1. Sorry for the initial hiccups after launch. Everyone should be able to login now.

    Welcome to the new Pavement Sucks!

    If you are having a problem logging in, try RESETTING YOUR PASSWORD HERE

Air Brakes on pickup trucks

Discussion in 'Newbie Tech' started by blasphemous, Nov 17, 2006.


  1. blasphemous

    blasphemous
    Expand Collapse
    New Member

    289
    0
    0
    First off, I'll admit I know nothing about how air brakes technically work. Would they be a bad option for pickups though running big tires? Can anyone chime in here with something positive to ad?
     

  2. muddog14

    muddog14
    Expand Collapse
    New Member

    455
    0
    0
    im not sure but i would think it would be a hell of a lot of work. depends if ur gonna be doing heavy towing only on highways you might be ok. but i wouldnt rely on just air brakes. you would also pri want an engine or exhaust brake also if u were going to do this. in a stop and go type driving it wouldnt be realalistic. u also have to remember that airbrakes are much more touchy. i dont think in a pickup it would be practicly. if your looking for a heavy break buy a bigger pad a rotar. tha will help ya. youll pri have to run a bigger wheel thou.
     

  3. 8=D

    8=D
    Expand Collapse
    New Member

    2,372
    0
    0



    you know big rigs still use huge a$$ drum brakes right?
     
  4. cduggan3

    cduggan3
    Expand Collapse
    New Member

    472
    0
    0
    can you do that?? how do air breaks work anyway? sorry...newbie question.
     
  5. ZacD

    ZacD
    Expand Collapse
    New Member

    4,995
    0
    0
    Air brakes run on the same principle as conventional hydraulic brakes. Instead of a hydraulic cylinder applying the force to push the brake shoes out against the brake drum, a pneumatic cylinder does.



    That being said, I don't think it's possible, as I've never (myself) seen or heard of a pneumatic brake caliper. As Black Sheep, I think it was, indicated, all large trucks run drums at each wheel.



    Further, air brakes wouldn't really be any more effective than hydraulic brakes, even if you could, simply, replace the hydraulic system with a pneumatic system. After all, a give sized caliper/wheel cylinder, given sized pad or shoe, and a given sized rotor or drum is only capable of so much braking ability, regardless of whether it's hydraulic power or air power applying the force. When the pad/shoe/rotor/drum reaches its temperature threshhold, that's it. Period. It's not like pneumatic power is going to make a vehicle stop any faster because it's, simply, pneumatic powered. When pads & rotors (or shoes & drums) get hot, they're hot.
     
  6. muddy

    muddy
    Expand Collapse
    New Member

    679
    0
    0
    I could be wrong, so correct me if I am.

    anyway, from what little I've seen of air breaks, they are basically just a big drum break(as mentioned above) but instead of being actuated by fluid like the breaks on a regular truck, they are actuated by an air cylinder.



    they might be ok if you were never going to go off road, but i'd imagine that the air cylnders would get beat up pretty badly if you were to take it off road.



    there is a picture at the top of this page, http://www.e-z.net/~ts/ts/brakpg.htm



    you can kinda see how the air chamber sits quite a distance from the back of the drum, and would be an easy target for getting bashed wile off road.
     
  7. blasphemous

    blasphemous
    Expand Collapse
    New Member

    289
    0
    0
    I thought big rigs still used drum brakes because they can get more braking surface from big a$$ drums?



    Good points on it's vulnerability and practicality. Thanks for chiming in guys!
     
  8. ZacD

    ZacD
    Expand Collapse
    New Member

    4,995
    0
    0
    And just, for the heck of it/sake of it, to throw this out there:



    Air brakes, such as those on transfer trucks, or "tractor trailers" as some folks call them, operate in the condition that if the engine isn't running, or there's no pressurized air in the system, the brakes are "locked up," per se. What I mean is that, in a big truck, for example, when it's sitting there, parked, and not running, the brake shoes are "applied" to the drums...i.e. like having the parking brake applied, except when you apply your parking brake in your pickup truck or passenger vehicle, the only wheels that have the parking brakes applied is the rear wheels. In a transfer truck, ALL of the brakes are applied when there's no air in the system.



    When the rig is fired up, the compressor is driven by an engine-driven belt, just like the alternator and such. The engine and, therefore, compressor have to run for a while until there's sufficient air in the braking system for the brakes to "release." So, in all actuality, a hydraulic system works in the opposite direction of a conventional hydraulic braking system. A conventional hydraulic system is applying no pressure until you direct it to apply pressure, via the brake pedal. In a pneumatic/air braking system, the brakes don't apply pressure until you hit the brake pedal which, in fact, RELEASES air pressure.



    So, keep that in mind the next time you see a movie and a big rig is sitting there, shut off, and all the sudden it starts rolling down hill or the driver hits the brakes and the truck won't stop. Pressurized air is what keeps the brakes from NOT applying. If the truck lost air pressure...the brakes would apply and/or lock up.
     
  9. blasphemous

    blasphemous
    Expand Collapse
    New Member

    289
    0
    0
    ZacD

    Somehow I knew that, it just didn't come to mind. A big spring inside that cylinder is what actually applies the braking force isn't it? I think I seen it on Trucks on the PowerBlock some time.
     
  10. Matty

    Matty
    Expand Collapse
    New Member

    2,301
    0
    0
    yes, brake pressure is always applied by a spring. I have been into the brakes on our freightliner before, and there is o way i would retrofit that crap to a pickup.



    as zac said, they work the opposite of what you would think, the air actually pulls the brakes away from the drums.



    also, the reasons for air over hydraulic in a big truck are:

    1.Safety while parked or in case of brake failure, as mentioned, with no air pressure, it won't move



    2.Heat. As mentioned, the contact surfaces will still over heat, but there is no brake fluid to biol and loose pressure



    3.Sheer size. It would take very large lines, master cylinders and wheel cylinders to operate as well as a very good booster for the master cyl. Why do you think larger trucks use hydra boost brakes? It take s a lot of pedal pressure to move all that fluid and those large cylinders.
     
  11. Mikeg1005

    Mikeg1005
    Expand Collapse
    New Member

    6,230
    0
    0
    Don't you need to have a CDL to operate a vehicle with air brakes? Thats at least what I have heard...



    Or is it both air brakes and weight?



    MIke.
     
  12. Matty

    Matty
    Expand Collapse
    New Member

    2,301
    0
    0
    Any vehicle equipped with air, requires at least a class B CDL. Pullng a trailer, you need a class A
     
  13. DIXIEDIRT

    DIXIEDIRT
    Expand Collapse
    New Member

    1,709
    0
    0
    to add onto what matt and zac said, if you have ever watched a trucker movie and seen them lose their air lines to the trailer the trailer brakes will automatically lock up solid.
     
  14. blasphemous

    blasphemous
    Expand Collapse
    New Member

    289
    0
    0

    You can't always believe what you see in the movies. Unless you're gullible :fu:
     
  15. Dodge97

    Dodge97
    Expand Collapse
    New Member

    4
    0
    0
    There are air brakes that don't lock up when no air is applied to the system. And there are air operated disc brakes on newer vehicles.
     
  16. beltbuckle

    beltbuckle
    Expand Collapse
    New Member

    70
    0
    0
    Hey I think a couple of you are sorta backwards. There are two types of brakes on a big rig, service and parking. The parking brake is held open by air pressure and remains so untill you either lose air pressure (below 60psi) or you release the parking knob. The service side you apply air pressure to engage the brakes. Oh and they do make air disk brakes they just arn't popular.
     
  17. Matty

    Matty
    Expand Collapse
    New Member

    2,301
    0
    0
    do you know hwo makes the air calipers? I'd be interested in seeing how that works.
     
  18. Dodge97

    Dodge97
    Expand Collapse
    New Member

    4
    0
    0
    I meant there aren't parking brakes on some air brake set ups. Hopper trailers are one example. You can tow them around with a dolly because the wheels don't lock up when you disconnect the air supply.
     
  19. BigGreenCTD

    BigGreenCTD
    Expand Collapse
    New Member

    1,320
    0
    0

    wrong because at work here in de we had a penski box truck rental it was under 26000lbs and had air brakes and did not require cdls. Perhaps thats just a delaware law though.



    But to the topic i remember seeing a early 90s f250 diesel forsale i think on ebay and it said it was equipped w/ air brakes.
     
  20. Matty

    Matty
    Expand Collapse
    New Member

    2,301
    0
    0
    I have a CDL and had to read that whole damn book. In ohio, ANY truck equipped with air, any truck 26,000 and over, and any truck /trailer combo over 10k you must have a cdl.
     

Share This Page