Ok guys, I need some help. I have a 1997 873 Bobcat with about 2400hrs. Had it for about 5 yrs and every once in a while, my right driving stick does not want to change directions. I pull it back a little to slow down the right side and it does not react until pulled back farther and eventually slams in and reacts. It only does it from time to time for a spell and then clears up. However, it seems to be getting worse. Also tonight, after returning home from about a 2 mile trek, the left side did the same thing. I have not changed the hydraulic fluid since I purchased it at about 1950hrs. It was supposedly new at the time and looks very clean. I have added Lucas Hydraulic booster to try to correct what a Bobcat mechanic told me was a varnish problem in the valve? Does this machine have valves separate from the drive motors or are they one unit? Please help. Time to buy a book for the machine.
I don't have all the model variations of Bobcat in my head so I can't say for certain on the 873, but the question is does your machine have manual linkage controls for drive or does it have electric servo controls for drive? Very simple, raise the cab. If you have linkage bars connected to drive levers that go to control levers on drive pumps, you have manual controls. If you don't have linkage bars, electric servo controls. If it's manual, most likely a loose pintle arm on a pump control shaft.
Had similar problem on 763, raise cab,check the linkage, there is a bobcat upgrade to the (not sure of technical name) pins/bolts that retain the return springs. bolts snap off, spring falls, causes all sorts of steering malfunctions. I also reversed the sliding block as detents had begun to wear into the block from the rollers. Just a shot in the dark, not sure how you 873 is configured.
i'd bet that machine has cable operated servo assitted pumps. cable ends may be worn, or loose, or the cables them selves may need to be replaced :drinkup
Got the cab up and the controls are cable. All cables in good shape and functioning properly. I can see back under rear that the cables are actuating the valve in the forward and reverse directions with the play in the system. Is is possible that air could be forming and bot purging from system? I noticed some kind of small line running up to an electronic devise by hydro filters. Looking for a manual on the machine tonight. Anyone have another idea? Just seems odd for it to only have spurts of this problem.
Got the cab up and the controls are cable. All cables in good shape and functioning properly. I can see back under rear that the cables are actuating the valve in the forward and reverse directions with no play in the system. Is is possible that air could be forming and bot purging from system? I noticed some kind of small line running up to an electronic devise by hydro filters. Looking for a manual on the machine tonight. Anyone have another idea? Just seems odd for it to only have spurts of this problem.
highly doubtful that air is getting in around the pump seals, while you are in there you may want to check all the suction hoses going to the pump, usually all large diameter hose with hose clamp connections. i think the hose you are referring to is connected to the charge pressure sender. i'm guessing you have either a single or double hyd filter, just in front of the cooling fan housing, and the hose comes up between them to a fitting with a roundish looking sender. the sener may have 2 wires connected to it, or may be a 2 wire molded connector. i just reread youre original post...... you may have a broken centering spring on the servo itself you may want to try cleaning the tops of the levers and get a look at the way the 2 parts of the lever operate, along with the spring. the cable is connected to one part of the lever assy, otehr part of the lever is conected to the servo control spool. the spring keeps them aligned and provides a dampening to lever action. the servo assited pumps/cables gave very little operator "feel" for what the machine was actually doing. :drinkup
Thanks crewchief888. Will get back in there and check that out tomorrow.