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?

 

[Richard]

terrain king, circa mid 80's ???

 

[oldnslo]

I suspect the wings would have 1500 PSI and center 2500 PSI.

Next time you use this mower mow a distance in taller grass where center and left are not cutting. Shut mower off while still in tall grass and check the motor housing temperatures vs inlet hose temperature.
Do the same with pump housing vs inlet line temperature.
If left and center motor are hot then suspect they are leaking internally from inlet to outlet. Same with the pump.

 

[Richard]

Sorry I disappeared. After this funeral (my wife's cousin), my father (95) went to hospice and finally passed. (he had a fantastic life)

Anyway, this cropped up in my head and I have a vague memory.

Going to attach a PDF that shows the schematic of the motors.

I had rebuilt these (my first time ever taking a hydraulic motor apart) 3-5 years ago. I really don't recall much about it other than....it was oily!

Given the age of these things, I thought it might be worth buying another set of rebuild gaskets so did so. Had these issues so maybe 2 years ago, pulled one off to rebuild, the rebuild.

Nothing struck me as an issue UNTIL.... look at page 2 and part #8...the end seperator.

When I was putting this back together I distinctly recall that the motor would NOT go completely together. Long story short, this part #8 sat under the impellers, raising them by the thickness of the seperator....so I removed it. The motor went back together as it should and I moved on.

This has me wondering, is this the motor that is cutting well.... is this the motor that is doing poorly? I don't even recall which of the three I redid!

I DO know, something you buy a rebuild kit and you have 54 parts......only of which maybe you use 45 depending on what you are rebuilding. I presumed that since this part prevented the halves from properly closing, that it was for a different motor.

NOW, I'm wondering if it DOES belong in there (as now it might be an internal leakage point and causing some of my issues) and maybe something other got missed by me, that was keeping it from closing. My take at the time is this part would be crushed, were the two halves to be forced to close, which is why I (think) I removed it.

Again, I have NO memory if I installed or didn't install this part in all three.... I should have two rebuild kits, I'm debating on yanking the two poor performers and now that I'm more in-tune to the various parts, actually pay attention to see if that part is/isn't in there when they come apart.

My thinking is if I take them apart and all appears well (presuming part is in there) then just put back together without using the kit.

I'll admit.... I don't care much for how dirty I might get digging into this stuff.....but aside from that, I do enjoy taking things apart, trying to fix and putting back so other than the oil part, I don't mind doing this. I also know that I'll never know the factual answer (did I or didn't I put part #8 in there) until I actually look.

 

[oldnslo]

Item 8 is required for the motor to operate correctly. It appears to be the seals for the pressure side load feature on the motor. High pressure oil is fed into the backside of item 12 (pressure plates) which pushes them against the gears limiting the side clearance and leakage or slip past the gears. Yes they can be a challenge to get all the pieces assembled correctly without pinching something.

 

[Richard]

Just spent 20 minutes in garage looking for the two extra rebuild kits (I rebuilt all three motors, had this issue, bought three more rebuild kits BUT, only did one so should have two unopened kits in garage)

I've not yet found them BUT, I did come across what appears to be the "original" rebuild I did.

I happened to find four #8's AND, I found two "#9's" the little star seperator in the center.

That would suggest extras for two motors. I happen to have two motors that don't cut as well as they should.

I'm willing to start believing my wife might be right. I might be a dumbazz..... I don't know if these are or are not in there (these might possibly be the old ones) BUT, I highly doubt I would have kept the old parts so these are indeed, likely the keepers I didn't put in!

Only way for me to find out. At the rate I'm getting to this it might be 2 years lol.

I didn't expect to find these parts in a baggie sitting in my tool cabinet.

 

[Richard]

Question....

Part #8 has what I'll call a flat side and the opposite side has a bit of a slope/angle to it. Not huge, let's call it a bit of a wedge shape.

Given I paid no attention to these when I originally took motors apart, I don't know if they go "up or down".

When I put back together, I put the 'flat' part against the top and bottom parts of the motor, items 4 & 16.

Would that be correct or, should I flip them so the impellers have the 'flat' side on them and the wedge side is on the "outside" against the top & bottom?

Dawned on me why it's taken soooooo long for me to get really annoyed with the poor cutting..... the summer after I rebuilt these, the farm was leased so my cutting went down to just trimming some areas and frankly, I didn't use it as intended. Now, lease over, fields are 4' tall and I need the extra oomph!

I just wish the diagram or commentary spoke to what side is 'up'.

 

[oldnslo]

Does item 8 fit around item 12 the pressure plates. Normally those seals or end separators are held captive in some fashion by a groove or machined space of some sort. With detailed pictures of the motors and related parts this is just based on experience from working on other brands of motors.

My best advice is carefully take one of the motors apart and study it. I think it may become more apparent on how the parts should fit together.

Is item 17 the body through holes for the gear set or does it have on end that is machined flat bottom?

 

[Richard]

Is item 17 the body through holes for the gear set or does it have on end that is machined flat bottom?

The holes where the impellers are held, I presume. My recollection is they are flat bottom and do NOT go completely through the body. I do recall very small edges 'cut' / formed/ in some of the pieces and I was able to get all that aligned. My problems were when I put the halves back together, the stack was too tall and the halves had say, a 1/8" gap. I feared if I forced it together, I'd smash the plastic parts (6, 7, 8)

#8 as I recall, had the impeller sitting on top of it so forcing closed would have indented the part (is how it looked to me)

I powerwashed motors yesterday, hope to remove today if I can escape the wife's to do list! Have a call out to the Alamo-Industrial dealer.....turns out he grew up in the very small town I now live in. I'm hoping that link will motivate him to call Alamo to see the direction of the parts. Actually, I'm sure he'd call them, I'm really hoping he gets ahold of someone that knows the answer!

 

[Richard]

For posterity if nothing else, I'll try to take some pictures as I remove, disassemble and put back together.

 

[LouNY]

So am I correct in assuming that your pump has two sections with an output line from each, one section feeds the center and the other section feeds both wings in a series plumbing, feeding to the left side and through that motor and to the right side.
The left and center are not functioning correctly but the right side is.
This would lead me to believe that the center and left motors are not assembled correctly and are just bypassing oil and not feeding through the gears, it could be excessive clearances on the motor gears or a bad relief valve.
One other thing to check would be the blade installation, is the cutting edge going with the rotation direction.