The right track moves slow, the bucket curl moves slow. Happened all of the sudden. Everything else works like it should. Here’s what I’ve checked. Pilot pressure is 700psi. I am leaning towards a bad pump, but here is what is throwing me off. The outer pump works the left track and some other functions and is making 4200psi when I put the function under a load (testing with engine at idle speeds). The inner pump works right track and the bucket curl (slow functions) but it still makes 4200psi when I bottom out the bucket curl or the track, even though they are moving slow. Can a bad pump have low flow rate causing the functions to move slow but still make full psi? Bucket curl is strong, just moving really slow… I’m stumped. Please give me some ideas of what to look for.
Hi The pump can still make very good pressure at its min displacement and also if the pumps volumetric efficiency is down The issue could be a worn or damaged pump or the pumps regulation such as a flow control solenoid maybe faulty electrically or mechanically. This is assuming that the issue is at the pump. Other members on this forum can assist you with technical information should you need it but you would need to state a serial number of the machine in order for anyone to be able to help. Best regards
Serial number is ymu1276
Possible that your machine is a domestic market import. They run Kawasaki 63cc pumps for the 10 and 12 tone machines and 112cc pumps for the SK150, ED180 and SK200 machines. Flow meters are required when testing pump flow and performance on the machine but if you don't have access to this type of test equipment then you may be able to try these tests. 1) Test the pump negative control pressures to the regulators. With test "t" fittings placed in the negative control lines to the front and rear pump regulators , check and see what these reading are at idle and at full rpm with the machine functions in neutral. The raise one track off the ground and record what the pressure goes down to when operating the travel function. You should see a change in the neg control pressure from the pump that operates that track drive. record reading and test again with the other track drive. Neg control pressure should read the same when in standby and this pressure should drop away when operating a function that corresponds with that pump supply. when this control pressure increase the pumps flow will decrease. 2) Note which pump is down on flow and see if you can swap both the main pump discharge hoses and the pump regulator negative control lines. Test the machine operation again and see if the problem has switched to the opposite track, if the issue changed sides the issue goes back to the pump or its regulation. You may need 1/4 and 3/8 Inverted BSPP test t fittings and 1/4 BSPP Test point fittings along with 2x 0-100 bar gauges and 2x 0-500 bar gauges + test hoses. images extracted from Kobelco Serviceman Mark-III handbook, Insane hydraulics blog, - https://www.insanehydraulics.com/backengthis/kawasakik3vdisplacementcontrol.html Kind regards
This serial number is Kobelco SK150LC Mark IV for the US market (YM=15 tons series and U=US market). Usually when encountering the symptoms of the disease as you described. The first thing we do is to check the independent travel valve; next is to disassemble and check the pump regulator. Attached below is the hydraulic diagram for your reference.
Got it, I’ll check it and report back. Thank you
Thank you so much for this information. The independent travel valve, would that be the valve connected to the travel sticks?
I’ve checked everything except the pump regulator, I haven’t had time to take it apart yet. I just want to thank you again for helping me. I will probably try and pull it off Saturday, and I will report back with what I find.