Excavator trouble

First bit of advice on the Cat excavator is don't take anything apart until you have done the proper checks, the tracks are driven by separate pumps, so their performance, or lack of it will, also show up in the speed of other operations. the steering valve only operates the pilot circuit, there are two separate spool valves which select track drive, controlled by the pilot system. The possible causes are:- one pump down on performance, one track motor has excessive port plate leakage, the track spool valves sticking and the most likely is leaking past the seals in the rotary valve in the centre of the machine. Get hold of the book, check the speed of all circuits first, then start working out most likely causes.

As you travel forward or reverse cycle on and off of the travel peddel a few times. See if you notice and popping and banging in the slow side drive lines. Also what happens as you try to correct the travel with the steering lever. Is forward and reverse travel the same?
Later Bob

First bit of advice on the Cat excavator is don't take anything apart until you have done the proper checks, the tracks are driven by separate pumps, so their performance, or lack of it will, also show up in the speed of other operations. the steering valve only operates the pilot circuit, there are two separate spool valves which select track drive, controlled by the pilot system. The possible causes are:- one pump down on performance, one track motor has excessive port plate leakage, the track spool valves sticking and the most likely is leaking past the seals in the rotary valve in the centre of the machine. Get hold of the book, check the speed of all circuits first, then start working out most likely causes.

Can I tap a set of pressure guages in line at these points ?

[quote="bob"]As you travel forward or reverse cycle on and off of the travel peddel a few times. See if you notice and popping and banging in the slow side drive lines. Also what happens as you try to correct the travel with the steering lever. Is forward and reverse travel the same?
Later Bob[/quote]

Bob-
When you compensate with the steering control and slow down the fast track all is fine , no strange popping or banging from below when cycled thur turning , forward & back , and yes same in forward as well as reverse , its very consistent , seems to have all the turning power that right track has ( but hard to tell ) ?

[quote="tacacat"]Bob-
When you compensate with the steering control and slow down the fast track all is fine , no strange popping or banging from below when cycled thur turning , forward & back , and yes same in forward as well as reverse , its very consistent , seems to have all the turning power that right track has ( but hard to tell ) ?[/quote]
I suspect the pump volume is low on that circuit. You need some one to help, remove and plug the signal line to the pumps(small line to bottom rear) then have some one try to drive while you look at what comes out of the signal ports on the pump. Servo leakage can shut down pump volume. Then try driving with lines off and see how it drives. Power will be low drive straight only.
Later Bob

You need a manual for the machine. Usually one pump runs a track and the stick, the other a track and the boom & bucket. Some machines have a foot peddle that combines the pumps for the boom lift. So time the extension of each cylinder ( full stroke) and compare to the spec. If they are on spec your pumps are OK and the problem is in the drive circuit. Since you have no issue other than being slow that would point to the rotary valve which has been talked about before. Also if one pump is poor you would notice that in it's digging ability as well.

Never had a 235, however did they have a two speed drive? If so maybe one side is in high and the other in low.

Never had a 235, however did they have a two speed drive? If so maybe one side is in high and the other in low.