maintien du régime car le poussoir était constamment en contact avec la membrane. Ce n'était pas conçu ainsi.)

- the plunger is set just right to damp out any surging at idling speed, and now it doesn't touch the diaphragm anymore at higher speed
(J'ai alors repris tous les réglages, et à présent, le poussoir est réglé pour amortir simplement les oscillations de la membrane au ralenti. Le poussoir ne touche plus la membrane à un régime supérieur - d'où le rôle du levier couplé à la manette des gaz, il entraîne un mouvement vers l'arrière du poussoir à l'accélération)

- the governor does fully his job now.
(le régulateur joue pleinement son rôle à présent)

Merci encore à John!
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Message par ponyman » 06 Mai 2011, 08:12

Merci John et merci Stephenk pour ces précieuses indications 8)

Si j'étais un poil exigeant en pensant à tous ceux à qui ça pourrait servir, je te demanderais bien une procédure complète de réglage :oops:
Quelle(s) cote(s) respecter pour cette fameuse tringlerie ?
Avec un petit schéma peut-être ? :oops: :wink:
Petit griz ou rouge (et des fois un coup de blanc)

Le soleil et le bois pour énergie http://www.marcenr.fr
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