I guess I'm going to haft to look at the pictures of back ends of military tractors in hopes, that one of them will be similar to a Kenworth on the set up for slack adjusters, and brake cams going to the wheels. That maybe one of them might have the good old S cam brakes, instead of the wedge brakes.

The only trouble is, I noticed that most military used the wedge brakes, why I have no idea, as a civilian, I would never have a set on my truck.

The military must of got a good deal on them, is the only reason I can figure why they used them, cause they were way to heavy, and didn't have as good a braking power, they faded a lot easier. Everything a owner operator wouldn't want.

But I guess they figured they would go at slower speeds, and didn't need the best brakes.

So if anybody has some pictures they could show me to, I sure would appreciate it.
Oh I almost forgot, for the ones that don't know how to tell the difference, S cam brake will only have one round bar going toward the wheel from the slack adjuster, where as the wedge set up has 2 round bars one each side I think going toward the wheel, see I'm not that familiar with wedge brakes cause nobody I knew ever used them, and I was shocked when I seen the military had them.

I thought they quit making them, cause everybody told me they were just about worthless.
Kerry

Kerry, I guess they save money by using the cheaper type of system, that way they can afford the 600.00 hammers.

kevin

Kerry:

What military vehicles have you been seeing with the wedge-setup ? The WW2 Dragon Wagon was S-cam (see Heavy Haulers thread for pix of the brake mech I added to the DW trailer), and a quick scan of my TM's for the modern 800-series, the HEMTT, and the PLS all seem to be S-cam.

Admittedly that is a small sample, but frankly until your post, I don't think I ever knew about the wedge-setup ...but I'm no expert .... and I only have data on US stuff.

Are you working on a specific vehicle that would help narrow the picture search?

John

Actually what I'm doing is that old 1/32 snap together Kenworth, I've already taken clay and done the top of the rear ends, and finished the headache rack on it, now I was hoping to make some scratch slack adjusters, with the S cam going to the wheels, plus the maxi canisters, for the parking brakes.

I wished I had just the picture of the maxi can and the brake can hooked up to the slack adjuster, shoot it don't even haft to be on a truck, as far as the S cam going to the wheel, it can only go one way.

The main thing is getting how to build the canisters hooked up to the slack adjuster.

The big canister is the parking brake one, and the little canister is the one that does the actual stopping of the truck every-time you push on the brake pedal.

The big one, is big like that because it has a spring in it the thickness of your thumb, and when you release the air that spring sets the brakes, or if you get to low on air pressure for safety, the brakes set up below 60 pounds air pressure.

Maybe if I do a little more explaining, more people will know what I mean, cause it does get confusing without knowing. That round bar coming from the wheel is call the S cam cause inside the wheel where you can't see unless the backing plate is removed, the backing plate is a cover to protect everything from dirt and debre.

Now back to the S cam, it has a S shaped cam to when it twist, it spreads the brake pads out against the brake drums, applying the brakes.

Then it comes out then has splines on it so the slack adjuster can fit onto it, and won't slip, which when air from the system pushes the little rod connected to the bottom of the slack adjuster, which pushes it back, which then turns the S cam. The slack adjuster has several holes in it to adjust the length of the throw of the rod that pushes it.

The hole at the bottom, gives more leverage, but less throw, and the hole at the top gives less leverage but way more throw, the slack adjuster also has a bolt in it, up by the top that is for adjusting your brakes, it has a sleeve around it to keep it from coming undone, all you haft to do is put your 9/16 wrench on the bolt, then smack it to push the sleeve back, so you can turn the bolt, then when your done you turn it just enough so that spring loaded sleeve will spring back out to lock in place.

That small rod at the bottom goes to your braking canister, as to when you apply pressure on the brake peddle, it sends air to push that rod out to push the slack adjuster back, when you only see the small canister, then there is no parking brake there, it is only when you see the big canister with the little one, that you also have parking brakes on that axle. That's like most tractors only have one axle with the parking brakes on them, the other 2 don't

Most tandem trailers only have one axle with parking brakes, now my trailer has both axles with Maxie's, but most only spend it on one set of maxis, that is what that big canister is called most of the time, and that is all that is required is one, so that is all they put, but I wanted mine to stay put, cause a lot of times I get into places where one axle will be off the ground because of the spread axle, so I needed both axles with Maxie's.

The same with Tractors on the 3 axles they normally put the Maxie's on the front drive axle, and that is it. That would get real expensive to put them on every axle especially if you had a big company with thousands of trucks.
Now after this more should know what I'm looking for the pictures of, I'm trying to make the Maxie, and the small canister hooked to it, then hooked to the slack adjuster so I can make them from scratch. I think I got this all down, any questions I'd be glad to answer if I know them.
Kerry

Kerry:

I haven't looked everywhere, but don't think I have an all-encompassing picture like you want. The Dragon Wagon used a driveshaft parking brake, so the tractor axle pix aren't quite what you want -- I will try to get some decent scans from my tech manuals & post 'em for you.

Meanwhile, go to My Gallery & look at pic on top row, right side (HVH11 .....). That shows brake mech on trailer -- the "cans" (brake cylinders) are inside the walking beams & not visible. Again, there is no parking brake on the trailer. And no, I didn't actually add the adjusting screws & al that stuff ....

John

I know it's hard to get a good picture of them cause they normally put them top of the axles to keep them out of the way from things on the ground, that also makes it hard to see them. Unless you got a set pulled out working on them, or right under it, you can't see them very well.

The shame of it is, I threw away a bunch of them, and now I need one to see how to make one, and I don't have any.
Kerry

Kerry... take a look at these pics:

http://www.compusmart.ab.ca/rprince/dru2-web.gif

http://www.edgarparts.com/airbrakeparts.gif

http://web.syr.edu/~wposcarl/AirBrakeWebQuest/ChambersPhoto-Copy.jpg

http://www.compusmart.ab.ca/rprince/120d-web.gif


Jim

I found out my memory isn't as good as I thought it was, I done some checking, real checking, and the big canister is all there is, I thought the two was hooked together but either it has a small canister, or a big one, and the big one having the spring brake inside it for the parking brake.

I also found some pictures at
http:// www.bendix.com/products/ActuatingDevices.shtml

Bendix is one of the leading manufacturers of these parts, I'm not sure if you can get to the rest of the site from this location, but they show just about every kind they got.

Now most of them will all look the same the 20/24 or 24/24, 24/30, 30/30, 30/36, 36/36 all look the same, one number is for the braking power, and the other is for the power it has for parking.

Those are real good pictures you found Jim, that says it all right there, even a good one of the Maxie, Thank You Jim
Kerry

Glad I could help Kerry.... I have changed a lot of s cams ... slack adjusters... and maxi-cans. What is fun is to take those maxis' out to the back forty and shoot the clamp that holds the spring compressed. I have heard the horror stories about when a person removes the wrong clamp... they have been known to go right through shop walls.

Jim

I always bought brand new ones, but this friend of mine bought rebuild ones, and I'll tell you why to never but rebuilt.

We were setting at that air force base just west of Phoenix, dropping off practice bombs, and one of his Maxie's started to leak air, so we got down there to see which one, and it looked in pretty bad shape rust and all.

Well after-wards, I was setting in my truck catching up on my book work, and he was out slamming and yelling about how things always go wrong, when all of a sudden, a big bang, and something hit the side of my trailer, well I got a custom pain job on all my trailer, so I come unglued, and went out to see just what he thought he was doing.

Well come to find out it wasn't him, it was that brake canister where it was all rusted, the spring had busted through the back end and came out and bounced against his spare tire, then hit the side of my trailer and I was parked a good 20 to 30 feet away.

So never buy rebuilt ones, cause they can bust through the rust they are so strong. Just think if that give a way a couple minutes earlier when we were down there looking at it, or if he was going down the road and it hit a car, somebody could of been killed.

That thing took a big hunk out of his spare tire where it first hit, on the tread. I've heard of horror stories to, and I know first hand they have the power to kill, if you would of seen that spare tire.
Kerry