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Choke's stuck on!
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Discussion Starter #1
Yesterday evening I was using the 770 loader on my '82 Ford 1500 to clear a road ditch in front of my house. In the end, it proved to be too muddy to complete this task. I was using the bucket to “claw” my way out of being stuck, as well as carrying full loads of mucky clay. After about 30 minutes of working the hydraulics, I experienced an input lag. It would take about 2-3 seconds from the time I actuated a loader control lever to the time the cylinders would move. The engine was dumping out a lot of heat (and I was getting fed up stuck in the mud) so I stopped working and just drove the tractor down the gravel road to fling mud off the tires for about 5 minutes in high gear, not using any hydraulics. When I returned the input lag was gone. Still I parked the machine to wait for dryer weather.

Spool valves were just cleaned and o-rings replaced. Also cleaned filter screen and have new-ish fluid. The pump seems strong as I can lift the tractor up using either boom or curl cylinders. I've never noticed this in the 2 years of owning the tractor. also never worked the hydraulics this hard before.

Is this normal or is there something I should check before it breaks?
 

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High fluid temperature will cause the fluid to thin out (lower viscosity) to the point where no amount of time will allow it to do work. You caught it when it could still build working pressure and took the correct route for cooling the system down by just running it with no load.

Fluid will find the easiest path back to the reservoir. When it is hot, it is thin enough that the normal clearances in the pump will offer that path when under lower pressures than normal..

Normal situation. Don't work it so hard, or improve the fluid cooling to compensate.

A plugged filter will also contribute to creating an overheated fluid condition.
 

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Premium Member
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492 Posts
I agree 100% with Tudor.
Also remember this. A front end loader is a Scoop, not a digging tool. Forcing it to do a job will cause it and the oil to heat up causing it to act sluggish. Welds in the lift arms can also become fatigued and crack under "unusual" stress situations as well.
 

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Choke's stuck on!
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496 Posts
Discussion Starter #4
Interesting, thanks gentlemen. I was over-determined to complete the job, and underestimated the soil wetness. I know it was the clawing out of one particular hole that heated everything up so. We are on day 3 w/o rain and forecast for at least two more so I remain hopeful.

A quick question while we have a quorum here: From a fluid heating perspective is it preferred to generally always operate a spool valve slowly (minimal stroke), or more of a rapid in/out? Of course the latter is harder on the loader frame (and operator), but I see the fluid forced through a smaller flow path as contributing to more heating.
 

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Pressure and orifice size are the determinents for putting heat into fluid. Speed for moving the spool is of such minimal time in comparison as to have little effect. If the spool is held at a position that is less than full for an extended time, then the reduced orifice size can add measurable heat to the system, but the cylinders will bottom out in only a few seconds at which point it becomes the relief valve that is generating the heat.

Under normal loader operating conditions, there is ample rest time between the use of the cylinders to allow heat to transfer through the large surface are of the cylinders and lines. When stuck in the mud, the bucket cylinders see a much higher frequency of use and can't discharge the heat as rapidly as it's being made. But the arm cylinders don't move much in the same situation and the fluid in the cylinders ends up being much cooler. Tip; periodically cycle the arm cylinders to full stroke to get that cooler fluid back into circulation.

It won't help much, but it will make a difference. Most of my loader work is snow removal and my tractor lives outside at sub zero temps. SOP upon starting the engine is to fully exercise all cylinders full stroke from 2-4 times, depending on ambient temperature, to move the cold fluid out of the lines and cylinders back to the reservoir and add some heat in the process. It's the same idea, just working at the other end of the thermometer.

How fast and far you move the control handle is of little consequence to the loader frame or you. The only effect for the loader frame is how fast it moves. The same effect can be created by adjusting the throttle. Since you are moving the handle, your body should automatically adjust for the change of operating speed. The effect on the handle with rapid movement is actually of more concern. I've broken handle linkages and handles in the past with no visible effects for the loader frame. On the other hand, if the handle breaks then your body will notice the lack of resistance to movement. :tango_face_devil:
 

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Also remember this. A front end loader is a Scoop, not a digging tool. Forcing it to do a job will cause it and the oil to heat up causing it to act sluggish. Welds in the lift arms can also become fatigued and crack under "unusual" stress situations as well.
Great theory, but not in evidence when working. There is little difference in force application between scooping from a pile of dirt and excavating fresh ground. The rear wheels can easily spin for both and it takes the same pressure to lift the payload.

I've done several excavations with my GT loader, including 150 yards of material just from my driveway.
 

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Choke's stuck on!
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496 Posts
Discussion Starter #7
Thanks TUDOR. I do cycle the cylinders full stroke after startup but never thought of doing it to purge hot fluid whilst working.

I can relate on the handle linkage! I've already replaced both with some homemade, hardened "Z" hooks after an unfortunate and crippling "stuck on the float detent halfway through plowing the drive" incident...
 

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I agree Tudor. A front end loader can dig to some extent.
I was referring to those that are inexperienced and try forcing the bucket down into undisturbed, packed hard soil like the digging bucket of a backhoe or excavator. Those fine folks are usually the ones that complain about burned up clutches (from attempting to force the tractor to move into the ground to dig which causes the clutch discs to slip) and/or broken & bent left arms from forcibly pushing the bucket into packed earth.
 

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Agreed, Poppa Dave. That's why I like a hydro. I can rock the pedal back and forth while putting the full front end load on the cutting edge to force it into the ground without worrying about a clutch. The ground in this subdivision is on the soft side anyway, so it isn't a real hard job to sink the cutting edge several inches.
 

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Choke's stuck on!
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496 Posts
Discussion Starter #10
Ditch clearing project is going along well. Just working on it about 45 minutes or so per day so as to aid in drying.

I haven't had any lag issues since topping off the fluid and taking things a bit easier. I'm impressed with this piranha tooth bar so far. A hydro would make it even better, as even in my lowest gear (0.35mph) it happens too fast. The only thing saving my clutch is assuredly the bald turf tires.
 

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OLD TIRED CDN. MECHANIC
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9,027 Posts
Agreed that a GT loader can and will dig. I've been down 5 feet with my Johnson 10TC and that was after breaking thru 5 or 6" of frozen ground on top, in December.

I didn't really "dig" like a backhoe as such, but rather set the bucket cutting edge to peel up an inch or two each time, and just drove forward till the bucket was full.

To get down 5', I had to ramp back about 25 or 30 feet but it got the job done without complaint. Hardest part was backing up the icy ramp when the bucket was full
 
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