Howdy, just joined today! Hope someone can help me out. I have a S169 Bobcat with the hydraulic unlock for the bucket release. It seems really weak. I have to run the engine wide open to get the cylinder to move to unlock/lock. Even with nothing hooked up it is still weak. The rest of the Bobcat hydraulics work fine, just the locking for the bucket seems weak. Also my neighbor has a S130 and it is the same on his. HELP please.
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The power Bobtach takes it hyd pressure directly off the pump so, really, only about three things could be wrong. The pump itself could be bad but if your other functions are fine then that is probably no the problem. The control valve on the pump may have a problem or the cylinder itself may need packing. A pressure test on the lines to the cylinder should tell you that. I would start with a pressure test of the main pump and then a test of the cylinder line pressure. Have fun. Bear in mind that the Bobtach cylinder doesn't have much power to start with.
It has done this since brand new. Just figured it was designed to operate this way to keep from breaking the release arms. It won't move at all at idle, but everything else works good at idle. I will have to live with it I guess. Thanks for your reply!!!
The power bobtach does not have much pressure ran to it, maybe 300 psi. Deadheading the hydraulic system will sent a pressure spike to it. If it moves really slow, the wedges are tight. There are grease zerks on the side. Lube them up real good and it should be fine. Pull the cylinder off and work the wedges back and forth manually while lubing to free them up.
Good plan, do the simple fixes first. Question: How can deadheading the hyd stytem hurt anything? Isn't that what pressure relief valves are for?
Deadheading won't hurt anything. The way the vavle is plumbed, it has a self closing feature that when you put a load on the system, fluid is metered to the power bobtach to keep it close. Unhook and lift the boom up and down with the the wedges up, they will go down by them self. Deadheading will put higher pressure to it. With them open, deadhead the aux, they will close very quick even without pushing the bobtach switch.
OldMachinist
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Looking at the schematic for the power Bobtach there are several orifices to restrict the flow so it's designed to move slowly. Also there's a filter in the system. If its getting slower the filter may need replaced.
7LBSSMALLIE
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once again old m spot on what he failed to mention was enage aux hit pwr bob while thumbing switch on rh cobra either left or right (as in open or close) as to can damage being done , probally so take care not to dead head get em open or closed an back off. ( not factory reccomened but will get it done)
mrdeere1959
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I have seen a lot of power bob tach cyl. bent and then they move hard
The cylinders get bent from people hitting stuff with them. Guys shear the hydraulic fittings off all the time. There is simply never enough pressure to that cylinder to bent it. Nobody knows there are zerks on the wedges, then again, nobody ever grease a machine ever. Customer look at me like I am on fire after crashing from outer space when I tell them they need to grease every 8 to 10 working hours.
reaperman
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Not from a mechanical, but as a operator point of view. When the levers get slow, as mentioned lubrication problems are what I have noticed. When they get bad on the machines I run, I take some motor oil and pour it on the pins. Then work the pins back and fourth. When they get real bad, sometimes a second person will use a pipe over the levers and help them get "freed" up. Motor oil works better than grease when they are getting real slow. After they are working properly, I grease them up good. Hope this will help.
