743 Drive problem

[kmerting]

I have a 743 that drives straight ahead and backwards fine. I can also turn right with no problem. When I go to turn left sometimes I get no movement. If I play with the controls the machine will jump hard to the left. Sometimes it will then engage the left side wheels and I can see that they are going in reverse with power. I put machine on blocks and notice that when I go to the left the wheels on the left side of the machine aren't turning and the ones on the right are. When I turn to the right I see that both sets of wheels turn. If I play with controls I can get them to go. Sometimes they go and they are moving at a slower speed than the other side. I've taken the pressure valves or I guess they're called relief valves out of the side of the pump (2 on each side - under caps - they have springs. There are 2 different pieces. One looks more like a relief valve and the other looks almost like a blank valve) I swapped them from side to side and the problem stayed on the left side. I am thinking shuttle valve could be problem, but not 100% sure. I haven't taken it out yet. Can a shuttle valve be causing this type of problem? Is it ok to just pull the valve out while the motor is still installed in the machine? Could it be a broken spring or some trash caught on the valve? Any help is appreciated. Thanks, Ken

 

[OldMachinist]

Are you sure that the pintle lever is tight on the pump shaft and that the key on the shaft is good.

 

[kmerting]

Are you sure that the pintle lever is tight on the pump shaft and that the key on the shaft is good.

Yes, they're both tight and the key's are good. I see the shaft moving with the lever as well.

 

[OldMachinist]

Yes, they're both tight and the key's are good. I see the shaft moving with the lever as well.

I was just hoping was going to be simple for you. Since you already switched the valves around the next place to look is the shuttle valve. You could switch motors from side to side just to verify it follows the motor.

 

[kmerting]

I was just hoping was going to be simple for you. Since you already switched the valves around the next place to look is the shuttle valve. You could switch motors from side to side just to verify it follows the motor.

Would you recommend pulling the shuttle valve out of the motor while the motor is still in the machine and look at it? Is that ok to do?

 

[OldMachinist]

Would you recommend pulling the shuttle valve out of the motor while the motor is still in the machine and look at it? Is that ok to do?

I think that depends on which Char-Lynn motor you have. The motors on the early models(S/N 17999 & below) you have to take the motor apart to get to all the shuttle valve parts out of the housing. The later ones you can get to without removing the motor.

 

[kmerting]

I think that depends on which Char-Lynn motor you have. The motors on the early models(S/N 17999 & below) you have to take the motor apart to get to all the shuttle valve parts out of the housing. The later ones you can get to without removing the motor.

Ok, I'm pretty sure that mine is the newer. My motor cover has two allen head set screws holding the shuttle valve in. I'll pull it out and see what I find. Thanks for the help. Ken

 

[Tazza]

Ok, I'm pretty sure that mine is the newer. My motor cover has two allen head set screws holding the shuttle valve in. I'll pull it out and see what I find. Thanks for the help. Ken

I would doubt its the shuttle.
The way you are talking really seems so sound like controls. If you move one steering lever and hold the other, ONLY one side should move. You mentioned you could move one and the other would turn too. You should be able to block the machine and get each side to move forward and back independently.
You may want to check your charge pressure too. It sounds like you may not be getting the corrct pressure to get the postons on that side to work correctly.
Swapping motors from side to side is simple. 4 bolts and 3 hoses. You will need to swap the fittings over too. Un-do the 4 bolts and the motor simply slides out.
Good luck.

 

[kmerting]

I would doubt its the shuttle.
The way you are talking really seems so sound like controls. If you move one steering lever and hold the other, ONLY one side should move. You mentioned you could move one and the other would turn too. You should be able to block the machine and get each side to move forward and back independently.
You may want to check your charge pressure too. It sounds like you may not be getting the corrct pressure to get the postons on that side to work correctly.
Swapping motors from side to side is simple. 4 bolts and 3 hoses. You will need to swap the fittings over too. Un-do the 4 bolts and the motor simply slides out.
Good luck.

I'll put it on blocks again and check. I'm unsure what it did when operating with only one stick. I was using with both. Trying forward, backwards, and then both directions for forward turns. My bushings for steering levers are slightly worn, but I went and adjusted the levers so that the tires did not move when in neutral (while on blocks), so I felt that I was ok even with the slight play in the levers. I'll swap the motors over the weekend and see what happens. I appreciate the help! Thanks, Ken