To Air Brake or Not to Air Brake?!?

[navonifamily]

To Air Brake or Not to Air Brake?!?

Pros?

Cons?

[BigBlue]

I’m confused, our bus has only air brakes I believe. Yours has both?!

[navonifamily]

LOL I guess it made more sense in my head.

Looking at Pros and Cons to Air brakes
And Pros and Cons to Hydraulic brakes

I think I know the answers but wanting to hear input..

[Tryonis]

I guess it depends on the bus, for me anything larger than a small van\bus i want air brakes. They do take some getting used to especially at low speeds.

[BigBlue]

Hehe gotchya! That makes more sense, honestly air brakes are so fun. I’ve barely driven our bus but the air braking felt so smooth and from what I hear there’s less maintenance on air brakes.
(I actually have no idea though [emoji847]✌️)

[cadillackid]

I have one of each.. my older bus is Air brakes..(1990) my newer bus is hydraulic brakes (1999).. the newer bus with hydraulic brakes is disc all the way around and has ABS.


air brake bus is drum all the way around no ABS..


ABS air brakes do exist and started to come in in the early to mid 00s


I stop quite well in both.. the air brake bus does have quite a weight transfer when I stop hard so I can lock the rear wheels up pretty easily in a Heavy-stop situation.. swith ABS on the bydraulic bus I never lock the wheels up.. even with a panic stop in the rain.



Air-brake busses have more of a chance of having air ride rear and driver air seat.. (though some like my hydraulic bvus still have air compressor and has air ride and air seat.. just not as common). Onboard air is also nice for pumping up your tires without a separate compressor.. you can put a fitting on that allows you to connect an air hose and air chuck to air up your tires..




the purely FUN FACTOR is ALL air brakes!!! nothin like pullin into my favorite star bucks and pullinfg the air brake handle with the Ssssss!!! as I shut down.. and also the neat sounds they make when you use them... Totally #BigRiggin with a Big-Grin in the air brake bus..



Hydraulic brakes drive the closest to feeling like your normal car.. air brajes are a but of an art to master completely controlling your stops.. not hard, just different.



-Christopher

[alpine44]

Originally Posted by Tryonis

I guess it depends on the bus, for me anything larger than a small van\bus i want air brakes. They do take some getting used to especially at low speeds.

This is an often repeated sentiment. However, one has to wonder why high-end motor coaches weighing in excess of 50,000lbs use hydraulic disc brakes.

The advantage of air brakes is that they are fail-safe (spring will lock the brake when pressure is gone) and that trailer brakes can be hooked up easily to the main brake system. IMO, the latter is THE reason that air brakes are so prevalent in OTR trucks and not that their performance is any better than a hydraulically actuated disc brake system would be. Why do we have run-away truck ramps and mandatory brake check areas on top of passes? Why is there not a month going by without seeing a truck with smoke billowing out of at least one rim?

The hydraulic disc brakes of my 25,950 lbs GVWR box truck are the last thing that comes across as under-rated on this vehicle. That truck could have twice the horsepower plus two more gears and the hydraulic disc brakes with ABS would still pin me against the seat belt reliably and easily controllable. I actually blew a crusty hydraulic brake line on one trip and the second circuit of the hydraulic systems stopped the truck just like the same design would in every car. Granted, replacing hydraulic brake lines is a whole lot more time consuming and nastier than pulling in a new plastic air line. The box truck has both, plastic air lines for springs and seats and metal lines for the hydraulic brakes.

I drove a couple of thousands miles on pavement in a military 5 ton truck with air brakes and boy does that thing need a gentle touch with the foot on the brake pedal when it's empty. If you over brake any of the 3 axles, it starts bucking like a bronc due to the ridiculously stiff suspension. The 5-ton designation means the truck is built for 10,000 lbs cargo load - off road, any terrain, any weather.

[cadillackid]

in GENERAL.. the rotors on disc brakes have less ability to disperse or "store" energy than the Massive drums on big trucks..



However the Rotors have the ability to dissipate heat much quicker than the massive drums do..



if the objective is that you may need to "store" lots of energy.. ie a panic stop.. or running down a mountain where you need to be on the brakes (i know downshift yada.. we are talking generals here).. then the massive drums have the ability to disperse more BTU of heat or more units of energy before brake fade than the discs do...



in single stop comparison tests with both in heavy massive vehicles, the discs tended to have more brake fade than the Drums do.. in multi-stop tests the discs won because they were able to dissipate the heat they did store quicker than the drums..



the other piece is also related to Juice brakes, maintenance and leakage control of the system.. any air in a juice system and your capacity is reduced greatly..



air brakes of course the air is simply constant-replenish.. there are rules as to how much air you can leak but the air system doesnt need to be 100% tight..



air discs DO exist.. but almost non existent (if at all) on the school busses we are looking to buy..



replacing the pads and components on hydraulic disc are just like working on your own car... air drums, not so much.. thats if you can even lift the drum..

[EastCoastCB]

Air brakes are safer and give me that satisfying sound every time I stop and park.
I had a short bus with hydro brakes and had no problems, fwiw. But I'd rather have the air brakes all day.

[navonifamily]

Our plan is for a 40' bus pulling a 16-18 foot car hauler all over the US. (Mountains, plans, deserts, ext). So kinda sounds as if I'd find a better brake system in Air brakes..

[Brad_SwiftFur]

I have a very strong preference for air brakes, but I will admit I am biased, and have a great deal of experience driving large air-brake equipped vehicles. Also, since my driveway is not flat, I wanted (needed) maximum possible holding power for the parking brakes; more than any driveshaft mounted brake could provide (and if I raise one wheel to change a tire or service the brakes, it renders the driveshaft brake useless).


That said, many thousands of hydraulic brake buses are in service with no issues and can be said to be just as safe as their air brake equipped counterparts (assuming proper maintenance, in both cases).


Ultimately this comes down to the same thing as "which is better, Ford or Chevy?" Both are good and they are fairly close to the same, they do the same job. So which is your preference? My suggestion - see if you can test drive one of each, and which you prefer.


One last *VERY IMPORTANT* thing - air brakes do *NOT* have the same pedal travel that hydraulic brakes do! Hydraulic brakes may have a few inches of pedal travel. For air brakes, this might be more accurately measured in millimeters! Air brake valves are, for all intents and purposes, a foot-controlled pressure regulator. The more pressure you give it, the more pressure it sends to the brake chambers. The valve is self-equalizing the whole time, so the pedal never really travels much beyond the equilibrium point. None of this is a bad thing, it's just different and something you should be aware of when driving one for the first time.