reverser oil flow question

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oljoe
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reverser oil flow question

Post by oljoe » Thu Mar 29, 2018 2:21 pm

I have a straight 450 that has had a problem for some time that I can’t get figured out. The transmission pump pressure will come up when first started to 130-150 psi. I can shift the reverser from forward to reverse a couple of times and the tractor will move both directions. The pressure starts dropping with each shift and then it won’t move. If I shut it down and let it sit for awhile it will go again then the same thing happens.
The problem started when I had a leak in the transmission front cover and I attempted to fix it. The gasket between the cover and transmission was removed and replaced with silicone. The clutch pump pressure blew out the silicone where the pressure enters the transmission case from the front cover. I made a gasket to replace the missing one. I think that I may have sent a piece of gasket material into the valve body when I made the new gasket.
I have removed and cleaned the accumulator housing and valves, the clutch valve and the shift valve. There was no debris found in any for the bores or valves. All moved free and had very little wear.

Now here is the question. Where would the oil flow direct a small piece of gasket material and could it cause the symptoms that I have described?
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oljoe
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Re: reverser oil flow question

Post by oljoe » Thu Apr 12, 2018 9:51 am

A friend and I have studied the tech manual trying to figure out the oil flow and where a piece of gasket material would cause a problem. We came up with a theory that a small piece of material (think a crescent moon shape) would flow through the oil pressure regulating valve, oil cooler bypass valve, clutch valve and through a check valve (ball valve) that is only in operation when the clutch pedal is depressed. The oil flow would then send foreign material to the needle valve that restricts the flow for softer shifts.

We theorized that the piece of gasket material could stop the oil pressure and flow at the needle valve and plug the passage to the clutches. With the oil being blocked the regulating valve and cooler bypass valve would open dumping oil through the cooler and back to the case. The pressure check point looks like it is at the bypass valve in the accumulator housing and downstream of the needle valve. If a plug occurred at the needle valve there would not be any pressure at the check point. We think that after the engine is shut down the accumulator pushes the foreign material away from the needle valve. This allows oil to flow again until the material reaches the needle valve again to cause another blockage. This would repeat continuously as long as the material was in there.

Do you this theory is sound? The only way that I can see to check for material in the control unit is to remove the entire clutch pack with the control unit. The accumulator housing will come off but the main body of the control unit is on the shaft for the clutch pack.

Any input will be gratefully appreciated.
Joe
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oljoe
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Re: reverser oil flow question

Post by oljoe » Tue Apr 17, 2018 7:56 am

I removed the needle valve this weekend and started the machine hoping that the oil flow would push out anything that might be in the passage. I let it run for 3 or 4 minutes with the needle valve removed and the access plug in place. While it was running I shifted the reverser several times in all positions hoping that any foreign material would be discharged through the needle valve opening. I replaced the needle valve, turned it in until hand tight and backed it up 3 turns per tech manual. I then started the machine and shifted the reverser to forward and moved forward 10 feet, shifted to reverse and moved back 10 feet. I was able to do this 5 times and then it would not move. The first couple of shifts it went into gear quickly, then it started to get slower to respond until it wouldn’t move.
I removed the needle valve again and stuck a piece of small wire, with a small hook on the end, in the hole hoping to pull out any gasket material that might be in the passage. Nothing came out but I may not have reached the needle valve seat. There is only about 4” between the transmission case and the frame rail and it’s another 3 or 4 inches to the seat for the needle valve. Trying to push the wire in the passage proved to be very difficult and I couldn't "feel" if I had hit the orifice or if I was off to one side.

There is one thing that I noticed during this test. With the needle valve in place there is a buzzing noise at the front of the transmission. With the needle valve removed the buzzing noise was not there.

Could this be the pressure relief valve buzzing from a blockage downstream?
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amos
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Re: reverser oil flow question

Post by amos » Wed Apr 18, 2018 7:11 am

I can offer no guidance but in reading your very detailed posts it seems as though you are correct in assuming some type of restriction in the control oil flow.How to clean the system is the question.
On other hydraulic system I have back flowed to a drain point(line removed etc). From the point of restriction reverse flow with hyd oil or air to the drain point and into some type of container to hopefully catch the contaminant.At best it's a 50/50 chance to correct the issue.
If it doesn't work it gets real ugly real fast and complete tear down is required.
Amos
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Stan Disbrow
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Re: reverser oil flow question

Post by Stan Disbrow » Wed Apr 18, 2018 7:45 am

Hi,

I have also been following, but never having had a 450 I have little to offer here. Well, other than suspecting that the buzzing sound is probably the bypass valve. I recall working with my dad on them in the dealership back in my teenage years, but can't recall one with this particular issue.

Stan
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Have: '58 JD 420c 5-roller w/62 inside manual blade
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oljoe
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Re: reverser oil flow question

Post by oljoe » Wed Apr 18, 2018 10:25 am

I pulled the needle valve out again last evening and screwed a bolt with the same thread size in the hole. This eliminated the “needle” part and plugged the hole so that it wouldn’t let the pressure just drain to the case. I thought maybe that might push anything on through and out to the case. It made no difference. The problem is as it was before.

Thanks for the replies Amos and Stan. I’ve been trying to figure this out off and on since August 2013. There are several posts about it on this forum outlining the steps that I have done to try to remedy the problem.

Any input....and I mean ANY is greatly appreciated.

Amos I like the idea of reversing the oil flow. I’ll have to study the tech manual to see if that can be done and where to make access. Come to think of it I should be able to connect at the top of the accumulator housing at the pressure check point. That should reverse the flow in at least some of the system.
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oljoe
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Re: reverser oil flow question

Post by oljoe » Thu Apr 19, 2018 11:41 am

When I got home from work last night I decided to try back flush the system as Amos suggested. I removed the bolt from the needle valve hole and hooked the air hose to the pressure check point. I left the needle valve access plug out of the case and put a screen wire strainer, from my wife’s kitchen, over the hole. I was hoping to catch anything that came out in the strainer. When I shot the air to it some oil came out but no debris. I shifted the HLR lever through all of the gears but got nothing but a little oil and air.

I shut off the air and screwed the needle valve back in about 4 turns. I thought that would be enough to hold it in place but wouldn’t restrict the orifice if anything came through. When I turned the air back on I could hear oil bubbling inside of the case. I shifted the HLR 10 to 12 times through the gears and could hear the air escape from different areas inside of the case as the pilot valve rotated past the neutral and high to low vents.

I removed the air hose and attached a pressure gauge and started the machine. The pressure rose to 140 psi and stayed steady. The noise from the buzzing “valve” that I had heard before was not there. I shifted the reverser to high and it went immediately in gear and moved forward. The pressure dropped and rose as it should during a shift. I tried reverse and everything worked as it should. I cycled the reverser 25-30 times moving from 10’ to 50’. Then the shifts started slowing and the gauge started bouncing from pegged to 30 psi. The buzzing “valve” noise also returned and it quit moving. That is where I am at this time....more to follow
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Re: reverser oil flow question

Post by big_bgk » Sun Apr 22, 2018 8:22 pm

Joe, I have the same problem with my JD450B and been testing it all day today, pressure is at 150 PSI but no reverse, good in high, low forward. I pulled the engine to get into the transmission and stopped for today to see if I could find out how to take this transmission apart. It is new water for me to do this without a diagram or book to show some steps... Mine was working just fine and got on it a week ago and no reverse. so here I am, need some advice... Thanks everyone..ahead of time..Bill

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amos
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Re: reverser oil flow question

Post by amos » Mon Apr 23, 2018 6:10 am

oljoe wrote:
Thu Apr 19, 2018 11:41 am
When I got home from work last night I decided to try back flush the system as Amos suggested. I removed the bolt from the needle valve hole and hooked the air hose to the pressure check point. I left the needle valve access plug out of the case and put a screen wire strainer, from my wife’s kitchen, over the hole. I was hoping to catch anything that came out in the strainer. When I shot the air to it some oil came out but no debris. I shifted the HLR lever through all of the gears but got nothing but a little oil and air.

I shut off the air and screwed the needle valve back in about 4 turns. I thought that would be enough to hold it in place but wouldn’t restrict the orifice if anything came through. When I turned the air back on I could hear oil bubbling inside of the case. I shifted the HLR 10 to 12 times through the gears and could hear the air escape from different areas inside of the case as the pilot valve rotated past the neutral and high to low vents.

I removed the air hose and attached a pressure gauge and started the machine. The pressure rose to 140 psi and stayed steady. The noise from the buzzing “valve” that I had heard before was not there. I shifted the reverser to high and it went immediately in gear and moved forward. The pressure dropped and rose as it should during a shift. I tried reverse and everything worked as it should. I cycled the reverser 25-30 times moving from 10’ to 50’. Then the shifts started slowing and the gauge started bouncing from pegged to 30 psi. The buzzing “valve” noise also returned and it quit moving. That is where I am at this time....more to follow
Sounds like it is narrowed down to trash in system. Next step: drain oil and fill with diesel or kerosene(diesel is a lot cheaper). Start unit and quickly (no more than 3-5 minutes at low RPM)go through shift cycle and then shut it down and repeat back blow. Drain and fill with clean oil and repeat. Then test with that oil. If good drain and fill with new oil.Still at a 50/50 chance of permanent repair but better to try first before complete teardown and proper disassembly and cleaning.
Amos
Pushin hard or diggin deep life is good.
What's ahead is what matters. What's behind is already done.
A fool of a man is he who doesn't ask questions...
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amos
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Re: reverser oil flow question

Post by amos » Mon Apr 23, 2018 6:19 am

big_bgk wrote:
Sun Apr 22, 2018 8:22 pm
Joe, I have the same problem with my JD450B and been testing it all day today, pressure is at 150 PSI but no reverse, good in high, low forward. I pulled the engine to get into the transmission and stopped for today to see if I could find out how to take this transmission apart. It is new water for me to do this without a diagram or book to show some steps... Mine was working just fine and got on it a week ago and no reverse. so here I am, need some advice... Thanks everyone..ahead of time..Bill
Bill, on your issue I would look at worn linkage pin on the shifter.Any slop in pin/linkage will cause your problem.Pull the top cover and reach in and look to see if there is any play:if there is reach down and move the linkage into full reverse position: if you have reverse you need to put in a bigger pin or a double nutted bolt to take up play from the wear.As little as a heavy 1/8" play will cause your problem.
Amos
Pushin hard or diggin deep life is good.
What's ahead is what matters. What's behind is already done.
A fool of a man is he who doesn't ask questions...
God gave us 2 ears and 1 mouth for a reason...

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Re: reverser oil flow question

Post by big_bgk » Mon Apr 23, 2018 8:24 am

Amos, I will check it this minute, not sure what it is right now, ready for a complete overhaul of reverse clutches I think.. Later Thanks for the heads up!.Bill

oljoe
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Re: reverser oil flow question

Post by oljoe » Mon Apr 23, 2018 3:07 pm

Over the weekend I removed the transmission top cover to take a look at the valves again. I pulled the accumulator housing with the bypass valve, pilot valve, accumulator valve and shift valve off of the oil manifold. After carefully disassembling and inspecting every restrictor, valve and spring I couldn’t find anything. I then went to the oil manifold which was still on the transmission and removed the clutch valve and the needle valve and made an inspection of the valves and bores. I couldn’t find anything there either.

While everything was apart I made an attempt to trace the oil flow through the passages and valves from pressure to discharge using a small zip tie. I blew through all of the passages with compressed air trying to blow opposite of the way that the oil would have pushed any type of debris. I did not see anything come out although it was difficult to see after 160 psi oil hit me in the face when I blew through one of them.

I reassembled the valves in the accumulator housing and did a bench test with air to make sure the accumulator and bypass valves moved and didn’t bind. Both valves worked fine when the air was applied to the proper passage and restrictor orifice.

When I had the metal supply lines off of the transmission case I turned the engine over with the starter to check the oil flow coming from the pump. It took a couple of revolutions of the engine to send oil out of the pressure port. When the oil started to come out it was a steady stream until I released the starter.

I put all of the valves and the assembled accumulator housing back in the transmission and attached the metal supply line to the case but did not attach it to the accumulator housing inlet. Instead I attached a pressure gauge to the line. This should give me a pressure reading from the pump. I set up some cardboard to deflect the oil back into the transmission case and started the engine. As the pressure came up the pressure gauge needle started jumping violently from 0 to peg. It was so violent that it bent the needle after running for about 30 seconds. That didn’t tell me anything except that there was pressure and I will have to buy a new gauge.

I decided to button everything back up and gave it a try. There was no joy. After 20-30 cycles of forward to reverse it stopped moving again.

I have had the engine, clutch housing and front transmission cover out of this thing 3 times and the top cover off at least that many. The accumulator housing and valves have been out twice and the transmission pump has been replaced with a new one. All of this was done trying to locate the source of this problem.

Albert Einstein is credited with saying “The definition of insanity is doing the same thing over and over again, but expecting different results.” I think I must be insane.
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psprague
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Re: reverser oil flow question

Post by psprague » Tue Apr 24, 2018 8:12 am

Do you think there might be a small crack or hole or un-torqued bolt in something and the change in viscosity of the oil or change in a casting's temp causes it leak internally and it to stop shifting?

I'm just wildly speculating over my first cup of coffee...
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psprague
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Re: reverser oil flow question

Post by psprague » Tue Apr 24, 2018 10:44 am

I've been looking at the supply oil flow diagram of a 'b' HLR and I'm just trying to think out loud (kind of like talking to myself, minus the profanity).

Trans pump pulls oil from the pickup and based on the shims in a pressure regulating valve, shoves oil both to the oil filter and cooler, and directly to the clutches (shifter valves et al). A shift will cause the pressure regulating valve to close and stay closed while the accumulator refills. Oil pressure to the filter should should rapidly fall as oil drains out of the circuit.

Resistance in the cooler/filter oil circuit will open the cooler bypass valve. This supplies oil to the circuit downstream of cooler/filter for lubrication of clutches and output shaft. However, the improper opening of the cooler bypass valve will lead to a loss of pressure for clutch engagement. So the cooler bypass valve pop off pressure should be higher than the pressure regulator valve or oil will always bypass the filter.

Random questions:

Would a completely out of whack pressure regulating value or cooler bypass valve have these symptoms?

When it's happening, what is the oil flow or pressure at the cooler/filter?
JD 450c forestry, JD 440A cable skidder

oljoe
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Re: reverser oil flow question

Post by oljoe » Tue Apr 24, 2018 12:19 pm

Thanks psprague for spending the time to look over the diagram.
psprague wrote:
Tue Apr 24, 2018 8:12 am
Do you think there might be a small crack or hole or un-torqued bolt in something and the change in viscosity of the oil or change in a casting's temp causes it leak internally and it to stop shifting?

I'm just wildly speculating over my first cup of coffee...
I had a talk with a John Deere tractor mechanic about that very same thing back when this first started. That is when I removed the engine, clutch housing and front transmission cover the second time. The front cover gasket that I had made was compressed everywhere it made contact with the transmission case and all of the bolts were tight. I inspected the cover for cracks or any kind of warp with a straight edge but didn’t have it magna-fluxed. I bought a JD gasket and replaced the home made one. The other thing is it never does get hot or even warm before the failure occurs. I Kind of ruled that out but will think about some more.
psprague wrote:
Tue Apr 24, 2018 10:44 am
Random questions:

Would a completely out of whack pressure regulating value or cooler bypass valve have these symptoms?

When it's happening, what is the oil flow or pressure at the cooler/filter?
During the 4+ years I’ve been working on this problem I haven’t checked the pressure at the oil cooler. I talked with my buddy about that yesterday after finding it in the tech manual. I bought 2 new gauges yesterday and got the hardware to hook them up today. The plan is to check the pressures tonight and have some results to share tomorrow. Thanks for the input.

Joe
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