Thanks for having me all. I'm just and old school bricklayer so bear with me. We have a w18 wheel loader in the yard, laborer parked it put on the parking brake (air). We jumped on her today and the brake won't release. You push the brake actuator in and it won't stay, pops right back out. I checked the bleeder on the tank and had good forceful air coming out so figure compressor is good right. traced all the airlines, I think and we do not here any hissing except when you push the actuator button in theres a slight hiss out of what looks to be a bleeder on the back of actuator valve. The air brake system looks pretty simple to me, comes up to valve goes out valve. I have not found anything electrical referring to the valve. There a broken wire coming off it but its been broke for years, so. Can you point me in the right direction. I was going to chase the air tomorrow see how far its making it. I here it at the dash valve tho. The actuator valve just won't stay in , is it the valve. The machine has been handed down so, We were using it to load stone parked it and &^%$#. no warning, parking brake went on and worked. Won't shut off. Okay Thanks all.
Sounds like the valve. Idk what you have but I've seen a few brake valves fail on semi tractors like that.
Okay so I found a parts list and diagram of the (Parking Brake Valve) on the dash is what I was talking about. You push it in and she won't stay,,just's pops back out. I was calling it the actuator,,which is the canister down under. lol I'm a Bricklayer what can I say. Anyways, is it the parking brake valve? Another thing?? the air gauge on the dash went quit working the same time, I guess. Whatever that means? I look under the dash and its just a mess of cut wires so. The diagram I found doesn't really show and electrical solenoid's or anything like that in the system. Any suggestion would help.
Thats what I was kinda thinking. To me it's kinda like a light switch, you turn it on you turn it off. I'm a bricky lol
If you don't have air pressure... Again, if its similar to a truck, the valve needs air pressure to stay in. In a semi truck, when air pressure drops to between 40 and 20 psi, the valve pops. Idk that yours works the same but you need air pressure, and it should build regardless of the valve in/out.
I'm going to rig up a gauge tomorrow, theres a quick connect on the tank. I can check it there hey? If its good at the take I'll have to follow the lines right?
Hey Bricky it's been a long minute sense I've worked on these machines but looking at the parts diagram the air pressure for park brake comes from the left foot brake valve so make sure that valve isn't stuck down not allowing air to get to park brake valve.
I'll check that out right away tomorrow and let you know. Thankyou for the info!
So I ran a line from my compressor to the air tank on the wheelloader. I had parking and wheel brakes, all worked. So the compressor, governor, and check valve on tank is all before the tank. check valve worked because I didnt loose pressure when on took my air of tank. It held for 15 minutes or more. check valves good,,right? whats left is governor and compressor. checked the belt has like 3/8 deflection. gotta be one of those right? Am I missing anything? Thanks
You said earlier that you could hear a hiss did you locate where that was coming from? Does your compressor cut out when all is hooked up?
Yes my compressor cuts out when pressure is built up. I have to hit the parking brake and pedals a half dozen times before my compressor kicks back in, so the system seems to be holding pressure from the tank on the wheelloader forward. I'm thinking governor or compressor. which is the only parts of the system before air tank, if I'm correct.
That is a possibility.
Sound like air psi does not hold very long One thing I have seen compressor changed and the problem end up being loose cover on hyd tank yes hyd tank is air pressured to help feed oil threw large suction filter in tank !!