Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

Russ Norris

I use a straight pin on the grade.

On Thu, Oct 8, 2020, 5:50 PM <Climax@...> wrote:
Wow, now I know why the cars I spot on my siding with a grade always seem to roll away.  Not really, I put the fishing line trick in place and now they stay put.

-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 5:04 PM
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question


Circa 1900 brake cylinders used leather gaskets to seal the brake cylinder, and they usually leaked off slowly.  This is why set out cars are supposed to always have the hand brake set.

The air and hand brake act independently, through the foundation brake gear, the set of rods and levers that carry braking force to the brake shoes.  The air brake cylinder piston has a hollow stem holding a push rod.  When the air brake is activated, this rod pushes on the connected lever.  The hand brake is connected to the same lever, usually through a chain.  When the hand brake is wound up. the chain pulls on the lever, and pulls the push rod partially out of the brake piston's stem. 

The triple valve is the heart of the automatic air brake, and some version has been used from the first automatic system of circa 1870.  The triple has undergone frequent revision ever since, to adapt it to evolving RR demands for better control of longer, heaver and faster trains.  But all versions have essentially operated in the manner that Earl described.  The KC or KD brake is simply the standard freight car apparatus of circa 1890-1940, fitted with the type K triple valve of circa 1902, and arranged  in the Combined or Detached format.  The principle improvement of the AB valve is the provision of separate service and emergency valves, with separate air reservoirs, so that full emergency power is always available.

John Stutz
On October 8, 2020 at 1:20 PM Climax@... wrote:

Lets say a box car was left on a siding with a grade.  Now there is either a very slow leak or can someone come along and pull the bleed off rod and would that result in the brakes being applied through springs to not let the car roll, or would the brakes release and let the car roll?  If it did roll, and you jumped on the car to get to the Brake wheel, does that apply or release brake pressure. 
The triple valve is on an AB system while a K system did not have that feature of  triple valve?

Russ Norris, MMR
Cape Cod, Massachusetts

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