Front loader and 3-point hitch slowly drop with or without the engine running
- Thread starter mans
- Start date
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
I'm guessing after 30 years of use/abuse , things are a tad worn... would have to see the 'plumbing' but ,yes, 'control handle' ( the valve assys ) are the likely cause.
TheOldHokie
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Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Two separate valves and sets of cylinders. The 3pt will not make the loader drop and vice versa.
Dan
If your B7200 has a 3pt lowering speed valve, you can test the seal by raising the 3pt and closing the valve. If it still drifts down, you probably have a piston seal leak.
TheOldHokie
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Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Yes. Is it a B1630 loader? What is drifting down on the loader - the bucket, the boom, or both?
Dan
Just to clarify, is the problem that the FEL and 3PH lower when you don't want them to, or that they lower slowly instead of fast?
They lower when I don't want them to. They work fine with the controls in all directions.
TheOldHokie
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Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
I have a B7200 with B1630 loader and have the same problems. These machines are getting old and worn.
Engine running or not does not matter. The valves still have to seal to hold pressure in the cylinders. The pump does nothing in that regard.
In the case of the loader the control valve is probably shot. Good news is its inexpensive and easy to replace. I'd suggest you make it the number one priority.
Three point is more difficult. That could be either the cylinder leaking or the control valve. The cylinder is easy to service - valve is not. Does the 3pt position control lever stay where its set or does it drop down along with the lift?
Dan
Thanks. That's what I figured, and clearly everyone else too, but you know what they say about "assume".
Dan -- I'm curious why you favor the control valve being the cause as opposed to a failing seal in the cylinder? Is it worth performing necessary diagnostics to confirm this hypothesis, or are you suggesting that OP just go ahead and replace the control valve?
--eric
TheOldHokie
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Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
The lift cylinder has to retract for the lift to drop and with a leaking seal that cannot happen. The oil has to either escape to the outside (external leak) or back to tank through the control valve.
Dan
Not to question the wisdom of the Hokie…. but if my tractor is not running and both FEL and 3pt are in the air… dropping the FEL by moving the joystick….WILL move the 3-pt also.
In fact, it the 3-pt is on the ground…and the FEL is dropped…the 3-pt will move slightly towards “up”.
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Leys assume the typical Kubota loader valve configuration.
The 3pt is being held up by the oil trapped in the lift cylinder. The 3pt valve is maintaining that seal.
The loader is being held up by oil trapped in the lift cylinders. The loader valve is maintaining that seal.
When the loader valve is shifted it opens the loader cylinders to power beyond and the oil flows through the open center in the 3pt vslve and back to tank. The spool in the 3pt valve never moves just like it does not move when the engine is running and oil from the pump is houng yhriugh the center. So how can the 3pt drop?
BTW I lower the loader with the engine off all the time and the mower in the back stays right where it is until I lower it with the position control lever.
Dan
I’m off on a trip…so I’ll have to see if I remember things like I. think I do when I return home.…if I can remember to remember to try it again….
I generally lower everything first when parking…THEN shut the engine down…then “relax” the FEL joystick…then raise the 3-pt lever (because I park in my hangar and must back-out next time I need the tractor…I keep the 3pt lever in the “up” position so that when I start up next time…the finish mower will come up in the air…and I won’t forget it sitting back there. I don’t have. problem remembering to raise the FEl before reversing. That routine is my usual practice.
I seem to recall that, one time, after shutting down and forgetting to lower the FEL with the engine already shut down…but with the 3 pt on the ground with the 3pt lever in the “up” position….that lowering the FEL w/joystick momentarily lifted the 3pt.
I’ll test this recollection when I return home in 2 weeks…if I can remember to do so …and if I can remember the way home….
Oh yeah that's right ... because the rod-end volume is less than the cap-end volume. You already schooled me on that, and then I watched an entire training series on hydraulics that included calculating rod-end and cap-end volumes, extension and retraction times, etc. Hadn't yet directed that knowledge to apply towards diagnosis. Thanks!
I'm going to have to bone up on "typical Kubota loader valve" ... I would have thought that the loader valve opens the loader cylinders directly to tank, not power beyond. I'm very interested in the hydraulics plumbing on my tractor, and it's on my to-do list to take another look at the diagrams in the WSM.
from the peanut gallery: I've nothing to offer the OP, but this is a great thread for educational value. This is the sort of thing that makes forums so valuable (particularly for folks that are new to tractors & hydraulics).
Thanks!
Thanks!