[dajones]

You need to be careful when using those test charging times for older valves. The tests are performed on a test rack with fixed size reservoirs, but the valves are designed to work with different size brake cylinders. I think the K1 is designed to work with an 8 inch diameter brake cylinder and the K2 works with a 10 inch cylinder. Like wise the L1 is designed for 8 or 10 inch cylinders, the L2 for 12 or 14 inch cylinders and the L3 for 16 or 18 inch cylinders. And the reservoir sizes need to match the brake cylinders. So when the valves are installed on a car with the correct size reservoirs, the charging times will be similar. The test rack used to test these valves is called a No 3-T test rack, but I haven't been able to find any documentation that says what the test rack reservoir sizes are.

Doug

[darwins]

dajones, on 09 November 2023 - 06:16 AM, said:

You need to be careful when using those test charging times for older valves. The tests are performed on a test rack with fixed size reservoirs, but the valves are designed to work with different size brake cylinders. I think the K1 is designed to work with an 8 inch diameter brake cylinder and the K2 works with a 10 inch cylinder. Like wise the L1 is designed for 8 or 10 inch cylinders, the L2 for 12 or 14 inch cylinders and the L3 for 16 or 18 inch cylinders. And the reservoir sizes need to match the brake cylinders. So when the valves are installed on a car with the correct size reservoirs, the charging times will be similar. The test rack used to test these valves is called a No 3-T test rack, but I haven't been able to find any documentation that says what the test rack reservoir sizes are.

Doug

Thanks for that. I have used the recharging times from there for there for the H and K valves in the tables below. Please let me know if you think that it would be better to use another value. The application and release times come from data published in "Introduction to the Study of Air Brakes, Ludy, 1908". Release times seem to have been faster than modern valves. Reduction in release times seems a logical step for handling longer freight trains as it gives more even release along the length of the train.

https://i.imgur.com/NjJXtoT.jpg
For passenger train valves, the data for the PM and L type valves comes from Ludy and for the UC valve from the PRR tests. These give faster applications - similar to UIC timings. Recharge of the auxiliary reservoir after a brake application is also much faster with the L type valve, as it is charged from a supplementary reservoir.

https://i.imgur.com/67Ondnf.jpg

I still have very little idea about the application, release and recharging rates of the oldest types of valves. The brake tests concentrate mainly on stopping distances. It would be good to get an idea of what these should be as more modern valves used around the world were developed from these.

[darwins]

With regard to Increased Emergency Pressure, this is a description of how it works with the Knorr K1 brake valve (and Kunze-Knorr valves in passenger mode):

When the triple valve is moved to emergency by a rapid drop in air brake pipe pressure, a port opens that connects the brake cylinder directly to the air brake pipe.
Air flows rapidly and directly from the brake pipe into the brake cylinder until the brake cylinder pressure is equal to the air brake pipe pressure.
A non-return valve prevents air from flowing back into the brake pipe when the air brake pipe pressure drops below the brake cylinder pressure.
Air then flows from the auxiliary reservoir to the brake cylinder until the pressure in both equalises in the normal way.

So it seems there is a rapid emergency brake application until the brake cylinder equalises with the air brake pipe.
Then the remaining increase in pressure is at the normal application rate.

Just starting to see what I can work out for UIC valves...

https://i.imgur.com/ljjvyOb.jpg

It occurs to me that Max Emergency Application Rate is probably the same thing as ORTSEmergencyDumpValveRate, just that instead of dumping into the atmosphere it is dumping into the brake cylinder.
Hence the only new feature would need to specify emergency dumps to brake cylinder.

In US the additional pressure seems to be specified as for example 60psi rather than 50psi.

For the Knorr brakes, although it depends on equalization as explained above, the end result seems to be 4.0bar rather than 3.5bar.

[darwins]

@Weter
I have attached a document with my attempt to find parameters for some AAR and UIC valves. Please feel free to add any for SU valves. At the moment it is only carriages and wagons. Will think about locos later.


@ anyone else...

Anyone else interested please feel free to add details or make suggestions and send back to me. Not sure about Božic brake. Assume modern French and Swiss brakes are similar to UIC standard given, but thoughts on those and historical examples welcomed too.

Attached File(s)

•  Triple Valve Development.zip (29.62K)
  Number of downloads: 36

[darwins]

Weter, on 12 November 2023 - 02:00 PM, said:

Locomotives here usually have the same air distributors, as cars - freight or passenger EP.

Weter, on 12 November 2023 - 02:00 PM, said:

Locomotives here usually have the same air distributors, as cars - freight or passenger EP.

In USA loco systems are quite different to wagon systems.

In Western Europe the Westinghouse type systems tends to have locomotive equipment that is different to wagon equipment, but in the Knorr type systems they are the same. Even with distributors of the same kind, the UIC rules require that locomotives have different application and release times to wagons.

In USA locomotives have a "Rotair" valve that selects either -
Freight - lower pressure with direct release or
Passenger - higher pressure with graduated release

In Western Europe locomotives (also wagons and carriages) have a "Goods/Passenger" switch -
Goods - gives slow application and release
Passenger - gives fast application and release

[Weter]

Quote

In Western Europe locomotives (also wagons and carriages) have a "Goods/Passenger" switch -
Goods - gives slow application and release
Passenger - gives fast application and release

Here, passenger AIR DISTRIBUTORS have long/short train switch; freight ones have two: Light/half-load/loaded (adopts for car's mass in total); and plain/mountain (adopts to route's track profile): Maximal BC pressure and release rate are affected respectively.
Autoregimes and high-friction composite brake pads require Light switch's setting.

[darwins]

Weter, on 13 November 2023 - 06:39 PM, said:

Here, passenger AIR DISTRIBUTORS have long/short train switch; freight ones have two: Light/half-load/loaded (adopts for car's mass in total); and plain/mountain (adopts to route's track profile): Maximal BC pressure and release rate are affected respectively.
Autoregimes and high-friction composite brake pads require Light switch's setting.

Does the plain/mountain switch work like UIC = slows down release (with graduated release) or like AAR "retainer" = holds a minimum air pressure in cylinder (used with direct release)?

What are "Autoregimes"?

Are there some locomotives used for both passenger and freight?

I assume long/short changes application and release times.

Light/half-load/loaded changes the brake force. Does it do this by changing the brake cylinder pressure or by changing the mechanical linkage?

Do locomotives have long/short train switch or plain/mountain switch or both or neither?

If you can add present day and historical examples to the document and repost (or send me the data), that would be good.

[ErickC]

pschlik, on 07 November 2023 - 07:05 AM, said:

Folks have had a habit over the years of dramatically overestimating the res charging rates. With just a bit of investigation it's not hard to determine that it should take minutes to get the auxiliary and emergency reservoirs up to pressure, setting the aux and emergency charging rate to ~ 0.5 psi/s (with uniform charging ratio of 2, set the charging rate token to ~ 1 psi/s) is way more realistic than 11 psi/s.

I think you're correct, I used 11 psi/s and thought it was a conservative value based on a calculated value of 13 derived from the quoted figure in Management of Train Operation and Train Handling (published by Westinghouse), which is "a single car will charge up to 80 PSI in about 6 minutes" (P. 72). Unfortunately, when I divided 80 by 6 to get 13, I forgot to also divide again by 60...

Quote

Other things I'd recommend is to NOT use ORTSMaxServiceCylinderPressure, there is no dedicated device to limit brake cylinder pressure on US control valves, as this allows different brake pipe pressures to be used. Hook up any regular freight car to 110 psi brake pipe and it will be able to produce 79 psi brake cylinder pressure. In that regard, BrakeCylinderPressureForMaxBrakeBrakeForce might be better set to something higher like 100 psi to allow use of the same code at higher brake pipe pressure (94 psi would result from an emergency application at 110 psi brake pipe pressure, and that's as high as it'll normally go), but you'd have to keep that pressure in mind when setting the brake force values.

I think it's perfectly reasonable that we should have the Trainline Air Pressure Adjustment Valve (typically located on the side of the AAR console) as an optional control in the cab.

Quote

I also find that folks tend to greatly overstate application and release rates. Various bits of research and testing I've seen show that the application rate on these newer valve types is like 5 psi/s and release is even more drawn out in the range of 1-2 psi/s. Maybe in the past valve designs were willing to throw air around in less than a second but that is exactly how you break a 100 car train in two.

The problem is that there aren't many reference materials for application and release rates for a single car, which is what we're really after. I have charts of application and release rates v. train length, but this is very hard to consolidate into values for a single car because the train lengths are 50, 75, 100, and 150 cars. I can certainly scan these items and post them here if it's helpful.

darwins, on 12 November 2023 - 10:29 PM, said:

In Western Europe locomotives (also wagons and carriages) have a "Goods/Passenger" switch -
Goods - gives slow application and release
Passenger - gives fast application and release

On a related note, on the 26L equipment at least, a combination of the cut-off valve and the 26F control valve is how locomotives switch from direct release (freight) to graduated release (passenger) operation. The components work as such:

The Equalizing Reservoir Cut-Off Valve

Quote

The Equalizing Reservoir Cut-Off Valve of the brake valve is arranged to
permit operation of trains employing both graduated and direct release type car
equipments. With car equipments employing the direct release feature, the
equalizing reservoir cut-off valve prevents recharge of the equalizing reservoir
except in release position of the brake valvr: handle. The equalizing reservoir
cut-off valve is, however, capable of maintaining brake pipe pressure against
leakage with the brake valve handle in either release or service position. The
equalizing reservoir cut-off valve is operated in Passenger Position of the cut­
off valve to cause this valve to remain open. In Freight Position of the cut ­
off valve, the equalizing reservoir cut-off valve is open only in release pOSi­
tion.

26F control valve

Quote

A direct or graduated release cap is also located on the service valve
portion. Its position is determined by the type of service in which the control
valve is to be used.

See: https://heritagerail...ENT-NOV1958.pdf

[darwins]

Quote

I think it's perfectly reasonable that we should have the Trainline Air Pressure Adjustment Valve (typically located on the side of the AAR console) as an optional control in the cab.

That would make Weter happy. He has been asking for that for years!

The Equalizing Reservoir Cut-Off Valve is functional in Open Rails at the moment. In the case of the 26L you would use the brake token GraduatedSelfLapHoldLimited to achieve this.
This brake token gives only direct release - the pressure in the EQ reservoir (and in the train pipe) can not rise unless a full release is made.

For passenger use then a different brake token (GraduatedSelfLapLimited) is needed to allow graduated release. So for a full description of the brake valve we might have:

Freight Mode

Brake_Train ( 0 1 0.1 0.2
NumNotches ( 7
Notch ( 0.0  0 TrainBrakesControllerReleaseStart ORTSLabel ( "RUNNING" ) )
Notch ( 0.2  0 TrainBrakesControllerGraduatedSelfLapHoldLimitedStart ORTSLabel ( "MINIMUM REDUCTION" ) )
Notch ( 0.25 1 TrainBrakesControllerGraduatedSelfLapHoldLimitedStart ORTSLabel ( "SERVICE" ) )
Notch ( 0.75 0 TrainBrakesControllerGraduatedSelfLapHoldLimitedStart ORTSLabel ( "FULL SERVICE" ) )
Notch ( 0.8  0 TrainBrakesControllerSuppressionStart )
Notch ( 0.9  0 TrainBrakesControllerNeutralHandleOffStart )
Notch ( 1.0  0 TrainBrakesControllerEmergencyStart ) ) )

Passenger Mode

Brake_Train ( 0 1 0.1 0.2
NumNotches ( 7
Notch ( 0.0  0 TrainBrakesControllerReleaseStart ORTSLabel ( "RUNNING" ) )
Notch ( 0.2  0 TrainBrakesControllerGraduatedSelfLapLimitedStart ORTSLabel ( "MINIMUM REDUCTION" ) )
Notch ( 0.25 1 TrainBrakesControllerGraduatedSelfLapLimitedStart ORTSLabel ( "SERVICE" ) )
Notch ( 0.75 0 TrainBrakesControllerGraduatedSelfLapLimitedStart ORTSLabel ( "FULL SERVICE" ) )
Notch ( 0.8  0 TrainBrakesControllerSuppressionStart )
Notch ( 0.9  0 TrainBrakesControllerNeutralHandleOffStart )
Notch ( 1.0  0 TrainBrakesControllerEmergencyStart ) ) )

The missing piece of equipment is the passenger/goods switch (USA = Rotair valve).

The idea of adding switches has been discussed before. It would be a major step forward covering goods/passenger/rapid, empty/part-load/loaded, mountain/plain, graduated/direct, perhaps one day even air/vacuum.

There are also some other thoughts about equalising reservoirs.

1) In most systems the equalising reservoir is by-passed during overcharge. (Eq res never charges to more than the standard system pressure). This is not the case in OR.

2) We can not yet model older air brake systems that do not have an equalising reservoir.

[Weter]

Hi, Darwin.
1. IIRC, it slows down release, not retaining small pressure.
2. Autoregime is a kind of device, placed between frame and bogie, which accomodates BC maximal pressure (by cutting-off BC filling) according to actual car's weight - no need to switch loaded/empty modes each time manually. Mounted on some freight cars (works continiously) and EMU cars (in that case, it measures load's mass at the moments, when doors are closing).
3. Tipically - no: special passenger locomotives have EP brakes, Pure-freight - don't. There are "universal" version of 2ТЭ10, with "у" index, but it has EP air brakes controller, circuitry and distributors with EP valves, or freight distributors - without them. Also M62, which is being used for both kind of service too.
Anyway, BP pressure reduction will actuate brakes even in trains, having mixed cars (freight&passenger, or passenger with and without EP distributors)
Note, than in cace of multiple BC presence, pneumo relays are used - as distributor can't fill more, than two BCs - so for 6&8 axle locomotives and EMU's motor cars.
4.Yes. Exactly - that is for prevention of stresses along 20+cars passenger trains.
5. Mechanical linkage can be adjusted by another automatic device - but not for braking force modification, but for maintaining of constant gap between brake pads and wheel's rim, according to pads wear.
Pressure is being agjusted by air cutoff before pipr to BC.
6. As locomotive have same distributors, as freight or passenger cars - there are corresponding switches on them.
7. I'll try to do something. Some work is already done - in form of include files for two freight and one passenger distributor.
Also, there is some data about main res volumes and compressor's ratings (refilling times).