Loss of Hydraulic Pressure ????

[DEBoyd]

Hi all,
Long story, ill try to make shorter. We where finishing a job with our Bobcat B300 Loader/Backhoe. It is a 4 wheel drive, 4 wheel steering hydraulic run drive, steer and bucket/hoe system. We where moving the B300 when out of no where we lost steering ability...absolutely zero pressure. The Bobcat CAN move forward and reverse no problem....but no steering pressure, no bucket or hoe pressure whatsoever.

The main pump connected to the flywheel of the motor has large lines which run to the transmission/drive unit. There appears to be a 2nd pump which is bolted to the back of the main 1st big pump.....the 2nd pump is small, and has one large line coming from the top of the hydraulic resevoir tank to it, and the out bound line runs to a manifold/solenoid bank, in which a bunch of hoses come off of that.

With the ignition off, if you turn the steering wheel its easy as nothing, and you can hear what sounds to be fluid sloshing in the area of the steering mechanism...which is hydraulic.
The bucket or hoe..either one...in which the cyclinder would be in gravity down will operate if you pull the levers...but nothing comes up....obviously due to no hyd pressure.

Is there a filter in the Hyd tank for the 2nd pump that could be clogged completely???

Is it more likely the secondary pump...if thats what it is....is bad????

Remember...forward and reverse operate perfectly.

Any other ideas ???

Bobcat B300 is a 2002 with 497 hours on it.

Thanks for your help

Dave Boyd
352-572-0800

 

[kubmech]

Is there a fuse and or relay for the loader/steering system?

 

[Catmando]

The Bobcat site says that the 300 can stear by turning the wheels or skid stear. Question is will it turn in the skid stear mode.

It sounds like the smaller pump operates the bucket and the stearing.

If the filter is plugged then you should hear a whining noise because the pump is cavitating.

No pressure? Is the pump still coupled to the motor? The way it quit it sounds like it is some kind of a mechanical failure rather than a pump failure. Unless the pump lunched itself. If that is the case there should be metal particals in the hydraulic fluid for that circuit.d

The other thing that I would look at is the pressure releif valve. It might be stuck open. d

No oil leaking anywhere?