Air Brake Question. Veteran Truckers Required

OK guys. Day 3 of trucker school. We looked at air brake stuff today. How they work. All that jazz. I have been around trucks for the past few years so I picked up on a lot of stuff with that, one of those being talking to a co-worker who has a dad that has been trucker for years. He's like 80 something now. Anyhow, here is what I heard.

That there are oooooold trailers that had an old air system, even before the 1974 system that got upgraded in '75. You know what I'm talking about right? Anyhow, the system requires that the air lines be reversed when hooked to the trailer.

I mentioned something about this at class. Instructor proceeded to tell me that there was no such thing. I'm looking for some veteran truckers to confirm or deny. Like some 70 plus year old truckers.

I'm really confused. It has no bearing on the tests or anything so it's not huge but I would just like to figure it out

You're talking about 42 year old trailers??

Seriously, you aren't going to see trailers that old, and nope.. don't have a clue what you're talking about.

There is absolutely no up side to showing up your instructor. Let It Go...

https://www.truckingtruth.com/truckers-forum/Topic-5525/Page-1/a-question-on-air-brakes

This might be what you're talking about, or send you off into the weeds, not sure.

Really old trailers were not required to have spring brakes. Since spring brakes are what keep the trailer from moving when it runs out of air pressure, they basically had no "parking" brake.

The way current trailers work is that the spring brakes are always activated unless you have the tractor's emergency (red) air line connected to the trailer and the red valve in the tractor pushed in. This supplies air to the trailer brakes, releasing the spring brakes. With old trailers it didn't matter if you did this, because there were no spring brakes. The only way to activate the trailer brakes was by connecting the service (blue) air line and stepping on the brake pedal.

Technically, if you wanted to use your trailer brakes as parking brakes (in addition to your tractor brakes), there was a way. Switch the air lines so you connect the tractor's red air line to the trailer's blue air line--then push in the red valve in the truck. As long as the tractor has air pressure (you'd want to idle to make sure it didn't run out), the red air line will continually supply air pressure to the trailer's service brakes and keep them activated. Of course you'd have to switch the air lines back once you wanted to start rolling again.

Technically you can still do this on modern trailers, but it's completely unnecessary since they are all equipped with spring brakes now.

Does that answer your question?

We actually have an old trailer like this in the DC I work in. When I'm hostling, all I have to do is back under the trailer til it clicks, lift up the 5th wheel, and go. I don't even have to get out to connect my air lines.

#ultralazymode

That there are oooooold trailers that had an old air system, even before the 1974 system that got upgraded in '75. You know what I'm talking about right? Anyhow, the system requires that the air lines be reversed when hooked to the trailer.

I think the link that vendingdude provided - is probably what the instructor was talking about. And he is correct about "not showing up" your instructor - even if it is better to be a smartass, than a dumbass.

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FMCSA 49 CFR 393.40

(e) Emergency brakes, vehicles manufactured on or after July 1, 1973. (1) A bus, truck, truck tractor, or a combination of motor vehicles manufactured on or after July 1, 1973, and not covered under paragraphs (d)(1) or (d)(2) of this section, must have an emergency brake system which consists of emergency features of the service brake system or an emergency system separate from the service brake system. The emergency brake system must meet the applicable requirements of §§393.43 and 393.52.

FMCSA 49 CFR 393.41 Parking Brakes

(b) Air-braked power units manufactured on or after March 1, 1975, and air-braked trailers manufactured on or after January 1, 1975. Each air-braked bus, truck and truck tractor manufactured on and after March 1, 1975, and each air-braked trailer except an agricultural commodity trailer, converter dolly, heavy hauler trailer or pulpwood trailer, shall be equipped with a parking brake system as required by FMVSS No. 121 (S5.6) in effect at the time of manufacture. The parking brake shall be capable of holding the vehicle or combination of vehicles stationary under any condition of loading in which it is found on a public road (free of ice and snow). An agricultural commodity trailer, heavy hauler or pulpwood trailer shall carry sufficient chocking blocks to prevent movement when parked.

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As far as the air lines "being reversed". Never heard of this before. The "Trailer Air Supply Line" (aka: Red or Emergency) - as what puts pressure in the air tanks of the trailer, releases the spring (emergency) brakes, and also supplies air to the tire inflation systems that are becoming common nowadays.

Putting the Emergency supply line onto the Service Air Line connection on the trailer (or reversing the lines by accident), would mean that the brakes would be applied (and stay applied) as soon as you supplied air to the trailer via the Trailer Air Supply Valve (Red Stop Sign). In the case of a current trailer - you would also never release the spring brake - and the trailer would never move, because the brakes would remain applied.

The main object of the spring brakes on the trailer (aside from parking) is BREAKAWAY PROTECTION. Of the trailer breaks away, and air supply is lost - the spring brakes will apply and bring the trailer to a stop (in theory at least).

Rick

(small correction to Rickepedia, but it was Bill F. who pointed out the non-wisdom of appearing to show up your trainer)

We actually have an old trailer like this in the DC I work in. When I'm hostling, all I have to do is back under the trailer til it clicks, lift up the 5th wheel, and go. I don't even have to get out to connect my air lines.

#ultralazymode

Thanks for the info on the old trailers! Reminds me of crazy stuff I learned about mobile homes manufactured before 1978 when I sold insurance.

Does that old trailer ever go out on the road for long trips, by the way?

Thanks for the info on the old trailers! Reminds me of crazy stuff I learned about mobile homes manufactured before 1978 when I sold insurance.

Does that old trailer ever go out on the road for long trips, by the way?

This particular one doesn't leave the yard--we just use it as a maintenance trailer. The funny thing about this one is that the tires are flat too, so we actually just run over the chock too. Makes me feel like an outlaw trucker...I do what I can. Sometimes it's hard not being a real driver anymore lol.

There was one not too long ago I pulled from a door that didn't have spring brakes--it was loaded to leave the DC. So there are some, precious few, still in use for actual transportation I guess.