Hi, wonder if anyone has had experience with a 688B where the slew cuts out after about 10 mins of use, if rpm is high it cuts out sooner and also if you're a bit sharp on the lever. It is only the slew that stops working and it has its own pump, plenty of flow and pressure from there until it cuts out and the flow just stops, - switch the engine off and back on again to drop pressure off and it kicks straight back into life again. Any help would be much appreciated! Thanks
I sounds like you may have an electrical problem for brake release.
Thanks for the reply, I have checked all this, all seems so to working correctly. The pump actually looses flow when it cuts out, as in I can remove the main feed from the pump and hold the pressure back with my thumb. The only electrics on the machine are the dead man switch, fuel sol and starter system. I was wondering if there's some kind of control valve before the slew pump itself?
Good day Case According to spec you have a tandem pump suspect a gear wheel type power the swing, you say you can hold the pressure back with your hand means the pump is defective, I would not recommend that you test the pressure with your thumb thats not so good for your health, use a pressure gauge. Kind regards Uffex
And to you uffex, It looks that way however I have had a gauge on it, it reads 6000psi or there abouts on stall until it 'cuts' out and reads bugger all, can't see how the pump could be faulty, if it was then it wouldn't work at all? It's a fixed displacent pump so no sticking swash plate and it also drives the pilot pump so if it were miss meshing or loosing drive then the pilot pump would also stop. Thanks again
What is the serial number of your machine please?
Long shot without all the information - but it sounds like TVC ( torque limiter or power control) cuts out your pump flow because your port relief valve was messed with, your pressure should never reach 6000psi, it should be more like 4700psi ( subjects to verification with manual ). And why in the hell you having such a high pressure on the swing in the first place?
Good day Case When you stall out the pump can you please explain how the gauge is installed and what you operate to stall the circuit ? Is there an option spool on the swing valve block? Kind regards Uffex
Blanked off the lines to the swing motor and installed the gauge on the control valve, that's the pressure it is capable of making, I suspected the relief valve to to be sticking open so I wound it down tight to test , and it still it cut out. I have since wound the valve back to around 4500psi. Sorry, What do you mean by an option spool? A 3rd service? Thanks again for the replies! Will get the serial number in a bit!
What did you mean by swing has its own pump? Is yours piston pump with triple stack of gear pumps? Can we have pictures of the pumps and name plate, the S/N of machine would be nice too!
Hi Case If I have followed your information you have installed a gauge after the control valve where the connection is made for the swing motor, this takes the pump out of the picture some what, it sound probable that the issue is with the control valve and connection parts. The relief valve is a good starting point it only takes a small particle to block the main orfice and that can give you an intermittent problem. yes my question was if there was another circuit (3rd service) we could use the check out the problem from what I can see the Case machine does not have one. If you have a hydraulic schematic or parts illustration of the swing control valve may be able to help with better detail. May I ask where in the UK are you ? Kind regards Uffex
Hi TVA The spec is similar to that of 1088 please see attached. Kind regards Uffex
Uffex, There is a feed off the valve that goes to third service yes, I already blanked that off as I had the same thought as you, still made no difference. I believe the problem to be before the pump, it has loads of power when working, clicks off and then I can physically take the line off the valve that is direct from the pump and there's basically no flow, turn the machine off and back on and it's hoarsing oil out. Would you know if there's a load sensing valve that feeds the pump? I have got a manual, it's a slightly different valve in the manual to the one on my machine. It does not have a very detailed schematic or diagram for the pump itself which may show load sensing or ports which feed the pump. Thanks again Ps serial number is CGG0010743
Hi Case The pump according to my information is a gear wheel type to have some kind of LS control on this would be a new device to me, as you describe the situation the flow directly from the pump comes and goes, take a close look at the suction hose for the pump if you cannot see any defects I would suggest remove the pump and take a close look the bench. If you can post a copy of the schematic it may well help us to help you, [email protected] KR Uffex
As an after thought have you checked out pump suction filters ?
That sounds right, it's a small piston pump driven off a gear, I've had it out, all looks good, no damage and is all nice and free. As far as I can see its just the one large filter in the tank? It's not a new one, but it doesn't look blocked and isn't collapsed or anything. Thanks again I've attached some photos
Pump schematic
Pump type
That’s a fixed displacement but it is piston pump - which adds variables to the equation! For piston pump oil level and suction is very important! You need to test that pump. Turns freely and easily is not a good thing for piston pump!
TVA, That's why I can't see it being the pump itself at fault. By "all nice and free" I mean the pistons are not sticking in the barrel. Its not possible to turn it without removing the whole pump from engine. Thanks for the reply
It’s actually the opposite if it’s to easy to turn, it means that valve plate don’t get pushed against piston block and it can end up in leakage.
Good day Case Thanks for the illustrations as you stated the pump unit is not the same as on the "B" series It is a fixed displacement piston pump look like a Rexwroth We are missing something here as a pump of that type is either working or not you have an intermittent issue which seems to be related to temperature, a sheared keyway that spins when the temp. goes up. My advice would be bite the bullet tear down the pump unit look close at the drive. When it works according to your experience works good so the pump itself sounds less probable so must be something with the drive. Please come back with your findings. Kind regards Uffex