Go BottomFord 770B loader bucket won t curl
 | Jsheds
Join Date: Jul 2003 Posts: 17 Coopersburg, PA 
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2003-04-06 52683
I've got a 1510 Ford with a 770B loader. I was using it to move some logs around today and putting them in a pile. To stack them on top of one onother I was pucshing and lifting at the same time. Worked great for a few hours.... Now I can't roll the bucket up or down. The loader lifts OK, the 3-point lifts OK, but when I try to tilt the bucket up or down, the cylinders only move about two inches. They are stuck almost closed. If I use the bucket to lift the front end of the tractor off the ground and then try to tilt the bucket up, I can get the cylinders to close all the way, but then when dumping the bucket they still only go about 3". I tried chaining the top of the bucket to a tree stump and backing up to roll the bucket down, but it'll still only go about 3". I disconnected the cylinders from the bucket and tried to extend them without the bucket attached and no luck. I disconnected the hoses from the cylinders and tried to move the rod in and out manually, but couldn't move either one at all. Is it possible that I bent the rods on BOTH cylinders at the same time? It's the only other things I can think of. Can a hydraulic shop straighten the rods, or are they shot? I can't call the dealer until tomorrow, anyone know what these cylinders cost?
As always, thanks for any help.
Jim
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 | DRankin
Join Date: Jan 2000 Posts: 5116 Northern Nevada 
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2003-04-06 52697
Every time that has happened to me I have had a quick-connect fitting come partially undone. Doesn't take much of a disconnect..... just a 16th of a inch or so will do exactly what you describe. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-07 52704
Yikes! I hope you haven't damaged the cylinders trying to move the bucket. MarkH's comment is likely the explanation, and the solution would be to simply find which quick-connect wasn't seated and reseat it.
Reseating one in this situation might prove a bit difficult. If there was a load in the bucket when a quick-connect comes apart then there may be high pressure in the hose to that loader cylinder. Mild versions of the same thing cn happen with an implement that's disconnected on a cool day and reattached on a hot day.
Pressure in a line often prevents seating a quick-connect. The solution is to relieve the line pressure, and that's done by manually depressing the ball in the connector end. A rag is wrapped around the end (because you get a squirt of oil that can be under enough pressure to injure you and it's also messy). For male connectors, a the ball can be pushed against something hard. Female connectors need something fairly soft like a brass drift punch to go into the end to reach the ball. Higher pressure problems usually require the ball to be hit with something fairly soft or the fittings loosened until the pressure can bled off. It can be tough trying to loosen fittings on a hose that contains pressure though.
There is a small bug in the system here that prevents use of the pop up reply window for messages with a ( ' ) in the subject.
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| Jsheds
Join Date: Jul 2003 Posts: 17 Coopersburg, PA
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2003-04-07 52707
I thought about the fittings, but hadn't checked them yet. If the fittings were the culprit, I'd think If I disconnected the hoses to the cylinder, I should be able to manually move the cylinder rod. Or is it so tight a fit that I can't move it by hand? ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-07 52717
Yes, probably they should move by hand. The weight of the loader itself ordinarily is enough to move to bucket. If a bucket is set on the ground with the lift in float, then operating the curl valve to open the return line should allow the bucket to flatten out. The valve should be moved in both directions unless you're sure which hose is the return line for the direction the bucket will move when it flattens out. In addition, the lift does have to be in float. Moving all valves in both directions to relieve line pressure when shutting down a tractor is good practice anyway.
To test and be certain of the results, both quick-connector fittings could be removed and the hose ends stuck in a bucket to catch the oil. A bucket can't move if either hose is closed. Doing it that way eliminates the spool valve as the problem, and quick connectors have been known to fail on their own. I keep spare quick-connectors around, so I'd probably just try to put spare female connectors on to my male hose ends without removing the fittings.
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 | marklugo
Join Date: Jul 2003 Posts: 281 Tifton, GA
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2003-04-07 52719
This was a problem on the older 770's. Try to direct connect your hoses by removing your quick couplers and use a straight galvanized fitting to reconnect. If this works, It is in the quick couplers. Also some backpressure was observed from time to time on the control valve. It would"lock" the contol handle and make it difficult to move. Only new valves would remedy this. All Ford would do was aknowledge problem but had no solution for this. Maybe now they might have a service bulletin on it. Go to your local dealer and have him to a search for a technical bulletin on this loader /tractor. ....
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| Jsheds
Join Date: Jul 2003 Posts: 17 Coopersburg, PA
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2003-04-07 52724
"Float" position? I don't think I have this option. My loader has the joystick control, not two lever, havn't found a 'float' position yet, but it sure would be handy!
I'm going to check my quick couplers first. Now that I think about it, the loader frame does wobble around a bit and is right next to the couplers. It wouldn't take much to nudge that coupler enough to knock it loose.
I priced the cylinder from NH - $299! Sounds kind of pricey, but they've got you. If it is a cylinder problem, I can replace the rod and seals for about $130.
I recently changed my hydraulic fluid from the stuff that looked like mayonnaise to the correct Ford 134 fluid, now things are starting to leak. Most notably the control valve for the loader. Is there a service kit to replace the seals on the control valve, or do I need to order all the small parts seperate?
Jim
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 | plots1
Join Date: Jul 2003 Posts: 563 mo 
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2003-04-07 52725
float is achieved by pushing lever all the way forward. at least thats how my 790 is set up. ....
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| Jsheds
Join Date: Jul 2003 Posts: 17 Coopersburg, PA
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2003-04-07 52735
Thanks for your thoughts, the problemn is solved. The one quick coupler right next to the loader frame was not properly seated. Everything seems to be working just fine now. And as an added feature, I discovered I do have the float option, but you have to push the stick pretty hard to get it to lock in.
Jim ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-08 52764
That's a good result and fortunate that nothing was damaged. However, I wouldn't be surprised if there was a bit of leak down now since there may have been a lot of pressure developed in the cylinders. Any circuit pressure relief valves would be in the valve assembly and only one side of the cylinders would be connected to the valve. Fortunately leak down is more of an aggravation in the lift than in the bucket circuit.
The same thing has happened to me often enough that I recognize the signs now. When it happens to me, there's usually enough pressure in the line that I have to bleed it off before I can connect the quick-connect. It also took me almost four years to discover a float on my backhoe boom. We're all in the buz of learning.
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2003-04-08 52776
Jim, good to hear the problem was an easy (read inexpensive) fix.
The one point however that I picked up on upon re-reading your post was that there was some limited movement in the circuit even though one side was effectively capped by the open quick-disconnect.
There is really only one thing that can account for this, you have a bit of a cavitation problem. You said you were stacking logs when it happened so I'm going to guess that the culprit is the load being lowered. When you set down a heavy object the load can sometimes create more fluid leaving on side of the circuit faster than the pump, which is at this point likely at an idle, can provide to the other side of the circuit, causing a suction and drawing up air from the sump instead of oil. While this not a really bad situation, it's not very good either.
The fix is very simple and easy though, you need to put a restictor on the one side of the bucket curl and loader boom circuits. This is the side that pushes 'up' on both of the circuits, this will restrict the speed at which this oil can leave the cylinders, and hopefully the pump can then keep up.
Best of luck. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-09 52817
G'morning Murf. I see a new tractor isn't quite enough to keep you from thinking about tech things.
When the problem has happened to me, the bucket (or hoe for that matter) will sort of lurch when a valve is operated in one direction and not move at all when it's operated in the other direction. My interpretation is that the lurch is from play in the pins. As you say, vapour in the cylinder is about the only explanation for any appreciable movement. I've never been certain how much cavitation vapour is air and how much is oil, but oil vapour would be reabsorbed when the vacuum is removed. I'm not sure how much vacuum it would take to open a quick connector if it became detached, which also could be a source of air in the cylinder.
For readers who haven't experienced it, when dumping heavy loads, the cavitation thing appears as an initial rapid dump followed by a long pause before the bucket starts moving again. The same can happen in the lift circuit but it is less noticeable. Flow restriction does cure the problem but also slows down the dump circuit for all operations. Use of a fast-dump feature (if equipped) prevents the problem. Fancy valves equipped with anti-cavitation circuits (really a variation on the regenerative fast-dump idea) also work. Running at higher rpm's helps.
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| Jsheds
Join Date: Jul 2003 Posts: 17 Coopersburg, PA
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2003-04-09 52821
The loader circuit 'should' have a restrictor in it according to the parts manual, and I haven't noticed any unusual behavior with the loader. Could be air trapped in there? All this discussion leads me to another question, how do you bleed the air from the hydraulic system if there is a little in the cylinder? Does it just work itself out? On hydraulic brake systems there are bleeder valves, but I havn't found any on my tractor yet (or the snowplow lift cylinder that got me thinking about this). ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-09 52827
The discussion got me thinking too. I hadn't though what might happen if a quick-connect came loose on the pressure side of a cylinder when it was cavitating. It might well draw air in through the quick-connect, but maybe somebody knows for sure.
Unlike auto brake systems, tractor hydraulics are open. Most times any air admitted to the system gets pushed through to the sump where it bubbles out of the oil before being pumped again. Occasionally some air stays in a cylinder and it's not uncommon to cycle them--move them to the limits of travel in each direction and hold the valve open for a few seconds.
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2003-04-09 52834
According to the boys at our local hydraulics shop, slowly cycling all the circuits a minimum of 5 times each, full limit, to full limit, with the machine at or near PTO speed will (as Tom mentioned) run all the air back to the sump.
While there may be a restriction in place in the factory assembled circuit, it may either not be enough in this case, or just not set right since a lot of times it is a screw-type adjustable restriction in the valve.
I'm told that the vacuum on the back side of a 'one-way' circuit will draw air either from the sump, or right past the gland seals (on the cylinder piston rods) long before it ever gets enough power to overcome the spring in the quick-disconnect. As for speed, all our machines are equipped with them and we have put them side-by-side with new unrestricted machines, the difference was so slight as to be unperceivable in normal operation. The restriction, in theory, only reduces the circuit to the maximum point at which it SHOULD be running anyways, and so should never influence operating speed.
The restrictor itself is almost always a 'rattle-type', even the screw-types now use 'rattle' technology, which is basically a funnel shaped chamber with either a ball, or a very small tube which cannot pass the narrow end, theother end usually has a pin across it so the check ball can't leave the other way either. It restricts the fluid by pushing the ball or tube down into the narrow end of the 'funnel', when the fluid travels the other way however, the ball or tube moves back against the pin and almost full flow is returned.
Best of luck. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2003-04-10 52900
Ah! Considerably more refined thinking than mine. I should have figured there is something better than the traditional washer with an 1/8" hole in it. Rattlers probably produce much better fluid flow mechanics too. I still want a valve with a regenerative fast-dump feature on it though. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2003-04-10 52917
Tom, while I was a little long-typed? (winded?) in my last post, I did omit a few tech. details that are critical to reasoning and decision-making.Also, these are very inexpensive items ($30-$40 Cdn. depending on capacity) and are readily available, even by mail-order for you lucky ones farther afeild in the hinterland than us. (Princess Auto Part # 8006748, page 26 of 2002 catalogue, your welcome, LOL)
The main detail I omitted was that these nifty little gadgets are ADJUSTABLE, they can be regulated from 0gpm, to the max. rated flow of either 7.5gpm or 11.25gpm, (depending on model) while NOT affecting flow in the oppisite direction at all. This means that the perofrmance of the opposite side of the circuit is completely unaffected, it does NOT hinder performance, it only improves it.
I have discovered, quite by accident, that they are also REALLY handy on a log-splitter, if you put one on the 'split' side of the stroke it can be used to limit the maximum speed at which the points close to one which is safe for all involved, meanwhile it stills allows for a fast retract, if you were to try the same thing by regulating pump speed, you would have less max. PSI and flow rates, not the same results at all.
In your case Tom, it could also be used to limit the 'lowering' speed of your forklift attachment to a gentle creep regardless of how far the remote valve moved, a nice safety, meanwhile it would not affect lift speed.
Best of luck. ....
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