I have a 2002 Komatsu 1.6 tonne with cabin, and 5700 hrs on the clock. Controls are purely hydraulic as far as I know. It was working just fine and I lowered the blade and extended the arm on top of a pile of wood to park it overnight, but decided last minute to move some stuff to give easier access for my car with a trailer the day after. I hadnt even shut it off, before trying to move again, but joysticks were suddenly completely dead. No rotation, no bucket/arm movement, the left track stick/valve seems completely locked up. Right track, arm sideways rotation and blade however works just fine. So it seems all functions normally killed by the safety function in the left armrest is out, as well as the left track?? Does that make any sense at all? I found the push button in the armrest that breaks contact when armrest is raised. Not sure how it disengages the hydraulics though, but the switch sure does break contact when lifted and vice versa when lowered. Seems right. All fuses are ok. Also it should be mentioned that there has been a weird thing with the hydraulic some times, almost like it had been "disengaged" until I have moved some other function, which wakes everything up again. Not quite sure about the sequence of it all though, as it hasnt been a big problem. I just know I have felt the same resistance in the track stick before. So it MAY be that the left track issue isnt really related and will work itself out if I find the reason for the joysticks not working... Heres the left track issue shown:
Did something fall under the arm rest keeping it from going down all the way ?
No.. the safety switch gets pressed in properly, confirmed with a multimeter...
Good day May I suggest you appeal for both hydraulic & electric schematics for your machine that would be a huge help when resolving problems, attached is a general machine instruction for trouble shooting control lock out. Kind regards Uffex
Well.. I have the shop manual now, and although I havent done any more testing on the digger yet, it looks like a faulty servo actuated safety valve or pump P2 (apparantly its a triple pump).
It's a three stage gear pump in a aluminium casing, save you time and trouble buy a complete new pump, most gear pumps with that many hours leak internally., exactly what you're has done
Good day According to the information Pump 2 provided s the pilot (Servo) power along with one of the tracks the other track is powered pump 1. Both pumps use a communal relief valve in a Rexwroth assembly not so clear where on the machine this resides but I guess you can locate it by following the pump hose’s. All three pumps appear the same specification so these could be switched to diagnose a pump issue. As you have lost power to both tracks but the swing (slew) & blade is OK it indicates a pump issue however if all is lost I would be inclined to check out that Rexwroth assembly with the main relief valve. Kind regards Uffex
Only left track lost power, not both. However I got it working again. It was actually a broken wire almost inside the solenoid on the safety valve. Soldered it in again and voila! Not sure that it will last forever, but at least I know and can look for a new solenoid - or remove it from the digger for a proper fix. Strange though that the left track gets disabled by raising the arm rest and right doesnt, but it looks right from the schematics as well, since its powered by P2. Thanks for any suggestions guys!
Thats good news you are out of trouble KR Uffex