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Cutting brakes, can someone explain a bit to me?

Discussion in 'Center Of Gravity' started by sled_dog, Oct 20, 2004.

  1. sled_dog

    sled_dog 1 ton status

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    Started thinking cutting brakes today. I thought I had a good grasp on it but I realize now I do not. I know what they do but not how to they work. I've always seen the big levers to actuate them between the seats on peoples rigs. But how is the braking force applied? Do you have to depress the brake pedal and hold one of the levers? Are they basically mechanical line locks then? A nice diagram of how to set them up with be great too. I doubt I will run them any time soon but I might build them into the rig just for the ease of doing it when constructing. WIll have a welded rear and Np241 so I wouldn't be able to just engage FWD(not sure thats a neccessity but in my mind it would be better that way).
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Typically the levers you've seen actuate small master cylinders that apply each rear brake independently. If you have a selectable locker, you can just put it in "open" mode and lock one wheel to try to pivot on the locked corner. How well it works depends on weight transfer and terrain. With an auto-locker rear, you put it in front drive and then you can apply only one lever to lock one side with the other free-wheeling. And with welded, it's like an auto locker except that you can not lock only one side and let the other free-wheel. Many people find that this works just fine and may work better than single side in some terrain and orientations.

    Some also use line-locks, but they don't have levers and are not as easy/fast to use since they require hard brake pedal, apply lock, release, do maneuver, apply brake, release.

    Physical installation requires considerable re-plumbing to get separate lines to the rear brakes but is not terribly difficult.
     
  3. sled_dog

    sled_dog 1 ton status

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    so wait, are their two brake lines to the rear? I mean when you press the pedal do all 4 corners lock up or would only the front actuate with the pedal?
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    No, the brake pedal still works all 4 when the cutting brakes are not in use. And each cutting brake lever (typically) operate only a single wheel brake. If I'm not mistaken, to make that work you have to put the "T" in the line before the levers, then through the levers in route to the rear wheel brakes. In the neutral position, both cutting brakes would allow fluid to pass normally. But, when applied, the cutting brake cylinder/lever would block the inlet side and send pressure only to the rear brake. Otherwise, it would pressurize both rear lines, locking both wheels. The normal brake system would still work with the remaining 3 brakes while giving you control over one via. the cutting brake lever. I've never studied them or hooked them up, but that's my understanding of how it works.

    But the easiest way is to just have one lever lock up both rear brakes, less plumbing that way. And a strong e-brake can do the same thing.
     
  5. PJTPW

    PJTPW 1/2 ton status

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    I've got 3/4" bore CNC cutting brakes on mine. One line in, two lines out. Each handle locks one side. With a Detroit and front wheel only, I can pivot off either side. Having individual levers gives more control. You can pivot off either of the rear tires. Also when you need to pivot, and move forward at the same time, you can only lock one tire and the other can still turn to go over a rock, ledge etc. Pull up on both and you can lock both sides at the same time.

    Here's what mine look like. They're behind the Art Carr and have an air hose over one of the arms.
    [​IMG]

    Ryan
     
  6. Nonesuch

    Nonesuch 1/2 ton status

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    Where did you get that set-up? I was going to run mechanical dual e-brakes to each rear but I like this idea too. I also have a brake for the rear output of my Atlas but I really like levers /forums/images/graemlins/thumb.gif
     
  7. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    CNC Brakes

    Lots of online sources you can Google.

    [ QUOTE ]
    One line in, two lines out

    [/ QUOTE ]
    So basically the "T" I mentioned above is built in when you get the CNC dual cylinder kit.
    [​IMG]
     
  8. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Nice diagram too...
    [​IMG]
     
  9. PJTPW

    PJTPW 1/2 ton status

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    [ QUOTE ]
    Where did you get that set-up? I was going to run mechanical dual e-brakes to each rear but I like this idea too. I also have a brake for the rear output of my Atlas but I really like levers /forums/images/graemlins/thumb.gif

    [/ QUOTE ]

    http://www.funrunr.com/ cheapest place I found 84.00? dollars. Somewhere in that price range.

    Yeah, I've got a highangle parking brake rotor on the rear flange of my 205. Works great. I just need to put the linkage back on it.

    Ryan
     
  10. Nonesuch

    Nonesuch 1/2 ton status

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    Thanks baddog

    I found it searching on pirate not long after that post. I am definatly giving them a call and ordering a 3/4" bore twin stick. /forums/images/graemlins/thumb.gif
     
  11. Nonesuch

    Nonesuch 1/2 ton status

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    Thanks Ryan
     
  12. Stomper

    Stomper ΜΟΛΩΝ ΛΑΒΕ GMOTM Winner

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    hyjack

    I've been kicking around the idea of useing my caddy calipers as cutting brakes. Get a couple emo brake handles out of a small car. With the apropriate cables. My thinking is that you could get dual use out of the calipers this way [emo and cutting] and save a few bucks along the way since I've got them anyway. Any thoughts?? /hyjack
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Cady caliper e-brake feature is barely adequate to hold a vehicle's weight on a mild slope. Trying to hold a wheel locked while powering forward with the leverage of a 35"+ tire working against it and it would not have a chance...
     
  14. ntsqd

    ntsqd 1/2 ton status

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    In concept it's a workable idea. The low dollar turning brake kits for VW's work this way. VW Bugs have both e-brake cables routed clear to the E-brake handle and the kits just add a lever under the adjuster nut.

    As BadDog noted the Cad calipers aren't up to the task, actually this is true of every hydro-mechanical caliper I've seen but the Cads are some of the worst. Drum brakes are better for static holding power. This is why late models use a drum P/E-brake inside the hat of the rear discs.

    A low dollar option may be to adapt the P/E-brake off of a Volvo 240 with the D44 rear axle. They have used a drum P/E-Brake inside the rear rotors for years. I've not had one apart, so I've no idea how this might work. Some Mercedes are this way too. I've not investigated this much though.
     
  15. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I've also kicked around trying to find/adapt a drum/disk from an Excursion or something. Probably too much money and trouble, but lack of decent (or any) e/p-brake is the reason I have not switched to disks on any of my 14FFs.
     
  16. sled_dog

    sled_dog 1 ton status

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    would be nice to have a nice rear ebrake setup. I'd like to put rear disks on my Suburban but losing the Ebrake is not an option on my stick daily driver.
     
  17. ntsqd

    ntsqd 1/2 ton status

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    That and apathy (maybe more like laziness) are the reasons I haven't converted either.
    The LM 14bff's have just such a P/E-Brake combined with their rear discs, but I've been led to believe that the flange on the housing is in a different place and/or has a different bolt pattern. Haven't found any to investigate further.

    For a smaller rig like an EB or a Heep the Exploder rear set-up appears to work fairly well. I'm not very fond of sliding calipers due my past wilwood employment, but they work.
     
  18. sled_dog

    sled_dog 1 ton status

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    driveline brake is the only thing I'd really consider, and seriouslly am, since my burb has the 241 already.
     
  19. Stomper

    Stomper ΜΟΛΩΝ ΛΑΒΕ GMOTM Winner

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    Thanks Russ,
    That's not what I wanted to hear but I'm glad you saved me some time and frustration /forums/images/graemlins/peace.gif
     
  20. 84gmcjimmy

    84gmcjimmy 1 ton status

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    can cutting brakes be used on the front too? Or just the rear?
     

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