#### Brake Ratio, was “double" brake systems

Guy Wilber

﻿Alex Schneider wrote:

“Did the MCB or later the AAR mandate how much brake effort a car should have, presumably based on loaded weight?”

As recommended by the AAR’s Brake and Brake Equipment Committee the Arbitration Committee added the following to Interchange Rule 3 in June of 1937.

Rule 3, Section (b), Paragraph (9). Braking Power:  On and after January 1, 1938, all freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 60% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars weighing 53,000 lbs. or more, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

The date of compliance was extended (annually) and minor revisions were made to the rule until the final compliance date of January 1, 1956 as announced in 1955 Supplement No. 1.

The 1956 Rule 3, Section (b), Paragraph (9):

All freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 50% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars that are not equipped with one-wear or multiple-wear wrought steel wheels, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

Guy Wilber

Alex Schneider

Thanks, that's what I was looking for. But I'm having a problem with the details.
I presume the brake force would be calculated as 50 psi x the area of the cylinder, approximately 78 square inches for a 10" cylinder. That's 3900 lbs. Even quadrupling that for a 20" cylinder doesn't get 60% of a 50,000 pound car, or 30,000 lb.

Alex Schneider

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Guy Wilber via groups.io <guycwilber@...>
Sent: Friday, December 2, 2022 1:49:16 PM
To: main@realstmfc.groups.io <main@realstmfc.groups.io>
Subject: [RealSTMFC] Brake Ratio, was “double" brake systems

﻿Alex Schneider wrote:

“Did the MCB or later the AAR mandate how much brake effort a car should have, presumably based on loaded weight?”

As recommended by the AAR’s Brake and Brake Equipment Committee the Arbitration Committee added the following to Interchange Rule 3 in June of 1937.

Rule 3, Section (b), Paragraph (9). Braking Power:  On and after January 1, 1938, all freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 60% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars weighing 53,000 lbs. or more, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

The date of compliance was extended (annually) and minor revisions were made to the rule until the final compliance date of January 1, 1956 as announced in 1955 Supplement No. 1.

The 1956 Rule 3, Section (b), Paragraph (9):

All freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 50% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars that are not equipped with one-wear or multiple-wear wrought steel wheels, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

Guy Wilber

Charles Peck

Chuck Peck

On Fri, Dec 2, 2022 at 4:19 PM Alex Schneider <Hudson5450@...> wrote:
Thanks, that's what I was looking for. But I'm having a problem with the details.
I presume the brake force would be calculated as 50 psi x the area of the cylinder, approximately 78 square inches for a 10" cylinder. That's 3900 lbs. Even quadrupling that for a 20" cylinder doesn't get 60% of a 50,000 pound car, or 30,000 lb.

Alex Schneider

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Guy Wilber via groups.io <guycwilber=aol.com@groups.io>
Sent: Friday, December 2, 2022 1:49:16 PM
To: main@realstmfc.groups.io <main@realstmfc.groups.io>
Subject: [RealSTMFC] Brake Ratio, was “double" brake systems

﻿Alex Schneider wrote:

“Did the MCB or later the AAR mandate how much brake effort a car should have, presumably based on loaded weight?”

As recommended by the AAR’s Brake and Brake Equipment Committee the Arbitration Committee added the following to Interchange Rule 3 in June of 1937.

Rule 3, Section (b), Paragraph (9). Braking Power:  On and after January 1, 1938, all freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 60% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars weighing 53,000 lbs. or more, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

The date of compliance was extended (annually) and minor revisions were made to the rule until the final compliance date of January 1, 1956 as announced in 1955 Supplement No. 1.

The 1956 Rule 3, Section (b), Paragraph (9):

All freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 50% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars that are not equipped with one-wear or multiple-wear wrought steel wheels, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

Guy Wilber

Alex Schneider

Um, pretty obvious, wasn’t it?

Thanks

Alex Schneider

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Charles Peck
Sent: Friday, December 2, 2022 3:41 PM
To: main@realstmfc.groups.io
Subject: Re: [RealSTMFC] Brake Ratio, was “double" brake systems

Chuck Peck

On Fri, Dec 2, 2022 at 4:19 PM Alex Schneider <Hudson5450@...> wrote:

Thanks, that's what I was looking for. But I'm having a problem with the details.

I presume the brake force would be calculated as 50 psi x the area of the cylinder, approximately 78 square inches for a 10" cylinder. That's 3900 lbs. Even quadrupling that for a 20" cylinder doesn't get 60% of a 50,000 pound car, or 30,000 lb.

Alex Schneider

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Guy Wilber via groups.io <guycwilber=aol.com@groups.io>
Sent: Friday, December 2, 2022 1:49:16 PM
To: main@realstmfc.groups.io <main@realstmfc.groups.io>
Subject: [RealSTMFC] Brake Ratio, was “double" brake systems

﻿Alex Schneider wrote:

“Did the MCB or later the AAR mandate how much brake effort a car should have, presumably based on loaded weight?”

As recommended by the AAR’s Brake and Brake Equipment Committee the Arbitration Committee added the following to Interchange Rule 3 in June of 1937.

Rule 3, Section (b), Paragraph (9). Braking Power:  On and after January 1, 1938, all freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 60% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars weighing 53,000 lbs. or more, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

The date of compliance was extended (annually) and minor revisions were made to the rule until the final compliance date of January 1, 1956 as announced in 1955 Supplement No. 1.

The 1956 Rule 3, Section (b), Paragraph (9):

All freight cars offered in interchange having single capacity brakes shall have a nominal braking ratio of not less than 50% nor more than 75% of the empty car weight, based on a brake cylinder pressure of 50 lbs. per square inch, except refrigerator cars that are not equipped with one-wear or multiple-wear wrought steel wheels, which shall have a nominal braking ratio of not less than 50 nor more than 60 percent of the empty car weight, based on 50 lbs. per square inch brake cylinder pressure.  In Interchange.

Guy Wilber

Nolan Hinshaw

On Dec 2, 2022, at 17:35, Alex Schneider <Hudson5450@...> wrote:

[in re: adding leverage to multiply brake cylinder force]

Um, pretty obvious, wasn’t it?
I have in my hot little hand a copy of _Braking Power and How Figured_, 1938, Eugene OR by Frank A Chilton, former SP carman. He claims, on the title page, "47 YearsbAsss Car Builder, Car Foreman, General Car Foreman, and Master Car Repairer"

The book is full of excruciatingly worked exercises calculating the braking effort resulting from an assumed train line pressure to the force applied to the wheels through the brake shoes, every example containing a diagram of the rods and levers, noting the ratios of the overall length of lever to the length between the intermediate hole in a lever and the hole in what we might call the business end of the lever.

I have not examined every detail of every diagram in the book, but it looks like there are fewer than four different lever ratios in each diagram, and more usually no more than two (it's the ratio of the two lengths of a lever and not the length of the lever!); this is the case for even three axle trucks!.

Giggle[sic] Books yielded lots of hits mostly on the combination of "braking" and "power", a very large number for volumes dated before 1920.

I suspect that I picked it up at a swap meet or in my neighborhood Little Free Library: <https://littlefreelibrary.org/>.
--
Willie saw some dynamite
Couldn't understand it quite
Curiosity never pays;
It rained Willie seven days.

Dave Nelson

-----Original Message-----
From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Nolan Hinshaw
Sent: Monday, January 23, 2023 7:28 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Brake Ratio, was “double" brake systems

On Dec 2, 2022, at 17:35, Alex Schneider <Hudson5450@...> wrote:

[in re: adding leverage to multiply brake cylinder force]

> Um, pretty obvious, wasn’t it?

I have in my hot little hand a copy of _Braking Power and How Figured_, 1938, Eugene OR by Frank A Chilton, former SP carman. He claims, on the title page, "47 YearsbAsss Car Builder, Car Foreman, General Car Foreman, and Master Car Repairer"

Alex Schneider

Thank you, Dave. It will be very helpful.

Alex Schneider

From: main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] On Behalf Of Dave Nelson
Sent: Tuesday, January 24, 2023 1:19 AM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Brake Ratio, was “double" brake systems

https://babel.hathitrust.org/cgi/pt?id=wu.89081524258&view=1up&seq=4

Dave Nelson

-----Original Message-----
From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Nolan Hinshaw
Sent: Monday, January 23, 2023 7:28 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Brake Ratio, was “double" brake systems

On Dec 2, 2022, at 17:35, Alex Schneider <Hudson5450@...> wrote:

[in re: adding leverage to multiply brake cylinder force]

> Um, pretty obvious, wasn’t it?

I have in my hot little hand a copy of _Braking Power and How Figured_, 1938, Eugene OR by Frank A Chilton, former SP carman. He claims, on the title page, "47 YearsbAsss Car Builder, Car Foreman, General Car Foreman, and Master Car Repairer"

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