HI Looking for help with a couple of 992K issues. Its an 880 prefix unit. Problem 1, It has a very poor boom soft stop at the bottom, boom will not start to decelerate until maybe 3' off the ground & causes a severe jerk when the soft stop does finally slow the boom down. Also have a 14 year old 992G that starts to decelerate the boom about half way down & has a very soft, not noticeable stop. Of course Cat & Dealer say we have the only one that does it... Very hard on the operators & they have started to just boom down manually to prevent the sudden jerk, just like we have done on our 20 year old Komatsu WA 800. Problem 2, When shutting unit down for lunch break then restarting there is no impeller clutch, only the brakes at the bottom of the pedal. Does not do it all the time but has a half dozen times & does not throw any codes or faults, shutting down & restarting does not solve the problem. Once again manufacturer & dealer say we have the only one with this problem as well. Imagine that! Thanks
Putting into French .......... bolleaux.......they would say that. But having worked for a dealer the factory used to say that to us as well, so we were no better off. Sometimes I think the factory imagine we came up the river on the last banana boat. Second thing first. Get into VIMS and find the parameter (press the "gauge" key and use the arrows to scroll through - it'll be there somewhere) for the Impeller Clutch pressure - it may be different on a 992K to what I'm used to so it's no good telling you what parameter to look for. One morning when the machine is cold - because you say the problem only comes when hot - check what the maximum and minimum IC pressures are with the engine at High Idle and the transmission in neutral. When you start up the engine the pressure should top out at 300+ psi for a couple of seconds (that's to get the clutch to bite) then settle down to somewhere around 285-ish. Minimum could be anything from 60-75psi, it depends on the solenoid valve and the converter. After lunch get that same IC pressure parameter up on the VIMS Message Centre before starting the engine. Do the same check of Max/Min IC pressure as above and see if the minimum pressure goes down to the same as it did in the morning. If the Minimum does not give you within 1-2psi of the morning reading or does not fall at all from Max then either you have a harness fault with the signal to the IC solenoid valve or the valve spool is sticking. I'd vote for the latter. There is I suppose also an outside chance that the piston is sticking in the IC itself, also the left pedal position sensor signal could be dodgy. Has the IC been calibrated recently..? You can't screw it up because the ECM retains the last successful calibration until another calibration is successful, so if the calibration fails you've lost nothing - but you can tell your dealer it failed. Press the keys 7378 on the keypad to enter Service Mode. Scroll through the menu with the arrow key until you get to the calibration for the left pedal. Press and follow the instructions on the screen, it's simple. Once you've done that it will kick you out of Service Mode so you have to go back in again the same way. The next parameter on the list after the left pedal position sensor is the IC calibration. Again press OK and follow the instructions on the screen. This calibration is best done when the machine is hot otherwise it takes a long time getting the powertrain oil up to the required temperature. On a hot machine the calibration takes 5 minute, a cold one it might take 20. For the modulation of the lower hoist kickout I would suggest first doing a full boom/tilt angle sensor calibration followed by a calibration of all the raise/lower proportional solenoid valves, there are 2 of each. AFAIK it needs a minimum of Customer ET to do that, I don't think you can do it from the keypad although the last 992 I worked on was a G, I've never worked on a K.
HI Nige Thanks for your reply. We had the Impeller clutch issue come up just before the Christmas holidays & the dealer was called in. Problem was/is we cannot leave the loader running for hours if not days before the dealer can get into see it, so it is shut down till it can be looked at. Seems that if the loader is shutdown for said time it will restart & no problem exists! The clutch has been calibrated again so well see if it is gone this time, although the Impeller has been recalibrated before as well to no avail...The K does not have a keypad like the Gs & a laptop is needed to diagnose & check codes & if no mechanic is around at the time (real time) it does not leave hard codes or a trail to follow... Oh the joys of technology! LOL Thanks again Nige & I will keep you updated.
We've got a couple of 854K's which are in effect a 992K with a blade on rather than a bucket. Let me play around with the next one that comes into the shop and see what I can come up with. Meantime what prefix is the machine serial number, 880, H4C, or ZMX..? P.S. You must have one of the really new machine susing the Advisor system. You can get into the Impeller Clutch Pressure using the Monitor System, Screen 3.
I think we had a similar problem occur with one of the two 992K's that we sold a mine. They are both 880 serial numbers. I was at the mine doing other repairs when the resident was dealing with the problem. I will ask him and see if it was the same problem and what he did to repair it or if it was even repaired.