I got a 583K side boom at work ( same as a D8K) and the breaks are weak on it. If you have the machine at just above idle in 1st, you can’t bring it to a complete stop even standing on one brake pedal, left Or right doesn’t matter. Using both pedals will stop it. There is a full 400+ psi at the pressure port on the housings under full brake application and brakes are set properly. Even tried them a bit tighter to see what happens and no difference. Pulled the steering clutches out today on both sides and there isn’t anything crazy to see. The bands seem to have lots of meat left on them but the drums seems glazed but only in a few narrow bands, not the width of the entire contact surface of the brake band. And tons of what I assume are heat cracks on both drums. Im kinda assuming here that over time operators have used the machine and forgot the park brakes applied and we have glazed surfaces that can’t grip. How thick is the friction material on new bands? Also should the drum surface be sort of knurled looking and rough? Where the bands don’t touch thats how it looks almost like a light cross hatch or knurled surface. What else could be our problem? Any thoughts? Thanks in advance!!
Can't have any drum that friction material contacts looking like or acting like a file. All drums are smooth surfaces, I suppose some friction materials can get burnt and glazed, hardened etc. but with the design of a band brake it should still have some clamping ability. How far from the rivets is the friction material? Maybe the servo's are sticking, or?
I wouldn’t say the drum is like a file, just some light cross hatch not chrome smooth. There is a good 1/4” plus of material on the bands and has a nice uniform diamond pattern. It just seems like the brakes do activate and clamp onto the drum, but just aren’t gripping the drum good enough to stop it. The pistons in the brake housing that actually push on the roller to activate the brakes seems to move freely.
From memory 1/4 inch seems low. How far are the rivets to the contact surface? Have you looked at a service manual yet, too much unpacking for me right now to do it. I've done diagonal roughing the drum surface with 320 I think back in the day.
Im away from the shop for a couple days but can look how much band is left. I think its around 1/4” total maybe a bit more, but it would be slightly less to the rivet heads. I did briefly look at the manual but got side tracked before I found the specs for band thickness. Its just a little weird the wear pattern doesn’t show full contact between the entire width of the brake drum and the brake band. The band is a good 5 or 6” wide and only a couple spots are chrome shiny maybe 1.5” wide rather than like on the brake drum of a semi, the entire shoe contacts the drum and is shiny. I suspect the drums are toast for sure with all the heat checking and cracks.
It reads more like a clutch release problem
But if the clutches won’t release it should still be able to stop at a low idle just tracking straight forward. Also it wouldn’t steer if the clutches won’t release, and it steers ok.
What are the brakes like at operating revs with the dozer in neutral . While you have it apart you may as well replace the brake fiber , does the dozer have the correct oil in it ? These are oil immersed correct ? If so there is less likely enough heat to damage the drums , more so on a side boom .
I would agree. Seems very unlikely the brakes got enough use to ever even get warm especially being a boom. The brakes feel normal for the most part they just won’t stop the machine. At a medium to low engine rpm pushing on the left pedal very hard it slows it to a crawl but won’t quite stop. I don’t know if the oil got contaminated so thats a possibility. (Operators lol)
Just a observation machines will drive thru the brakes in low gear you should however be able to hold at full throttle 2nd or 3rd It's a safety thing being able to pull thru the brakes in low
i hear ya there. And yes, they typically will pull thru the brakes at a pretty decent amount of power. Like probably around 3/4 or so, but it usually lugs them pretty good and makes it work. This one will drive thru the brakes without much effort and only about 1/4 throttle maybe less.
Does the Tractor steer correctly if so why are you worrying ???
Mostly because its a sideboom. As a dozer probably wouldn’t matter. It makes it difficult for the operator to precisely control the machine if he can’t stop easily. Often they are manoeuvring with 20 some odd thousand pounds of pipe trying to line it up with the next chunk With the right foot running decel the machine needs to stop with one brake pedal without using herculean forces to do so. Also, i feel like the brakes should just work as intended otherwise something is not functioning correctly.
I used to work on Pipeline equipment like Trenchers and Sideboom's for about 10 years, here in the U.K. close to me we have possibly one of the biggest global hire company's of Pipeline kit, so I know how a Boom has to perform plus I have around 50 + years of working on large CAT Tractors and still put in 6 shifts a week on them, more info would be handy plus pictures of the brake bands sitting with the drums in them to show the margin of clearance between the band and drum, exchange bands are often deformed even from CAT, look forward to your pictures and info on the speed setting of the engine that is Low, High and Decelerator low speed, it might be worth checking the torque outlet pressure as well, the comment was that the steering oil pressure was good and all the linkage was correctly set, hard spots on the drums is somewhat standard do they measure up correctly ? the brake bands are common to find with lining sections damaged or missing so it's uniform wear you are looking for.