Angle Cocks on C-3s vs. M-1/M-3/M-7s

Hello.

I wanted to know if anyone has any information about the differences between the brake pipe hookups between cars. Does the M series have the same angle cock device as the ones found between the C-3 cars, or is it a different set up all together?

Thanks in advance for a reply!

All the M series cars make brake pipe through the drawheads automatically upon coupling up. Poppet valves are depressed on each drawhead, opening up a pathway for brake pipe through. The angle cocks are normally left alone (open). We cut out angle cocks on the M cars if you get a "partial" couple or uncouple, where the poppet is blowing air.
(Dutch, anything you need to add to that, go ahead.)
I don't know if C-3 has automatic brake pipe makeup, or done manually via angle cocks.

BTW This is why it is exceedingly important for the other person helping with the departure brake test to be in the last car of the train. If an angle cock is closed somewhere in the train, the engineer can charge up normally, get brake release fine, etc. But if the train goes into emergency, brake pipe will only vent up to the closed angle cock. (M1/M3 only the EMV-Emergency Magnet Valve in head pair de-energizes. The rest of the train brake pipe "dump" is strictly pneumatic. I'm fairly certain the M-7 has all EMVs de-energize in the train. That would be better. The entire train would still dump around a closed angle cock.)

Tom

N340SG wrote:I'm fairly certain the M-7 has all EMVs de-energize in the train. That would be better. The entire train would still dump around a closed angle cock.)

Tom

That is correct if the enginneer places the controller in Emergency, all the EMVs in the consist will vent. However if the emergency brake valve is pulled the brake pipe will only vent in that car. If there is a angle cock closed in the 3rd car and the dump cord is pulled in the 1st only the the fist 2 cars will dump. That is why it is neccessary for the engineer to pull the dump cord during the M7 departure test. Unlike the M1/M3 applying the emergency brakes with the controller on an M7 does not verify brake pipe integrity.

Guys, thank you both for the info. :D

THOR,

Just for giggles, if you want to see view of mechanical coupler part, click on link.
http://www.l773.com/coupler1.jpg 73k JPEG

See "detail A" for brake pipe tappet ("poppet") valve.
The plungers in the center mate up and depress each other, opening up the pathway for brake pipe through.

The two smaller ports to the left and right of the brake pipe port are for compressed air to go through to the mated car's uncoupling latch, in order to retract that latch, when the Engineer pushes the uncoupling button. You need both latches to retract (your car, and the mated car) to uncouple. The Engineer is listening for 2 distinct "pops" when he wants to uncouple, ensuring both coupling latches are retracted.

Tom

P.S. For those that don't know. The air line cutout cocks are "backwards" from what you would normally encounter in the real world. Handle in line with the pipe is cut out. Handle perpendicular to the pipe is cut in.

The above post cites mechanical uncoupling.

Electrically, pushing the uncoupling button energizes the Coupler Relay in your car. That "loops" your P-wire , bypassing the brake release in the pair(s) you are trying to uncouple from. That ensures that the other pair(s) will remain stationary while you back away from them. (The cars left behind should also vent brake pipe upon uncoupling.) Also, trainline #3 is cut off from the other pair(s), so that they do not draw propulsion power while uncoupling from them.

Tom

P.S. The M-7 does not have a "Coupler Relay" per se. It has a pneumatically powered "Drum Switch" that rotates and makes or breaks numerous electrical circuits through the coupler faces.

I forgot to mention in my original post that the reason the train can charge brake pipe around a closed angle cock is because the CMVs (Charging Magnet Valves) are all energized in the train by #B5G (or M-7 equivalent) trainline when the Engineer depresses the recharge button. So, brake pipe pressure will approach the closed angle cock from both sides of it.

Tom

P.S. Speak of the devil. After posting the original message, that night when I go to work, I get an M-3 car to work on. One of the defects listed was "no dump through"...crew found angle cock closed.
It had of course already been normalized, so we sent it on it's way....after removing two GTLs, that is. One was a dead ground in door circuit (reported for tripping door breaker)...other was HVAC wiring harness sitting in puddle of water in HVAC box...had to do a little Rotor Rooter/hair dryer work.

N340SG

Thanks for the additional info. I did my first Class 1A and 2 brake test today for DE/DMs. During the walking 1A, I got to see and touch (except HEP of course ) everything so I am getting a good grasp on the equipment. The M series equipment, Ill be doing next week.

Thanks again! :D

Thor,

No problem..good luck.

Here's one more for you.
M-1 EP cutout....remember handle "In is [cut] out ; out is [cut] in"