843 bobcat drive issue

[843bobcat]

Left side drive speed is about 1/2 the right side speed going forward. Reverse is fine. All other hydraulics function as they should. Any help would be great.

 

[Tazza]

Does it still have good power on that side? can you get the wheels so spin?
It could be a few things, worn linkage not allowing the steering lever to go fully forward, ensure it's not hitting the part under the seat where the levers come through with the rubber boots.
It could be a failing seal in the drive motor allowing oil to by-pass, but generally this will cause a loss in drive power too, not just speed.

 

[843bobcat]

Does it still have good power on that side? can you get the wheels so spin?
It could be a few things, worn linkage not allowing the steering lever to go fully forward, ensure it's not hitting the part under the seat where the levers come through with the rubber boots.
It could be a failing seal in the drive motor allowing oil to by-pass, but generally this will cause a loss in drive power too, not just speed.

Thanks for the reply. Both sides wil spin - the left side just spins faster. Don't think it's a linkage issue - both sides move the same. There doesn't seem to be any acceleration on left side after moving the stick past about 1/2 way, which seems to correspond with the secondary movement of the servo.

 

[Tazza]

Thanks for the reply. Both sides wil spin - the left side just spins faster. Don't think it's a linkage issue - both sides move the same. There doesn't seem to be any acceleration on left side after moving the stick past about 1/2 way, which seems to correspond with the secondary movement of the servo.

Does your machine have the hydraulically assisted steering? If so, this complicates things a little. Still weird that backwards is the correct speed, only forwards is the issue.

 

[[email protected]]

Does your machine have the hydraulically assisted steering? If so, this complicates things a little. Still weird that backwards is the correct speed, only forwards is the issue.

has to be a linkage issue.

 

[843bobcat]

Does your machine have the hydraulically assisted steering? If so, this complicates things a little. Still weird that backwards is the correct speed, only forwards is the issue.

I'm not sure what you mean by hydraulically assisted steering. There is a servo unit connected to each sides linkage.

 

[Tazza]

I'm not sure what you mean by hydraulically assisted steering. There is a servo unit connected to each sides linkage.

The servos you speak of are hydraulically assisted. A little like power steering in a car.

 

[843bobcat]

The servos you speak of are hydraulically assisted. A little like power steering in a car.

I see - so it doesn't seem like the servo would cause my issue? Thanks

 

[Tazza]

I see - so it doesn't seem like the servo would cause my issue? Thanks

I think it could be the issue. If they aren't operating correctly, you may not be getting full travel out of the linkages to the pump.
I have never owned one, but i have done a small amount of work on one that lives a few houses up the road. His main issue was the servo cylinder was snapping rods.
I guess if the seals were bad, it could cause it to not move fully forward or backwards to move the pump linkage.
What i'd do is flip the cab up, block the machine, start it up and see how far the linkages on the pump move when you move the sticks. Also check how far in and out the rods go in and out of the servos move too. Each side should move the same amount.
I'm pretty sure other members have had issues with them, mostly a delay before it starts to move after you move the stick. Not sure if it was just their machine, or the nature of that system.

 

[843bobcat]

I think it could be the issue. If they aren't operating correctly, you may not be getting full travel out of the linkages to the pump.
I have never owned one, but i have done a small amount of work on one that lives a few houses up the road. His main issue was the servo cylinder was snapping rods.
I guess if the seals were bad, it could cause it to not move fully forward or backwards to move the pump linkage.
What i'd do is flip the cab up, block the machine, start it up and see how far the linkages on the pump move when you move the sticks. Also check how far in and out the rods go in and out of the servos move too. Each side should move the same amount.
I'm pretty sure other members have had issues with them, mostly a delay before it starts to move after you move the stick. Not sure if it was just their machine, or the nature of that system.

Thanks for your suggestion. I will check it out.