Jack Bradshaw has a great article in Foretravel Motorcade Magazine explaining how air and parking brakes work.
Well written using proper technical terms.
It also points out the two different braking systems Foretravel used:
Meritor through 2004, and Dana / Bendix after 2004.
We generally think that everyone has the same system used in our own coaches, so we need to be aware when sharing advice that others may have a different braking system.
Article is below:
The midland-Grau antilock brake system is obsolete and non supported. I found you cannot replace the antilock brake parts
You have to change the axles if yours fails if you want ABS. Midland was bought up and their products scrapped. Bendix? Wanna bet?
A good write up..... I read it yesterday, I knew the basics but was unaware of some of the built in safety features. ^.^d
Be aware, this write-up does not apply to U225 and U240 which have wedge-type drum brakes. Used widely in Europe during that time.
Been too long since I inspected an ORED, so can't comment on their brake system.
Most air brake ORED coaches had the wedge drum brakes but there were a few that had the 300 hp 3208 that had the cam drum brakes on the front.
My FTX has s cam drum brakes on all wheels
You had a Hendrickson chassis
I had a look at that PDF and all it did was convince me that there is a lot of cross pollination on the subject of brakes.
1 PDF says Disc brakes on '88 and newer models ......I have an '88 and it's got Drums all round.
2 Not sure what a "wedge" brake is, I know what an S cam brake is as I have torn them down to replace shoes and speedy sleeves, bearings and races.
3 My '88 has S cam on the front axle with auto slack adjusters, with as far as I can ascertain 275 hp 3208 cat.
Mick
I have wedge rears and cam front.1987 sept chassis build date .
3208 278HP :)