Allis 5040 slow Hydraulics

[ametcalf]

Well I put and PHD on this morning and dug a hole. At 1500 rpm the tractor pulls the PHD right out of the ground with no problem. Before we started all of this I had to run the tractor at 2400 rpm and it would just barely pull the digger out of the ground. This is so much safer because the auger is turning at a nice slow/safe rate. At 2400 rpm it was spinning so fast I didn't feel like it was a safe operation.
I got the new screen ordered and I am thinking about keeping the pump I ordered just to have on hand for when this pump actually does go out.
Thanks for everyones help.

 

[MHarryE]

Is your hydraulic pump mounted on the side of the engine and does it have a suction line that goes to the sump (which I assume is the transmission housing) so the fluid level is lower than the pump? I had assumed a flooded inlet (oil level higher than the pump inlet). If the oil level is lower than the inlet, an air leak could cause the problem you described. This really has me curious because you described a system that functioned properly but wouldn't come up to relief pressure and also was very slow. Even your service manual troubleshooting said to look at the relief and then the pump. Did you have the inlet off before, or was the first time when you pulled the strainer? I was curious as to whether when you pulled the strainer you cured an air leak in the suction line.

 

[ametcalf]

Is your hydraulic pump mounted on the side of the engine and does it have a suction line that goes to the sump (which I assume is the transmission housing) so the fluid level is lower than the pump? I had assumed a flooded inlet (oil level higher than the pump inlet). If the oil level is lower than the inlet, an air leak could cause the problem you described. This really has me curious because you described a system that functioned properly but wouldn't come up to relief pressure and also was very slow. Even your service manual troubleshooting said to look at the relief and then the pump. Did you have the inlet off before, or was the first time when you pulled the strainer? I was curious as to whether when you pulled the strainer you cured an air leak in the suction line.

You bring up some interesting points. I am leaving town for the week-end in a few minutes. (Grandparents day in Milwaukee for our granddaughter). I will write a response to your points when I get back. Thanks for your insight.

 

[J_J]

If the gage is installed, and you want to test the 3pt, you raise the lever to max, and the relief will activate and you can read the pressure on the gage. Move the 3pt lever sown to neutral for normal operation.

While you are at the back, test the descend rate on the 3pt. See if it will lock an implement in place, and the descend rate is what you want.

 

[J_J]

J_J, Don't you sleep?
I appreciate all your advice.
Once I take the QD off the hose that I ran into the bucket there is no restriction in the line. The hose has half inch fittings on it and I would guess it is a half inch hose. The remote had never been used in the 30 years we have owned the tractor until I got the dump wagon last summer. In order to use the dump wagon, I had to change the QD on the remote hose. When I took the old QD off I realized the fluid in the remote hoses had turned to gunk so I took them off and cleaned them out throughly so I know there is no restriction in them. You are right about the flow, I don't know what I was thinking. When I got 2.5 quarts I thought the flow was good not thinking that it should have been gallons instead of quarts. I am a little hesitant to run the system too much without the screen in it. We did this flow test with the old screen in the system. Once I get the new screen we will try it again before I change the pump. I think when I install the new screen I should should take the whole line off between the bottom of the transmission and the pump and change all the o-rings and such to make sure we aren't getting any suction leaks.

As near as I can tell there is no way to set the remote pressure relief valve. It is a cartrige type afair that just screws out. The book says when there is a problem with it that it should be changed. I didn't realize until this morning that there are separate PRVs for the 3 pt hitch and the remote. I now see them in the book. The one I took out before was the one for the remote. Next time I go to the barn, I will try and find the one for the 3 pt hitch. You are right the remote does come before the 3 pt hitch. The book says the relief on the 3pt should be between 2062 psi and 2205 psi and the remote should be between 2133 psi and 2489 psi. It tells how to test the remote on the tractor but I can't find how to test the relief on the 3 pt hitch while it is on the tractor. The way I see it, if the 3 pt. hitch will lift what I need (the PHD) without engaging the relief valve it will be OK.
Well I am going to order the screen now and then go see how fast it lifts the PHD. Thanks again.

You may be right about the remote relief valve. Some valves have a fixed relief and can only be cleaned or replaced. If that is the case, and the relief setting is below the 3pt relief setting, the remote valve will be the first relief to go off.

Also, you can't get a pressure higher than the remote relief valve setting to set the 3pt, so just set the 3pt the same as the remote relief valve.

Depending on your valve manufacturer, you might be able to get an adjustable relief for your valve.

By the way, does your remote valve have PB?

I would set the 3pt valve relief to 2205 psi.

Reading your post again, you state a variable of between 2133 psi and 2489 psi. That sounds like an adjustable relief. Difference of 356 psi.

That variation in pressure can affect your 3pt cyl by 2517 lbs of straight on lifting force. I assumed a 3 in cyl with 1.5 shaft.

 

[ametcalf]

Is your hydraulic pump mounted on the side of the engine and does it have a suction line that goes to the sump (which I assume is the transmission housing) so the fluid level is lower than the pump? I had assumed a flooded inlet (oil level higher than the pump inlet). If the oil level is lower than the inlet, an air leak could cause the problem you described. This really has me curious because you described a system that functioned properly but wouldn't come up to relief pressure and also was very slow. Even your service manual troubleshooting said to look at the relief and then the pump. Did you have the inlet off before, or was the first time when you pulled the strainer? I was curious as to whether when you pulled the strainer you cured an air leak in the suction line.

Home again. Thanks again for all your help. Attached is a copy of the drawing of the hydraulic system from the service manual. Over the 30 or so years we have owned the tractor I have changed the fluid a number of times and also had it changed at a tractor dealer a few times. I always cleaned the screen when I changed the fluid and I assume the shop did too. The pump is mounted on the front of the engine and gets its power from the timing gear on the engine. The feed line comes from the bottom of the transmission, goes through the screen, on to the pump and back to the hydraulic remote control valve. I assume it goes from there into the 3 pt hitch valve and back to the transmission. If I had to guess right now here is what I think has happened. I never changed the o-ring when I cleaned the screen. Given the fact that the hydraulic fluid has bubbles in it I think you are right in surmising that there was a leak in the suction line. When I took the screen out and tested the system, the o-ring got a good seating, hence the increase in pressure. The volume is still low and I don't want to run another test until the new strainer comes which should be in the next few days as it was shipped on the 26th.

...............

By the way, does your remote valve have PB?

I would set the 3pt valve relief to 2205 psi.

Reading your post again, you state a variable of between 2133 psi and 2489 psi. That sounds like an adjustable relief. Difference of 356 psi.

That variation in pressure can affect your 3pt cyl by 2517 lbs of straight on lifting force. I assumed a 3 in cyl with 1.5 shaft.

J_J, Thanks again. I don't think the remote has PB. In looking at the tractor or the drawings I can't see where it would be. You have to remember though, until I started reading your posts a few weeks ago, I didn't even know what PB was. I am sorry to be so confusing when I gave the variable psi. The variation was due to me varying the rpms of the tractor, not me making any adjustments.

The fittings have come for me to put a tee in the line and run some test with my dump wagon. As I stated above, right now I am waiting for the new screen to come so I can resume work on this project.

 

[MHarryE]

I was looking for information on your tractor system when I saw a picture of the pump mounted on the engine side and realized what likely happened when you pulled the strainer. We changed the hydraulic tank on the main machine I worked on from above the hydraulic pump to below it in 2003. The assembly line quickly found out they needed to pay special attention to the supply line which was plain hose on barb fittings secured with hose clamps. On the old version if a person didn't get the clamps really tight there was no problem - the oil didn't leak. Air can get through where oil can't and it only takes a little air to screw things up, and there is no oil drip to identify the leak. If I remember right pump condition is also more sensitive since it has to draw oil rather than have atmospheric pressure pushing oil into the pump. Having spent 45 years in the business, 5,000 hours is a lot of time for a pump. Power steering isn't shown in the hydraulic circuit. Is that a separate circuit? I would have expected this to have a pump with a priority flow divider for steering like we had on the combines of that era or a 2 section pump. Surely the tractor has power steering, right?

 

[ametcalf]

I was looking for information on your tractor system when I saw a picture of the pump mounted on the engine side and realized what likely happened when you pulled the strainer. We changed the hydraulic tank on the main machine I worked on from above the hydraulic pump to below it in 2003. The assembly line quickly found out they needed to pay special attention to the supply line which was plain hose on barb fittings secured with hose clamps. On the old version if a person didn't get the clamps really tight there was no problem - the oil didn't leak. Air can get through where oil can't and it only takes a little air to screw things up, and there is no oil drip to identify the leak. If I remember right pump condition is also more sensitive since it has to draw oil rather than have atmospheric pressure pushing oil into the pump. Having spent 45 years in the business, 5,000 hours is a lot of time for a pump. Power steering isn't shown in the hydraulic circuit. Is that a separate circuit? I would have expected this to have a pump with a priority flow divider for steering like we had on the combines of that era or a 2 section pump. Surely the tractor has power steering, right?

Thanks for your expertise. Yes the tractor has a separate power steering system. It bolts on the back side of the timing gear right behind the main hydraulic pump. In looking at the book there are two different types of systems. Those that use the transmission resevoir and those that have their own resevoir. Ours is the type with its own resevoir. When I got the new screen yesterday I realized how old and plugged the old screen was. I had been washing it in mineral spirits periodically but I didn't realize that it should have been changed long ago. I took the whole assembly from the pump back to the transmission off so I could clean the strainer housing out thoroughly. I didn't like the looks of the bolts that hold the line to the pump so I am going to ACE this morning to get new ones. When I get it back together, I expect things to work much better. One of the bolts holding the line to the pump wasn't on real tight, so I can see with a screen that was giving a lot of resistance and o-rings that had probably never been changed there was a chance that air was being introduced at that point. I found a place about 4 miles away tucked back on a street that I didn't even know existed that specializes in o-rings. They sold me the four new ones for a buck. It took the guy about 10 minutes to size the old ones, get them from inventory and write up the ticket. After he looked on the computer for the prices he said, "How about giving me a buck." I gave him two just so I wouldn't feel so guilty. I hope he does better with other customers than he did with me.

 

[ametcalf]

Here is the latest,
I put everything back together. New screen, o-rings and new hydraulic fluid. (I left the old pump on the tractor.) I took the QD off the remote hose and ran the fluid into a bucket and got about 2 gallons in 20 seconds. Even though it didn't have any back pressure the 2 gallons is a lot closer to the amount that it should be.
I then put the tee and gauge in the line by one of QDs at my dump wagon and ran some tests that way. At 1500 rpm it took 26 seconds to raise the dump. At 2000 rpm it took 20 seconds to raise the dump. At 2400 rpm it took 17 seconds to raise the dump. The gauge only shows about 200 psi when the dump is going up but when the cylinder gets fully extended the pressure jumps to 2600 psi and the relief valve kicks in. There is no weight in the wagon during this time. It is just raising the empty bed.
Now back to when I ran the fluid into the bucket. There are a lot of air bubbles in the fluid. I let the tractor warm up for about 10 minutes before I ran the fluid into the bucket. When the tractor is not running there aren't any leaks in the intake line. There are some around the remote valve when the relief valve kicks in but none from the bottom of the transmission along the line to the filter and on to the pump. There are none in the pressure line from the pump to the remote valve. Does anyone have any ideas how the air is getting into the system. I think it has to be between the transmission reservoir and the pump. Taking into account that I changed all of the o-rings and all the joints seem tight, I am wondering if I have a small crack in the line some place. I think I saw a used one someplace on the internet that I may try to find. If it wasn't for seeing the air bubbles I wouldn't know there is a problem. The system is working better than it has in years and is certainly good enough for our purposes. One thing I don't know, is it possible for air to get into the system in the pump itself? I have the new pump that I ordered and it looks like it will fit the tractor if I need to change it but I would just as soon not change it if I don't have to.

 

[J_J]

Air can be generated by the relief valves, and any other small orifices. Lots of fluid passing through small cavities will cause cavitation, which makes bubbles.