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Thread: Brake system questions

  1. #1
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    Brake system questions

    This is a picture of the brake system off my loader/backhoe. Can anyone tell me how this works? As usual the pedal plunges into a master cylinder that a small steel reservoir is bolted inline. On the far end of this reservoir is the one brake line that runs up though park brake valve then splits to all four wheels. What I donít understand is why there is a hydraulic line coming out of the primary hydraulic pump into the master cylinder then out to the steering system. Is this some kind of charged/hydraulic pressurized brake system? I took off the cap on the reservoir and it was dry in there. also pulled some bleeders at the wheels and they were dry too. The pedal currently freely goes to the floor. Whatís a good way to bleed this system? any help is greatly appreciated.

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  2. #2
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    You didn't say what kind of machine you have but it sounds to me like you have a hydralic system for the brakes and the steering. How does the steering work? Or does it? The reservoir i am not sure about. If you in fact have a line coming off of your main hydralic pump and that reservoir is your fill point, then it may need some fluid. I would suggest you find out if the hydralic pump is running something other than the brakes and the steering. If that is the case, and everthing else is working good, then i would say there is some other problem. If the brakes and the steering are the only things driven by the hydralic pump though, maybe all it needs is some fluid. Then you would bleed the brakes like you would on any other vehicle. Without any information on the machine, that is the best 2 cents i can offer. There are those on this forum with more knowledge than me. In any case it sounds like you have a simple problem. Good luck, Joe

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    Thanks Joe. It is a late 70s Do Mor 707. It a component tractor made in Michigan. This tractor has all wheel steering. When its running it does have steering. The brake unit is upline to the steering so I am isolating the issue to this brake unit. The hydraulic line must go to this brake unit maybe add pressure similar to what a booster pump does in the typ car....?? i was trying to bleed but with very little pressure. I wonder if i can only bleed the system if the tractor is running or maybe the seals inside this funky master cylinder are just shot. thanks for the response.

  4. #4
    Senior Member alrman's Avatar
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    I would like to see some pics of this "Do Mor" - never heard of one.
    Post them in the "Pictures of your backhoe" thread
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    Have you updated your user profile yet?

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    Super Moderator willie59's Avatar
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    I can't say for certain, but Parking Brake valve you describe sounds like a Mico brake valve, should not be used for parking. As for the master cylinder arrangement, with hoses coming from hyd pump going to steering circuit, that sounds like a hydro boost for brake system, Galion cranes used to use a hydo boost system similar to that on their brake master cylinders.
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  6. #6
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    Quote Originally Posted by willie59 View Post
    I can't say for certain, but Parking Brake valve you describe sounds like a Mico brake valve, should not be used for parking. As for the master cylinder arrangement, with hoses coming from hyd pump going to steering circuit, that sounds like a hydro boost for brake system, Galion cranes used to use a hydo boost system similar to that on their brake master cylinders.
    Hmmmmmmmmmmm..........Hydroboost. Beyond me! If it was in front of me i could probably figure it out.

  7. #7
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    Quote Originally Posted by DO-MOR FAN View Post
    Thanks Joe. It is a late 70s Do Mor 707. It a component tractor made in Michigan. This tractor has all wheel steering. When its running it does have steering. The brake unit is upline to the steering so I am isolating the issue to this brake unit. The hydraulic line must go to this brake unit maybe add pressure similar to what a booster pump does in the typ car....?? i was trying to bleed but with very little pressure. I wonder if i can only bleed the system if the tractor is running or maybe the seals inside this funky master cylinder are just shot. thanks for the response.
    If i had known there was something out there called a do mor, i would have got it from your forum name. Anyway..... Sounds like you need a manual my freind. If the brakes lines are completely empty, then it is going to take a lot of bleeding. Especially with that parking brake before the wheel lines. As for doing it with the engine running or not....... i would say try it. I don't think it can hurt.

  8. #8
    Senior Member bowen's Avatar
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    Is this the same company?
    http://www.domorequipment.com/

  9. #9
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    i dont think so

  10. #10
    Senior Member HATCHEQUIP's Avatar
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    Like Willie said hydraboost and you can start bleeding brakes without it running turn the mico brake valve so that the fluid can go thru it fill reservoir and open all the bleeders making sure their clear and not stopped up cut them off when they start dripping might take awhile keep master cyl. full if they want start dripping close them and start pumping and cranking lines while someone holds pedal down when you start feeling some pedal crank it and bleed it some more at that time you'll have power to the brakes. That mico brake lock works by applying the brakes and while holding the pedal down you flip the valve and it blocks the fluid so the brakes stay on but don't don't trust them they will will leak off

  11. #11
    Senior Member Tinkerer's Avatar
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    Here is a couple of pictures of pwrstroke6john's. http://www.heavyequipmentforums.com/...07-Skip-Loader Do-MOR FAN had his for sale in June 2013. I wonder if he got the brakes fixed ?

  12. #12
    Senior Member DMiller's Avatar
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    Looks like some of the machines custom built for aviation snow removal here, is one similar but Ford at Chesterfield Airport for tight areas snow removal.

  13. #13
    Senior Member HATCHEQUIP's Avatar
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    didn't realize post was old

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