I dont have a WSM for your tractor so I have not researched that particular system but main system pressure is 2500 PSI
Ostensibly the function of the PTO pressure regulator is to reduce that pressure to 350 PSI.
Dan
L4200 pto problem
- Thread starter Gjackson
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Ostensibly the function of the PTO pressure regulator is to reduce that pressure to 350 PSI.
Dan
Exactly and the regulator is maxed out but only producing 350psi, so my thought was i need to shim pump to get presure up to 2500 (presuming it's low at this stage) and then hopefully the regulator will have enough range then to get me to 370 psi.
North Idaho Wolfman
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Very very unlikely the main pump is anywhere near 350psi, and if for some wild reason it is then there is a serious issue.
Ah ok fair enough.
So maybe let's go back to basics. My pto was intermittent, I found gearbox oil was very low so I topped it up. Pto works but has no power to turn anything and presure was found to be 250 PSI. Its now 350psi but still doesn't have enough power, although better. Is the only way to increase this up to 370psi with the allen screw on the regulator on the top of the external pump on the front right of the engine?
Without a WSM I cant speak to the specifics of that tractor but based on these comments it sounds like the PTO is fed by the PS pump. If so the implement pump is totally out of the picture.
Do you have the WSM? If so have you read the description of how that portion of rhe hydraulic system operates? Have you done the PS and PTO tests described in it?
Dan
Basically I had the tractor at a local independant and they have just said it can only be the pto clutch which is thousands to have changed, so I wanted to be 100% sure before committing to anything. I do have the manual and i now have the adaptor to connect my guages up so I'll have a play shortly. I am an old school car mechanic so this is just a little different to me. Thanks.
I just looked at the WSM for the Grand L40. It appears to use the same PTO design as your tractor and the hydraulic PTO clutch is supplied by the PS pump and pump mounted regulator valve. The clutch is operated by s PTO clutch valve mounted on the rear housing. Operator control is via a lever snd cable linkage.
There are numerous possuble causes including a malfunction of the PTO valve for your symptoms. I would like to know the reasoning the indie used to reach their conclusion..
I suggest you break out your WSM and start running the PTO tests described in it before spending big bucks on a new clutch pack.
Dan
Well their theory was that the pto test port pressure was high enough and the pto was turning but with no power. I must admit I am a bit dissapointed in them. So I have now got my test port to read 370psi So im going to hitch up my little chipper and see how much power I have.
The pto valve... I'm presuming that's just the lever assembly that the cable attached to in the side of the gearbox?
I will print off some pages of the wsm but I didn't see much more tests in there tbh. Thanks.
The PTO valve on the GL40 is more than a lever. The transmission mechanism section of the GL40 manual goes into considerable detail on how the the PTO clutch and valve work. The servicing section has diagnostics.
As usual the organization of the manual makes finding every thing relevant to your needs an exercise.
Dan
Ha, yeah and I think that's the problem I'm having. I was thinking of printing it and getting it bound so I can actually flick through it. Ok appreciate your help, I will do some more reading tonight. I mean correct pressure reading at the pto test port is a good start.
Ok so I've just hitched my little chipper up and it literally spins at 104 rpm. Bearing in mind I now have 370 psi at pto test port, what is the next test you would be doing?
Thanks
I would be reading the mechanism section in the manual looking for insight into how pressure is applied to the clutch.
Dan
Mmm, I'm going through the manual now but I'm getting confused between pto and gst as there is a lot of info on gst but not a lot on pto. I know the two systems are combined to a degree but I dont want to be going down the wrong route. As you say I need to understand how the presure gets to the pto pack.
I've been following along here, somewhat blindly since a WSM isn't readily available. Also, it might help to know which transmission you have, shuttle or glideshift.
First, based on the shuttle shift parts diagrams, you have a duplex (or tandem) pump, so your implement system is completely separate from the steering and PTO system, as TheOldHokie said.
Regarding pressure testing; I'm not clear on where you are testing. Are there test ports on the regulator/priority valve and on or near the PTO valve? If you could post the PTO valve diagram in the M section of the WSM, it might help. Someone with a BX had a similar problem several years ago. The valve has (yours may have) some metering holes to prevent abrupt clutch engagement. But if you have clutch pack or seal ring leakage, it limits the pressure the clutch sees. If you could post that diagram, it might help us make recommendations.
I have to admit with the history of low clutch pressure and slippage, I'm afraid you're looking at a clutch overhaul, but let's eliminate the easy items first.
First, based on the shuttle shift parts diagrams, you have a duplex (or tandem) pump, so your implement system is completely separate from the steering and PTO system, as TheOldHokie said.
Regarding pressure testing; I'm not clear on where you are testing. Are there test ports on the regulator/priority valve and on or near the PTO valve? If you could post the PTO valve diagram in the M section of the WSM, it might help. Someone with a BX had a similar problem several years ago. The valve has (yours may have) some metering holes to prevent abrupt clutch engagement. But if you have clutch pack or seal ring leakage, it limits the pressure the clutch sees. If you could post that diagram, it might help us make recommendations.
I have to admit with the history of low clutch pressure and slippage, I'm afraid you're looking at a clutch overhaul, but let's eliminate the easy items first.
I presume it's also worth checking the relief valve setting in case it's relieving straight after pressurising if that makes sense. Wm says relief should be set at 412-427 psi or am I barking up the wrong trees?? I'm getting a bit stumped i think
On the GL40 series the same PTO system is used with all the different transmissions. The only difference noted is the source of the hydraulic pressure.
On the manual and GST models pressure comes from the regulator valve mounted on the PS pump.
The HST machines do not have a regulator valve and pressure comes from the retrun side of the HST charge pump.
Dan
Hard to see how you would get 370 PSI at ths test port if the relief was unloading at a lower pressure but check it anyway.I presume it's also worth checking the relief valve setting in case it's relieving straight after pressurising if that makes sense. Wm says relief should be set at 412-427 psi or am I barking up the wrong trees?? I'm getting a bit stumped i think
Dan
Hi, thanks for your reply... mine uses a clutch but has 4 gears on gearstick and forwards/backwards on the steering column. Interesting though as I thought you didn't need to depress the clutch, so presume mine is shuttle box? I'm not 100% sure which bits of manual you are looking for. Im sorry tractor mechanics are new to me, I do old VW's
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North Idaho Wolfman
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Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
The next thing you can do is pull the clutch control valve and check it completely.
