Brake Light Question

It isnt operated by air. The switch is under the dash and it is mechanical. As you depress the pedal your moving the arm away from the switch. This is a normall closed switch. When the pedal comes to the up position it pushes the plunger in and disconnects the switch.

 

It is the same thing on a car. Open the car door and lay on your back on the car floor. Industry is lazy, their view is why make something new when you can get it off the shelf for pennies on the dollar.

 

Oh but some,, or most are operated by air. They are mounted so as you apply brakes, air goes into the switch which makes the electrical contact to activate the lights. What most switches are mounted in is called a air manifold. Mayby some newer semis have a automobile type like you mentioned, i don't know. Have never seen them though. A lot of petes actually have 2 brake light switches. One for the foot brake, and one for the trolly valve. They are mounted drivers side in behind the plastic that helps cover your steering linkage. IH used to mount switch on firewall drivers side. That was on a 9400 model. Models obviously.

 

My 2012 Volvo is air operated. If I let the tanks drain to 0 and hop in and push the brakes with the key on, it will not activate the tractor's brake lights.

 

I have had compressors fail.

Mr Buttons tell me they are popped out and all out of air. No go. Fix me.

Its REAL fortunate the last compressor failed quietly during dinner instead of at speed on I-95 that night towards DC. (395, 95, 495 go together in one spot. Be a hell of a spot for that...)

If the truck wants to throw a fit because the airs all gone, the last thing I think about is the lights back there working. Who knows? I have to find a hole to put her in quick. Then fix it.

Your first post shows a working understanding of the air brake system as in english with a couple of little rough spots, but all that will become clear as you run.

Before Westinghouse Air Braking was implemented by law for Trains in the 1800's they used to constantly catch people trying to get between cars to build a train. There they get squished to death. Or try to slip on a wet rail jumping clear. Only to be pinched to death. Sometimes a mountain track breaks the train in two. Uneven hand braking up top. Engine now has to open wide and run with the whistle in constant blast. Either shorts coming up on stations for emergency or one big long all the way down. Whats coming behind it is something that will kill alot of people badly.

Airbrakes, Arent they fun? Just wait until you hit a humid winter day, say a nice frosty -45 set the brakes and then find that they are now part of the wheels. You aint going anywhere.

 

X, there are two different issues with trains, one is the braking system and the other is the coupler of the cars.

Trains were equipped with air brakes because it eliminated the guy on the top of a moving train running between the cars to apply the brakes or standing on the last car to apply the only brake system for a long line of cars.

The air brakes had nothing to do with coupler. The coupler that was used was a chain and hook, which caused about 40% of all yard workers to get hurt or killed. The person doing the coupling had to get in between two cars, one moving and throw the chain on the hook and get out of the way.

There was a guy back in 1873 that came up with the idea of the buckeye coupler, he actually carved a couple of them out of wood while he working at a dry goods store.

 

The original coupler was called "pocket and loop" method. Each car has pockets with a vertical pin. One of the cars had a long oval shaped loop. The trick was to lift the loop to guide it into the hole on the other car and drop the pin in.

These days a piece of sheet metal could have been used to keep the person from getting his or her(s) fingers from getting crushed.