im thinking of purchasing a poclain sc150 which tracks sideways. its cheap. to diagonise the problem i am thinking of making up new steel lines and swapping over the hoses that go the the left drive to the right and right to left and running the machine jacked up to see if it is actually the final drive of the valve section in the pump. or........... can you purchase or check somehow the pressure to each side of the final drives to see if they are getting equal pressure??? (this would be much easier)))) also, why does everyone always say...... a 1980's excavator .boy thats old, when WW2 bulldozers are still around and going strong??? any ideas. dave----- from down under.
i'm not a mechanic but i would definitely pressure check the hydraulics,in my experience i know a stuck valve on the same circuit can cause a track to drag.
I would make up some fittings to adapt a pressure gauge(o to 5000 PSI)to the lines on the the drive motor.both lines should be plugged off separately with one having the gauge in it.have someone work the travel lever and obseve the pressure. on the older machines you should see at least 2000 to 2500 psi.Always wear proper safety attier when working around hydraulics.Saftey glasses ,shirt,glove's ect.I had a friend that got hydraullic oil injected into his hand while looking for a leak.With that said,if the pressure look's good than its the drive motor.
ok excellent, this would be my first excavator, and first time working around hydraulics as well so i very much appreciate the safety aspects, tips etc. please clarify something. the circuit going into the final drive (and every hyd component) is a loop system, and your saying put a pressure gauge in the line going into the inlet of each hydraulic final drive pump ( at seperate times) and block the return line?? or hook the pressure gauge in line and let the pressure still feed the final drive thus completing the loop?? or is a a dead end??? cheers David
Work on one final drive motor at a time.I plugg bothe lines going to the motor ,with the gauge in one of the two lines.you will have to work the travel lever one way or the other depending on what line the gauge is in.This will give a pressure reading of what's going to the drive motor.Keep in mined ,we are working down on the final drive motor,not around the hydraulic pump's .Never plug off a pump ahead of main valve body as thier would be no relief valve to protect it and something will bust.Hope this helps.
Don't forget the center swivel joint.
a common kawaskai pump issue with prior than the last 2 years used in excavators hi, if i maybe of service, i will need to know if the main hydraulic pump assy. is made by Kawasaki? the model number will help too... K3V... NV111... tracking to one side could be as simple as leaking o-ring in the hyd pumps' regulator valve. can be checked very quickly. in hyd motors, like the travel motors, high speed results in low torque output and low speed results in high torque output. 6 times of 10 the one pump is delivering way too much hyd oil to the motor trying to turn the motor too quickly...but it cannot...the track drags for it does not have developed the same equal torque as the opposite side. get me the info and you e-mail/fax and i can circle where to check visually. no pressure gauges required. if right the fix is $6.00 in o-rings and your time. Adam. Parts & Service Mgr. ph: 905-888-9070 [email protected]
hi, thanks for your help, but the Hydraulics are made by Poclain themselves!!! the guy selling the machin is having second thoughs at the moment, so i'll keep you all posted!!!
Second Thoughts!!! Bummer! Does it track like this in both directions? If I work on an excavator that tracks to one side, the very first thing I check is the drive controls, then move to the more complex stuff. I have seen dirt build up under the parts that operate the drive control valve spools preventing drive lever to fully engage. Simply and easy stuff to check first.
ATECOEQUIP is correct about checking the easy stuff first. Dig the dirt out from under the pedals before you do anything else. There are usually gauge connections on the main valve or right on the pump you can use to test your hydraulic circuits. If this machine has pilot controls to the main valve spools you should check pressure at the spools to main sure you are getting full pressure to shift the spool all the way. The components in each travel circuit include the pump, usually one pump feeds one track and the other the opposite, the control valve, center swivel and the track motor. Any of the above can cause problems. The most common in my experience is usually the center swivel which is also usually the least expensive to repair. I have found Poclains to be troublesome machines in almost all aspects. Hydraulic systems and electrical systems have some very lousy engineering. In an earlier post someone mentioned using a 5,000 PSI gauge to test the pressures but I can tell you that you have to use a 6,000 PSI or higher gauge for these machines and a 10,000 PSI gauge is probably better. Parts are hard to come by for these machines in the States. They should be better in Europe but I still could never recommend the brand to anyone. If the owner is having second thoughts I would suggest you just got lucky.
ok, thankyou for your thoughts!! if you think parts are hard to come by in The States, try Australia!! they say poclain who??? oh yeah i think i know!!! mmmm i might go an old Kato!!!
RED-355, you should get in touch with Murray at Travel Motors Direct in Queensland.
POCLAIN........YIKES run fast very fast...... I work at a Case dealer, in the early 90's I had the privelege of working on these fine pieces of *&%$$#@!@$% when Case thought it was a good idea to jump in bed with them. They were nothing but problems at least the Case branded Poclains. Sticking brake spools, bad center swivels, bad motors, planetary problems. They had so many different cylinders on them there was a book on how to identify them.
I'm new, so gotta post 3 times to start my own thread.
ok thanks again for all your help and advice!!!!!!!!!!!
Want an easy and good indicator of travel motor problems? No gauges? All bidirectional travel motors have a case drain. A general rule is that there will be 1-3 gpm or low flow from this drain at full stall pressure. Block the tracks and using a long rubber hose, direct the case drain from the motor, into a Bucket..NOT ON THE GROUND!! ( See "tree hugger in dictionary") Slow easy drain from good motor is OK. but SIGNIFICANTLY higher flow from slow motor is trouble in all cases. Simply checking pressures will not always show a bad motor. Even bad at full stall main pressures can still show up. The slower motor will show lower pressure than the fast motor during travel unless the counterbalance valve is sticking or noisy internal gear problems. Then it will show higher. Good Luck
dave did you manage to diagnose the problem? I am new to the excavator scene, and have a similar problem on my hitachi ex-120, and was curious.
hi, i never got round to purchasing the machine. the guy never rang me back, so its still sitting in the paddock rusting!! he may have saved me a huge headache!!!!!