L785

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onyxtour

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Hoping for some suggestions. L785, hydraulics work right wheels move left do not, any suggestions???
 

skidsteer.ca

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When you move the left lever, does it make any sounds like something is trying to happen, or just nothing. If you jack up the left side can you turn those wheels by hand?
Could be anything from as serious as a wheel motor or one side of the hydrostat pump to as minor as a bolt fell out of the steering lever linkage. How many hours? do you know the history? or did you buy it as a fixer upper?
Let us know
Ken
 

onyxtour

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Jan 13, 2007
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When you move the left lever, does it make any sounds like something is trying to happen, or just nothing. If you jack up the left side can you turn those wheels by hand?
Could be anything from as serious as a wheel motor or one side of the hydrostat pump to as minor as a bolt fell out of the steering lever linkage. How many hours? do you know the history? or did you buy it as a fixer upper?
Let us know
Ken
I'm having a problem with my left side tires moving forward and/or backwards. All hydraulics work, the bucket and arms and the right side moves forward and backwards perfectly; to the point that I can even spin out...or in circles now, since the left side completely stopped moving. This problem began shortly after adding a premium hydraulic fluid that subsequently turned the rest of my fluid a milky white. The first noticeable symptom, no noises, was that the left side tires started jerking...work then stop, work then stop, with the hydraulic charge light coming on when I pushed the control arm forward or pulled it backwards. I changed both hydraulic filters. Cleaned the filter/screen in the canister next to the two hydraulic pumps. I pulled the rear pump (the one for the left side) and after pulling it apart found nothing wrong, other than a couple of cracking o-rings. I replaced the rings, put the pump back together and reinstalled the same. Still, however, the left side does not move forwards or backwards. Note though, when I lifted the left side wheels off the ground, and worked the control arm, both wheels responded immediately. Both forward and in reverse. They may not have matched the rpm of the right side but they would rotate. I guess what I'm saying is that the rotation was weaker than normal and that when I grabbed a wheel while it was rotating I could stop it even though the control arm was pushed all the way forward. In reading several threads I saw mention of a hydrostatic pump, could this be the problem and if so where can I find it on my machine and what does it look like? I also saw that a milky looking hydraulic fluid implies that water is in the fluid and should be changed out. Could this be the problem, and if so why would all my other hydraulic devices be operating so well but not the left side wheels? Should I change out my fluid? I then read that a gage can be used to test the pressure coming out of the rear pump (left side wheels). Should I try this and if so what is this gage called and where can I obtain one? Do you know what the pressure is supposed to be? Or, and I suppose this is the worst case scenario, is the problem my left side drive motor (if that is what it is called)? If it is do you have any information on how to take the motor out and check/test it? Finally, I have found the NH part number for the left side drive motor (632483), if it has to be replaced does anyone know where a good used, if appropriate, motor can be purchased around the NC area?
 

Tazza

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I'm having a problem with my left side tires moving forward and/or backwards. All hydraulics work, the bucket and arms and the right side moves forward and backwards perfectly; to the point that I can even spin out...or in circles now, since the left side completely stopped moving. This problem began shortly after adding a premium hydraulic fluid that subsequently turned the rest of my fluid a milky white. The first noticeable symptom, no noises, was that the left side tires started jerking...work then stop, work then stop, with the hydraulic charge light coming on when I pushed the control arm forward or pulled it backwards. I changed both hydraulic filters. Cleaned the filter/screen in the canister next to the two hydraulic pumps. I pulled the rear pump (the one for the left side) and after pulling it apart found nothing wrong, other than a couple of cracking o-rings. I replaced the rings, put the pump back together and reinstalled the same. Still, however, the left side does not move forwards or backwards. Note though, when I lifted the left side wheels off the ground, and worked the control arm, both wheels responded immediately. Both forward and in reverse. They may not have matched the rpm of the right side but they would rotate. I guess what I'm saying is that the rotation was weaker than normal and that when I grabbed a wheel while it was rotating I could stop it even though the control arm was pushed all the way forward. In reading several threads I saw mention of a hydrostatic pump, could this be the problem and if so where can I find it on my machine and what does it look like? I also saw that a milky looking hydraulic fluid implies that water is in the fluid and should be changed out. Could this be the problem, and if so why would all my other hydraulic devices be operating so well but not the left side wheels? Should I change out my fluid? I then read that a gage can be used to test the pressure coming out of the rear pump (left side wheels). Should I try this and if so what is this gage called and where can I obtain one? Do you know what the pressure is supposed to be? Or, and I suppose this is the worst case scenario, is the problem my left side drive motor (if that is what it is called)? If it is do you have any information on how to take the motor out and check/test it? Finally, I have found the NH part number for the left side drive motor (632483), if it has to be replaced does anyone know where a good used, if appropriate, motor can be purchased around the NC area?
The hydrostatic pump(s) that are mentioned are the pumps that drive the wheels. As you said you opened the one that controls the left side. These pumps should have a built in relief valve, did you open up all the plugs that were on it when you opened it up? it could be as simple as something holding the relief valve open.
As for oil, milky white is not a good colour. Did you replace the oil with the proper grade oil? it must be hydrostatic oil not standard hydraulic oil. If the oil was too thin it would make a lot of noise and cause damage.
One way to test the motor is to swap it with the right hand motor.
I would start with the relief valve on the pump and work from there.
 

skidsteer.ca

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The hydrostatic pump(s) that are mentioned are the pumps that drive the wheels. As you said you opened the one that controls the left side. These pumps should have a built in relief valve, did you open up all the plugs that were on it when you opened it up? it could be as simple as something holding the relief valve open.
As for oil, milky white is not a good colour. Did you replace the oil with the proper grade oil? it must be hydrostatic oil not standard hydraulic oil. If the oil was too thin it would make a lot of noise and cause damage.
One way to test the motor is to swap it with the right hand motor.
I would start with the relief valve on the pump and work from there.
Your sure the oil turned white as soon as you added the premium oil? What i'm wondering is if water got into the system about the same time you added that premium oil. It could be a reaction between two oils, but it sounds like water. Anyway you need to get it out of there, it can't be good. How many hours betwee the oil turning white and the leftside problem starting?
The guage your talking about would measure your charge pressure, but being the hydraulics and the one hydrostat work fine I doubt its that, as one charge pump feeds all 3 pumps in most systems.
Either the left side hydrostat is not pumping oil at any pressure (for what ever reason, ie. stuck relief valve) or the wheel motor is shot and the pressure is slipping through it without converting the pressure and flow back to energy. One easy(ier) test is to swap the rs wheel motor into the left side and see if that makes it work, as Tazza mentioned.
If the left side still does not work try the original ls motor on the rs of the machine. If it works there the wheel motors are fine and the trouble is in your hydrostat somewhere
Most machines are just fine with good old 10w30 for hydraulics and hydrostatics. Thats what my NH ls 160 calls for. There are a couple of NH guys around this forum, I just started a month back with mine, but I believe the principles of their system is simular to Bobcat.
Keep us posted
Ken
 

onyxtour

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Your sure the oil turned white as soon as you added the premium oil? What i'm wondering is if water got into the system about the same time you added that premium oil. It could be a reaction between two oils, but it sounds like water. Anyway you need to get it out of there, it can't be good. How many hours betwee the oil turning white and the leftside problem starting?
The guage your talking about would measure your charge pressure, but being the hydraulics and the one hydrostat work fine I doubt its that, as one charge pump feeds all 3 pumps in most systems.
Either the left side hydrostat is not pumping oil at any pressure (for what ever reason, ie. stuck relief valve) or the wheel motor is shot and the pressure is slipping through it without converting the pressure and flow back to energy. One easy(ier) test is to swap the rs wheel motor into the left side and see if that makes it work, as Tazza mentioned.
If the left side still does not work try the original ls motor on the rs of the machine. If it works there the wheel motors are fine and the trouble is in your hydrostat somewhere
Most machines are just fine with good old 10w30 for hydraulics and hydrostatics. Thats what my NH ls 160 calls for. There are a couple of NH guys around this forum, I just started a month back with mine, but I believe the principles of their system is simular to Bobcat.
Keep us posted
Ken
Yesterday I swapped out the hydrostatic pumps, left side with the right side. Started the machine and.....had the same results. right side works great, with the left sides hydrostatic pump, and the left side does nothing. I checked the pressure and it came out to be around 2700 psi. This problem occurred within two days of me adding the premium oil. Everyone keeps saying that water got into my oil but I find that fantastically hard to believe. The oil was fine before I added the premium, obviously I had to check to see whether it needed the oil, and between the time I added the premium to the time this problem occurred...two days...we had no rain, I have no water leaks and I can't imagine someone walking up to my machine and sticking a garden hose in my hydraulic tank to fill it with water. I have now torn everything back out of the machine ie., the hydrostatic pumps, the hydraulic pump for the left side and the hydraulic pump for the right side, removed the braking system, and am now trying to figure out how in the world the L.H. drive motor comes out. That too is completely unbolted. It just doesn't slide back, up and out very easily. I spent three hours yesterday trying to get it out with no luck. I made sure the nothing but the motor was pulling back through the hole but the shaft, not sprocket too. But still no luck. Anyone know where I can see an exploded view of this L.H. Drive Motor, or something visual on how others have pulled them out? Should I just take it apart right there in the machine and pull half out at a time? AND DID SOME ONE SUGGEST I PULL THE RIGHT SIDE OUT TOO........not in this life time.
 

onyxtour

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The hydrostatic pump(s) that are mentioned are the pumps that drive the wheels. As you said you opened the one that controls the left side. These pumps should have a built in relief valve, did you open up all the plugs that were on it when you opened it up? it could be as simple as something holding the relief valve open.
As for oil, milky white is not a good colour. Did you replace the oil with the proper grade oil? it must be hydrostatic oil not standard hydraulic oil. If the oil was too thin it would make a lot of noise and cause damage.
One way to test the motor is to swap it with the right hand motor.
I would start with the relief valve on the pump and work from there.
Tazza, I swapped out the pumps, left for right and right for left. Both pumps work fine. It just somthing deeper. PSI is around 2700. Any thoughts on how to pull out the drive motor for the left side.
 

Tazza

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Tazza, I swapped out the pumps, left for right and right for left. Both pumps work fine. It just somthing deeper. PSI is around 2700. Any thoughts on how to pull out the drive motor for the left side.
The pressure reading won't tell you a great deal on its own, you really need to restrict the flow and check pressure vs flow rates.
You did confirm the pumps seem to be fine, it has to be the motor.... I am un-sure how the motors are removed though. Bobcat ones you just remove 4 bolts and the 3 hoses and it simply pulls out. Took me all of 10 mins.
I would not advise pulling the motor down when still attached, you need to line holes up when re-assembling the valve plate to get the correct timing (assuming its an eaton/vickers motor). There must be an easy way to remove it....
 

skidsteer.ca

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The pressure reading won't tell you a great deal on its own, you really need to restrict the flow and check pressure vs flow rates.
You did confirm the pumps seem to be fine, it has to be the motor.... I am un-sure how the motors are removed though. Bobcat ones you just remove 4 bolts and the 3 hoses and it simply pulls out. Took me all of 10 mins.
I would not advise pulling the motor down when still attached, you need to line holes up when re-assembling the valve plate to get the correct timing (assuming its an eaton/vickers motor). There must be an easy way to remove it....
Go to NH web site here
http://www.newholland.com/na/promo/parts&service/index.asp?Reg=NA&RL=ENNA&NavID=000001294003
(this link is in the NH section on this forum)
and click the seach for parts link, enter your model , I they have exploded views for my ls 160, hopefully for your too
Ken
 

onyxtour

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Jan 13, 2007
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The pressure reading won't tell you a great deal on its own, you really need to restrict the flow and check pressure vs flow rates.
You did confirm the pumps seem to be fine, it has to be the motor.... I am un-sure how the motors are removed though. Bobcat ones you just remove 4 bolts and the 3 hoses and it simply pulls out. Took me all of 10 mins.
I would not advise pulling the motor down when still attached, you need to line holes up when re-assembling the valve plate to get the correct timing (assuming its an eaton/vickers motor). There must be an easy way to remove it....
I hack sawed through the one hose and pulled the emergency brake sprocket. The motor then pulled right out. The hose $32.50, the time and frustration it saved, priceless. You mentioned that when re-assembling the motor I had to line up the holes for the correct timing. Can you explain this a little more? I went to a NH dealer today and a new motor is $1,400.00, or right around there. They have no re-build kits. It is an Eaton motor. The service manager, however, suggested a seal kit. When he said that I remembered having the chain exposed and watching the fluid flow back into the resivoir. I saw the return line shooting in oil and I saw where the motor was, fluid kind of flowing, heavily, down the back side of the tank. I'm not sure if this was supposed to happen but I said yes to the seal kit. When I replace the seals I've regrettfully decided to swap the left and right side motors just so they can, once and for all, be eliminated. When I went to NAPA the manager there told me that my issue wasn't a pump or motor, but rather a control valve. He said with steering arms, rather than a wheel, controls the opposite sides flow of fluid. Is this true? The only control valve i can find though is down by the left foot pedal. It has a line coming off of the gear motor attached to the second or most forward pump.
 

skidsteer.ca

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I hack sawed through the one hose and pulled the emergency brake sprocket. The motor then pulled right out. The hose $32.50, the time and frustration it saved, priceless. You mentioned that when re-assembling the motor I had to line up the holes for the correct timing. Can you explain this a little more? I went to a NH dealer today and a new motor is $1,400.00, or right around there. They have no re-build kits. It is an Eaton motor. The service manager, however, suggested a seal kit. When he said that I remembered having the chain exposed and watching the fluid flow back into the resivoir. I saw the return line shooting in oil and I saw where the motor was, fluid kind of flowing, heavily, down the back side of the tank. I'm not sure if this was supposed to happen but I said yes to the seal kit. When I replace the seals I've regrettfully decided to swap the left and right side motors just so they can, once and for all, be eliminated. When I went to NAPA the manager there told me that my issue wasn't a pump or motor, but rather a control valve. He said with steering arms, rather than a wheel, controls the opposite sides flow of fluid. Is this true? The only control valve i can find though is down by the left foot pedal. It has a line coming off of the gear motor attached to the second or most forward pump.
Is the Napa guy familiar with a NH skidloader.
The foot pedals and the valve they connect to, have nothing to do with the wheels. They are for the loader and the aux hydraulics.
Your steering levers are connected to the 2 hydrostats, one for the left wheels and one for the right wheel (usually these are built into one case with the hydraulic/ charge pump on the end away from the motor) and this is where the swash plates are that controls the direction and volume of flow to the wheel, if they are anything like a bobcat.
This fellow in Indiana keeps pumps but I'm not sure about motor parts or hydrostats. I have never done any business with him, but you can inquire
http://cgi.ebay.ca/New-Holland-L781...4446899QQihZ002QQcategoryZ41506QQcmdZViewItem
Ken
 

sterlclan

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Is the Napa guy familiar with a NH skidloader.
The foot pedals and the valve they connect to, have nothing to do with the wheels. They are for the loader and the aux hydraulics.
Your steering levers are connected to the 2 hydrostats, one for the left wheels and one for the right wheel (usually these are built into one case with the hydraulic/ charge pump on the end away from the motor) and this is where the swash plates are that controls the direction and volume of flow to the wheel, if they are anything like a bobcat.
This fellow in Indiana keeps pumps but I'm not sure about motor parts or hydrostats. I have never done any business with him, but you can inquire
http://cgi.ebay.ca/New-Holland-L781-L783-and-L785-pump-690858-Eaton_W0QQitemZ120074446899QQihZ002QQcategoryZ41506QQcmdZViewItem
Ken
Check with theese guys got my drive motor for 700 dollars prompt service easy to deal with www.precisionfluidpower.com or email the salesman at [email protected] good luck Jeff
 

Tazza

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Check with theese guys got my drive motor for 700 dollars prompt service easy to deal with www.precisionfluidpower.com or email the salesman at [email protected] good luck Jeff
I don't think he knows what the system is that you have, the hydrostatic pumps are vairable displacement. When you move a lever forwards or backwards this changed the volume and direction of the fluid, there is no valve as such.
If its an eaton motor you will be able to get a re-build kit and a seal kit.
When i get home i will try and remember to show you what i mean about the holes in the valve plate.
 

Tazza

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I don't think he knows what the system is that you have, the hydrostatic pumps are vairable displacement. When you move a lever forwards or backwards this changed the volume and direction of the fluid, there is no valve as such.
If its an eaton motor you will be able to get a re-build kit and a seal kit.
When i get home i will try and remember to show you what i mean about the holes in the valve plate.
Have a look at: http://users.tpg.com.au/tazza_/hydromotor/
These are pages i scanned from my manual for my old 731 bobcat, this shows in pretty good detail what is inside the motors. Your motor will not be the same, but it will be very close.
I hope it is of some help
 

onyxtour

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Have a look at: http://users.tpg.com.au/tazza_/hydromotor/
These are pages i scanned from my manual for my old 731 bobcat, this shows in pretty good detail what is inside the motors. Your motor will not be the same, but it will be very close.
I hope it is of some help
I see yours is valve operated. My motor is just like the pumps, all driven by 9 pistons each. I like seeing though that they use vaseline on the gaskets and o-rings. Question: If you go to the NH web site you can go to service and parts and search for parts by model number. There in figure 104 it shows a pressure switch that controls the flow to my servos. Remember now I swapped out the servo before (calling them hydrostatic pumps), left for right and right for left, and the left side (where I'm having the wheel problem) worked properly on the right side. However, if the pressure switch is bad my swapping established nothing. Am I correct? Or, in the full scheme of things, as long as the control arm is moved to adjust the swash plates flow does this pressure plate make a bit of difference? Question: I have two relief valves at the top of each piston pump where the fluid comes into the pumps from the filter. Can these relief valves be malfunctioning to the point that this is the problem; and can I just swap them out i.e. take the ones out of the rear pump, that I'm having the problems (if it is the pump) and put them in the forward pump just to see if their the culprit?
 

Tazza

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I see yours is valve operated. My motor is just like the pumps, all driven by 9 pistons each. I like seeing though that they use vaseline on the gaskets and o-rings. Question: If you go to the NH web site you can go to service and parts and search for parts by model number. There in figure 104 it shows a pressure switch that controls the flow to my servos. Remember now I swapped out the servo before (calling them hydrostatic pumps), left for right and right for left, and the left side (where I'm having the wheel problem) worked properly on the right side. However, if the pressure switch is bad my swapping established nothing. Am I correct? Or, in the full scheme of things, as long as the control arm is moved to adjust the swash plates flow does this pressure plate make a bit of difference? Question: I have two relief valves at the top of each piston pump where the fluid comes into the pumps from the filter. Can these relief valves be malfunctioning to the point that this is the problem; and can I just swap them out i.e. take the ones out of the rear pump, that I'm having the problems (if it is the pump) and put them in the forward pump just to see if their the culprit?
oh, yours uses piston motors, lust slightly different than a geroler setup....
The servos you speak of, your machine is late model that doesn't have physical linkages between the steering levers and the pumps? When you swapped pumps, did you actually swap the pumps and have heaps of oil pour out or just servos for the pumps? If it was just servos and the problem switched sides you know exactly where the problem is.
The relief valves i believe are for charge pressure, not high pressure. I see no reason why you can't swap them over to test if that is the problem.
 

charger

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oh, yours uses piston motors, lust slightly different than a geroler setup....
The servos you speak of, your machine is late model that doesn't have physical linkages between the steering levers and the pumps? When you swapped pumps, did you actually swap the pumps and have heaps of oil pour out or just servos for the pumps? If it was just servos and the problem switched sides you know exactly where the problem is.
The relief valves i believe are for charge pressure, not high pressure. I see no reason why you can't swap them over to test if that is the problem.
you have a 5000 psi relief valve on each hydrostatic pump, 1st thing change your oil, 2nd you can try swapping relief valves from pump to pump, 98% of the time when a unit does not drive on one side like this one its your hydrostatic motor and yes all parts are available to rebuild these units from new holland!
 

onyxtour

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you have a 5000 psi relief valve on each hydrostatic pump, 1st thing change your oil, 2nd you can try swapping relief valves from pump to pump, 98% of the time when a unit does not drive on one side like this one its your hydrostatic motor and yes all parts are available to rebuild these units from new holland!
When you say hydrostatic motor are you talking about my drive motor? I swapped out the relief valves (two for each piston pump), with no luck.
 

onyxtour

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oh, yours uses piston motors, lust slightly different than a geroler setup....
The servos you speak of, your machine is late model that doesn't have physical linkages between the steering levers and the pumps? When you swapped pumps, did you actually swap the pumps and have heaps of oil pour out or just servos for the pumps? If it was just servos and the problem switched sides you know exactly where the problem is.
The relief valves i believe are for charge pressure, not high pressure. I see no reason why you can't swap them over to test if that is the problem.
I just swapped the servos. The problem, however, remained on the left side. Today, I discovered that the left drive motor had no seal on the shaft that goes through the resevoir wall to connect up with the main drive sprocket. When I took it off all there was, was two large washers and a bunch of form a gasket. I'm assuming the previous owner just made his own seal. I'm suprised it lasted so long though, or I guess that's why it felt weaker on that side. Anyway, I put everything back together, with a new seal, thinking I was Mr. fix-it and nothing. Still does not move. I put the pressure gauge back on the out-put line, #19 if you're looking at figure 096 on the new holland web site, and removed the servo to work the control by hand. when no pressure was applied my reading now comes up ZERO. When I grabbed the control arm, directly connected to the rear piston pump, and worked it myself the pump got a mind of its own and shot up to at least 5000 psi. I dove out of the loader thinking my gauge was going to explode...but then the machine stalled out. Still the wheels did not move on the left side. Tomorrow, I'll see if the hoses will reach to hook up to the right side motor with the rear pump, or the forward piston pump with the left side motor, if those hoses will reach. I can't see that #17 is blocked (same figure), because i had it completely unhooked and blew through it, thinking there may be a plug. While I was re-testing though fluid would come out of #19 from the motor not hard and fast but at a steady pace.
 
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