I got to repair this big ugly yesterday. This is a 2004 model, sold to a county here in Oklahoma. This was an auction machine bought by a "equipment dealer" AKA "a company that buys auction crap, fixes a few things, and sells it for profit". The machine was delivered to the county less than a month ago and they tried to use it........but the park brake kept applying and the hydraulic speed was uncontrollable. The seller spent the last 3 weeks replacing parts ...........almost everything having to do with the park brake: pump; solenoid valve, pressure sensor, and a VCU recalibration. Not sure how many $1000.00's spent so far and NO FIX.
I will fix it for what is spent already plus parts.
The first thing I got was the electrical and the hydraulic schematics from Etnyre and had them blown up to poster size so I could read them. After talking to the operator and the county commissioner about the symptoms, I decided to start with pressure checking the brake system. I tee'd into the service brake line and got 250PSI.......low pressure since it is supposed to be spec at 400PSI (operates off off pump charge pressure.) So next I remove the park brake line at the park brake (spring applied, hydraulic release). Notice that I have a 1000 PSI guage on the line. I'm looking for 400PSI when the park brake is disengaged. Hit the switch............NOTHING. Hit it again several times......NADA. I then look down at the park brake line through the floor panel (The end that is hooked to the hydraulic manifold) and I can see it flex with the switch every time. HMmmmmmmm
SO.........I engaged the hydraulics and guess what?! I get pressure at the park brake line...........plenty of pressure, as a matter of fact , it dam near blows my gauge apart. Bent the needle and ruined my gauge. Interesting!! SO I decide to trace the hoses out and find the other end of the park brake line hooked to.................. THE RIGHT SIDE OF THE PUMP COMPENSATOR! LMAO
Well, this is definitely NOT right..........so I go to the hydraulic manifold and find the park brake outlet...... Marked as PB of course, THIS hose should be the one at the park brake housing. SO why did I get a huge blast of pressure at my park brake line when I engaged the hydraulics you say? I trace the above line to answer this question.
ITS because...........it is plumbed in at................take a wild guess here!................ ITS LOCATED AT LS1! LMAOO!!!!!!!!!!!!!!!!! Switch the 2 lines where they are supposed to go and WAHHLAAAA, problem solved! SO.........the moral to this amazing story is "DO YOUR OWN TROUBLSHOOTING REGARDLESS OF WHAT YOU ARE TOLD!" MAN, I LOVE my job!!
Electrical and hydraulic problems are my favorite ones to solve. Because when you find the problem and fix it you are the hero. And no matter how well you explain how you found the problem and what you did to fix it. If it happened again tomorrow they still couldn't fix it. Good job on finding the problem.
I drove 3 hours to fix this in 1 hour. These are the perfect jobs! I wish I had 100's of these lined up!
That s a sheeeeit ton of attaboys you just racked up!
I hope your invoice includes a charge for a replacement 1000psi pressure gauge........
Of course it did!
Just a thought but that's a perfect use for a Tetragauge when you have no idea what pressure is actually in a system, although you may have an idea of what OUGHT to be in it....... With the biggest gauge range of 5000psi you're never going to wind it off the clock.
How much is one of those now?
Genuine Cat gauge - 6V-7830 about $900. This copy - $575 https://www.anythingtruck.com/product/480-12740008.html
Ahhhh, a job well done. Get paid properly for your knowledge and skills!
any idea why the lcd unit on the chipspreader won't work. Just comes on and goes off