Trying to help this old bloke with his grader. It is not building up air pressure. He changed out the Air Governor. Made no difference. I connected up an external air compressor to the Grader air tank and found that the Treddle Vv was leaking. We replaced it and there is still a very slight leak out if the new Treddle Vv. Air pressure will still not build up? Is there antwhere else we shod be looking?? I am about to resort to blanking off air lines individually to see if there is a leak somewhere else. Or, is there a compressor unloader Vv and where would I find it? We disconnected the discharge pipe from the compressor and the compressor is pumping air, but I'm not sure it is the correct amount. It is about as strong as a person could blow through a 1/2 inch pipe but in small bursts. Any help would be appreciated. Ta
Here's the SysOp for the braking system. See if it helps. it includes information on the compressor and governor. I took a punt at the Serial Number because there are four different models of 130G with differences within the ranges as well. Post it just for confirmation that the attached information is correct.
Thanks. identification No is 12w0996 Serial No is 07708949. Engine arrangement No is 2W0821. I will read through that and conti he my search. As I only connected the external air compressor to o e side of theta k, maybe there is another leak on the other side of the system that is preventing the pressure to build up. Thanks again.
The governor is the usual culprit when our 12G fails to build pressure. What if you hook the discharge line of the machine compressor to the tank of the external compressor and see if it builds pressure there?.
Great idea. Thanks
There is a check valve down by the air tank. Some have one tank but two compartments so there could be two check valves located on each end of the tank. These check valves can stick allowing air back to the compressor allowing it to leak.
My 130G had the same trouble a few years ago and it was the check valve on the right side of the tank
Thanks for that, both tanks hold pressure when discharge pipe is blanked off. Left side tank no worries. Right side tank is leaking through Treddle Vv still.
Found a blown hose under the engine. Replaced it, air pressure holds in left side tank, but doesn't in the right tank. Treddle Vv still leaking out of discharge port??? When air tank discharges are blanked off, air pressure in left tank is way higher than the right tank?? Possible leak???
This is a single tank with two compartments (left & right), rather than being two completely separate air tanks - correct..? I said earlier that I took a stab at S/N. The attached SysOp document appears to be more relevant than what I posted before, especially regarding the air schematics.
If you study the diagram of the Two Tank system in the attachment hopefully it will give you a clue of which hose goes from where to where.
Awesome stuff Nice. Thanks for all your assistance. I have sorted out the treddle valve and it's lines. Brakes are working. Now though, the park brake won't disengage?? Another weird thing is that the left side air tank got to 270psi and the right side only gets to 100psi? I'm thinking that I have possibly three other issues, first the unloader valves aren't working and second that the right side tank relief valve may be leaking? I blanked off both discharge sides on tanks and installed a separate pressure guage on the gauge line. Third issue, I think is the rotochamber may be corroded and not working properly??? Thoughts???
Pressure building up, but I get 270psi in left tank and only 100psi in right tank???
270psi in one tank is downright dangerous - it's more than double what the max pressure should be. Get the tank safety valve working ASAP, followed shortly thereafter by the compressor unloader would be my suggestion.
Thanks. Will be taking them off and replacing. Will keep checking other stuff. Thanks again for all your help.
If I recall correctly, the rotochamber isn’t serviceable, or at least, Cat don’t sell parts for them. Ours was intermittently refusing to release....replaced the chamber and it hasn’t missed a beat for ten years.
Sounds like a plan, thanks for your input.
Have you verified the pressures you are seeing (270/100) with any other guages, just to make sure you're not on a wild goose chase.?
Morning Nige, I used the same gauge.. removed the tank yesterday and took both relief valves off. They are stuck solid and full of dust and grit. Replacing both. Also, the check valves are corroded and probably not seating properly. Still plodding along one thing at a time. Unloader valves next.
G'Day. Thanks for the confirmation. I just didn't want to see you diving down any rabbit holes that you didn't need to. Thinking out loud I wonder what condition the rest of the valves in the system are like if the tank safety valves were as you described. I also fear for the internal condition of the tanks and hoses, etc. Can you shine a light in the tanks and take a look.? By the sounds of it this system has been full of water at some point, probably no-one ever drained the air tanks for an extended period. Do the condensate drains even work.? Maybe the dust/grit has come from a compressor that was sucking unfiltered air - another thing to look at. Jeez the list gets longer. Once you get the tank safety valves replaced it'd be interesting to see what pressure the left side tank pops off at. TBH I'd do that experiment before playing around with the compressor unloader, just for sh1ts & giggles.....
Yep. I agree totally. A lot of dust and moisture throughout system. Tank has a lot of crap in it. Flushing it out, the old treddle valve was full of moisture and stuck solid too. I'm fearing that we at the tip of the ice berg. But it's a good challenge when you've never done it before. I suspect that the rotochamber will be the same. But I need to get less air in left tank and more in right tank first. Then I'll move on. Thanks again for your assistance and advice. It is greatly appreciated.
Oh well, onward & upwards............ At least you'll know the air system & brakes inside-out by the time you're done.
Must not be an air dryer in this system as you'd have asked about it too
No dryer...
Ok, right side tank relief valve busted spring. But both were fully clogged with red dust. New ones ordered. Stand by for other findings.
Post photos as welll. It's amazing what people might be able to spot that hadn't occured to you while pulling stuff apart.