Other then upfront costs, I don't see any downside to them. Europe uses them exclusively. Whats the holdup? Are the big fleets really that resistant to newer better technology?

They already tried them and they worked well , BUT didn't last long.

The company I was leased to has a yard full of old gasoline tankers with them, the mechanics said they were bad news, they used to change the pads every few weeks.

I've heard of the old design not working well either. The new ones are supposed to last longer and the pads are much easier to replace then shoes. I'd love to see the whole design in front of me and compare it to the current brakes. We all know how many problems there are with the current brakes. Clevis pins braking, s-cam rollers seizing and binding, s-cams wearing out, s-cam bushings wearing out. Some of this is preventable with maintenance, but not all of it.

They are also much more expensive to rebuild than drums from what I've heard.

The old ones were easy to change also, just had to do it often.

In 30 years I've never had any real brake problems, other than them wearing out, only replaced the "S" cam bushings on 1 trailer, must be my good maintenence that keeps them this way

sure it does ...

I don't know, I think drums are a severely inferior design in many ways. For example, up here we have problems with the s-cam rollers. They simply rust away, and bind up. I had a problem with my front axle pulling to the left, the stroke was the same and everything. Turned out one of the rollers was seized. How am I supposed to "maintain" that? It has to come apart to do anything. Those rollers don't get any grease.

no, they don't. i do however grease them where they run in the shoe web

that sounds like a salt brine issue?

i've only ever heard bad stories about air disks; short life accompanied by high maintenance costs... i've never worked on equipment that had them.

in the shop, hydraulic disks on medium duties were quite expensive, and a short life..., i would expect the same with heavies.

are disks a better performing brake? yes

are disks more economical? no, and when disks do dominate the market, none of us here will ever see the price of brake maintenance (cost per mile) down where it is today again.

...but, they're comin' ;0)

Well from what I understand they will be coming sooner rather than later with the new stopping distance requirements. I too have heard nothing but bad about them, the various products by all manufacturers. I think that the good old 16.5x7" drums work great but I guess the stopping distance is not where the government wants it to be so we throw cautious driving out the window and replace it with gobs of money. Frustrating

Birken

drum brakes can stop just as well as disc brakes, its the reaction time that differs but guess what there gonna be slow anyway in a 70 foot long 80k pound truck.

you can keep the decreased fuel mileage (disc pads are always touching the rotors in one spot or another and every little bit counts) and increased maintenance and cost of replacement.