disk brake trailers?

I copied this from an article. Good info on the systems.


”Air disc brakes cost more, so there isn’t a more cost-effective way to stop a truck than a drum brake,” says Joe Kay, director of engineering for brake systems at Meritor, which offers both types. He means on tractors, which the “121” rules affected, and for which drum brakes were specifically improved. But discs can stop those same tractors quicker, which is why some fleets are adopting them. And discs hold up better in severe-service applications, like trash collection trucks, many of whose operators have embraced them.
“There’s an added expense with disc brakes and operators need time to get a proper payback,” says Gary Ganaway, director of marketing and global customer solutions at Bendix Spicer Foundation Brake, which also offers both drums and discs. Cost for air disc brakes varies by truck builder: At Kenworth and Peterbilt they’re standard on the steer axle. For all the other builders the cost of upgrading is $800 to $1,000 per axle.
In some cases there can be a payback through maintenance. With discs, “refuse trucks doubled their brake life,” Ganaway says. With drums, “they get hot and wear rates increase exponentially.”
It’s easier and quicker to change a set of pads on disc brakes than shoes on drums, Kay and Ganaway both note. Pads take as little as 15 minutes to change out compared to almost an hour for a set of shoes. That’s where the maintenance payback can come into play.
But the advantage is less if original linings on a drum-brake system can be made to last a long time, which is possible with larger brakes. To meet 121 stopping requirements, steer axle brakes have gone from 15x4 inches to 16½x5 inches, while drive-axle brakes stayed with 16½x7s, Ganaway explains. Daimler Trucks chose to make 16½x8-5/8-inch drum brakes standard on drive axles for Freightliners and Western Stars.
However, there is a movement to air disc brakes and it’s accelerating. “We announced the sale of our half a millionth air disc brake at the Louisville truck show, which was only two years after we announced the first 250,000th” following introduction of current models in 2005, says Bendix Spicer’s Ganaway. “Fleets are paying more attention to foundation brakes and began experimenting with air disc brakes. They are becoming more and more comfortable and are coming back for more.”
“Air disc brakes are progressively increasing,” says Steve Hampson, director of sales and marketing at Wabco, which sells discs. “There are two levels of fleets: those looking for brake performance — like tankers and heavy steel haulers — and those who want a longer lifetime. With discs you don’t have to touch the brakes as often.” Adoption percentages vary: On trailers it’s 8 to 10%, on trucks and tractors it’s 12 to 15%. The usual configuration for tractors is discs front and drums rear.
Brake adjustment is another reason for disc brake growth. Out-of-adjustment brakes are often an issue in roadside inspections, and citations now affect a fleet’s Compliance, Safety and Accountability ratings, Hampson adds. “Disc brakes are encapsulated and have fewer moving parts, so out-of-stroke is not an issue. Some fleets are looking at disc brakes so they don’t have the concern over adjustment.”
Disc brakes are inherently self-adjusting and have no “stroke” to measure, so are difficult for inspectors to gauge unless they have dynamometers to measure performance. Some states do.

 

Having out of adjustment brakes has been the only thing I've been knocked for in an inspection. Everything else has been fine.

 

I've seen Navajo's and Celadon's, and they're still using S-cam foundation brakes.

I've used trucks with disc brakes and EBS outside of the US... great system, but we can't have EBS here because, as a standalone system, it's not compliant with FMVSS 121.
The older disc brake setups were prone to heating up quicker... they've come a long ways since, and I think it won't be too much longer before they're much more commonplace.

 

i've got a 2015 kw 900l and it's got disc brakes on all axles. good stuff imo.

 

from a truckers POV how does it stop compared to drum? are you an O/O or a company driver?

 

Our trucks and new trailers have discs. They stop a lot better.

Fully loaded with a new trailer I can stop from 60 to zero a lot quicker than when I'm pulling our older trailers with drums.

Its instant too, almost like braking in a car, no brake lag. As soon as you touch the pedal it grabs

 

ah ok, when i get my truck( in about 3-4 years) will prob convert then to disc, can you tell me waht life expectancy is?

 

Not sure but our mechanics say the rotors and pads last a lot longer than drums

 

we trade trucks at 500000 and haven't touched the brakes
haven't had disc that long on trailers yet

 

We have one truck with 400k and still on the original pads.