Brakes

[Fred Mc]

I was told that on my GMPD4106 the majority of braking comes from the rear brakes. Is this true because on a car the opposite is true?

Regards

Fred

[luvrbus]

I don't think so the GM buses some had a manual proportioning to take braking away from the front axle

[DoubleEagle]

The proportioning valve was used on some trucks as well to increase steering control in slick conditions. A locked up front wheel does not steer as handily as one that can turn a little. There is more weight in the rear, and therefore more braking potential.

[luvrbus]

Eagle in all their brilliance decided small (tiny brakes shoes) on the front would put more braking on the rear axle that didn't work good because of tiny brake shoes on the rear axle,the model 10 up they tried to correct that,the 01 and 05's all we had was hope and pray brakes,the front brake shoes are always the first to go for some reason.These new anti lock disc brakes seem to wear pretty even now days on buses and large RV's   

[chessie4905]

That's the main reason I push greased hubs on older coaches. Oil seal leak coating rear brake shoes on one side can really increase stopping distance. The mess to clean up consumes a lot of rags or towels and several cans of brake clean.

[richard5933]

I was told that on my GMPD4106 the majority of braking comes from the rear brakes. Is this true because on a car the opposite is true?

Regards

Fred

Yes.

When I first got my 4106 I had problems with the front brakes fading from getting too warm. After a conversation with Luke, I learned that the rear brakes do the bulk of the stopping on the 4106. He suggested I adjust the front brakes to kick in slightly after the rear brakes to ensure that the front never are being over worked, maybe a 1/4 turn or less. He suspected my front brakes had kicked in first, took too big a bite trying to slow down, then faded. By the time the rear brakes were fully applied the front were already hot from trying to slow the bus. Since adjusting them like he suggested I've felt the braking to be better, and I've continued this on my 4108.

[luvrbus]

I can kinda see that on the older single air systems backing the front off,on the dual system which has been the standard since 1974 the front axle brakes first.In the Bendix class they made no mention of the single air system on how it works   

[TomC]

From experience with trucks, the first thing I did on my transit bus was to switch the greased bearings to oil bearings. That was 26 years ago and still no problems. Good Luck, TomC

[buswarrior]

The  vehicle does it's braking where the dynamic weight is.

On our cars, that's the front, with the pitch forward.

On our buses, it's down the back, there isn't the same pitch forward.

Brake engineering 201.

But all the brakes are involved, and losing any of them will put you in the trunk of the car ahead...

Happy coaching!
Buswarrior