Good day, I've tried testing out a Link Belt Quantum 2800 today, I've pressure tested and here are my results (Heavy Mode Selected): Pilot Pressure = 580 PSI (low idle), 610 PSI ( High Idle) P1 Main Pump Pressure = 4100 PSI when stalled - Arm In or Arm Out or Boom Up - Engine Dies out, about 1 second from stalling function P2 Main Pump Pressure = 4100 PSI when stalled - Bucket Close or Bucket Open or Boom Up - Engine Dies Out, but slowly after 6~7 seconds The Power Shift Pressure from the Pump Solenoid reads 500 PSI whether low idle or high idle, drops to around 300 PSI when function stalled The Negative Flow signal to the P1 Pump regulator reads 350 psi, Engine Low Idle, reads 400 PSI Engine High Idle With Arm Function Stalled, same P1 negative flow reads 110 psi then the engine shuts down completely, Should i be concerned about the pump regulators and the pump with results such as this? I've checked the two valves on top the control valve (I believe this was for the negative flow control) but no signs of any faults there. If i'm missing out any checks please inform me. Any ideas will help greatly, Thank you and best regards,
Hi I guess that the fuel system is all good does this have a filter in banjo bolt fuel feed into the injection pump as this always starves machine . does you neg control signal drop off when a service is pulled you could do with two gauges in at the same time as you can get a better veiw of things .i used to work for case and 18 years at jcb so i believe these are very similar in the workings .hyd pumps used to get a fault with the bearing cups on the swash plate wearing causing the pumps to stick and not to travell on bearing surface due to the swash angle always working at the same spots .need to find out if its one pump or both dragging engine down ,i had a js 300 do similar and traced to wiring loom corroded due to sea deference work and be tracked through sea water upto and into cab. there is a horse power control and engine speed sensor to look at. jeff
It's cool you mention the JCB, i looked at a JS200 and the hydraulics and engine are the same exact match to this Link Belt. Just the 8-solenoid valve group looked different cause they use different coils but i'm sure they both share the same functions. The negative flow control pressure (PT1 port) did dropped to 100 psi when functions stalled. I did tee into the Pm1 and Pm2 Ports and when i activated the "Fine Control" Mode it supplied a 520 psi pilot signal to down-stroke the pump, but it didn't help, the engine still bogged down. After this test i pulled the regulator for the P1 Pump, tried moving the servo piston with a pry bar and was really hard to move, it did get a little loose after a few back and forth movements but you could feel it biting along the middle of its stroke. The owner of the equipment told me he won't consider doing a pump overhaul just yet, so i just serviced up the regulators and installed them as is. I did service all the solenoids and relief valves, made adjustments, the engine still dies down, but it takes a little longer to do so as from before, the owner said he's pleased with that for now and will consider taking down the pump later on. I could only agree with you it's the pump swash plate, it was mostly the P1 Pump functions (Arm, Boom and Left travel that was stalling the engine), the Bucket function didn't affect the engine much, But i must say, these link belt and jcb excavators are great machines.
I guess if you have neg control dropping off at the pumps the spring should destroke the pumps so it would seem that the pumps are worn how many hours does she have they also start to make cavitating noise a good sign of pendinging pump doom.You could for you sanatiy sway pi and p2 over to see what difference it makes. I have had a js200 have a floating hammer spool the spring came loose would not always show on neg control but it took several attempts to find it as it was always good when you turn up put gauges on . I guess its wait for the call i need a new pump then.
The excavator had about 11,290 hrs, the pump didn't make any abnormal noises, for one thing the pressure was only maxed to 4100 psi when the bucket was stalled, engine didn't shut down, the arm/boom was also the same pressure but the engine died off, since it's the same pump and engine as the JCB i would expect the pressure to be at 4980 psi for attachments, maybe around 3500 for swing? Wish i could continue with troubleshooting but that won't be until she calls for a new pump, Next week i'll post my results of troubleshooting a JCB JS200, the owner told me it has slow arm and bucket function... Thank you for taking the time to reply, it's helped me a lot. Best regards,
Back onto the neg control then.