HI. I have already posted this but on the excavator forum, this section is probably more suitable. I have a case cx16b 1.5 tonne 2005 1900hrs. everything else works great but when i reverse track motors they are slow and have little power. They are two speed and go forward no problems with plenty of power. if i hold the blade lever up it helps it but only slightly. I wondered if anybody has come across this before i start striping everything down. I was thinking it could just be a bit of muck trapped in valve block? or could it be the two speed solenoid? hope somebody can help, we are using machine daily due to being busy but want to sort it before it gets worse. Thanks
Not real familiar with your machine, but on most excavators you first want to check that dirt/debris isn't restricting full movement of drive levers. Just a thought.
Thanks for your reply. we had the foot plate of and the levers are free to move ok. the older machines we have are track levers with rods connected directly to the valve block but this one has pipes going to the valve block. we have checked the oil levels in the transmission housing and they ok. i've had this machine from new and its the first with two speed tracks and it has never turned in 2nd, but i guess thats normal. thanks
If it has pipes going to the control valve, it's pilot operated valves that the drive levers operate. That's what I was referring to checking for dirt. The levers can still operate free, but dirt build up at the actuator spools of pilot valve will restrict how far the pilot valve operates. Make sure it's clean around pilot valve actuators. It's unusual for a motor to be weak in one direction only, not impossible though, and very unusual both track motors are doing the same thing, just more likely something else is causing your problem. You could remove the case drain lines from motors and check for excessive case leakage in both directions indicating failed motor, but I just can't square that with both motors being weak in reverse. Next likely cause I would suspect would be the rotary joint in the center of the machine. I hope you get it sorted out.
Thanks again I'll have a look at the lever pilot valves.
Hi. I know its been a while since last reply but still got this nagging problem. ok we looked at the valve on the levers, no problem their. we looked at the valve in the main valve block and that was ok. so we re piped one track motor to run off of the the valve that the blade is piped up to, because that does not use pilot controls but has rods connecting it. and the track motor ran perfectly. so we are thinking it is the pilot controls that are at fault. the pump is a variable displacement pump with a small pump on the end that just feeds the pilot controls, could it be that the pump is failing. but why would it operate the the valve one way and not the other? is it that it is easier to push one way than the other? and why is it on the just the track motors? could that be that tracking is harder on the pump than the rams? Any thought would be greatly appreciated.
without getting too technical i can give you some idea's, start with the basic's swap the pilot hoses around from the travel valve to the main control valve, if it makes no differance that will tell you the fault is in the main control valve, travel circuit, travel motor somewhere if the problem changes from a slow reverse/normal forward to a slow forward/normal revserse you'll know is its a pilot circuit issue I'm not familar with the machine but i'd be think it will have some sort of relief valves on the travel motor, CAT call them "crossover relief valves" if they start playing up or the seals fail you can have he same issues that you seeing but one will generally go before the other so you will get the machine not tracking straight in forward but ok in reverse visa-versa is the rotary coupling/swivel joint leaking? another thing which may cause the same fault is internal bypass of the coupling allowing high pressure oil to travel back into the case drain ports of the travel motors causing all sorts of issues
Hi Guys I am also looking for some advice on final drive problems on a Hitachi ex35 u , the planetary gears have totally collapsed on one drive motor , the hydraulic side of things seems fine as you can hear the shaft still spins in forward and reverse , my main concern is if i can get away with just dismantleing the mechanical side of the drive without removing the whole drive motor hydraulics and all ? the break down of the procedure i had sent from the local dealer only shows removing the whole deal ! which i am trying to avoid like the plague .