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Sloppy controls on Toro Z turn


HenryJ's Avatar
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Join Date: May 2006
Posts: 25

02-21-07, 06:00 AM   #1  
Sloppy controls on Toro Z turn

I have posted this elsewhere and have not received a clue. Any Idea's? Thanx

I got a Z turn, not a deere but I think they are all cousins anyway, it is an El Toro with a Kaw V block. It is the type that has two separate hyd pumps that run each hyd motor on the rear wheels respectively.

RPN's at full.

When you impart a control movement to the handle it seems to lag a little ant then all at once the imput takes place and it kinda jerks to where you have set it to go. Running slower like going in and out fo the barn, you can imput the control and it will continue in the same direction for a nano second and then make a little hyd screech and jerk to the setting you had put in the lever. It does this in both fwo and reverse and on both sides. Kinda wierd. Of course the service manager at the stealer with his hat n backwards kinda gave me the deer int he headlight look.

I have changed the hyd filter and put the right kind of oil in twice. Even tried stiffer oil and that gave zero difference.

I have thecked all linkage rods-no slop-when you move a lever it immediately puts the inpup into the respective pump.

I forgot to add that this is the type that controls the wheels by the levers working a connection to each pump, which has to be running a control valve inside the pump assembly.

Also new pump drive belt and trans filter from Toro

 
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cheese's Avatar
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02-21-07, 08:08 PM   #2  
It sounds like you've done everything you can to eliminate all sources of the problem. If the linkage is immediately moving the lever in the tranny, you might be getting the best performance you're going to get. Has it done this always?

I'm not sure what setup you've got, but generally the lever on the tranny moves a swash plate, which controls the volume of fluid that is driven through the drive motor. When the plate is flat in relation to the pump pistons, there is no volume, and when it is at full angle, it is pumping full capacity. There shouldn't be any residual movement once the plate moves, so unless it is not moving immediately or fully to the selected position, it should respond immediately. Try spraying some lube/penetrating oil at the spot on the side of the tranny where the lever pivots. There may be some sort of friction control there that is getting sticky.


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gardener321's Avatar
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Posts: 180
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02-22-07, 06:56 AM   #3  
I have experience with hdrostatic crane drives up to 250hp. Basically they all, from the smallest to the largest work the same.
Dealing with something that I have never seen before, as your mower, I am trying to figure out from your description how the pump and two motors are connected. Maybe you could give me a better overview if you describe how the wheel motors are connected. From what you described, sounds as though this mechanical linkage goes directly to each wheel motor and there is a compact pump/motor package at each wheel. The only other scenerio that I can imagine is one pump in the chasis feeding thrugh a four port control valve to each motor.
If the pump is belt driven, you may hear a belt squeal if directly driven from the engine what you are hearing is one of two things. A high press relief valve popping off or cavitation at the pump intake. I do not know if your system uses two filters or not, but if it has an intake filter, it may need cleaning hence the cavitation squeal which will eventually damage the pump.
Careful about changing the oil. A heavier oil is not the answer because it too can cause cavitation. Make sure you use the specified oil. Hydraulic oil MUST be of the non foaming type, or here is the cavitation/pump damage situation again.
Knowing no more about your particular system than I do, I do not know whether I can help you or not, but I will surely try. Tom

PS another possible control method could be this: engine running at governed rpm. Forward and reverse being controlled by the swash plate via your foot pedal control while the rods to each motor by pass fluid in conjunction with the position of the steer handles, which would steer the machine as well as provide zero tuning radius. In that case the linkage may have been tampered with and need to be both set to neutral with steer handles in neutral. Try jacking up the rear end and note which way if any the wheels are turning. With the steering in neutral, adjust both control rods at the motors for zero rpm. I am anxious to hear.
Don't laugh, I don't have much to go on at this time.

 
30yearTech's Avatar
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02-22-07, 05:08 PM   #4  
Most of the time I have found that the jerky motions are caused by the linkage from the steering control where it attaches to the pump motor is loose and not rotating completely the input shaft that moves the swash plate in the pump. In addition if the steering dampeners are worn out that also can cause a jerky motion when trying to move from the neutral position. The steering dampeners look like little tiny shock absorbers that are connected to the steering arms to dampen their motion. Most of the systems used on Toro Zero turn riders use 20w50 HD motor oil.


Last edited by 30yearTech; 02-22-07 at 06:14 PM.
 
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