MXU115 (TSA115) lost #1 & #2 spools

[Richard Devon]

Its a '04 model with CCLS and 3 x mechanical/cable operated valves.

For some time its been playing up, first it lost pressure/flow from #2, then #1 decided it had also had enough. Only #3 works now.

With a flow-meter running out of #3 at about 500psi I can get the #1 valve to come to life, they run together, but disconnect the 3rd valve and it dies again

I am thinking its those "top-hat" check valves in the slices maybe not seating correctly, but before I pull them apart has anyone had similar and what did they find?

 

[del_boy]

Sounds like the compensation valve has failed or stuck on the pump. Or could possibly be the small shuttle valve sticking on the small t piece pipe that comes out of the spool block

 

[Richard Devon]

Sounds like the compensation valve has failed or stuck on the pump. Or could possibly be the small shuttle valve sticking on the small t piece pipe that comes out of the spool block

If it was the comp valve surely I would have lost all 3 services?

 

[del_boy]

Possibly. Just strange that it works when you use another spool at the same time which is increasing the pressure.

 

[forblue]

First remove and dismantle shuttle valves they only have a ball bearing inside and they can wear, no idea what size ball should be as never took a new to pieces, if ok then as stated could be comp valves, but don't touch unless you have a pressure and flow meter to set them up. unless you just replace, they are at bottom of ccls pump held on with socket head bolts.

 

[Richard Devon]

First remove and dismantle shuttle valves they only have a ball bearing inside and they can wear, no idea what size ball should be as never took a new to pieces, if ok then as stated could be comp valves, but don't touch unless you have a pressure and flow meter to set them up. unless you just replace, they are at bottom of ccls pump held on with socket head bolts.

Where are the shuttle valves? - the "top hat" check valves between the slices?

 

[forblue]

They look like small t pieces on sensing lines.

 

[del_boy]

Where are the shuttle valves? - the "top hat" check valves between the slices?

Coming off the spool block you'll have a 't' piece and small metal pipe.

 

[Richard Devon]

the signal line comes out the baseplate of the hyd stack and goes directly to the pressure/flow valve on the pump....don't see any tees in the line

i have changed the signal check valves between the slices and it didn't make a bit of difference.

 

[forblue]

Ok, might sound daft but have you changed hyd filters and cut open the old ones to check as brake wear contamination seems to cause spool valves a problem when they are worn.

 

[Richard Devon]

Ok, might sound daft but have you changed hyd filters and cut open the old ones to check as brake wear contamination seems to cause spool valves a problem when they are worn.

Good point, its been serviced and I pulled the brakes apart there about 18 months ago, the discs were still OK, but changed them anyway. Since then its really only done a bit of loader and top work, not heavy trailer jobs.

I was thinking if it was part of the flow control that regulates the oil going to the signal port.
The external knob works as it should but wondering if something internal may have come adrift.

 

[forblue]

Can you block flow to the other valves so it only goes to one , then try each one in turn.

 

[Richard Devon]

Can you block flow to the other valves so it only goes to one , then try each one in turn.

they are in a stack, but I get what you mean, I will pull the cover off and wedge the signal valve down on no.3 to drop it out. I did pull out the flow restrictor on No.1 today, it seems to be working fine.

This is the load check valve, the other thing that crosses my mind is how tight a fit it needs to be in the areas marked (tractor got 6500hrs) .....