TO20 Hydraulics

I recently acquired a 1951 TO20 that had been sitting for several years and got it back up into running condition with only minor work and a few small electrical components. Really surprised by how little effort it's taken to get the little tractor back into working condition. Anyway, I backed it up to my 5' Bush Hog finishing mower last week (weighs about 5-600 lbs.), both to move the mower and try out the hydraulics on the little Fergie. I engaged the PTO lever and then moved the control lever rearward, of course expecting the mower to lift off the ground. The lift arms visibly nudged upward and came under tension, but didn't even move the mower. Now I had checked out the hydraulics earlier, doing both a manual pump-up before I purchased it and checking them again once I got the tractor running and everything seems to work as it should. In the elevated position, the 3-point will support my 200 lbs. without leaking down so I thought there was at least a fair chance things were in good order.

We're forecast to have some decent weather this weekend and I'm planning to dedicate at least some time to troubleshooting this issue. As I understand it, this should involve hooking up to an implement and with the tractor running and in a lift configuration, looking for fluid bypass via the inspection covers.

No, I will NOT be sticking any body parts into those inspection covers while the tractor is running!

Some online reading leads me to believe the most obvious culprits will be the cylinder/piston located in the top cover or the control valve (spark plug-looking thing) just below the yoke assembly. I'm thinking it will be pretty obvious if fluid is pouring out around that upper piston but what signs will indicate a faulty control valve? Does it discharge fluid when functioning normally, or not? Also based on the hydraulics functioning normally with no load, what are the other likely areas I should be looking at during initial troubleshooting?

you did have clutch pedal in upper most position ? pto and hyd will not work unless clutch pedal is out.

You might find the bottom of the sump full of water and rusty control valve/ pressure relief valves on bottom of pump as they are sitting in
water.

I think the best place to start is with a manual. The Ferguson manual would be the best but the IT manual works.

Tom

You're on the right track.

Hook up to the mower, open the inspection covers, idle up the engine and tell it to lift.

Look inside for oil coming down from the cylinder, some dripping is normal, but not flowing.

Look down beside the pump for swirling oil, that is likely the relief valve bypassing.

If the lift was jerky and slow when you operated it with a light load, that is a sign of bad pump valves.

you did have clutch pedal in upper most position ? pto and hyd will not work unless clutch pedal is out.

Click to expand...

It had to be asked, I know. :lol:

Yes, the PTO lever was engaged, clutch released, and this was all verified by the PTO shaft spinning and the lift arms nudging upward. It was trying...

You might find the bottom of the sump full of water and rusty control valve/ pressure relief valves on bottom of pump as they are sitting in
water.

Click to expand...

Hadn't thought about water standing in the bottom of the sump. I'll do a siphon test first thing when I get underway and see what comes up from the bottom of the case.

I think the best place to start is with a manual.

Click to expand...

I've got both the Operation and Maintenance manual and the dealer service manual. The owner's manual tells how to make it work and the dealer's manual jumps right into tearing everything down to the last nut and bolt for a total rebuild. I need the manual that's right in between those two. :lol:

Look inside for oil coming down from the cylinder, some dripping is normal, but not flowing.

Look down beside the pump for swirling oil, that is likely the relief valve bypassing.

If the lift was jerky and slow when you operated it with a light load, that is a sign of bad pump valves.

Click to expand...

I thought the lift was smooth and not at all slow with no attachment involved. Moving the control lever forward dropped the lift arms all the way down and again, very smooth and at an appropriate speed. That's leading me to believe it's a bypass issue. It seems to me the system is behaving as it should, aside from being unable to lift a 500 lb finish mower.

thanks for not getting angry with me

So today in Kentucky, we experienced this super-rare weather phenomenon where the temperature was above freezing and it WASN'T RAINING!!! Not to worry though, as rain will resume in just a few hours...

Anyway, I took the narrow window of opportunity and pulled the hydraulics inspection plate on my TO20. The one with the dipstick. With the tractor running at what I guessed to be 15-1800 rpm and the PTO engaged, I moved the control lever up into the lift position. The lift arms nudged upward but stopped when the weight of the finish mower came to bear on them. Looking inside through the port, I did not see any fluid dripping from the top cover, nor did I see any swirling around the control valve. What I did see was a significant pulsing of the fluid in the area outlined below. Is this normal on a Fergie or am I about to learn everything I never wanted to know about rebuilding one of these hydraulic pumps?






And if this is normal, any suggestions on what to look for next? I'm at a serious disadvantage working outdoors like this but if I had a shop, the whole back end of this tractor would probably already be disassembled. :lol:

I opened up the Fergie again this afternoon and what I found has prompted an update, along with additional questions and observations.

I was using a stronger light and larger inspection mirror to see all inside the housing, looking for a telltale leak that would explain my troubles. Any further inspection of the hydraulic ram (the big cast iron thing bolted to the top cover that contains the main piston) will require disassembly, but it's dry as a bone when configured to lift and under full throttle. Not saying that isn't part of my problem, but thought there would be seepage if the piston was bypassing.

Revisiting the control valve, I began looking closely at the fluid in the area immediately behind the hydraulic pump. Still no swirling but you may notice I've only drained my oil down to the bottom of the inspection cover/top of the pump. Would the swirling be concealed by this much oil if the control valve was indeed bypassing?

Now this next observation may be related to a faulty control valve, or it may be an altogether different issue. I was periodically operating the control lever back and forth, looking for any changes inside the housing. The control yoke moved forward (toward the pump) when I lifted the lever up, moved rearward when I pushed the lever down. Nothing changed from the other day as regards the lift arm action. They would still lift and nudge the implement but not lift it, and then return to the relaxed position when I lowered the control lever. I stopped glancing at the lift arms and stared directly at the control yoke as I pulled the control lever up. The yoke pushed the control valve in and I could feel the tractor shift as the lift arms nudged the implement.

[b:fbf43ae1e3]That's when I saw the control yoke shift rearward like 1/16"!!![/b:fbf43ae1e3]

The movement was so small that I hadn't noticed it before. I immediately did what what any buffoon would do and slid a large screwdriver in behind the control yoke and pried very gently forward. In just a second I had a 500 lb. finish mower hanging up in the air off those lift arms! When I relaxed the screwdriver, the control yoke shifted slightly rearward again and the lift arms dropped as though I'd lowered the control lever.

Having seen the system actually function as it should I'm left asking if this sounds like a faulty control valve, or would you say I'm dealing with worn or otherwise tweaked control yoke/lift quadrant components?

maybe your lift is out of adjustment? new to this stuff, but logically to me if its being pushed back too far, you could try and adjust your lever (if possible) so the yolk doesnt push back so far. cant remember what the manual says the lever should be adjusted to...but maybe tweaking it the guide for the lever (my terminology sucks, sorry) so it would stop where it lifts well. feel ya with all this man, hard to work in winter weather without a shop, good luck!

maybe your lift is out of adjustment? new to this stuff, but logically to me if its being pushed back too far, you could try and adjust your lever (if possible) so the yolk doesnt push back so far. cant remember what the manual says the lever should be adjusted to...but maybe tweaking it the guide for the lever (my terminology sucks, sorry) so it would stop where it lifts well. feel ya with all this man, hard to work in winter weather without a shop, good luck!

Click to expand...

I don't believe there's any means of adjusting the control yoke's travel, based on what limited information I've seen about the Ferguson's top cover assembly. I was watching this video about removal and disassembly of the top cover:

https://youtu.be/uDpb18hJRrw

...and noticed the control yoke in this example seemed to have quite a bit more travel than mine. I'm now thinking I've got some kind of wear in the connection between the lift lever and control yoke that simply isn't allowing the yoke to properly seat the control valve.

We are forecast to have some bizarre January weather today. Partly cloudy and 40*F so I'll be pulling the cover and checking out the geometry and wear of these components, with an update and photos to follow this evening. With the weather momentarily cooperating, naturally I've been hit with a sinus infection that feels like hospitalization may be warranted. :roll:

Here it is a week since my last post on this issue. I was far too sick last Sunday to go outside and then the polar vortex came. The outside temperature was falling to below zero and my internal temperature finally topped out at 102.5F, and here we are today. I'm feeling some better and in typical Kentucky fashion, today's bizarro weather is sunny and near 70F! Anyway, let's talk Ferguson hydraulics, shall we?

Points learned today:

1. There is no positive forward engagement of the control valve. The only thing I see pushing the control valve in to the "lift" position is that big extension, or "storm door spring" attached to the yoke. When the lift control lever is moved to the lift position, it rotates a shallow crank arm (for lack of a better term) out of the way that allows the spring to draw the yoke forward and push the control valve into the hydraulic pump body. Very little pressure involved here.

2. The BIG drain plug underneath the hydraulic pump? In case you've never pulled that plug and no one else tells you, that drain hole is about the size of a tennis ball. You'll want a BIG drain pan to catch what's coming out, even if yours is already drained to the bottom of the inspection cover like mine was. Have towels handy too, because it only takes like six or eight seconds to dump everything in that tractor. There's apt to be some spillage.


So the tractor is now drained, side covers are off, and the lift cover is off. I'm not seeing any wear to speak of. Moving the lift control lever allows the control yoke to move through a long arc with no binding of any kind. The control valve looks fine in all respects and while I haven't mic'd the diameter, it seems to fit well inside the pump body and travel back and forth without binding.

Any other ideas as to why the valve would be kicking out just as the lift arms encounter the weight of the implement?

no one has mentioned that you can loosen the 4 bolts that hold the quadrant to the top cover, then it can be moved forward. Had this happened, forgot to to tightened the 4 bolts, nothing worked.slid forward tightened bolts, perfect!

(quoted from post at 11:21:46 02/22/19) no one has mentioned that you can loosen the 4 bolts that hold the quadrant to the top cover, then it can be moved forward. Had this happened, forgot to to tightened the 4 bolts, nothing worked.slid forward tightened bolts, perfect!

Click to expand...

I just found Bill's response last night when I came to read through this thread again. Unfortunately, it doesn't appear to apply in my case. The quadrant assembly is bolted firmly in place and adjusted toward the forward direction of adjustment. You can judge its relative position by looking at the alignment of the quadrant mounting plate's forward edge in relationship to the top cover casting. If the plate aligns with the the edge of the casting, that's approximately the middle of the plate's adjustment. Mine overhangs the casting just a bit, indicating it's already adjusted forward. More importantly (I think) is with the lift lever moved up into the lift position, my control yoke tabs rest against the hydraulic piston's chamber as they're supposed to. Additional play added to the quadrant assembly wouldn't produce any additional travel to the control yoke. You can't really see that they're making contact in this photo, but the tab right off the tip of my finger is the tab I'm talking about.




I've installed a new control valve hoping that would help, but it didn't seem to change anything. Today's project will be fabricating a bit heavier yoke spring. My reasoning is that if just a bit of help nudging the yoke forward makes it lift like a champ, a little heavier spring should serve the same purpose. Making the spring too heavy would likely accelerate wear on the yoke and pins, so this project will be something of a balancing act. Here's my spring, which looks exactly like the original Ferguson part to me:




I was recently watching an Australian video on YouTube about rebuilding a TE20 top cover and found several interesting points. The most interesting to me was the comparison of a badly worn control yoke versus one with only light wear. Mine seems to lean much more toward the lightly worn one, which is a good thing.

So, if I understand correctly, you saw the control fork move up against the back of the pump at first, then move away as the arms started to lift the mower.

(quoted from post at 16:53:50 04/10/19) So, if I understand correctly, you saw the control fork move up against the back of the pump at first, then move away as the arms started to lift the mower.

Click to expand...

(Hmm, seems like I'm not allowed to post a link to a photo, nor edit my own post. Let me rephrase..)

Seems like that would mean something is deliberately moving the fork, like maybe the linkage from the top arm (draft control).

Try taking out the pin that holds the rocker for the top arm to the control lever (with the big spring on it). If that lets the mower come up, then there has to be a problem with that link (draft control). I think, YMMV, etc.

(quoted from post at 19:53:50 04/10/19) So, if I understand correctly, you saw the control fork move up against the back of the pump at first, then move away as the arms started to lift the mower.

Click to expand...

That's correct. The fork backs out just a bit as the lift arms start bearing the weight of the implement.

Try taking out the pin that holds the rocker for the top arm to the control lever (with the big spring on it). If that lets the mower come up, then there has to be a problem with that link (draft control). I think, YMMV, etc.

Click to expand...

I think I've tried that, but can't say for certain. I've tried so many different things! I'll be back into it this weekend and once reassembled I'll definitely give that a try, just to know for sure. Thanks!

My dual spring idea seems to have worked. It snatched the Bush Hog right up in the air and held it! I used a common 9/16" extension spring bought off the shelf at my local Lowe's home improvement store for around $5. I cut the ends off with a Dremel and straightened out the ends into hooks about the same size and shape as the original spring. I was thinking the two springs might nest together and bind up the works, but they would do nothing of the sort with the assembled top cover sitting on the bench. At first they were too tight and would pull the quadrant lift lever back down when released, but I stretched them out until that stopped happening and it works fine, now.

My only guess as to the root cause of this issue would be a worn control valve sleeve in the hydraulic pump itself, maybe allowing just enough blow-by to back the valve out? I have no clue, but am just glad to have the lift operational. I've bought a complete hydraulic pump unit to rebuild and install later, so will probably try going back to the OEM spring when I get around to installing that.

I ran across a very old post by John (UK) the other day in which he mentioned laying down on the tractor and using both hands to fit the control valve "T" into the control yoke. Perhaps everyone else but me knows this trick but having fought that &%@*!&? valve repeatedly from each side of the tractor, I can tell you this method easily outshines all other approaches I've tried. This setup worked perfectly:





The board (a 2x10 in this example) gives you something smooth and comfy to lay on, of course. My top cover has a couple of seat studs sticking up about an inch, in addition to all the other bumps and bolt heads.

Anyway, straddle the PTO as you see in the photo and just lay down on the board. Thread a hand in each inspection cover hole. I'm right handed, so I took hold of the left-side ball on the control valve's "T" with my left hand, and slid my right hand between the main shaft and PTO shaft to push on the left side control yoke leg with my fingertips. It was so easy to get the ball popped right into its socket! Then I switched out hands and repeated the process for the right side. In and out in something like 30-45 seconds.

The paper towels are handy right there on the trans cover for when you finish and bring both hands out covered in oil and/or blood. It's amazing how many sharp bits and pointy things there are inside that housing, and I'm certain I got bit by every one of them. At least twice.