have went completely through the brakes system on my 580c case backhoe and felt like oh man i'm on a roll here i'm doing good for a rookie lol, But here the puzzle after hooking up the parking brake when you pull it they hold and hold good ,and will release, but if you step on the brake pedals while the parking bake is on the pedals brakes will lock up and you have to open the bleeder screw to release them this has me scratching my head cause the parking brake is only a cable so it should have nothing to do with locking up the slave cylinders. Anyone got a clue on what it is.
did you do any thing to the master cyls. ???
yes had to put new ones on and replace some section of the metal line as well and both of the flexable hose and both of the slave clys. and put on new brake shoes
580C's locking up is a very common issue unless you 'completely' go though the brakes.... this includes the ball and seat areas in the brake discs a lot of times the springs are weak or stretched from people doing the R&R wrong and the springs will need to be replaced also the seat ramps for the ball get worn and you would need new parts there also.
residual pressure left in brake system is most likely due to the adjustment of the master cyl push rod being to long not allowing the return port in the mc to be uncovered. should have about 1/8" play between end of rod and piston in mc
If the brakes will not release after you release the pedal the master cylinder plungers are not returning to allow the fluid to return to the reservoir, the push rods on the master cylinder should be adjusted so the pedals move a little before the piston actually is touched by the push rod, that is known as free play. Also, make sure your pedal return springs are good and the pedals are returning firmly against their stops.
Chas and I doubled, his message was there when I came back from entering mine, he is absolutely correct.
ok thanks guys i'll have a look at that but just so you know i'm a newbie at all this backhoe stuff, so may take me a min to figure it out, but I did have to replace both masters cyls so that may be the problem, the brakes work good until you pull the E brake and push the pedals then they lock up, well the pedal get hard let me rephrase that. but when you bleed the line they go back to a free pedal again I may not have explain that right at first.
The pedal getting hard under the circumstance you mentioned is perfectly normal, the emergency linkage has the mechanism pulled up tight and when you push the pedal it pushes against brakes that already applied. Your description was clear enough, It is frustrating when messages get dumped as you said but we all have suffered through that a time or two.