Air brake help needed

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Dr. Dig, May 23, 2019.

  1. May 23, 2019 #1
    Dr. Dig

    Dr. Dig Bobtail Member

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    Can anybody identify these air brakes and how to cage them? They are on an early 90s interstate 20 ton beaver tail trailer
     

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    Dr. Dig, May 23, 2019
    Dr. Dig, May 23, 2019
    #1
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  3. May 23, 2019 #2
    AModelCat

    AModelCat Road Train Member

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    You don't cage them. They are service brakes only, no park.
     
    AModelCat, May 23, 2019
    AModelCat, May 23, 2019
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  4. May 23, 2019 #3
    Dr. Dig

    Dr. Dig Bobtail Member

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    I need to move the trailer a short distance with no air. Will this trailer move?
     
    Dr. Dig, May 23, 2019
    Dr. Dig, May 23, 2019
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  5. May 23, 2019 #4
    AModelCat

    AModelCat Road Train Member

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    That trailer will likely have what is called a Relay Emergency valve. When you exhaust the trailer supply line, the Relay Emergency valve will send full trailer reservoir pressure to the service chamber (old school guys called it "dynamiting" the brakes). Once reservoir pressure leaks down, the brakes slowly start to release. So make dang sure you chock those trailer wheels when you unhook it.
     
    AModelCat, May 23, 2019
    AModelCat, May 23, 2019
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  7. May 23, 2019 #5
    AModelCat

    AModelCat Road Train Member

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    Unless the shoes are seized to the drums it should roll ok. Although I wouldn't recommend towing a trailer with inoperative brakes.
     
    AModelCat, May 23, 2019
    AModelCat, May 23, 2019
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  8. May 23, 2019 #6
    Dr. Dig

    Dr. Dig Bobtail Member

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    Thank you.
     
    Dr. Dig, May 23, 2019
    Dr. Dig, May 23, 2019
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  9. May 23, 2019 #7
    Goodysnap

    Goodysnap Road Train Member

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    Gotta be careful with those........the air leaks off over time and no park brake. Young guys dont know to hook up and charge the trailer before backing under it.
     
    Goodysnap, May 23, 2019
    Goodysnap, May 23, 2019
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  10. May 23, 2019 #8
    Hammer166

    Hammer166 Crusty Information Officer

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    Bleeding off the air tanks will release the brakes on these.
     
    Hammer166, May 23, 2019
    Hammer166, May 23, 2019
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  11. May 25, 2019 #9
    Freddy2times

    Freddy2times Light Load Member

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    EnduraSure_Spring_Brake.59caba010c2ce.jpg the picture above is a spring brake (2 chambers) THIS ONE NEEDS TO BE DISARMED. (CAGED) the ones in the pics you posted are single chamber. No need to cage.
     
    Freddy2times, May 25, 2019
    Freddy2times, May 25, 2019
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