Will this matter?
#81
09-25-2007, 06:24 AM
Originally Posted by Sizzle
I was taken into Truckee, CA at the scale for an inspection recently. For those of you from other parts of the country that's on top of Donner, one of the most notorious mountains out west with wicked snow and chaining during the winter time! It is West of Reno, Neveda. Always a fun stop. NOT!!!!
The DOT Officer who inspected my truck informed me that the older trailers did not have self adjusting brakes; hence, someone had to manually adjust them. However, he explained to me that the newer trailers-I think he said within the last 7 years [but don't quote me on this] have self adjusting brakes. He said that if you pump them a few times they will self adjust. So for those of you who have been around longer than us newbies [3 years-drove mostly brand new Volvos out of the factory] you probably had the "pleasure" of adjusting your own brakes. However, I would never attempt to adjust a brake. I do the mountains out west all the time and wouldn't have a clue what I was doing. This isn't the part of the country you want to "guess" about how to adjust the brakes. Although, people have mentioned courses on this thread that's fine and dandy. Personally being able to put air in my own tires-since I have a line and taking care of fluids is enough for me. I don't relish the idea of becoming a mechanic on top of a driver. I don't get paid enough to service my own truck. So for those of you who are so inclined have at it. I'm a female who wears skirts and hate getting dirty while hooking to a trailer that's enough grime for me.
Checking the slack in the brake mechanism is a part of a pre-trip inspection. A driver is required to complete a pre-trip inspection, a systematic check of the tractor-trailer’s parts and systems, before every trip and/or at the start of the day, as required under FMCSR 392.7. There are both self-adjusting and manual slack adjusters.
Do self-adjusting (automatic) slack adjusters need to be inspected during the pre-trip inspection? Yes. Every slack adjuster, whether manual or self adjusting, must be inspected as part of the pre-trip. A large number of out of service violations for out-of-adjustment brakes are for self-adjusting slack adjusters.
For every 100 degrees Celsius a brake drum heats up it expands 1/10 of an inch. In other words a push rod measured on a cold drum at 1 3/4 inch would measure 2 1/4 inch on a drum at 500 degrees Celsius. Most self adjusting brakes require several brake applications of at least 80 psi to adjust properly. Drivers are responsible to ensure brakes are checked daily for proper adjustment.[/color]
If the gap between the brake drum and lining becomes too large, either due to the failure to properly adjust the brake with a manual type of slack adjuster or the inability of the self-aduster mechanism to make the proper adjustment, the actuator push rod will move outward or overstroke to the point where the actuator force is reduced. In the extreme case, the push rod will "bottom-out" inside the actuator housing before developing any force on the slack adjuster. At this point, the brake force will be zero.
Brake stroke monitoring systems can aid carrier personnel in discovering air brake adjustment and operation problems in a timelier manner that may be due to the following defects: * Worn, seized, or out of adjustment manual and automatic slack adjusters * Brakes shoes that may be "hung-up" due to other faults in the foundation brake system or slack adjuster faults
Automatic or Self-Adjusting Slack Adjusters
Automatic slack adjusters (Fig. 53) adjust themselves during full brake applications to accommodate brake lining and drum wear. However, they must be checked daily to ensure they are maintaining proper push rod travel - one inch (25.4 mm) - when manually pulled, and two inches (50.8 mm) when the brake is applied. Normally two to four brake applications of 100 psi (689 kPa) per day will keep the brakes properly adjusted. If they are badly out of adjustment it may take up to 12 brake applications to adjust them. If they are still out of adjustment, a qualified mechanic should repair them. Do not try to adjust them yourself unless you have been trained by a mechanic or trainer who is familiar with setting up and backing off this type of automatic slack adjuster. Automatic slack adjusters must be checked daily. kc0iv
#82
09-25-2007, 01:18 PM
I can not remember a time during my days as a driver that I didn't have to adjust brakes. Mostly on the trailers.
My first job as a gas jockey taught me to stop before getting to Myrtle Beach and adjusting the brakes on the entire truck. I usually did this on the side of the road next to the Myrtle Beach Air Force base on hiway 17. In the summer months the traffic and stoplights where so bad before they built the bypass you needed all the brakes that you could get. We didn't have auto-slacks back then and I came from a mechanics background to to driving so working on a truck was no problem for me and I could have the problem fixed hours before any kind of service help would arrive. I also changed my own tires and sometimes for other company drivers if I was going in their direction. The company paid me for this and I always carried a mounted spare, unmounted tire, tube, and flat. Plus I had a 20 ton jack, tire hammer, and irons so I could break down a tire on the side of the highway. We ran dayton wheels and 2 piece rims. I could change a tire and be back on the road in less than an hour, sure beats the four hours that I waited one time and I vowed that I wouldn't wait on someone else to help me again. I made the suggestion to my company and we set a price that they would pay me and it worked out pretty good. This probably flies in the face of most of you on this board but my stance is to do what ever it takes to get the job done. As far as the certification for adjusting brakes, I can agree with that as the auto-slack adjusters require more knowledge to adjust and you can make the brakes worse if you don't know what you're doing. By watching the air pressure gauges during the pretrip I could tell if my brakes needed to be adjusted. It takes more air to apply brakes that aren't in adjustment. Mad Fatboy |
