Brakes Act Funny in Reverse

luvrbus · March 18, 2016, 08:41:15 AM

Quote from: eagle19952 on March 18, 2016, 08:30:31 AM
never seen one... got a picture I have a OTC brake buddy never use it takes to much room to work

http://flxibleowners.org/article-the-brake-system-an-airbrake-primer/

lostagain · March 18, 2016, 09:12:46 AM

If your brakes are out of adjustment, (you have to measure the amount of slack), with automatic slack adjusters, then the adjusters are faulty and should be replaced. Taking up the slack with a wrench is just masking the problem and is dangerous. I would replace with manual slacks if you don't already have them.

JC

buswarrior · March 18, 2016, 09:13:14 AM

Brake stroke needs to be measured, in order to decide whether to adjust.

Installing a set of brake stroke indicators is a great way to accomplish this.

After a manual adjuster has been adjusted, measure the applied stroke to confirm everything is right.

An automatic adjuster that is found over-stroking is broken, or there are other brake related problems, all of which needs a technician level knowledge to diagnose and repair. (worn bushings, cracked drum, cracked/bending mount, broken bits)

If all this brake stuff was simple, you have to ask yourself why brakes continue to be the number 1 defect when the authorities inspect commercial vehicles?

If the people who get paid, and know they are exposed to regular roadside inspections, can't get it right....?

Read a lot, publications from reputable sources, take a course, pay attention to the consequences of glossing over the irregularities or jumping to conclusions as to the defect that it looks like.

happy coaching!
buswarrior

eagle19952 · March 18, 2016, 10:05:43 AM

Quote from: buswarrior on March 18, 2016, 09:13:14 AM
Brake stroke needs to be measured, in order to decide whether to adjust.

If all this brake stuff was simple, you have to ask yourself why brakes continue to be the number 1 defect when the authorities inspect commercial vehicles?

If the people who get paid, and know they are exposed to regular roadside inspections, can't get it right....?

happy coaching!
buswarrior

Seriously...adjusting the brakes/slacks has got to be the simplest maintenance that can be done with a tool..on a vehicle/rig so equiped.
Heck it is easier than greasing...easier than an oil change...
The reason it isn't done are lazy complacent drivers who think it beneath their status and dignity...steering wheel holders.

I recall the argument as to who is ultimately responsible to adjust the frictions on 100T cranes. It is virtually impossible to satisfy a crane operator. As a master mechanic, I would not allow any operator/driver on my job that wouldn't or couldn't adjust their own.

MB LeMirage · March 18, 2016, 10:12:37 AM

Yup.

jav9956 · March 21, 2016, 10:41:54 AM

Here is the break in question. Interestingly enough I did not hear any issues when reversing this weekend. That is either very good or very bad. I have not played around with any adjustments as of yet. To my untrained eye these are not automatic slack adjusters but perhaps someone who knows what they are talking about can fill me in!

lostagain · March 21, 2016, 12:25:43 PM

That is a manual adjuster. The spring loaded lock ring around the adjusting bolt should be out farther and almost even with the outside edge of the nut. When you are done adjusting, you turn the bolt a little one way or the other so the ring springs up to lock the bolt in position.

JC

buswarrior · March 21, 2016, 12:54:04 PM

Needs some grease via the zerk, and some penetrating oil around the collar to free it up.

This whole area would benefit from the pressure washer.

A caution, all that crud ends up on the ground. Don't wash it off someplace that will get mad at you for the mess.

happy coaching!
buswarrior

Runcutter · March 21, 2016, 04:08:09 PM

And, don't underestimate the importance of that lock ring that should pop out to secure the adjusting bolt. Many years ago, when I had the department heads of both Transit Operations and Maintenance reporting to me, I'd walk through the shop a few times every day. I recall seeing one fishbowl in every other day for a while, and asked what was going on. Turns out, I was the only one that noticed that it was the same bus in for a brake adjustment every two days. Made them dig deeper, and the lock ring wasn't popping out to do its job.

Arthur

brmax · March 21, 2016, 07:46:42 PM

Jav, its a standard time for the putty knife and a pan. I'm passing on that scraping party.
Only in an emergency would I adjust without a bit of scraping. I tell you I still to this day haven't got a "shorty spray wand" but musta swore a hundred times I would!
Nothing like all hid up in an undercarriage with a three foot pressure wand.
Uvex makes some nice clear goggles, I need another pair to think about it.
Good day there
Floyd

eagle19952 · March 21, 2016, 09:40:22 PM

it is clearly evident that those have been neglected... but... they are in the wide open, easy access (many are not)... I would remove them and scrape clean and soak in diesel then re grease...pull the pin and a snap ring... easy peasy...

and heck the clevis for wear too they are cheap...

jav9956 · March 21, 2016, 10:36:22 PM

I see there is agreement that the brakes need to be cleaned... I will add this to the list of things to do

.

I will report back with pictures once finished with cleaning and adjustment in the upcoming month or so...

brmax · March 21, 2016, 11:27:13 PM

Yes, It is spring brake come to think about it

Have a good week there, then a dissertation
cheers
Floyd

buswarrior · March 22, 2016, 06:47:31 AM

Accumulated dirt like that is evidence that nobody has touched that adjuster in some time.

That suggests to the experienced eye careless preventive maintenance.

In a commercial enforcement situation, it would attract unwanted attention, like waving a flag in front of a bull.

And excess grease hanging around helps start those wheel end failure fires.

Clean equipment is easier to maintain, and sends the message you want: Somebody cares about this vehicle.

Nobody wants to unwittingly attract the attention of an enforcement officer, and getting full body dirty every time you go near the coach gets old fast.

happy coaching!
buswarrior

bevans6 · March 22, 2016, 07:29:22 AM

I don't know if this has been mentioned before, but S-cam brakes are single leading shoe design. They have a leading shoe and a trailing shoe, and the leading shoe has a "self-servo" effect. Basically the geometry of the shoe install mechanically drags in into the drum surface, so there is a mechanical boosting effect and it does far more of the braking work than the trailing shoe, which mechanically is thrown away from the drum surface as the drum rotates. This means that the shoes wear differently, and with different patters, yet the adjustment is equal for both. Which shoe is leading and which is trailing is completely dependent on what direction the drum is rotating so when you drive backwards the normal trailing shoe is leading and grabs unusually hard for it, and the normally leading shoe has almost nothing to do. This is a big cause of odd noises and grabbing brakes when driving a vehicle with single leading shoe brakes in reverse.

Brian