we have normal functions of all cylinders with one exception--we do not have power on pushing the stick back out. we have normal crowd but not power to crowd out. we switched the pattern change valve from John Deere to cat and the same crowd out was still not good. we tried it at all engine speeds with no effect. the stick with stay in an extended and retracted position in the air without any settlement. we had a hose on this cylinder blowout last week. anyone have any suggestions.
so the machine isn't applying force to crowd out? It is not hitting the reliefs, and working the motor? You could try powering the cylinder off a different circuit like the auxiliaries, but I'm going to bet on a internal cylinder problem like you blew the piston off the rod, or a blown seal / gland on the piston inside the cylinder. reson being... 1. problem didnt change when the pattern changer was switched. 2. you have power to crowd the cylinder in which usually pushed the piston against the rod. when you crowd out, the nut hold the piston to the rod, and if that nut came loose, the piston would slide up and down freely. If you have motion but not power, maybe you blew a seal out and when you crowd in it seals itself for now. 3. The hose blew on the same cylinder and its a newer machine tells me that there was some pressure somewhere in that vincinity. 4. with the stick staying in position, I'd lean towards a seal problem but you will not know till you pull it apart.
the machine has about 5000 hours on it so i assumed it was normal. the hose blew within an inch of the coupler. so i should focus on the cylinder?
Got to agree about the piston coming off the rod,seen it happen a few times the stick will go in as the oil forces the piston against the rod but when you try stick out the oil sends the piston off the rod and back down the cylinder
Yea do a by-pass test on the cylinder, i would think it is some thing do with the cylinder due to the fact all else seems fine!
"the stick with stay in an extended and retracted position in the air without any settlement." does this mean it doesn't drift anything when in the air? Does it move but are weak or no movement at all?
ok, i am an idiot! the first thing i asked the guys to do on the phone was, "switch it from Cat controls to JD controls. Does that same cylinder still have the problem?" the answer was YES still that cylinder. I drive an hour to get there and get the machine and goof around. Volvo told me to lift each track and run it three times around. each track operates on a different pump. they should be the same. both were 28.75 seconds. i try a few more things. no drift. very slow reaction to none at times. just like the guys said. so, i finally open up back door and put it in JD. EVERTHING WORKS! i switch it to Cat. EVERYTHING WORKS! they didn't have the pattern change valve locked and it moved into a position part way between the Cat and JD. the machine is up and running again. i learned a lot about hydraulics and cylinders not to mention wasted a lot of peoples time. thanks for all the suggestions. btw, if anyone needs a red label rebuild kit of that cylinder i have one.
I was thinking the same thing (pattern changer). I had the same issue with my Bobcat mini. The crowd got slow (very slow) and week in the out direction. I just about popped a gasket (I have had lots of trouble with that machine), and started thinking of all the dollars it was going to cost to find the problem, let alone fix it. The problem started out intermittent, but settled into constant. I had an appointment to take the machine in when it dawned on me to check the pattern changer. It was half way between the two patterns. On the Bobcat, the pattern changer is on the floor (by your right heel) with no locking mechanism. It's a lever that moves along a radius (like an upside down smile) between the selections. I must have bumped it with my heel. Cheapest, and easiest fix ever. I have never been so happy to make such a fool out of myself. Why doesn't every one just learn how to use CAT CONTROLS. Obviously the world would be a better place if everyone did.