JD-40T 1953 Dual Hydraulic system fail

[Russ JD40T]

I have a JD 40T 1953 with the dual cylinder Touch-o-matic hydraulic system. Yesterday while mowing with a bush-hog I hit a large rock shearing the pin. I tried to raise the mower with the hydraulics moving the the RIGHT control lever backward. The LEFT control lever was forward. It did not raise. I discovered that the Dual cylinder selector lever was in to the rear position and the lift arms were locked. Yikes!
I read in the Operator's manual (pg 28) "CAUTION: Do not under any circumstances place right lever to rear and attempt to operate the system with the left lever while cylenders are parallel and Load-and-Depth Control is set to operate. This may cause damage to the unit."
Has someone else made this blunder?

What is the probable damage since the hydraulics will not raise the implement with any combination of controls?
Where do I start to troubleshoot this fail?
All help is appreciated.

 

[crsutton81]

I have a JD 40T 1953 with the dual cylinder Touch-o-matic hydraulic system. Yesterday while mowing with a bush-hog I hit a large rock shearing the pin. I tried to raise the mower with the hydraulics moving the the RIGHT control lever backward. The LEFT control lever was forward. It did not raise. I discovered that the Dual cylinder selector lever was in to the rear position and the lift arms were locked. Yikes!
I read in the Operator's manual (pg 28) "CAUTION: Do not under any circumstances place right lever to rear and attempt to operate the system with the left lever while cylenders are parallel and Load-and-Depth Control is set to operate. This may cause damage to the unit."
Has someone else made this blunder?

What is the probable damage since the hydraulics will not raise the implement with any combination of controls?
Where do I start to troubleshoot this fail?
All help is appreciated.

I had a early 420 that I recently sold that I mistakenly did the same thing. I don't have the books for this hydraulic system anymore as I let them go with the tractor, but I would rig up a hydraulic pressure Guage and check to be sure the hydraulic pump hasn't sheared anything and is still pumping to start with. There is a designated test port seems like on the left side that one can be installed to test by. I want to think when I made my boo boo, it stuck a relief valve open on the inside rear below the cylinder bores for the rockshaft. The seat, rockshaft housing, and plumbing had to be pulled to expose the 2 valves, as each cylinder has one. Once it gets fixed, may I suggest to take a zip tie and tie the lever that doesn't need to be moved in the correct place to prevent this from happening again.

 

[crsutton81]

I had a early 420 that I recently sold that I mistakenly did the same thing. I don't have the books for this hydraulic system anymore as I let them go with the tractor, but I would rig up a hydraulic pressure Guage and check to be sure the hydraulic pump hasn't sheared anything and is still pumping to start with. There is a designated test port seems like on the left side that one can be installed to test by. I want to think when I made my boo boo, it stuck a relief valve open on the inside rear below the cylinder bores for the rockshaft. The seat, rockshaft housing, and plumbing had to be pulled to expose the 2 valves, as each cylinder has one. Once it gets fixed, may I suggest to take a zip tie and tie the lever that doesn't need to be moved in the correct place to prevent this from happening again.

Well I told you partially wrong. I still have the repair manual for it. In the 2nd picture, part number 15 is a relief / bypass valve. Both cylinder bores have 1 each. If they ever hang open for whatever reason, it will not work at all. After reading my notes, you might get lucky and disconnected the metal pressure inlet line to start with, that feeds into the unit on the left side, by the oil filler cap. Once it's removed from the TOM unit, apply short sharp blast of compressed air into the unit itself. With the lucky part in play, it can dislodge the stuck valve ( s) without having to dive deeper into the unit. The 3 pt lift arms should rise and fall back down again when this is done, with the control levers set as they should be for operation mode. Hope this helps.

 

[Russ JD40T]

crsutton81

Thanks for your spot on advice. I'm sure going to zip tie that inboard lever. I'm not needing the dual independent capability. I have the JD-201 shop manual. I'll follow your lead on checking the pump pressure before the TOM. If the pump is not pumping, am I correct to assume the Woodruff key (Fig JD890 part #4) has sheared?
Then I'll proceed to try my luck with dislodging a stuck relief/bypass valve with compressed air. Just a couple of questions. Did you completely drain the hydraulic fluid (30W ND) before applying compressed air? Exactly where did you apply the compressed air?
Much appreciation,
Russ

 

[crsutton81]

crsutton81

Thanks for your spot on advice. I'm sure going to zip tie that inboard lever. I'm not needing the dual independent capability. I have the JD-201 shop manual. I'll follow your lead on checking the pump pressure before the TOM. If the pump is not pumping, am I correct to assume the Woodruff key (Fig JD890 part #4) has sheared?
Then I'll proceed to try my luck with dislodging a stuck relief/bypass valve with compressed air. Just a couple of questions. Did you completely drain the hydraulic fluid (30W ND) before applying compressed air? Exactly where did you apply the compressed air?
Much appreciation,
Russ

Yes, a sheared keyway on the pump drive would be my first guess if no pump action. If anyone else reading this sees different, please correct me as it's been years and a lot of water passed under the bridge since I was last into the pump portion on one of these tractors. As to testing....I did not drain the oil from the unit. The only thing I did was unhook the ( maybe 1/2 ?) Steel line coming from the pump at the point it screws into the TOM unit. Once it was rotated out of the way, I took the blow gun and applied air pressure at this connection on the unit itself. I was fortunate enough to dislodge a stuck valve 1 time with this method, but it kept reoccurring. The fix for me was to replace the bypass valves. On another note, I assume you have ample oil level in the unit to the point it run out the rear check petcock ? Another thing is on the suction line from the pump to the reservoir, there are a couple of unions that have a rubber packing in them. They can draw air and prevent the pump from operating as it should. Just some random things that I ran across while I owned the 420 I had.

 

[Russ JD40T]

crsutton

All you advice is greatly appreciated!

Russ

 

[Rusty wheel]

I have a JD 40T 1953 with the dual cylinder Touch-o-matic hydraulic system. Yesterday while mowing with a bush-hog I hit a large rock shearing the pin. I tried to raise the mower with the hydraulics moving the the RIGHT control lever backward. The LEFT control lever was forward. It did not raise. I discovered that the Dual cylinder selector lever was in to the rear position and the lift arms were locked. Yikes!
I read in the Operator's manual (pg 28) "CAUTION: Do not under any circumstances place right lever to rear and attempt to operate the system with the left lever while cylenders are parallel and Load-and-Depth Control is set to operate. This may cause damage to the unit."
Has someone else made this blunder?

What is the probable damage since the hydraulics will not raise the implement with any combination of controls?
Where do I start to troubleshoot this fail?
All help is appreciated.

I think you should first make sure the pump is pumping oil. If it is then by all means follow the great advice you have been given. I rebuilt the duel hydraulic system on my 40 because I took it to a plow day and the field turned out to be a rock garden. the load control kept jerking the plow up and down until it sheard the roll pins in the rock shaft and part of the pin went through the pump and sheard the bolts in the coupling driving the pump. I backed the bolt out that prevents the load control from working. It works great now and I will never allow the load control to work again.