Hydraulic (flexwing mower) question...

[Richard]

I've got this 15' flexwing that is powered by hydraulics which are powered by the 540 shaft and a pump.

Has three hydraulic motors, one for each blade. The right side rotates clockwise, the center and left side, both rotate counter clockwise. They are considered (I believe) a geared motor. Looks like little straight fingers that interweave and as the oil passes through, it powers them.

Situation, when I get into high grass (waist high & higher) the middle blades (on their own circuit from pump) and the left side, (shared circuit with right side) slow down to the point that:

1. Right side blades, which by the way, are on the circuit AFTER the left side blades.... the right blades are pretty much cutting anything down that dare stand in front of them.

2. Left side blade will slow down and leave say, 50% not really cut so it stands back up. Given the right side cuts everything, I have to believe the left side is getting good flow since it then goes to the right side.

3. The center blades can become useless.....not cutting anything leaving a trail of tall grass behind it.

I've rebuilt each motor (I'm told these are old Tyrone M-20 series, now owned by Parker)


In the stereo world (my left speaker sucks, it doesn't play anything or, plays much softer than the right speaker.... to diagnose, you might swap the wires to your amp to see if the issue follows the wires (amp issue) or, stays at the speaker (speaker issue)

I'm guessing that if I can get the hoses hooked up, that these motors are swappable so I can see if the center issue, moves to the new location or not.

Ultimately, this is what I'm wondering.... I don't believe that the motor knows nor cares which way it's rotating. That's dictated by the oil flow. Would I be correct in that presumption and would swapping the motors around, be a viable way to try to locate the problem?

I really like the no moving parts on this but am finally considering replacing this with a more traditional shaft driven unit.... I'm just cringing at the expense of them so am open to spending some more $$ to see if I can figure out and fix the problem so I don't have to use a 15' mower, but make 5' (good) cuts with it and going over it two/three times!!

I'm not an engineer nor a hydraulic expert.....however, tomorrow, I AM going to be staying in the same town, that also has a Holiday Inn!! So, does that count?

 

[Richard]

In case someone nails me for not giving all the facts (pump attached to 540 might not be sufficient input) The pump is attached to a speed increaser that takes the 540 up in speed, by a factor of 4 and that is what the pump hangs onto.

 

[K5lwq]

I would think there should be filters somewhere around or on the tank. Have you ever changed them? There also should be a manifold for each motor that would have pressure relief valves. Those might be the problem.

Might have to rig up a pressure gauge on a long enough hose so you can see pressures when you get into the tall grass while mowing.

Pictures and or brand and model number might would help us figure out how the system is designed.

 

[oldnslo]

You are correct on left motor getting flow if right motor is turning Are there any valves in the lines to the motors? Suspect that with the two motors in series there might be valves at one or both motors.

Depending on how the motors are built they may or may not be bi-rotational so be careful if you start swapping hoses.

Did you check the gear cases for wear between gear teeth tips and case? This is the most common wear point on gear motors that allow leakage flow past gear teeth.

 

[Richard]

new filters, new pressure reliefs (presuming they sent correct psi, which i think they did)

 

[Richard]

no valves. have 3 gauges, needles bounce all over. ran over one so it needs fixed. discovered low on oil, maybe thats it....filled up, "burped" it, went to crank up to pto speed, a one half inch piece blew out of the channel holding filter seal so now waiting on replacement housing to arrive. was amazing to see the geyser of high pressure oil blowing out the (thankfully) back.

 

[oldnslo]

Where all three relief valves the same part number? Can you take pictures of how where they are in the circuit. Any make and part numbers on the relief valves?

 

[Richard]

different. im out of state currently (attending funeral today) as i recall center was 1500 psi (only motor in circuit) and wings are 2500 psi in shared circuit...or vice-versa.

they each attach to a block that is attached to motor.

just realized i might be able to swap them to see if that swaps the issue

 

[K5lwq]

Is it two separate filter housings, one for each circuit? Also is the pump a tandem pump, one for each circuit?

Being that there is a problem with both circuits, one would want to look at any shared components. In this case it may be two separate issues.

For the wings, swapping the relief valves may move the problem. But the left manifold could be cracked internally allowing fluid to bypass. I wonder if the manifolds are identical? Might could swap reliefs first then if no changes swap the manifolds.

Not sure how to figure out the center circuit issue though.

 

[workinonit]

Not that it really matters but who manufactured this bush hog?