Hello, a few weeks ago I purchased a 1989 CAT 235C. It’s my first excavator and I’m not very familiar with excavators. It has Deere Controls now but I want to change them to be CAT controls. I got the service manual and operator’s manual, and finally found some time to look at the pilot controls. It looks to me like the previous owner just switched the pilot hoses under the seat where they connect to the floor using some 4 foot long hoses. He took the stick control hoses on the left and disconnected them from the floor. Then he ran the hoses to the right side and connected them to the floor, in the place that the boom hoses would normally connect. Then he did the some for the boom hoses. As far as I can tell I just need to change them back. But first… I did some reading in the service manual where it talks about the main control valve for boom and stick crossover and also I read where it talks about the pilot control valves. And before I change the hoses I want to check to see if I’m correct in my understanding. From what I understand the actual valves in pilot controls (on the seat) are the same for both stick and boom. Also I believe that the main control crossover valve works the same way for both stick and boom, therefore they’re interchangeable. But if I’m incorrect please let me know. Will changing the hoses under the seat screw up the crossover valve? How can I tell if the previous did more then just changing the hoses under the seat? Thanks for your time any help you can give:salute Matt
Well, I'm not a 235C expert, but generally speaking, you would switch apporpriate pilot lines in joints closest to the joystick valves, not at the main control valve connections. Many excavators send the pilot lines from joystics to a manifold either under the floor or directly behind cab, and many of the manifolds have quick connect hose connections. I've seen many Cat machines have this manifold for pilot lines and the lines have colored tags on them to show you where they connect. If your rig has this type setup, should be easy for you to determine the proper connections.
I've done the same on a 235C before, before you get into it, follow the lines under the floor there should be a bulk head under the cab hidden behind the belly gaurd/s (if they still there) they might have been swapped over at the point as its easier than swapping them on the pilot contol valves or the floor Also get some small coloured cable/zip ties and mark all the hoses where they were and draw abit of a diagram as its not just a case of swapping them left to right as the slew hoses must stay in the same ports on each side but the bucket circuit you use the opposiste ports from the other valve for each hose our particuar machine was converted 30 odd years before hand from new via the CAT dealer and after swapping the hoses back to the "right" way the machine was jerky and not smooth but we didnt look any further as it was due for replacement so the higher powers let it go
From what you are describing it should be no problem to take the splices out and connect things the way they were before. I know nothing about 235s but if he just stuck a splice in there to reach the other side where the original hoses were it should all be running the same pressures, flows, etc. I'd give it a whirl, just mark how everything came apart so that if it doesn't work you can simply go back to how it was and start over.
on another side not there was an option with those and even late model CAT diggers to have a switchable pilot control valve block which will change the pilot controls over from the CAT standard style to O&K/backhoe style configuaration or back again with a manuel lever behind the cabin i seen it on a 235C and a brazillian import 330CL
Thanks for replying guys. I’m pretty sure that my excavator doesn’t have the option to switch the pilot controls with a valve but I’ll check again to make sure. I didn't think it would be a problem to switch the hoses back but I’m a new on the excavator scene and I wanted to know what some other people thought about it. I hope to be able to find some time after work this week to switch it over. Thanks again. Matt
Matt how it is done is exactly as these other guys above said. It is done through switching the pilot lines at or before the pilot manifold. The pilot pressure is the same for all controls and by changing the lines around there instead of at the main control valve ( main Hydrulic lines ) there will be no relief valves to reset. Whoever told you to change lines at the main control valve is wrong. I got 32 yrs experience and mostly Cat ( worked at a dealer forever )
I got some time to work on it tonight. I marked each hose to id them. Then I connected the left pilot hoses back to the floor. I took the 4 hoses the previous owner ran over from the right side and connected them together, and left them behind the seat. This way I can easily switch the controls back if I ever want too. It took less then an hour, I didn't really lose any oil and it seems to work. Thanks for all the help guys. And thanks for your time Matt