The Stovebolt Site Forums The Parking Lot Big Bolts '69 C60 Air brakes... where to buy parts?

Looking for parts and info for air brakes on a 69 c60 dump truck we use at the ranch.
Have a slight leak near the pedal valve and I'm trying to identify the part. It looks like a pressure regulator.
I'm just not that familiar with air.

Thanks!

Most air brake systems are pretty generic. There are two basic systems, the cam and lever type, and the "wedge" brake system. Cam & lever is much better, IMHO. Can you post a pic of the part that's leaking?

The basic idea behind air brakes is a pilot valve operated by the foot pedal that switches main line pressure on and off the diaphragms in the air chambers. There will be relay valves close to the wheels, controlled by the foot valve air signal. It's sort of like a low-current relay controlling a high-current device like a starter solenoid, except with air pressure, a small amount of air volume can be applied, not a wide open or off situation like a solenoid does. Sometimes the relay valves develop leaks that can show up a long way from the malfunctioning valve because the pressure backs up through a control line and finds an escape route through the exhaust port of the foot valve or a dump valve for the air chambers at the wheels. Have fun tracking the leak to its source!
Jerry

Jerry, Thanks for the quick reply...

The leaking part in question is tee'd off of the brake pedal valve. It looks like it has a small (1.5") diaphram and goes no where else so I assumed it was some sort of pressure regulating device.
The brakes had been leaking down when the engine was not running and this was the only "hiss" I found. Well, at least before the main line to the tanks blew yesterday afternoon. I was in pretty rough terrain and it looks like it has been rubbing on the frame. I figure it's time to go thru the system.

I'll get a picture this afternoon.
Dan

Hy Coyote, there are many valves that could have been swapped into your truck since it was built, if you could give us some pictures of what is leaking, that would help identify the part. Once the part is identified you can probably purchase a replacement part or repair kit at any place that supplies heavy duty truck parts. Hotrod Lincoln said there are two basic types of air brakes, that is true as to how the linnings are made to touch the brake drums, those two types are "S" cam brakes [not cam and lever, that was a "Ross" steering box] and wedge brakes. There are also single system and dual system and anti-lock so it can be as simple or complicated as system as you require.

Let's see if this works...

Finger pointed at leaking part.

Also, should there be a cover over the exposed rubber diaphram shown?

[image]http://s1194.photobucket.com/albums...k/?action=view&current=airbrake1.jpg[/image]

Hy Coyote, the picture is very small, the valve looks like a pressure regulating valve it is mounted in the secondary system of the dual circuit application valve. Can you tell me how many lines connect to it? I have looked in my maintenance manuals but I can't find a correct dual circuit schematic that would help me identify that component. Is the truck a tractor or a single unit?

I've added a larger picture which might help.

There's only the one line connected to this part. A small diaphram (approx 1.5") and a plug in the opposite end of where it is connected. If it is a pressure regulator, I was wondering if the slight leak is normal. Although, I would think it would stop when the set pressure was reached.

Another off topic question regarding this truck...

It has a Spicer 3152A 5 speed and I cannot locate the filler plug. Forty plus years of grime to scrape off to have a good look but I sure didn't notice one.

Dan

Hy Coyote, I wish I new more about computers, that picture is still too small for me to see much. Have you traced the line connected to that device, I am assuming that the primary system is operating the rear brakes, so this device is probably connected to the front brake system. There aren't any wires connected to this device are there? As to your trans. question, I believe the fill plug is on the left side just in front of the pto opening. Is this truck a tractor or a single unit?

No wires attached to the device.

She is a dump truck although, I'm not sure it was that originally as there is about two feet of space between the cab and box.

I need to source a 3/8" rubber air line approx 12" long. The ends are male compression type fittings. Is this stuff common on air brakes?

I picked this thing up to move dirt at the ranch. It has six new tires (22.5" on steering), tight front end, powered by a 366 V8, 5 spd with a 'very loose' two spd axle. The paint is peeling badly but, after she does a little work I'll treat her to new paint.

I'd like to tighten up that axle backlash if that can be done. Driveline is tight but lots of slack in the differential.

I'll look on the left side for the transmission filler.

Thanks.
Dan

Hy Coyote, Does the line end in 3/8" male pipe fittings, what does the line do? You can purchase made up line through most big truck parts places.

Yes, 3/8" male threaded fittings one each end. It is a line that goes from the engine mounted compressor to the line running down the frame. The piece I need is the rubber hose that connects the two hard lines. The hard lines have a compression bead and female fitting. Local parts house tell me they don't do air lines.

I haven't traced it out but I belive it goes to the rear.
The hose has been rubbing on the frame and developed a leak.

I've been searching on line for a service manual for this series truck. No luck so far.

Hy Coyote, Weatherhead makes their p/n 38097-1800 which is an 18" long [that is the shortest one listed] 3/8" i.d. line designed for connecting brake chambers to relay or quick release valves. The hose itself is catalog number H33806 that hose is 3/8" i.d. and 3/4" o.d., fittings that you can use to make up your line are Weatherhead 338'B' series, see if anyone in your area can find you either of those.