Disc brakes on a semi?

We have these starting to become more common over here.

The ones i have towed so far, are great. It is ok to run disc trailer and drum tractor as the trailer pulls the truck up nicley. Just woudnt want to do that on a slippery road

 

Regarding the size of the pads...

The Gov requires a certain amount of square inches per pound of stopping force, so the pads on a disk brake have the same area as a drum brake at the same rating.

The disks I have seen were vented and were built strong. They were on a flatbed trailer come to think of it.

 

There're not new. I know Texaco ran them on their gasoline super tankers back in 1992. There's alot of weight to stop and almost all of their driving is in the city. The drivers didn't really have much to say about them. Of course all of us asked them if they were better and none of them would say one way or another. It wasn't something they were jumping up and down about. Now ABS was much different.

 

Of course, don't forget the 'cool factor'. It's just plain inherently cooler to have disc brakes on your truck than drum. Lends a certain snob appeal.

Already the brake shoes on trucks are ... well... huge. But there's not a lot of room for them to increase in size.

If you increase the size of the wheel, the circumference (where the shoes would apply) will, of course increase. But the area, where the disc pads would apply, grows MUCH more. So, increasing the wheel size from 19(?) inches to 21 won't help standard brake shoes much, but will provide something like six times that much (increased) area for pads. (to be clear, if the increase in shoe area is X, the increase in pad area would be 6X). I think.

 

I would think disk on the tractor and drum on the trailer.. how would that work?
Just curious...
Thanks
Mary

 

You bumped a 5 year old thread

 

Ok, but on my phone i can only see the posts without scrolling back and forth.
Next time i'll check the date before i post
mary

 

DISC

not disk.

disc brakes stop faster. so whichever unit has the disc brakes. that be the one doing more stopping. as for wanting the trailer to have abs. the trailer has drum brakes why do you need abs. you'd want the abs on the tractor cuz that's the one with more stopping power. drive on ice and the tractor will lock up before the trailer ever does. or vice versa.

i'd defenitly want both units to have the same brakes.

 

Unless I'm needing to use the brakes often fully loaded, I'll take drums. Discs almost always have some drag and with 10 sets of brakes it adds up to a lot of wasted diesel.