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


Earl Knoob
 

When the brakes are initially charged up, 90 lbs of air pressure is sent down the brake pipe.  This air not only fills the brake pipe, but it charges up the auxiliary reservoir in each car.  There is a valve called the "triple valve" which connects the brake pipe, the brake cylinder and the aux. reservoir together.

Once the aux reservoir and brake pipe are fully charged, the brakes are functional.  To make a controlled "service application". The engineer releases air from the brake line.  This causes a pressure imbalance between the aux air res pressure (still at 90 psi) and the brake pipe (now something less).  The triple valve then sends air from the aux. reservoir to the brake cylinder.  Once the pressures equalize, the triple valve "laps" and stops the flow of air.  If more braking is need, more air is released from the brake pipe, again causing a pressure imbalance, letting the aux. res. to put more air into the brake cylinder.

To release the brakes, the brake pipe pressure is restored, the triple valve again recharges the aux. res. and the brake cylinder pressure is exhausted to atmosphere.  The retainer valve is placed in the brake cylinder exhaust line.  It is simply an either spring loaded valve or a dead weight valve, that holds air in the brake cylinders while the brake pipe and auxiliary reservoir pressure is restored.  Holding the air in the brake cylinders allow the brake to drag while recovering the pressures.

If an air hose breaks, all the air is lost from the brake pipe.  This creates a massive pressure imbalance between the aux res and the brake pipe.  The triple valve then dumps all the aux res air into the brake cylinder at once as an "emergency application".

In theory, the brakes would remain set until the brake pipe pressure is restored.  Or you can go to each car and pull the bleed off rod, which releases the air out of the aux res.  As the triple valve is in emergancy position, the aux res it is connected to the brake cylinder through the valve, so when the aux res air is drained out, so is the brake cylinder air.

Clear as mud, right?


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 12:19 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 

I always thought that the lack of air pressure set the brakes.  If a line rupture they cylinders would empty and as it did the brakes came on slowly.  Am I wrong?  If a car is set on a siding and some nitwit came along and released the air the brakes should set no matter what, unless someone is smart enough to burn the brake wheel to release them or does that only set them?
Dave
-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 2:07 PM
To: HOn3@groups.io
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question

Thanks Earl

You are quite correct, on both counts, although one only needs to close the angle cocks to uncouple and switch cars wile the brake reservoir is charged.

John
On October 7, 2020 at 7:22 PM Earl Knoob <earlk489@...> wrote:

The semi-official term for releasing the air from the aux reservoir under the car is called "bleeding the car off".  It is used when a car with the brakes charged is uncoupled and the brake hoses part, setting the brakes.  In order to release the brakes without hooking the hoses back up (switching without air brakes is pretty common), you have to pull on the "bleed off rod" to release the remaining air out of the aux reservoir and brake cylinder. 
 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Tuesday, October 6, 2020 1:46 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Mark

This use of dump is new to me.  In North America, dumping the air on a car means to release air form the car's air reservoir.  Dumping the air on a train means to release essentially all air from the train line, which immediately triggers emergency braking. 

From your description, dumping air to release the brakes, the Wolsztyn line is using a straight air brake. 

John
On October 5, 2020 a t 11:12 PM Mark Kasprowicz <mark@...> wrote:

A few years back I drove steam trains on the Wolsztyn line in Poland. Each of the locomotives had a brake dump operated by a wire inside the cab. It was situated by the cab side on the drivers side. It was used to release the train brake when it was slow to release.

Mark K
Oxon England

 


Climax@...
 

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?
Dave

-----Original Message-----
From: Earl Knoob
Sent: Oct 8, 2020 3:27 PM
To: "HOn3@groups.io"
Subject: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

When the brakes are initially charged up, 90 lbs of air pressure is sent down the brake pipe.  This air not only fills the brake pipe, but it charges up the auxiliary reservoir in each car.  There is a valve called the "triple valve" which connects the brake pipe, the brake cylinder and the aux. reservoir together.

Once the aux reservoir and brake pipe are fully charged, the brakes are functional.  To make a controlled "service application". The engineer releases air from the brake line.  This causes a pressure imbalance between the aux air res pressure (still at 90 psi) and the brake pipe (now something less).  The triple valve then sends air from the aux. reservoir to the brake cylinder.  Once the pressures equalize, the triple valve "laps" and stops the flow of air.  If more braking is need, more air is released from the brake pipe, again causing a pressure imbalance, letting the aux. res. to put more air into the brake cylinder.

To release the brakes, the brake pipe pressure is restored, the triple valve again recharges the aux. res. and the brake cylinder pressure is exhausted to atmosphere.  The retainer valve is placed in the brake cylinder exhaust line.  It is simply an either spring loaded valve or a dead weight valve, that holds air in the brake cylinders while the brake pipe and auxiliary reservoir pressure is restored.  Holding the air in the brake cylinders allow the brake to drag while recovering the pressures.

If an air hose breaks, all the air is lost from the brake pipe.  This creates a massive pressure imbalance between the aux res and the brake pipe.  The triple valve then dumps all the aux res air into the brake cylinder at once as an "emergency application".

In theory, the brakes would remain set until the brake pipe pressure is restored.  Or you can go to each car and pull the bleed off rod, which releases the air out of the aux res.  As the triple valve is in emergancy position, the aux res it is connected to the brake cylinder through the valve, so when the aux res air is drained out, so is the brake cylinder air.

Clear as mud, right?


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 12:19 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 

I always thought that the lack of air pressure set the brakes.  If a line rupture they cylinders would empty and as it did the brakes came on slowly.  Am I wrong?  If a car is set on a siding and some nitwit came along and released the air the brakes should set no matter what, unless someone is smart enough to burn the brake wheel to release them or does that only set them?
Dave
-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 2:07 PM
To: HOn3@groups.io
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question

Thanks Earl

You are quite correct, on both counts, although one only needs to close the angle cocks to uncouple and switch cars wile the brake reservoir is charged.

John
On October 7, 2020 at 7:22 PM Earl Knoob <earlk489@...> wrote:

The semi-official term for releasing the air from the aux reservoir under the car is called "bleeding the car off".  It is used when a car with the brakes charged is uncoupled and the brake hoses part, setting the brakes.  In order to release the brakes without hooking the hoses back up (switching without air brakes is pretty common), you have to pull on the "bleed off rod" to release the remaining air out of the aux reservoir and brake cylinder. 
 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Tuesday, October 6, 2020 1:46 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Mark

This use of dump is new to me.  In North America, dumping the air on a car means to release air form the car's air reservoir.  Dumping the air on a train means to release essentially all air from the train line, which immediately triggers emergency braking. 

From your description, dumping air to release the brakes, the Wolsztyn line is using a straight air brake. 

John
On October 5, 2020 a t 11:12 PM Mark Kasprowicz <mark@...> wrote:

A few years back I drove steam trains on the Wolsztyn line in Poland. Each of the locomotives had a brake dump operated by a wire inside the cab. It was situated by the cab side on the drivers side. It was used to release the train brake when it was slow to release.

Mark K
Oxon England

 


John Stutz
 

Thanks again Earl

For a clear and concise explanation of RR automatic air brake construction and operation. 

From what you previously wrote, I infer that the dump valve on RGS 20's tender is to allow the head end brakeman to trigger an emergency stop, if he finds cause while monitoring the train.   And I now recall that most cabooses also have one in the cupola, for the same reason.

John Stutz


Earl Knoob
 

First off, there are no springs involved.  Truck air brakes use springs.  Railroads use nothing but air pressure to hold the brakes on a car.  If it leaked off, or someone bled off the car, it would roll free.  Your only recourse is to climb on the car and wind down the hand brake.  The hand brake uses mechanical pressure to pull on the brake levers to set the brakes.

This is why it is constantly driven into RR employees to never rely on the air brakes alone to hold a car stationary.  Always set the hand brake and/or chock the wheels so that it can't roll.


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 2:20 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
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?
Dave

-----Original Message-----
From: Earl Knoob
Sent: Oct 8, 2020 3:27 PM
To: "HOn3@groups.io"
Subject: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

When the brakes are initially charged up, 90 lbs of air pressure is sent down the brake pipe.  This air not only fills the brake pipe, but it charges up the auxiliary reservoir in each car.  There is a valve called the "triple valve" which connects the brake pipe, the brake cylinder and the aux. reservoir together.

Once the aux reservoir and brake pipe are fully charged, the brakes are functional.  To make a controlled "service application". The engineer releases air from the brake line.  This causes a pressure imbalance between the aux air res pressure (still at 90 psi) and the brake pipe (now something less).  The triple valve then sends air from the aux. reservoir to the brake cylinder.  Once the pressures equalize, the triple valve "laps" and stops the flow of air.  If more braking is need, more air is released from the brake pipe, again causing a pressure imbalance, letting the aux. res. to put more air into the brake cylinder.

To release the brakes, the brake pipe pressure is restored, the triple valve again recharges the aux. res. and the brake cylinder pressure is exhausted to atmosphere.  The retainer valve is placed in the brake cylinder exhaust line.  It is simply an either spring loaded valve or a dead weight valve, that holds air in the brake cylinders while the brake pipe and auxiliary reservoir pressure is restored.  Holding the air in the brake cylinders allow the brake to drag while recovering the pressures.

If an air hose breaks, all the air is lost from the brake pipe.  This creates a massive pressure imbalance between the aux res and the brake pipe.  The triple valve then dumps all the aux res air into the brake cylinder at once as an "emergency application".

In theory, the brakes would remain set until the brake pipe pressure is restored.  Or you can go to each car and pull the bleed off rod, which releases the air out of the aux res.  As the triple valve is in emergancy position, the aux res it is connected to the brake cylinder through the valve, so when the aux res air is drained out, so is the brake cylinder air.

Clear as mud, right?


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 12:19 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 

I always thought that the lack of air pressure set the brakes.  If a line rupture they cylinders would empty and as it did the brakes came on slowly.  Am I wrong?  If a car is set on a siding and some nitwit came along and released the air the brakes should set no matter what, unless someone is smart enough to burn the brake wheel to release them or does that only set them?
Dave
-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 2:07 PM
To: HOn3@groups.io
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question

Thanks Earl

You are quite correct, on both counts, although one only needs to close the angle cocks to uncouple and switch cars wile the brake reservoir is charged.

John
On October 7, 2020 at 7:22 PM Earl Knoob <earlk489@...> wrote:

The semi-official term for releasing the air from the aux reservoir under the car is called "bleeding the car off".  It is used when a car with the brakes charged is uncoupled and the brake hoses part, setting the brakes.  In order to release the brakes without hooking the hoses back up (switching without air brakes is pretty common), you have to pull on the "bleed off rod" to release the remaining air out of the aux reservoir and brake cylinder. 
 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Tuesday, October 6, 2020 1:46 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Mark

This use of dump is new to me.  In North America, dumping the air on a car means to release air form the car's air reservoir.  Dumping the air on a train means to release essentially all air from the train line, which immediately triggers emergency braking. 

From your description, dumping air to release the brakes, the Wolsztyn line is using a straight air brake. 

John
On October 5, 2020 a t 11:12 PM Mark Kasprowicz <mark@...> wrote:

A few years back I drove steam trains on the Wolsztyn line in Poland. Each of the locomotives had a brake dump operated by a wire inside the cab. It was situated by the cab side on the drivers side. It was used to release the train brake when it was slow to release.

Mark K
Oxon England

 


Earl Knoob
 

Yes, cabooses have a dump valve as well, but it is a bit fancier it that is can also set the brakes at a service rate to stop the train without an emergency application.  There are emergency brake valves in the cabs of all locomotives, in spot where anyone in the cab can grab them.  On steam locomotives, they are usually on the back wall of the cab in the gangway between the engine and tender.  In addition, there are dump valves inside doghouses where the head end brakeman can pull the air on the train.


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Thursday, October 8, 2020 2:35 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Thanks again Earl

For a clear and concise explanation of RR automatic air brake construction and operation. 

From what you previously wrote, I infer that the dump valve on RGS 20's tender is to allow the head end brakeman to trigger an emergency stop, if he finds cause while monitoring the train.   And I now recall that most cabooses also have one in the cupola, for the same reason.

John Stutz


Climax@...
 


Great, that explains a lot in my mind how it works.  Thanks

-----Original Message-----
From: Earl Knoob
Sent: Oct 8, 2020 4:41 PM
To: "HOn3@groups.io"
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

First off, there are no springs involved.  Truck air brakes use springs.  Railroads use nothing but air pressure to hold the brakes on a car.  If it leaked off, or someone bled off the car, it would roll free.  Your only recourse is to climb on the car and wind down the hand brake.  The hand brake uses mechanical pressure to pull on the brake levers to set the brakes.

This is why it is constantly driven into RR employees to never rely on the air brakes alone to hold a car stationary.  Always set the hand brake and/or chock the wheels so that it can't roll.


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 2:20 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
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?
Dave

-----Original Message-----
From: Earl Knoob
Sent: Oct 8, 2020 3:27 PM
To: "HOn3@groups.io"
Subject: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

When the brakes are initially charged up, 90 lbs of air pressure is sent down the brake pipe.  This air not only fills the brake pipe, but it charges up the auxiliary reservoir in each car.  There is a valve called the "triple valve" which connects the brake pipe, the brake cylinder and the aux. reservoir together.

Once the aux reservoir and brake pipe are fully charged, the brakes are functional.  To make a controlled "service application". The engineer releases air from the brake line.  This causes a pressure imbalance between the aux air res pressure (still at 90 psi) and the brake pipe (now something less).  The triple valve then sends air from the aux. reservoir to the brake cylinder.  Once the pressures equalize, the triple valve "laps" and stops the flow of air.  If more braking is need, more air is released from the brake pipe, again causing a pressure imbalance, letting the aux. res. to put more air into the brake cylinder.

To release the brakes, the brake pipe pressure is restored, the triple valve again recharges the aux. res. and the brake cylinder pressure is exhausted to atmosphere.  The retainer valve is placed in the brake cylinder exhaust line.  It is simply an either spring loaded valve or a dead weight valve, that holds air in the brake cylinders while the brake pipe and auxiliary reservoir pressure is restored.  Holding the air in the brake cylinders allow the brake to drag while recovering the pressures.

If an air hose breaks, all the air is lost from the brake pipe.  This creates a massive pressure imbalance between the aux res and the brake pipe.  The triple valve then dumps all the aux res air into the brake cylinder at once as an "emergency application".

In theory, the brakes would remain set until the brake pipe pressure is restored.  Or you can go to each car and pull the bleed off rod, which releases the air out of the aux res.  As the triple valve is in emergancy position, the aux res it is connected to the brake cylinder through the valve, so when the aux res air is drained out, so is the brake cylinder air.

Clear as mud, right?


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 12:19 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 

I always thought that the lack of air pressure set the brakes.  If a line rupture they cylinders would empty and as it did the brakes came on slowly.  Am I wrong?  If a car is set on a siding and some nitwit came along and released the air the brakes should set no matter what, unless someone is smart enough to burn the brake wheel to release them or does that only set them?
Dave
-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 2:07 PM
To: HOn3@groups.io
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question

Thanks Earl

You are quite correct, on both counts, although one only needs to close the angle cocks to uncouple and switch cars wile the brake reservoir is charged.

John
On October 7, 2020 at 7:22 PM Earl Knoob <earlk489@...> wrote:

The semi-official term for releasing the air from the aux reservoir under the car is called "bleeding the car off".  It is used when a car with the brakes charged is uncoupled and the brake hoses part, setting the brakes.  In order to release the brakes without hooking the hoses back up (switching without air brakes is pretty common), you have to pull on the "bleed off rod" to release the remaining air out of the aux reservoir and brake cylinder. 
 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Tuesday, October 6, 2020 1:46 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Mark

This use of dump is new to me.  In North America, dumping the air on a car means to release air form the car's air reservoir.  Dumping the air on a train means to release essentially all air from the train line, which immediately triggers emergency braking. 

From your description, dumping air to release the brakes, the Wolsztyn line is using a straight air brake. 

John
On October 5, 2020 a t 11:12 PM Mark Kasprowicz <mark@...> wrote:

A few years back I drove steam trains on the Wolsztyn line in Poland. Each of the locomotives had a brake dump operated by a wire inside the cab. It was situated by the cab side on the drivers side. It was used to release the train brake when it was slow to release.

Mark K
Oxon England

 


Randy Hees
 

Its not narrow gauge but we have a Western Pacific steel caboose with 6 dump valves...    We have no idea why so many...

Randy Hees

On Thu, Oct 8, 2020 at 1:46 PM Earl Knoob <earlk489@...> wrote:
Yes, cabooses have a dump valve as well, but it is a bit fancier it that is can also set the brakes at a service rate to stop the train without an emergency application.  There are emergency brake valves in the cabs of all locomotives, in spot where anyone in the cab can grab them.  On steam locomotives, they are usually on the back wall of the cab in the gangway between the engine and tender.  In addition, there are dump valves inside doghouses where the head end brakeman can pull the air on the train.


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Thursday, October 8, 2020 2:35 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Thanks again Earl

For a clear and concise explanation of RR automatic air brake construction and operation. 

From what you previously wrote, I infer that the dump valve on RGS 20's tender is to allow the head end brakeman to trigger an emergency stop, if he finds cause while monitoring the train.   And I now recall that most cabooses also have one in the cupola, for the same reason.

John Stutz


Mark Rosche
 

Guess I opened a can of worms with my question „So my model us incorrect?“.  I thank all of you who answered and am grateful for the insights on how the air brake systems actually work...now to build in some emergency stop practice and add some additional check boxes to the operator cards for op sessions to ensure all operators know how to properly „park“ their decoupled freight and passenger cars (albeit not on a grade as our little models do not have working brake systems 👍🏻😁)...

Regards,

Mark

Don‘t take life too seriously...no one gets out alive anyway....

On 8. Oct 2020, at 22:46, Earl Knoob <earlk489@...> wrote:


Yes, cabooses have a dump valve as well, but it is a bit fancier it that is can also set the brakes at a service rate to stop the train without an emergency application.  There are emergency brake valves in the cabs of all locomotives, in spot where anyone in the cab can grab them.  On steam locomotives, they are usually on the back wall of the cab in the gangway between the engine and tender.  In addition, there are dump valves inside doghouses where the head end brakeman can pull the air on the train.


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Thursday, October 8, 2020 2:35 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Thanks again Earl

For a clear and concise explanation of RR automatic air brake construction and operation. 

From what you previously wrote, I infer that the dump valve on RGS 20's tender is to allow the head end brakeman to trigger an emergency stop, if he finds cause while monitoring the train.   And I now recall that most cabooses also have one in the cupola, for the same reason.

John Stutz


John Stutz
 

Dave

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?
Dave


Climax@...
 

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

Dave

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?
Dave


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

Dave

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?
Dave


--
Russ Norris, MMR
Cape Cod, Massachusetts
http://blacklogvalleyrailroad.blogspot.com/


Climax@...
 

Since I model the 1900 to 1927 era this is important to me.  If, as you say, a train set a few cars on a siding did all the hand brakes need to be cinched down or would they only do one car?  Dave

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

Dave

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?
Dave


John Stutz
 

Dave

I speculate that official rules called for tying down all hand brake on set out cars, but that crews often did less, and relied on the air brakes with cars that were only temporarily set out.  Check published or online rule books for operation of trains.  My knowledge comes mostly from air brake instruction manuals, which tend to focus on ideal rather than actual operating practices.

John

On October 8, 2020 at 5:52 PM Climax@... wrote:

Since I model the 1900 to 1927 era this is important to me.  If, as you say, a train set a few cars on a siding did all the hand brakes need to be cinched down or would they only do one car?  Dave

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

Dave

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?
Dave

 


Climax@...
 


Thanks John

-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 10:01 PM
To: HOn3@groups.io
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

Dave

I speculate that official rules called for tying down all hand brake on set out cars, but that crews often did less, and relied on the air brakes with cars that were only temporarily set out.  Check published or online rule books for operation of trains.  My knowledge comes mostly from air brake instruction manuals, which tend to focus on ideal rather than actual operating practices.

John
On October 8, 2020 at 5:52 PM Climax@... wrote:

Since I model the 1900 to 1927 era this is important to me.  If, as you say, a train set a few cars on a siding did all the hand brakes need to be cinched down or would they only do one car?  Dave

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

Dave

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?
Dave

 


Mike Conder
 

Perfectly clear now, great explanation of something that I didn't understand before.  Thanks!

Mike Conder

On Thu, Oct 8, 2020 at 1:28 PM Earl Knoob <earlk489@...> wrote:
When the brakes are initially charged up, 90 lbs of air pressure is sent down the brake pipe.  This air not only fills the brake pipe, but it charges up the auxiliary reservoir in each car.  There is a valve called the "triple valve" which connects the brake pipe, the brake cylinder and the aux. reservoir together.

Once the aux reservoir and brake pipe are fully charged, the brakes are functional.  To make a controlled "service application". The engineer releases air from the brake line.  This causes a pressure imbalance between the aux air res pressure (still at 90 psi) and the brake pipe (now something less).  The triple valve then sends air from the aux. reservoir to the brake cylinder.  Once the pressures equalize, the triple valve "laps" and stops the flow of air.  If more braking is need, more air is released from the brake pipe, again causing a pressure imbalance, letting the aux. res. to put more air into the brake cylinder.

To release the brakes, the brake pipe pressure is restored, the triple valve again recharges the aux. res. and the brake cylinder pressure is exhausted to atmosphere.  The retainer valve is placed in the brake cylinder exhaust line.  It is simply an either spring loaded valve or a dead weight valve, that holds air in the brake cylinders while the brake pipe and auxiliary reservoir pressure is restored.  Holding the air in the brake cylinders allow the brake to drag while recovering the pressures.

If an air hose breaks, all the air is lost from the brake pipe.  This creates a massive pressure imbalance between the aux res and the brake pipe.  The triple valve then dumps all the aux res air into the brake cylinder at once as an "emergency application".

In theory, the brakes would remain set until the brake pipe pressure is restored.  Or you can go to each car and pull the bleed off rod, which releases the air out of the aux res.  As the triple valve is in emergancy position, the aux res it is connected to the brake cylinder through the valve, so when the aux res air is drained out, so is the brake cylinder air.

Clear as mud, right?


From: HOn3@groups.io <HOn3@groups.io> on behalf of Climax@... <Climax@...>
Sent: Thursday, October 8, 2020 12:19 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 

I always thought that the lack of air pressure set the brakes.  If a line rupture they cylinders would empty and as it did the brakes came on slowly.  Am I wrong?  If a car is set on a siding and some nitwit came along and released the air the brakes should set no matter what, unless someone is smart enough to burn the brake wheel to release them or does that only set them?
Dave
-----Original Message-----
From: John Stutz
Sent: Oct 8, 2020 2:07 PM
To: HOn3@groups.io
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question

Thanks Earl

You are quite correct, on both counts, although one only needs to close the angle cocks to uncouple and switch cars wile the brake reservoir is charged.

John
On October 7, 2020 at 7:22 PM Earl Knoob <earlk489@...> wrote:

The semi-official term for releasing the air from the aux reservoir under the car is called "bleeding the car off".  It is used when a car with the brakes charged is uncoupled and the brake hoses part, setting the brakes.  In order to release the brakes without hooking the hoses back up (switching without air brakes is pretty common), you have to pull on the "bleed off rod" to release the remaining air out of the aux reservoir and brake cylinder. 
 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Tuesday, October 6, 2020 1:46 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Mark

This use of dump is new to me.  In North America, dumping the air on a car means to release air form the car's air reservoir.  Dumping the air on a train means to release essentially all air from the train line, which immediately triggers emergency braking. 

From your description, dumping air to release the brakes, the Wolsztyn line is using a straight air brake. 

John
On October 5, 2020 a t 11:12 PM Mark Kasprowicz <mark@...> wrote:

A few years back I drove steam trains on the Wolsztyn line in Poland. Each of the locomotives had a brake dump operated by a wire inside the cab. It was situated by the cab side on the drivers side. It was used to release the train brake when it was slow to release.

Mark K
Oxon England

 


Earl Knoob
 

The railroads were, and still are,  quite vague in the number of handbrakes to be set when setting out cars.  Generally, the rule stated "a sufficient number of handbrakes must be set to prevent movement."  So, the company left it up the employee's judgement as to the number of handbrakes that needed to be set.

A quote from the Cumbres & Toltec Scenic RR Rulebook , dated about 1993:  

"101. When cars are left standing on any track a sufficient number of handbrakes must be set to prevent movement.  Cars left on grades must also have a sufficient number of wheels blocked to prevent movement when the engine is detached."

I can't find my D&S rulebook, but they took it further by requiring, the hand brake applied, then the air brakes bled off, so that the hand brake was to sole method of braking applied.  You then pulled away from the car to see if it stayed put.  Other places I have worked had special instructions for tying down trains at certain locations.  At the last place I worked before retirement - the Copper Basin Ry - when you tied the ore train down at the end of the day, you set all the locomotive hand brakes (3 units), plus the first 5 cars of the train. 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Thursday, October 8, 2020 8:01 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Dave

I speculate that official rules called for tying down all hand brake on set out cars, but that crews often did less, and relied on the air brakes with cars that were only temporarily set out.  Check published or online rule books for operation of trains.  My knowledge comes mostly from air brake instruction manuals, which tend to focus on ideal rather than actual operating practices.

John
On October 8, 2020 at 5:52 PM Climax@... wrote:

Since I model the 1900 to 1927 era this is important to me.  If, as you say, a train set a few cars on a siding did all the hand brakes need to be cinched down or would they only do one car?  Dave

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

Dave

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?
Dave

 


Mike Smith
 

At the end of my career, the handbrake instructions were to tie the handbrakes with the engines attached, Then release the train air and the engine brakes.  If the handbrakes held the train with the engines attached, you were good to cut off and go.  If the thing moved, you had to go back and tie more handbrakes.  So if you had a lot of engines, you tied a lot of extra brakes.  You couldn't get away with not following the instructions, because it all showed up on the event recorder. (Black Box) 

Mike Smith
Tucson 

Glad to be retired and playing with trains when the sun is up!

On Friday, October 9, 2020, 05:03:06 PM MST, Earl Knoob <earlk489@...> wrote:


The railroads were, and still are,  quite vague in the number of handbrakes to be set when setting out cars.  Generally, the rule stated "a sufficient number of handbrakes must be set to prevent movement."  So, the company left it up the employee's judgement as to the number of handbrakes that needed to be set.

A quote from the Cumbres & Toltec Scenic RR Rulebook , dated about 1993:  

"101. When cars are left standing on any track a sufficient number of handbrakes must be set to prevent movement.  Cars left on grades must also have a sufficient number of wheels blocked to prevent movement when the engine is detached."

I can't find my D&S rulebook, but they took it further by requiring, the hand brake applied, then the air brakes bled off, so that the hand brake was to sole method of braking applied.  You then pulled away from the car to see if it stayed put.  Other places I have worked had special instructions for tying down trains at certain locations.  At the last place I worked before retirement - the Copper Basin Ry - when you tied the ore train down at the end of the day, you set all the locomotive hand brakes (3 units), plus the first 5 cars of the train. 


From: HOn3@groups.io <HOn3@groups.io> on behalf of John Stutz <john.stutz@...>
Sent: Thursday, October 8, 2020 8:01 PM
To: HOn3@groups.io <HOn3@groups.io>
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question
 
Dave

I speculate that official rules called for tying down all hand brake on set out cars, but that crews often did less, and relied on the air brakes with cars that were only temporarily set out.  Check published or online rule books for operation of trains.  My knowledge comes mostly from air brake instruction manuals, which tend to focus on ideal rather than actual operating practices.

John
On October 8, 2020 at 5:52 PM Climax@... wrote:

Since I model the 1900 to 1927 era this is important to me.  If, as you say, a train set a few cars on a siding did all the hand brakes need to be cinched down or would they only do one car?  Dave

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

Dave

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?
Dave

 


johnny graybeal
 

The best way to think about it is to see a balanced beam on a fulcrum. Pressure goes one way and then another, in releases and charges. The triple valve controls the balance and is the fulcrum. It is a constant moving back and forth with each move of the brake valve.
One thing not mentioned so far is when a car is parked on a siding, you can turn the valve on each end and keep the air in the pipe under the car. In theory, that would allow the car to stay parked with the air in the line, but in reality there is always a leak somewhere. Thus the line left alone, will lose pressure one ounce of pressure at a time until it all hits 0. At that point there is no break pressure and the brakes release, actually before when it drops to a certain point. That is why all cars have to have the hand brakes tied down. The brakes will NEVER hold it over time. 

Reading the old books on this can be very confusing, but less so than talking about how a check valve lets water of less pressure go into a boiler of higher pressure. That still gives me headaches.
Johnny Graybeal


Mark Lewis
 

Johnny,

😱🚂💥

Mark Lewis


On Sat, Oct 10, 2020 at 12:41 PM johnny graybeal <johnnyg@...> wrote:

The best way to think about it is to see a balanced beam on a fulcrum. Pressure goes one way and then another, in releases and charges. The triple valve controls the balance and is the fulcrum. It is a constant moving back and forth with each move of the brake valve.
One thing not mentioned so far is when a car is parked on a siding, you can turn the valve on each end and keep the air in the pipe under the car. In theory, that would allow the car to stay parked with the air in the line, but in reality there is always a leak somewhere. Thus the line left alone, will lose pressure one ounce of pressure at a time until it all hits 0. At that point there is no break pressure and the brakes release, actually before when it drops to a certain point. That is why all cars have to have the hand brakes tied down. The brakes will NEVER hold it over time. 

Reading the old books on this can be very confusing, but less so than talking about how a check valve lets water of less pressure go into a boiler of higher pressure. That still gives me headaches.
Johnny Graybeal


Climax@...
 


What do you mean "have the hand brakes tied down"?  Do  you use a rope or a chain or something or is it just a slang term for setting the brakes?
Mule

-----Original Message-----
From: Mark Lewis
Sent: Oct 10, 2020 12:59 PM
To: HOn3@groups.io
Subject: Re: AIR BRAKES 101.... was Re: RGS #20. Was: [HOn3] Division Point K-27 question

Johnny,

😱🚂💥

Mark Lewis

On Sat, Oct 10, 2020 at 12:41 PM johnny graybeal <johnnyg@...> wrote:

The best way to think about it is to see a balanced beam on a fulcrum. Pressure goes one way and then another, in releases and charges. The triple valve controls the balance and is the fulcrum. It is a constant moving back and forth with each move of the brake valve.
One thing not mentioned so far is when a car is parked on a siding, you can turn the valve on each end and keep the air in the pipe under the car. In theory, that would allow the car to stay parked with the air in the line, but in reality there is always a leak somewhere. Thus the line left alone, will lose pressure one ounce of pressure at a time until it all hits 0. At that point there is no break pressure and the brakes release, actually before when it drops to a certain point. That is why all cars have to have the hand brakes tied down. The brakes will NEVER hold it over time. 

Reading the old books on this can be very confusing, but less so than talking about how a check valve lets water of less pressure go into a boiler of higher pressure. That still gives me headaches.
Johnny Graybeal