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dump trucks

Discussion in 'The Lounge' started by 84gmcjimmy, Aug 4, 2005.

  1. 84gmcjimmy

    84gmcjimmy 1 ton status

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    I have a question for big rig guru's...

    On my way to Victoria this past 2 weeks, I saw these 2 dump trucks. Normally dumptrucks here in Cranbrook have 2 front wheels, then 2 sets of duallys axles in the back.
    These trucks I saw driving through the US had 2 front axles, and 2 rear dually axles...
    What are these for? Would it be harder to steer, or are both the front axles steering?

    Also, on any dump truck, there are these "can" things on there axles at the back, I don't know what there called. Anyone know what i'm talking about?
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    2 FRONT axles???

    I haven't seen any trucks with 2 FRONT axles!. :confused: ...those "cans" are for a rubber diaphram to apply the air brakes--I dont know much about how they work,but its probably similar to the brake booster on a GM truck--I used to sell the rubber diaphrams for them,but never got into how the air brakes worked in detail..as far as I can understand,the brakes on a semi are locked all the time,until enough air pressure builds in the system to release them--so if anything leaks or fails,the brakes apply automatically--if I'm wrong,someone here will set me straight I'm sure!...
     
  3. big94gmc

    big94gmc 1/2 ton status

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    Tandem front axles are for better weight distribution. Check these examples and specs out:

    tandem front axle1.JPG

    tandem front axle2.JPG
     
  4. divorced

    divorced 3/4 ton status

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    They are called brake chambers. There are two types - some are for service brakes only and others are for service brakes/parking brake. On semi trucks, usually only 1 drive axle on the tractor will have the parking brake type, and both trailer axles will have the parking brake type. There is a rod coming out of these chambes that make the brakes work.
     
  5. 84gmcjimmy

    84gmcjimmy 1 ton status

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    Chris, that second picture looks exactly like what I remember. There was just a dump bed with it im pretty sure.

    Thanks everyone else.
     
  6. R72K5

    R72K5 Banned

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    interesting i have never heard of or seen a dual front axle truc before lol unless i have sene one on military base, does the military have any ??


    thats crazy

    i am actually surprised, in which is a rare thing for me, it really takes something truly interesting to actually surprise me anymore in this life.

    this one is pretty interesting, otherwise im pretty jaded,

    heh
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Most twin steer trucks I've seen here are for hauling heavier than normal loads. Cement trucks here are more than 50% twin steer, as are crane trucks. The restrictions for max weight per axle on the road make these things 'necessary' sometimes.

    Many years ago we built a tilt up deck deal as a one off for a customer. It was able to tilt up to just past vertical and lift a large silo, then power it down onto the truck for transport. It was a COE frieghtliner and it was also twin steer.

    Rene
     
  8. 84gmcjimmy

    84gmcjimmy 1 ton status

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    Yeah I thought it was really interesting. i wish I got a picture but no camera. Surprisingly I saw 2 in one day... :laugh:
     
  9. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Beg to differ...all Freightliners I see in the shop (dealer) have maxi pack brakes (service and emergency/parking) on both drives. Not to mention ABS as well.

    Those "can" things are generally called brake chambers. The rod has a clevis on the end of it and is pinned to a slack adjuster. The slack adjuster is splined to an S-cam which goes into the brake assembly and forces the brakes out on either side. After the air goes into the chamber, the brakes are purely mechanical.

    The maxi pack works as an emergency brake in this way:
    It has a spring inside it forcing the rod all the way out and a diaphragm to allow air to push on the spring. When the emergency brakes are on, all air is out of the pack, letting the spring force the rod out to engage the brakes. When the packs are supplied (released), air flows in and pushes against the spring to release the brakes. When you press the tradle valve (brake pedal), air is sent to the spring side of the chamber and forces the rod out to engage the brakes. As a fun part, if you lose your air compressor and pressure drops, you get a warning light in the dash at about 60-65 PSI. After that light comes on, you have a few more brake applications before the supply valve (yellow triangle) pops out, spring brakes lose air, and you are stopping whether you want to or not.
     
  10. big94gmc

    big94gmc 1/2 ton status

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    I'm surprised you know my name....and wondering how!!
     
  11. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Says it in your profile...
     
  12. 84gmcjimmy

    84gmcjimmy 1 ton status

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    I know everything! muahahahha







































    just kidding. I saw it in your profile...
     
  13. newyorkin

    newyorkin 1 ton status

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    :haha: :haha: :haha:


    I get it now...

    A couple years ago I was theorizing with a heavy equipment guy about towing a semi-trailer by just using a dually 1 ton pickup with one of those dolly's for piggy backing two trailers. I asked him how the trailer parking brakes would be released, and he told me to remove a bolt from one of those canister things, which would release all the air and allow the wheels to move. I always thought that seemed a little dangerous, to rely on constant air presure to maintain the brakes.

    I guess he was having a laugh on me...
     
  14. big94gmc

    big94gmc 1/2 ton status

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    Well, I'll be! Forgot 'bout that. :doah:
     
  15. jarheadk5

    jarheadk5 1/2 ton status

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    Anyone looked up the available engines on those trucks?

    "Caterpillar's "King of the Hill" 625-hp C15 provides 2,050 ft-lb of torque at 1,200 rpm and constant torque to 1,500 rpm. Maximum 625 hp is developed at 1,800 rpm with 595 hp at 2,100 rpm."
    -Modern Bulk Transporter magazine

    Man, if you can't move a load with that, maybe it's not supposed to be moved..........
     
  16. 70~K5

    70~K5 1/2 ton status

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    The dump trucks you saw may have had a "self steering" pusher axle instead of 2 steering axles.
     
  17. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Yeah, those bolts are called "Caging bolts" When your air pressure is gone and you need to be towed or whatever, you put that bolt into the end of the maxi pack and put a nut on the end and start tightening. The bolt pulls the spring and releases the brakes..without air pressure. Sounds like it was a mix of joshin you and not knowing himself...lol...good times
     
  18. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Mhmm, now trying working on one. It has twin series turbos, low and high side. They like to crap out turbos, generally at the same time too, but that's a hoss engine when it's working right... One guy I talked to in a Volvo said he's done over 120 MPH in west texas with a full load. Cool stuff, but could you imagine trying to make an emergency stop??? Ha!
     
  19. Kiwi John

    Kiwi John 1/2 ton status

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    The twin steer / twin drive axle configuration is very common in UK. Used mainly for weight distribution on trucks in city areas so they dont wreck the road surface. These trucks are usuallydump trucks for dirt/rubble haulage or tarmac supply to road making machines, (heavy loads on short trucks) and concrete mixers. Also the steering geometry is pretty nifty as the front axle has a different turning circle than the second axle.
    People seem to have explained the brake chambers pretty well.
     
  20. 84gmcjimmy

    84gmcjimmy 1 ton status

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    Saw another one in Calgary today, it was a cement truck! Drove right by us!
    I said to my mom "Look, aren't those cool!" she just snuffed at me :haha:
     

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