M-600 Bobcat Variable Speed and Parts.

Dubbya Are · Jul 10, 2015

Still having problems with the variable speed on my M-600 .. it will go to high position at full throttle but quickly bleeds back to slow ... ( I have kits ordered for both variable speed valve and drive pulley cylinder) and after the hydraulic oil gets good and warm the lift cylinders get jerky (lifts fine cool) I'm thinking bad pump?
Also looking for a used parts source for these older units .. I'm in need of a rear inner axle hub now (engine side with dust cover) pic to follow (maybe?)
Thanks in advance for any help you can offer.

Bob · Jul 10, 2015

Unless the variable speed cylinder is throwing oil EXTERNALLY it is NOT the cause of your speed change over time.

Dubbya Are · Jul 10, 2015

(quoted from post at 10:32:25 07/10/15) Unless the variable speed cylinder is throwing oil EXTERNALLY it is NOT the cause of your speed change over time.

Not throwing oil but I have it apart and waiting on new seals for it.
What do you think about the speed control valve or will the problem go all the way back to the main spool. .... Thanks

IowaJohn · Jul 10, 2015

If it's slowing down real quick and it's the cylinder inside the drive pulley there should be a lot of oil on the belt and most of the inside of the frame. When that leaks it makes a heckuva mess at least on my 610. Won't hurt to put a kit in it anyway. Otherwise it's in the valve. I've never had mine apart so I can't give you any help there. As far as the jerky bucket is the oil lever in the case up to the plug on the side and how does the oil look. Fresh oil makes alot of difference at least on mine. Check the sealing surface on your axle if it's grooved at all get it built up, turned smooth and put new seals in it, takes 2, while you're there, they all get to leaking.

Roger in Iowa · Jul 10, 2015

Problem should be with the speed control valve only.

Dubbya Are · Jul 10, 2015

(quoted from post at 10:48:12 07/10/15) If it's slowing down real quick and it's the cylinder inside the drive pulley there should be a lot of oil on the belt and most of the inside of the frame. When that leaks it makes a heckuva mess at least on my 610. Won't hurt to put a kit in it anyway. Otherwise it's in the valve. I've never had mine apart so I can't give you any help there. As far as the jerky bucket is the oil lever in the case up to the plug on the side and how does the oil look. Fresh oil makes alot of difference at least on mine. Check the sealing surface on your axle if it's grooved at all get it built up, turned smooth and put new seals in it, takes 2, while you're there, they all get to leaking.

Pulley drive cylinder wasn't leaking but will rebuild when kit gets here .. oil isn't to old but looks dark already.
Axle does have a little groove x's 2 where the seals contact the shaft but old seals were rough and hard ... Bobcat used to offer a drive on sleeve that fixed the problem but is no longer available.

Dubbya Are · Jul 10, 2015

Haven't taken it apart yet to see what it looks like inside but it's not leaking oil external that I can see .. I'm hoping this is the leak back problem. However ... the lift cylinders leak down also which concerns me a little.

Dubbya Are · Jul 10, 2015

Did find a inner hub from Buddy's Bobcat Service ... found contact in an old post ... super nice guy.

IowaJohn · Jul 10, 2015

I've used the sleeves but they don't hold up well the seals wear thru them pretty quickly.

Dubbya Are · Jul 10, 2015

(quoted from post at 15:29:01 07/10/15) I've used the sleeves but they don't hold up well the seals wear thru them pretty quickly.

Thanks John, I'll see if I can get it built up and sized.

M-600 Bobcat Variable Speed and Parts.

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