Air Throttle

[HagerHawk]

Good Morning,

On my coach I just bought  it has a Williams Controls air throttle for a foot pedal. The  motor home sat up for most of the past year and the throttle hangs a little and takes a bit to idle back down. It was just a little fun on my drive home as you have to really plan your stops in advance. If I take the air hoses off and put a little air tool oil in the valve should that unstick or is there something else i need to look for?

I've never seen a air throttle, how do these work in regards to moving the throttle back on the engine. I was assuming there was a cable, but iwth it being air does it have a servo or something back on the fuel system?

Thanks,

Tony

Edited January 13, 2021 by HagerHawk

[richard5933]

I've got an air throttle on my 1974 coach, and many would be surprised to find out that they haven't changed very much in the years since. My throttle started acting oddly, and it was pretty simple to get rebuild kits to put things in good shape again.

If you look at the air throttle, probably on the cylinder behind the pedal, there should be either a label or a tag with the model/part number. With that number you can get the appropriate rebuild kit. Not very difficult to do.

The same would be for the slave cylinder on the engine. There will be a kit for that as well.

The cylinders contain o-rings and a piston cup which rides inside the bore. These are lubricated with a special grease that is compatible with the rubber when assembled or rebuilt. If you put a few drops of pneumatic tool oil inside it might help things move more freely, but I'd be careful to use something which is safe for rubber and plastic components. If you put too much in there, it might thin out or remove any grease remaining inside and in the end not help. Of course, at that time you can certainly just rebuild the two cylinders.

It might be a good idea to try and figure out which of the two cylinders is sticking, or if it's ever the air throttle all. It is possible that the problem is in the governor/throttle control on the engine. My first step would be to disconnect the air cylinder from the engine and then confirm that the engine side of things moves freely. After that I'd try to manually move the cylinder with the air line disconnected and see if they return to the neutral position easily.

One last thought would be to make sure that the exhaust port on the system is open and allows the air to leave. Mine is on the pedal cylinder and there is an airline going down and out of the bottom of the coach.

[HagerHawk]

Thought I would update, after purchasing a $250 new throttle and it doing the same thing, I finally realized what was happening. The third airline is a pressure relief line and something had clogged it up under the coach somewhere. I took a piece of wire and ran through the hose and eventually got it cleaned out and my throttle works like a champ!

[hermanmullins]

Thanks for the update, it will help people that may have your same issue.

Again thanks,

Herman