955L no controls

[Pralhad Birdi]

Hi everyone,

I'm running a 955L, and I seem to have lost all bucket controls. The machine still drives as it should, but I'm not getting anything from the boom and bucket . Any ideas what the issue could be?
Thanks

 

[Welder Dave]

Is there a pool of oil somewhere? Is the hyd. reservoir full? Did/does it make any strange noises before or after it quit? Did it work one day and then the day next day didn't? It really helps to give some history on how the problem developed. If the reservoir is full and it's not making any weird noises I'd guess it's a pump problem. If I recall a 955 uses pucks in the coupler from pump to the engine. I'd look there to make sure the pump is turning. Other possible problems could be a collapsed suction hose or something got in the reservoir and is plugging the intake. I'm not sure if the pump shaft has splines or not but that could be a possibility or the pump is just worn out.

 

[Pralhad Birdi]

Thanks for the prompt reply mate. As far as I'm aware there weren't any strange noises, although I will have to confirm this with the operator (machine is way out in the Bush in an area with very patchy cell reception). It was working fine one moment, then all of a sudden no controls. Hydraulic oil was at the recommended level, and no serious leakages. I'll get down to checking the hydraulic tank and filters tomorrow. How would I go about checking the engine-pump coupling?
Thanks again

 

[Nige]

How would I go about checking the engine-pump coupling?

It would be good to have a Serial Number for confirmation, but they all look pretty similar.
The pump (Item # 14) is gear-driven off the front RH side of the torque converter housing. See illustration below

 

[dozr]

did bucket drop fast a hard had a 951 break a shaft have had spine to wear out , check to see if you have any presser.

 

[Pralhad Birdi]

Machine serial number is 43V14380, 3304PC engine. So the filters and tank are clean, next step is checking whether the suction pipe is actually taking oil to the pump. However I'm told the pump is not making any strange noises, so I doubt it's oil starvation. Tried disconnecting one of the hydraulic hoses on the ram and no hydraulic pressure there. I'm at a bit of a loss to be honest, as the machine has worked perfectly without any issues at all for the past 8 months or so.

 

[Welder Dave]

That's the engine serial number. Need the machine serial number. Do you mean no pressure or no oil?

 

[Pralhad Birdi]

Sorry, my bad. 955L - 57M0747
So it's not shooting out any oil from the ram pipes when you try and operate the controls.
Thanks

 

[Pralhad Birdi]

Update: the hydraulic pump splines are good and the drive from inside the torque converter housing is good as well. Any ideas as to what else we could check?

 

[dozr]

pump shaft turning pump mine broke like cut with saw, right in side pump, was victors pump.

 

[Nige]

Update: the hydraulic pump splines are good and the drive from inside the torque converter housing is good as well. Any ideas as to what else we could check?

i assume you must have had the pump removed to make those checks. I suggest CAREFULLY remove the pump end plate and check for a broken shaft.

Also check for a blocked pump suction line.

 

[Pralhad Birdi]

Pump suction pipe is supplying oil as it should, but when the outlet pipe is loosened, there's just a trickle of oil coming out. Unfortunately it does seem like the shaft is the culprit (I was hoping for a less expensive problem like the relief valve or something lol). Machine is about 200km from civilisation so I'm going to get the pump removed and brought to the yard and I'll open it up and have a look.
Again, thank you very much for all the excellent info and assistance, and I'll give you guys an update once I have the pump.
Cheers

 

[Welder Dave]

Are you sure the reservoir is full? Loosen the intake pipe and see if oil is coming out. I don't know if it's possible the cap on the reservoir is faulty and not venting which won't let the pump work. I had a faulty fuel cap on my skid steer and it wouldn't get fuel. Maybe the same type of thing could happen with the hyd's?

 

[Pralhad Birdi]

Yes the reservoir is full and the intake pipe is bringing oil down to the pump. I'll ask them to give it a shot without the tank cap and see what happens. Cheers mate.

 

[Welder Dave]

If it's a vane pump maybe the vanes are worn out? Knew a guy that always kept a spare cartridge for his excavators with Vickers vane pumps.

 

[Pralhad Birdi]

If that's the case, how much do you reckon a replacement cartridge would cost? Because my local Cat dealer (Mantrac) would probably charge me more than the machine's worth based on previous experiences I've had with them

 

[Welder Dave]

Not even sure what model of pump it is or if it uses a cartridge with vanes. I think you should follow Nige's instructions above and remove the end plate to look for damage.

 

[Bls repair]

Pressure relief valve stuck open?

 

[Pralhad Birdi]

Pressure relief valve stuck open?

That's what I thought (and hoped for) initially, but the pump outlet is not bringing hydraulic with any pressure when the outlet pipe is loosened.

 

[Dave Neubert]

Vane pumps will snap shafts and break vane housings Costex shows cartridge for $199 Cat $1000