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Boom lift Drive Wheels torque fade

Ronray

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And the wheel with more flow will have more torque, and therefore continue to spin if it is not getting traction, correct?
 

TVA

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The wheel with more flow will get more speed. But it will rob the torque (pressure) from another wheel.

You think someone removed flow divider?
 

Ronray

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thanks TVA. No I do not think anyone removed the flow divider. I was just thinking of removing it myself as an experiment to see if both of the wheels will keep spinning even if they lose traction. Currently, it is just acting like a passenger automobile with posi traction where if you get stuck in mud or sand, just one wheel is spinning while the other one stops turning. On my farm tractor for example if I drive diagonally across a ditch, and 1 rear driving wheel lifts off of the ground and continues to spin while the other one does not spin and I go nowhere, unless I engage a foot pedal that locks in the rear axle for both Wheels and the one wheel that is still contacting the ground will propell me forward out of the ditch.
 

TVA

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Yeah! Looks like your flow divider is not working! could be spool stuck or bypassing.

But I don’t like the design of this thing - it is steerable vehicle, and your flow divider should only be ingaged for short while in spinning situation otherwise you will be tearing things apart! That mis labeled component kinda looks like pressure compensated flow divider on diagram, but missing the arrows through orifices symbols! So who knows?!
 

Ronray

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The main hydraulic pump attached to the engine may not be original, since it is painted yellow and everything else is white. It is also aluminum body, except for the head portion that the large hoses attached to. The head portion is magnetic and appears to be cast iron.20190328_185526.jpg
 

TVA

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The aluminum shavings can be from original pump which went bad.
 

TVA

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So I’m still unclear, is your problem that only one side works correctly, or both sides pretty much one wheel spins while the other has nonpower?
 

Ronray

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If I jack the rear end up with both Drive wheels off of the ground, they both spin normally. But when I lower the rear end back onto the ground, both Wheels start to push the machine forward a few inches, but then the right wheel stops turning, and the left wheel continues to spin without getting traction and digs deeper into the ground, but only when the swashplate levers are in the 17 degree position. When they are in the 3 degree position, both Wheels stopped turning after they have pushed the machine forward several inches. And this is even when the main pump is producing 2500 lb of pressure. And it does the same thing even when I switch the hydraulic wheel drive motors, this is why I think the problem is in the valve manifold.
 

Ronray

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Okay, I completely disassembled the valve manifold last night and here are some pictures that I will post in this message and the next message of valves that I don't know what they are

20190328_205024.jpg 20190328_205216.jpg 20190328_205108.jpg 20190328_204107.jpg
 

Ronray

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And there are two of these ball valve looking things.

Also FYI, I did not find any more of those little metal flakes in any other parts of the manifold valve body as I disassembled it.
 

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TVA

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The balls with weak springs most likely is check valves associated with counterbalance valves, there should be a shuttle valve somewhere could be ball or small spool with or without weak springs on both sides.

The bigger spool looks like your flow divider and smaller ones could be the Same but these should be connected too smaller “pilot” passeges connected to the motor ports.
 

TVA

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Swapping of the motors didn’t move the problem to the other side?
 

TVA

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The right side of the big spool have scratches on it! I think bore has scratches even bigger ( being aluminum) and I think it is your problem.
 

TVA

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The bigger one not even a spool in direct meaning, it’s more of a sleeve! And it’s not supposed to move aside from installing, so how it got those scratches?

Does it have freedom to move inside the block when assembled?
 

TVA

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And pictures pretty much confirm that it is a pressure compensated flow divider.
 

TVA

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Is the 3 degrees the spec for low speed swash angle, or it’s something you measured? I think it should be somewhere half between 0 and 18 degrees.
 

Ronray

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I didn't even notice those scratches on the end of the big spool until you pointed it out, but they are so small that they are only visible with the Flash on the camera, or if I tilt the spool sideways in the direct sunlight. There are no lengthwise scratches in the cylinder of the big spool but there are what appears to be just machine sideways scratches. The big spool does not have any free play end-to-end when the cover nut is in place, but it can spin around, and I can spin it with my fingers.

When I swapped the hydraulic motors 2 the opposite sides, it made no difference. The same driving Wheels acted the same way, which is why I started to look at this valve manifold block assembly. I might be able to switch the big hoses from the wheel Motors to the manifold block and see what that does, but I might have to get some longer hoses and extra 90 degree adapters.
There are lots of small passages within the block approximately 1/16 of an inch in diameter.
So far I have also been unable to remove the Allen screws in the side of the block even with an impactor, which you previously said you thought were for testing ports.
3 degrees is the low speed spec angle of the swash plate lever and 18 degrees was the high speed angle according to the specs, and that also looked visibly correct. I did not measure it. But I confirmed that the lever did move the swashplate when I had the hydraulic motors completely disassembled. At three degrees, both of the driving Wheels would stop turning after moving the machine several inches in either direction. And at 18 degrees, only the left wheel would stop turning, and the right wheel continue to turn and spin even though it was not getting traction.

I'm wondering if I just took all of these spools and ball valves out of the valve manifold block if that would get equal volume and pressure to both Motors while disengaging the brakes at the same time?
 

TVA

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Are the smaller spools slide freely inside big one both ways, is there any scratches or other damage inside of bigger spool?
 

TVA

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The way the pressure compensated flow divider works is: it should proportionally cut the flow from spinning wheel. Looks like it’s working one way. So it’s either small spools do not slide one way like they should, or Fluid bypassing somewhere, or both!

Maybe 3 degrees worked when motor s were fresh but now when motors are “tired” you may wanna start increasing that angle until machine will start moving. I think 3 degrees is low.
 
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