hydraulic power / loader

[mickd]

I recently bought a ford 1700 with a770 loader. I'm still changing oils, re packing cyllinders etc. before I haul it to our camp .
I notice that the loader will not pick front tires off the ground ----- ? should it be able to ? If so where should I start looking for the problem . Thanks Mick

 

[jinman]

Mick, how did you go about trying to lift the front? If you had the bucket flat and tried to use the lift arms only, you might not get the front into the air. You either have to put the bucket flat on the ground and then curl it to the dump position or put it in the dump position and the lower the lift arms. If that is what you did, then you might have weak hydraulics and you probably need to invest in a 3000 psi gage hooked to a quick-connect adapter so you can put it into the loader hydraulics and measure the pressure. If your loader won't lift, you need to identify whether the problem is the pressure or maybe an internal cylinder leak. The pressure gage will really help with that. Also, if you lift your loader with the bucket flat and then turn off the engine, does the bucket sag? Arms drop? Either of these could mean you still have an internally leaking cylinder or your joystick valve is bypassing. When you center your joystick, you remove the pressure relief valve from the circuit, so any leak-down is probably internal cylinder leakage.

 

[mickd]

I was working the lift and bucket cyllinders full in and full out after replacing the packing in the bucket cyllinders, then turned the
bucket (cutting edge down ) and tried to raise the front end by the loader arms- not enough down force to pick it up. Before trying to raise the tires off the ground, I did cycle all functions numerous times in hopes of getting any trapped air out of the system

 

[mickd]

Jim , when I get home ,I'll try lifting the machine by dumping the bucket,(those cylls just re packed ) . If that picks up the tires , should that mean the hyd. pressure is ok ? I will also shut it down with the loader off the ground and see if it holds or settles, as you suggest. I would hope not to have to get into a hydraulic pump, the cyllinder re packing was'nt so bad. I'll let you know tomorrow how it went Thanks.

 

[jinman]

Mick, picking up the front really is only a quick way to verify that your loader can do some real work. It doesn't guarantee anything about maximum loader efficiency or power/pressure. On an older tractor, I'd suspect you might not have full pressure from your pump, but if you force the loader arms down as far as they go, you should be able to hear the system relief valve lift if you have good hearing. If the system relief valve is lifting, most likely you have normal pressure unless the relief valve spring is fatigued from old age or somebody has removed shims. On your 1700 model tractor, you may have a separate relief valve in the 3PH circuit and one in the supply for the FEL. The one for the FEL should be in a block on the right side of your tractor just in front of the foot rest. On later model 1700 series, this is the location of the relief valve.

 

[mickd]

Jim, the pic you sent does,nt look familiar, mine is an 80, and fluid is fed to the controls from 2 hoses originating under the right side of the seat, I'll look for the relief valve and listen though. I just got the tractor ,seems to have been pretty well taken care of, previous owner passed 10 or 11 years ago and it sat in a garage til now. Only shows 550 hrs on the meter so I hope its a minor fix. I'll let you know

 

[J_J]

What Jinman said plus.

Yep, get your self a 3000 psi hyd gage with a QD on it to allow you to plug it in wherever. Your best position for the gage is up by the control levers where you can see it to monitor and trouble shoot the hyd system. Add a tee with a QD at the IN port of the loader valve . Plug your gage in the QD.

What it can tell you is this. With no hyd lever engaged, you should see no or very little pressure as the fluid is just flowing through all the hyd valves.

You will see relief pressure if you max out the cyl, in retract or extend.

If you raise the 3pt to max, you will see relief pressure for the 3pt.

As you raise a load, you will see what pressure the lift cyl's are developing.

You can also check and set your relief pressure for any relief valve.

Just lifting the wheels off the ground might only take about 1000 psi, and might not reflect the max pressure or load the tractor is capable of.

If your pump and cyl can develop the factory stated relief pressure then you have a base line to work from.

 

[mickd]

JJ, I was hoping for the easy fix, for me that would be re packing the lift cyllinders ,then all 4 would be gone over. Is the test gage a specialty tool I'm going to have a hard time finding ? Is it expensive ?

 

[J_J]

No, the test set would cost no more than $30.

Can find at any TSC

Surplus Center

A tee that will fit your hose and screw into the IN port of the loader valve, and a QD

 

[wdchyd]

Mickd,

Correct me if I'm wrong but those lift and bucket curl cyls have each a single set of v-packings for the piston seals....Yes/no..??.... Hercules Sealing Products-Hydraulic cylinder repair seals and seal kits, replacement cylinders and cylinder components for construction and many other heavy equipment industries.

the lift cylinder v-packing set is positioned so the main function will be doing lifting (push out).....and the bucket curl v-pkg set is positioned so the main function will be doing pulling.....(to hold the full bucket of dirt)

Did you happen to notice how these were different when you took them apart, they should be

770-SERIES FORD LOADER (1/79-12/83)

Even though all four cyls are ported for double-acting usage, their main function was intended for one way under full pressure......not the other

To sum it up, trying to lift the front end is not a good way to test cuz the lift cylinders will slightly by-pass while using them for pull (lifting off the ground) and are not pressure tight in that direction

Also the v-pkgs sets are very sensitive to having the right "tension" when they go back together (not too tight and not too loose).....You should feel a healthy snug fit with a light plastic hammer

 

[mickd]

Jim, Last night I warmed up the tractor , with the bucket flat on ground ,rolled bucket in dump direction which lifted the front wheels off the ground with ease. Again tried to lift the front end with the loader arms , again it failed. Then did as you mentioned and raised the loader several feet off the ground to see if it holds. At this time, there was no load in the bucket and bucket in level position then I shut her down. Checked an hour later and lost 5 inches ( bucket still level ), Checked again this morning , lost another 16 inches, again bucket remained level. Does this tell me that the lift cylls are internally leaking thru or possibly the control valve ? I could'nt hear the relief valve making any noise / that 2 cyl motor may have had something to do with that. JJ thanks for the info, Im glad to hear the test kit can be had at TSC, ther'es one handy. WDCHD, Thank you also, I was unaware the cylls were designed for full pressure in one direction, with the V rings in one direction, that makes sence. I did'nt re pack the lift cylls so i was not aware the V rings being pointed in the other direction-( they were'nt leaking, at least externally ). I am tempted to order up packing kits for the lift cylls and a kit to freshen up the control valve. What do you guys think ?

 

[J_J]

Are the cyl DA cyl and do you have two hoses going to each on lift arms cyl?

Usually in a SA cyl set up, one of the work ports is plugged, and a filter screen is in one of the cyl ports.

If your system is set up for DA operation, and

If your bucket is flat on the ground, and the cyl is fully retracted, and you push the down lever, you will not be able to lift anything. You are at the end of a retracted stroke.

The relief should activate if you keep the lever in the down position.

Some tractors can cause the front to rise using down pressure on lift arms, based on bucket mount and depth, probably only a few inches.

If you raise the lift arms and curl the bucket down, then you can push the down lever and raise the wheels off the ground.

You can also put a rail road tie under the bucket and put the bucket on top and push the down lever and raise the front wheels.

It is not a good idea to use SA cyl in a DA valve setup and two hose operation.

Can you show pictures of the valve, and the cyl.

 

[wdchyd]

JJ,

I'm sure he has a DA valve and cyl setup but the older fords have a strange way of putting in just one (directional) set of v-pkg.......it will go both ways but rarely do they hold pressure tight in the other way....Just something to consider.....lifting the tractor off the ground wouldn't prove or disprove anything......actually my 2010 kubota won't lift the front end up in some circumstances

I would use the pressure guages to confirm valve holding a load and PRV settings.....

If the control valve comes out to be the culprit then I would be suspicious of some contaminated hyd oil doing the damage to the control valve and wear in the cyls

 

[mickd]

Good morning guys. Thanks for your responses. JJ Both the lift and bucket cylls are DA, I've tried turning bucket cutting edge down which gives me about a foot of travel left on the lift cylls , then trying to lift the front off the ground with the lift arms --- not enough down pressure, but i can lift front end by rolling bucket in dump direction when it is laid flat on the ground. The lack of pressure seems to in the lift cylls only. WDCHD, since the loader did'nt hold in place when machine was shut down , do you think the V-packing may be installed in the wrong direction or just worn out and letting fluid leak thru internally ? the lift cylls are not leaking externally. also I do intend to change the hyd fluid & clean or change the filter and suction screen. As this machine is new to me , I do'nt know where they are located. I,ll put a manual on the list of things to order.

 

[wdchyd]

If it were my machine, I'd repack those cyls anyways just cuz you don't know where they've been....a little extra work ain't gonna hurt them

I wouldn't suspect they were in wrong unless it shows they were done recently..( I've seen this)...more than likely just wear and tear

 

[mickd]

JINMAN, In your post you sent a pic of the relief valve on a F-1700, can you lead me to the hydraulic filter and suction screen on the 1700 ?

 

[jinman]

JINMAN, In your post you sent a pic of the relief valve on a F-1700, can you lead me to the hydraulic filter and suction screen on the 1700 ?

Mick, I think a 5" drop in an hour is VERY GOOD for a tractor as old as yours. 16" overnight is better than some almost new tractors. My 2000 model TC45D drops more than that. In operation, that kind of leak does nothing to take away from the loader's power or workability. Most loads are on the loader for no more than a minute. Even if you transport a distance and the loader sags a tiny bit, just a touch of the joystick controls puts it back to normal. There is no way I'd suggest you try to "fix" that kind of leak. If you have power or lift problems and don't have sufficient pressure, then look to something else as the problem. It's not that tiny leak.

Your tractor doesn't have a regular spin-on filter or cartridge type filter. All it has is a screen. Follow the big line off the top of the hydraulic pump. Where it goes into the transmission case on the right hand side, there is a round cover under a banjo connector. Take the banjo connector loose and remove the round cover. It is attached to the screen. Be sure and drain your hydraulic fluid before removing the banjo fitting or cover. After cleaning the screen, you can add your fluid back. Here's a diagram of the screen (item 15). The screen is on the suction side of the pump.