Topics

brakes

Schuyler Larrabee
 

Today we learned the difference between KC and KD brakes.  Does anyone know the origin of the K in those designations?

 

And similarly, why are AB brake systems so referred to?  Where does that designation come from?

Schuyler

Dave Parker
 

Schuyler:

There is some conflicting information out there with respect to exact dates (e.g., the NMRA info looks suspect), but I tend to rely on the 1913 Westinghouse handbook for information about K brakes:

https://archive.org/details/westinghouseairb00inteuoft

My understanding is that Westinghouse came up with the "quick-action" triple valve in 1887 (replacing the "plain" valves), and rapidly cornered the marked on air-brake equipment. The first such triple was the "H" valve (H-1, H-2), which was the superseded by the "K" design sometime around the turn of the century (I can't find the exact date with a quick search).  These were just Westinghouse model designations, but they were the de facto industry standard, which is why you see "K-2 Triple" (or K-1) stenciled on so many pre-1927 cars.

In case the clinic didn't cover it, the K-1 valve was for use with 6- and 8-in diameter cylinders, while the K-2 was paired with 12-in cylinders.  KC was short for "cylinder and reservoir Combined", and KD for "cylinder and reservoir Detached".

Hope this helps with the K side of your questions.  I'll leave AB to someone who who models in that era.
--
Dave Parker
Swall Meadows, CA

Randy Hees
 

The original Westinghouse automatic brake valve was designated the "F"  It was patented in 1872.   It did not have "fast action".  In general it was good for a train of 8-10 cars.  The F valve did not meet the minimum standard (no valve did) at the first Burlington Air Brake trial in 1886, which used a 50 car train..  In response Westinghouse offered the "H" brake valve, which did have "fast action".  In a fast action, the air brake valve not only applies air in response to dropping the air pressure in the train line, but also recognizes a rapid air pressure loss as an emergency, and in that case in addition to a maximum brake application the valve also vents the train line, reducing pressure in the train line.  As a result the change in pressure is much more rapid, and the brakes apply much quicker.

The "K" valve was introduced in 1906/07 as an improved "H" valve.  They used the same mounting flange (to the brake reservoir if a "HC" or "KC" ("F" used a different flange) Externally the only difference between a "H" and "K" was an added flange on the valve body casting.  Westinghouse offered a kit to convert a "H" to a "K".  That kit included a sheet metal flange to be added to the valve body to give the "H" valve the same silhouette as a "K".

On the D&RG(W) "F" valves were used on tenders until the end of operation.  Most passenger cars on the D&RG(W) had "F" valves, and they are in use on the C&TS historic cars.  The D&RG freight car order of 1903 (3000 class box cars, 30' stock cars, & drop bottom gons all had "H" valves, all of which were converted to "K" with the added sheet metal flange.

Randy Hees

Dennis Storzek
 

I've never read that the Westinghouse brake schedule designations had any meaning beyond just being a designation for the schedule of equipment, but they had to come from somewhere. The meaning of C and D in the K brake schedules are pretty obvious, as are several generations of locomotive equipment; 6ET equipment was used to equip Engines and Tenders, 14EL equipment was used on Electric Locomotives, and 24RL was used on Road Locomotives. However, Westinghouse avoided attaching any significance to the letters, which left them free to use the next letter in line, or a different letter, when they developed an upgrade. P was the designation for the passenger triple valve that was contemporary with the K freight brake, but the next improvement was L, and M and R were used on electric railway motor cars.

Dennis Storzek

Ken Adams
 

And here I thought KD's were model couplers.....
--
Ken Adams
In splendid Shelter In Place solitude, about half way up Walnut Creek

Schuyler Larrabee
 

Thanks, Dave, and thanks particularly for that link.  That merits some careful reading, I’m sure.

 

Schuyler

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Dave Parker via groups.io
Sent: Saturday, June 13, 2020 7:08 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] brakes

 

Schuyler:

There is some conflicting information out there with respect to exact dates (e.g., the NMRA info looks suspect), but I tend to rely on the 1913 Westinghouse handbook for information about K brakes:

https://archive.org/details/westinghouseairb00inteuoft

My understanding is that Westinghouse came up with the "quick-action" triple valve in 1887 (replacing the "plain" valves), and rapidly cornered the marked on air-brake equipment. The first such triple was the "H" valve (H-1, H-2), which was the superseded by the "K" design sometime around the turn of the century (I can't find the exact date with a quick search).  These were just Westinghouse model designations, but they were the de facto industry standard, which is why you see "K-2 Triple" (or K-1) stenciled on so many pre-1927 cars.

In case the clinic didn't cover it, the K-1 valve was for use with 6- and 8-in diameter cylinders, while the K-2 was paired with 12-in cylinders.  KC was short for "cylinder and reservoir Combined", and KD for "cylinder and reservoir Detached".

Hope this helps with the K side of your questions.  I'll leave AB to someone who who models in that era.
--
Dave Parker
Swall Meadows, CA

Schuyler Larrabee
 

Thank you, Randy, this is great background information.  Much appreciated.

 

Schuyler

 

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Randy Hees
Sent: Saturday, June 13, 2020 8:05 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] brakes

 

The original Westinghouse automatic brake valve was designated the "F"  It was patented in 1872.   It did not have "fast action".  In general it was good for a train of 8-10 cars.  The F valve did not meet the minimum standard (no valve did) at the first Burlington Air Brake trial in 1886, which used a 50 car train..  In response Westinghouse offered the "H" brake valve, which did have "fast action".  In a fast action, the air brake valve not only applies air in response to dropping the air pressure in the train line, but also recognizes a rapid air pressure loss as an emergency, and in that case in addition to a maximum brake application the valve also vents the train line, reducing pressure in the train line.  As a result the change in pressure is much more rapid, and the brakes apply much quicker.

The "K" valve was introduced in 1906/07 as an improved "H" valve.  They used the same mounting flange (to the brake reservoir if a "HC" or "KC" ("F" used a different flange) Externally the only difference between a "H" and "K" was an added flange on the valve body casting.  Westinghouse offered a kit to convert a "H" to a "K".  That kit included a sheet metal flange to be added to the valve body to give the "H" valve the same silhouette as a "K".

On the D&RG(W) "F" valves were used on tenders until the end of operation.  Most passenger cars on the D&RG(W) had "F" valves, and they are in use on the C&TS historic cars.  The D&RG freight car order of 1903 (3000 class box cars, 30' stock cars, & drop bottom gons all had "H" valves, all of which were converted to "K" with the added sheet metal flange.

Randy Hees

Dave Parker
 

You're welcome Schuyler, and apologies for the semi-obvious typo.  The K-2 triple was paired with 10-inch diameter cylinders; it was the "long" dimension that was 12".
--
Dave Parker
Swall Meadows, CA