[cesarbl]

I implemented two little changes regarding electric brake system devices:

- Adding "Emergency_Solenoid_Valve" to BrakeEquipmentType includes an electrically operated valve that uniformly and quickly applies brakes during emergency braking.
- Adding "ORTSEPBrakeInhibitsTripleValve ( 1 )" to the wagon prevents the triple valve from applying brakes as long as EP brakes are operational.

[darwins]

 cesarbl, on 19 December 2024 - 02:05 AM, said:

I implemented two little changes regarding electric brake system devices:

- Adding "Emergency_Solenoid_Valve" to BrakeEquipmentType includes an electrically operated valve that uniformly and quickly applies brakes during emergency braking.
- Adding "ORTSEPBrakeInhibitsTripleValve ( 1 )" to the wagon prevents the triple valve from applying brakes as long as EP brakes are operational.

Interesting.
Somewhere between these we would have an electrically operated triple valve / distributor.
Such a device could be the basis of Air Single Pipe, EP braking. Three systems that might use this are:

Early Westinghouse EP "High Speed" braking system in USA.

Soviet and Russian EP brake system.

Modern ECP brakes in USA where a single brake pipe remains fully charged and charges air reservoirs on each wagon. Triple valves on each wagon being controlled electronically.

[Weter]

Hello, Darwin and Cesar.
Yes, that's interesting.
What for "Soviet" EP:
Single-pipe Triple valve is being added with two EP valves: for braking and release.
Either these two are being operated by electric signals, supplied via wires from controller, attached to brake valve's handle, either triple valve will act, according to brake pipe's pressure changes, as "classic" Air Single Pipe Auto Brakes.
In first case, brake valve uses "Lap with feed" for EPApply and EPHold actions (BP is resupplied with compressed air, up to defined "working/normal" pressure, against leaks and drops, caused by connection of BCs to BP directly through Brake EP valves on each of cars; then being fed against leaks. In Release position, Release EP valves on each of cars open BCs to atmosphere, releasing air in moderate rate.
Apply and Emergency valve's positions work as usual, opening BP to atmosphere, dropping it's pressure in normal or emergency rates.
Conventional triple valves on cars react as usual too, releasing air from BP in addition, when in emergency mode.

EP can be turned Off and ON by switch - for Air brakes check and in case of any malfunction. - then system works as pure Air Single Pipe.

[Weter]

#Cesar:
Will BP pressure be reduced at application, when ORTSEPBrakeInhibitsTripleValve is set to ( 1 )?
Which position name is appropriate: EPApply, or what?

[Traindude]

I'm not sure there is much of a "market" for this, but apparently some urban light-rail and mass transit vehicles use hydraulic (yes, like on an automobile) brakes instead of air brakes. Here are the specifications for the light rail trains used in my city.

Here's my interpretation of the brake specifications:

Quote

Spring-applied, hydraulic release

This is actually the opposite of how most rail brakes work. In most rail braking systems, the brake cylinders are pressurized during application and de-pressurized for release, but these brakes are designed to be applied by the springs when the hydraulic cylinder is not pressurized, and released when the hydraulic cylinders are pressurized. In the case of these vehicles, only the two outer trucks/bogies have this arrangement.

Quote

Hydraulic applied on center truck

The center truck, which is an idler truck, has the more conventional "pressurize to apply" brakes, but using hydraulic fluid instead of air as a medium.

Is this something we want to eventually model?

[cesarbl]

Quote

Single-pipe Triple valve is being added with two EP valves: for braking and release.

Then it's not an electrically operated triple valve. I must be completely sure about how things actually work before implementing them. The codebase already contains many legacy features that are badly implemented but have to be kept for backwards compatibility (e.g. the DoesBrakeCutPower is implemented in user code for air brakes and in OR code for vacuum brakes). I'll try to understand the pneumatic schemes to see if I can add it in the future.

Quote

Will BP pressure be reduced at application, when ORTSEPBrakeInhibitsTripleValve is set to ( 1 )?
Which position name is appropriate: EPApply, or what?

EPApply will reduce BP pressure, while EPOnly will not. Which one to use depends on the locomotive. The only thing that changes is that triple valve is isolated from the brake cylinders while EP brakes are active. Typically this is done in real trains by means of a selector valve that either connects to the EP converter or to the triple valve.

Quote

This is actually the opposite of how most rail brakes work. In most rail braking systems, the brake cylinders are pressurized during application and de-pressurized for release, but these brakes are designed to be applied by the springs when the hydraulic cylinder is not pressurized, and released when the hydraulic cylinders are pressurized. In the case of these vehicles, only the two outer trucks/bogies have this arrangement.

This is typically the case also for parking brakes, so it's something that could be done in the future, although it's not a very common system otherwise.

[darwins]

The early US equipment - Westinghouse High Speed / HSC system is described in this document: https://archive.org/...stsreport00penn

See pp50-53

The system seems to consist of a standard graduated release triple valve that can be electrically operated by use of three electro-magnets for application, emergency and release.

There are no additional reservoirs other than the auxiliary, service and emergency reservoirs used for normal pneumatic braking.
In this system brake pipe pressure would also be reduced during brake applications allowing it to operate with normal air braked cars in the same train.

I believe the Russian system is similar to this except that it allows for EP only service applications without reduction in the BP pressure. (Emergency application is by rapid reduction of pressure.)

I am sure that Weter can find a diagram of the car equipment.

==============

ECP braking seems to be functionally similar to modern wire controlled EP systems. (In all such sytems there is a single air pipe running the length of the train, in European and Japanese systems this is the Main Reservoir pipe. The US system differs from these in that the single pipe is the conventional air brake pipe and vehicles must be able to operate using conventional pneumatic braking signals.)

Quote

Also with ECP, the brake pipe remains charged during operation. This allows the reservoirs on the cars to continuously charge making it less likely for the braking air supply to be exhausted. Further, since the cars can also send their status to the locomotive at the front, the engineer can monitor the state of the train and know at any given time the braking capabilities available.

https://en.wikipedia...neumatic_brakes

http://www.railway-t...c-brakes-d.html

It is described like this in an Australian document https://railknowledg...=MjY1OQ==&rCFU=

Quote

Typical AAR ECP brake systems; replace the service and sometimes the emergency portion with a Car Control Device (CCD) and a vent valve. The AAR ECP system uses an onboard battery to emulate conventional air brake operation during electrical power failure. The AAR ECP system supplies compressed air directly into the brake cylinder from the reservoir/s through full flow control valves. Although in both ROA and AAR systems the pneumatic signal for braking is replaced by an electrical signal, brake operation is still performed using conventional reservoirs and brake cylinders.

[cesarbl]

Quote

The system seems to consist of a standard graduated release triple valve that can be electrically operated by use of three electro-magnets for application, emergency and release.

Electrically operating a triple valve makes no sense to me, unless I'm missing something. If you force the valve to go to "Apply" state, it will go back to "Release" as soon as you remove the electrical order, since the auxiliary reservoir pressure would be lower than the brake pipe pressure. It's more likely that the system is equivalent to the Hold/Apply EP system but taking air from BP instead of MRP.

Quote

https://archive.org/...stsreport00penn

The electrical brake application of this system is that of the UIC EP brake: it locally vents the brake pipe in all cars.

[darwins]

cesarbl, on 20 December 2024 - 04:50 AM, said:

Electrically operating a triple valve makes no sense to me, unless I'm missing something. If you force the valve to go to "Apply" state, it will go back to "Release" as soon as you remove the electrical order, since the auxiliary reservoir pressure would be lower than the brake pipe pressure. It's more likely that the system is equivalent to the Hold/Apply EP system but taking air from BP instead of MRP.

The electrical brake application of this system is that of the UIC EP brake: it locally vents the brake pipe in all cars.

That sounds correct. There does not appear to be a separate valve however. It all seems to be part of the same triple valve / distributor assembly. Can we model this on a single pipe system? The Russian system (like ECP which has separate reservoirs and a CCD valve) does not vent the brake pipe locally during service applications. Perhaps Weter can give you the details of the valve.

[Weter]

Hello.
First, thanks for answering my questions.
Second, I gave examples (diagrams and descriptions) multiple times in this thread already.
I'll try and look back to provide links in those posts later.
If something would be missed or unclear - additional info would be searched on your demand.

https://www.elvastow...post__p__298966
https://www.elvastow...post__p__298970

Quote

It's more likely that the system is equivalent to the Hold/Apply EP system but taking air from BP instead of MRP.

You are right: the valves are Apply (BT) and Hold (ВП)

[darwins]

Finding the earlier discussion the Soviet version was basically the direct-acting ep-brake. The essence of the construction is that the brake cylinders are filled and emptied directly with the help of the electric signal, by passing the triple valve, through an air line. The triple valve therefore only has a role if the electrical signal is lost for some reason. https://www.elvastow...post__p__298967

From a modelling point of view this would cover all three options. The old US one using EP where air pressure in the brake pipe is also controlled, but the Russian one and the modern ECP being "EP only". The ECP system having additional storage reservoir on wagons. Perhaps this can be designated as "ECP" for brake type so we have Air Single Pipe, Air Twin Pipe, EP and ECP.

[Weter]

Hello.
Some batches of Valve#395 have the same mechanical parts as #394-th: very thin opening in VЭ position to discharge BP at so slow rate, that triple valves don't react. In freight-type valve (#394) this position (VA) is used for braking very long trains, avoiding brake-vawe propagation (can cause so huge in-train forces, which can break couplers) and smooth transition from Apply to Lap - to avoid hydraulic shock in BP, when step of application done. It's already possible in ORTS, by means of Slow Apply notch and definitions of rate for that and air brakes insensitivity threshold.
What for EP - that's not principal for their usage - because brake application is so fast, that discharge of BP is subtle within that time.
I guess - that was only for unification of 394-th and 395's parts, plus - for smoothing of pure-Air brakes application and lapping.
Remind again: pneumatic part remains in "Lap with feed" (hold BP pressure) mode, so as air from BP is used to fill BCs, valve connects BP with MR of locomotive to compensate pressure drop, so BP pressure is being maintained equal to pressure, set in ER (normal)

[cesarbl]

I included the BrakeSystemType ( "EP_single_pipe" ) which should handle EP brake systems without main reservoir pipe. Please tell me if that works.

[Weter]

Great!, Thank You!
Unstyable version?

[cesarbl]

Yes, in a few minutes.