i have changed the brake cylinder and master cylinder for the left side of my dozer. i bled all the air out of the lines but i still cannot get a brake pedal or get it to work properly any suggestions
Congratulations on your first post @Nick & Pat 1) Is the slave cylinder moving when you depress the pedal? 2) Have turned the adjustment screw to see if the pedal height changes?
Hopefully this did NOT get brake fluid put in it? And I would check the adjustment FIRST if has the correct oil in it.
450B's actually do use DOT3 in the brake master cyls - remember, these were built in the 70's
Been awhile Forgot
Was the master bench bled before install Many times did have issue with air lock that would not move unless bench bled
Yes I have checked the slave cylinder and it is moving correctly it should move between 1/8 and 3/16" to be properly adjusted it moves the same amount that the other side moves that is working properly the pedal height does not change
It uses DOT 3 brake fluid not hydraulic fluid I have been using DOT 3 brake fluid all along
yes that's correct, I've been using brake fluid all along
I did not bench bleed the master cylinder, but it works because I placed the master cylinder output line on the other brake cylinder and it worked fine I also took off the entire brake assembly to check if there was a mechanical problem inside but everything is working perfectly Balls between the 2 plates are free and moving as designed and brake pads are in very good condition
Gonna have to fall back to adjustments at this point, either the lining will not adjust up or you have an internal fault not allowing the brake to function as needed.
The arm that the slave cylinder pushes against is mounted on a fine spline. If the slave is moving & you have checked the internals & all the linkages/clevis pins are in place, & it is not responding to the adjustment screw - it can only be that you will need to remove the arm from the shaft & rotate it at least one tooth. **TIP - mark the location of the arm & spline BEFORE you remove it to know exactly your starting position & which way you have gone.
The shaft spline was marked before it was removed and put back in the same location so that should not be a problem could the transmission control valve have something to do with this since there is 1 hydraulic line running from the master cylinder to the transmission control valve and 1 line running back to the brake cylinder. They are the only 2 hydraulic lines used for the whole braking system. Also, there is NO clutch cutout valve on my model as shown on my service manual that the brake line are shown to go into before they go to the transmission control valve. I'm not quite sure what part the transmission control valve plays in this system
yes, i did that before i took it apart by the way, i like the quote too
The clutch cut out valve allows you to select whether you want declutch or not while using the brakes. Some models have them, others not. The brake lines go to the transmission control valve to operate a neutralising valve, so the tracks are put into neutral as the brakes are applied. If there is a problem with them, you will lose brake fluid from the master cylinders into the transmission, & the slave cylinder will not get enough pressure to operate. If you keep pumping the brake pedal, the slave cylinder should move the piston all the way to the circlip in the cylinder - but if that is happening, the adjustment is not correct.
That makes so much sense. I am losing brake fluid from the master cylinders, don't see any leaks, and am wondering where it's going. Now I see it's going to the transmission. By the adjustment, do you mean the travel of the brake arm movement by the brake cylinder?? It appears to move the same as it did before and travels the amount it's supposed to. The manual specifies that the arm is to move between 1/8" to 3/16" and that is what it's moving. There is also a measurement from the brake cylinder bracket to the bottom of the brake arm bracket of 4" and it is 4". So I'm sort of thinking it's not an adjustment problem but you may still be right I also put a socket and breaker bar on the adjustment screw and manually moved the brake arm more that it's supposed to try to get the brake to engage and it will not. If it is the transmission control valve, is there any way to take care of that issue? Looking at the exploded parts diagram, there doesn't seem to be many movable parts for the brake part of the transmission control valve. There are only some washers and o-rings. It seems to be more for the spools for the transmission levers. Thanks so much for your help. I think we're getting closer to the actual problem.
If I may, you're overthinking this problem. To adjust the brakes, you turn the adjusting screw clockwise in increments & regularly check the pedal height by simply depressing the pedal. If there is not enough adjustment on the screw to attain pedal height - the pivot arm needs to be re positioned on the spline. You want the brakes to be applying about halfway to the floor / or half the pedal travel. Any higher & you will have the brakes dragging as they warm up. Once the pedal height is correct, I think you will find that the slave cylinder travel distance will also be within the spec you have mentioned. However, if the neutralisers are leaking, & you want the brakes to work effectively, you will need to reseal them to allow full pressure to to be applied to the slave cylinders. If they are leaking, the pedal, once adjusted correctly & applied, will slowly move to the floor as the brake fluid escapes past the leaking seals. The neutralisers have nothing to do with brake adjustment - only pressure. Please note - the brakes on a 450B should only be used in tight manoeuvring or to stop the machine safely when loading or working in steep terain. The machine is designed to be steered by using the transmission control levers in hi & low range.
well sir you are 100% correct i adjusted the long adjusting bolt as you mentioned and played around with it like you suggested and it works PERFECTLY i did not have to re position the spline on the pivot arm either i can't begin to tell you how much i appreciate your help and your willingness to share your knowledge and wisdom with someone like me this has been so frustrating trying to figure this out but you certainly saved the day and put me in the right direction again, many thanks and God bless you for your kindness nick p.s. i noticed you are from australia so: G'day Mate no worries i wish i was there so i could buy you a nice cold foster's
@Nick & Pat You're very welcome! Straight back at ya! BTW Fosters is not all that popular a beer down here - But, it's obviously one of the best advertising brand names for Australia.