JCB 3C MK2 shuttle Pressure

There were two models of the old shape JCB that that had shuttle shift,the early one was know as a TC,it had a manual transmission that had a high and low range,the shift levers were on top of the gearbox in the centre of the cab floor,the torque and shuttle pump was mounted on the back of the power steering pump on the right side of the engine,with that setup having the pump remote from the shuttle any place it could draw air it would so check that none of the lines have got damaged or are loose,check the suction strainer,the other model known as a Power Train had a Borg Warner shuttle,that is a self contained unit,the pump is internal and the shuttle has to be removed to access it,look under the machine,if you can see a propshaft between the axle and gearbox you got a Power Train,if you got a solid housing,axle and transmission all one piece you got a TC,both were good old workhorses.
AJ
 
AJ,

Good to hear from you, I believe I have talked with you before of this matter.

This tractor has the pump on the side of the engine and also operates the power steering. 4 speed gear box, no high-low.

The idea of it getting air into the system sounds like the problem, but have gone over this several times before and nothing. There are areas that are very hard to get to, loader, tractor frame, etc. but I will go over it again.

There are times that after having presure it will push air and oil out the vent which is between your legs at floor level.

I got my service manual and they spoke of Directional valve possibly the problem, not sure of that. When ever I start the tractor gear shift in neutral and shuttle lever in neutral.

I do have stupid question as no one seems to know, oil level on dipstick on full, when at temp, running, in neutral with pressure, or when cold not running?

Thanks, Bob.
 
You got a TC machine,that machine was the last backhoe that JCB built on a tractor base,it was only built for a short run,I forget what the filter setup was on them but it would be normal for it to have a suction strainer to stop anything getting to the pump,that pump has been known to siphon oil in from the steering pump section into the shuttle,hence the oil in the shuttle would rise so make sure the suction side has no restrictions,if it drives good when it does have pressure that says the clutches and torque are good,have a look at your manual regarding the direction valve,the manual should also tell you about the oil level,that pump is a PIA to RR,secure the loader in the raised position as a lot of struggling has to be done should you have to remove the pump.
Good luck
AJ
 
AJ,

I am attempting to send you a scan picture from the manual.

Bob.
a75087.jpg

a75088.jpg
 
Ok got the picture,#11 would be the suction filter,the plate under the shuttle would have to come off which means draining the oil,use a clean container so you can reuse the oil,when you know the strainer is clean and the suction hose good you would need to determine the pressure coming from the pump,the manual will tell you how,if the oil level has been rising it would be my guess that the pump is drawing in hydraulic oil from the steering section of the pump,the pump has two sections,one for the shuttle and the other for the steering,each has their own oil and it should not mix,the starting point is the suction strainer,
Good luck
AJ
 
AJ,

Had a little time to work on the jcb. Checked the suction lines best I, even put a little air pressure in tank to try to find leak, nothing. Let me back up a little, removeed plate and drained trans, cleaned screen, no blocked and changed filter, also no blocked. Put in fluid, still nothing reved motor several times and got it to come up to 150 and fell back to 20-25. Now I put a little air to tank, could find no leaks in suction lines. Did some more reading in manual and they speak of a Pressure Maintaning Valve or worn pump. I remember you mentioning that the power steering uses it's own fluid and could pass over to other side of pump, Power Steering still works fine no growls or anything of the like. Where would the storage tank be for the PS, I see nothing like that.

This Pressure valve sounds like a possibility, in the repair manual it states to replace if defective, not to rebuild. Got ahold of the JCB dealer and all he said was "You got a what" i asked ever so tackfully how old he was, 26 he stated, I'm thinking, my lucky day, but he did mention that they had some old microfish(sp) and would check into it, we'll see. Any idea of a part # on the pump of valve this may help getting him close. The pressure valve would be #7 in the picture, just a head of the direction valve. Also want to add, that for the few seconds I have pressure the shuttle works as it should both forward and reverse, It will lift the front wheels when it takes off, motor reved up to keep pressure up, then pressure falls back and tractor stops moving. Any help is excepted any number sure would be helpfull.

My numbers are 3C - 111923/3 ... JCB machine Ser.# 384B 202635 ... Tractor Ser. # 31425

Thanks agian AJ, Bob.
 
The power steering uses the main system hydraulic oil,the feed hose connects to the hollow frame of the machine that doubles as the hydraulic oil reservoir,look near the pump and you will see one of the hoses connects between the frame and the pump,if the seal between the two sections of the pump has failed it will be easier for the shuttle section to draw oil from the steering side than lift it from the shuttle,then of course the shuttle oil level would rise,if the oil is not rising in the shuttle it just could be the shuttle pump is worn and not making enough pressure,look at the pressure valve in case any o'ring on the body maybe gone hard and leaking,the machine is a bit older than 26,if I remember correctly it had a short run for about a year and I think that was 1978/9 making it over 30,you may have to bite the bullet and remove the pump,any hydraulic shop should be able to test it.
Good luck
AJ
 
AJ.

Do you think the pressure valve is still availible, possibly new old stock? I do have a shop that I think can check out the pump. I'm just thinking that the pressure valve would be the cheaper of the to to replace/overhaul.

Thanks again for your help.

Bob.
 
AJ.

Do you think the pressure valve is still availible, possibly new old stock? I do have a shop that I think can check out the pump. I'm just thinking that the pressure valve would be the cheaper of the to to replace/overhaul.

Thanks again for your help.

Bob.
 
If you have a dealer near you he can test the valve for you,I do not know if parts are still available from JCB, the shuttle was not made by JCB,see if you can id it maybe Borg Warner or the like.
AJ
 

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