[Csantucci]

I selected the Taurus 1016 locomotive for some brake tests. I noticed that it has its triple valve at emergency at game startup. So I investigated a bit and found that the .eng file requires that at startup the brake controller is at the TrainBrakesControllerHoldLappedStart, and that brake pipe leakage is foreseen (1 psi/sec, which seems high to me, even if it is within the range foreseen by Realmuto's .eng manual); OR reduces the brake pipe pressure from its release value down to the equalizing reservoir pressure (OK); the brake pipe leaks, so that the brake pipe pressure goes under the equalizing reservoir pressure; at this point OR lets the brake pipe return to the equalizing reservoir pressure only if the brake controller is NOT in a lap position; if the controller is in a lap position the brake pipe continues to lose pressure due to leak, and when the brake pipe pressure is one psi below the full service pressure, the triple valve goes to emergency.
So my question is: is is prototypical that, when the brake controller is in a lap position, the brake pipe continues to lose pressure due to leaks, and therefore the triple valve goies to emergency?

[steamer_ctn]

Csantucci, on 30 August 2017 - 10:54 PM, said:

So my question is: is is prototypical that, when the brake controller is in a lap position, the brake pipe continues to lose pressure due to leaks, and therefore the triple valve goies to emergency?

It very much depends upon the brake system type installed on the locomotive.

Older style brake systems such as the 6ET operate in the fashion that you describe, where in the lap position the train brake pipe is disconnected from everything including the air reservoir, and consequently will loose air pressure over time.

Newer systems, such as the 26L, have a self-lapping position which I understand does not loose pressure once the pressures have stabilised.

There are two tokens in OR which I suspect would be more appropriate if a true self lapping brake system is fitted to the locomotive that you are testing - TrainBrakesControllerSelfLapStart, TrainBrakesControllerGraduatedSelfLapStart (Though I am not certain how they have been coded in OR)

This is probably a case where the MSTS tokens were not fully understood, and therefore over time any token was selected. At one time I did start to try and identify the most appropriate controllers for the most common brake systems, but I haven't completed it.

[copperpen]

I am not familiar with the real world Taurus, but I think if the brake system is used for parking the locomotive with no power, then this behaviour would be correct. The lap position on a brake controller should maintain the brake system pressure at whatever it was when lap was selected if power is on with the compressor replacing lost air. Bit pointless placing the system in lap with power on if leakage is going to stop the loco or train.

[ebnertra000]

Here in North America, when an engine is going to be sitting unattended for some time, they have handbrakes which can be applied. I can't speak for anywhere else

[Csantucci]

Thanks for the replies; so it seems that a lapped brake controller doesn't allow to compensate for brake pipe leaks. The code however foresees operation in the opposite direction, that is it causes the brake pipe to reduce pressure (by venting?) if the brake pipe pressure is higher than the equalizing reservoir one, even when the brake controller is in lap state. Shouldn't lap mean that neither actions to increase brake pipe pressure nor actions to decrease brake pipe pressure are performed?

[engmod]

Westinghouse 24-RL Brake Valve

This information has been extracted from various Westinghouse publications, some of which may be found in the Useful References. Whilst a few different styles and types have been used, the following information should apply in general and give a reasonably close approximation of its operation.

The operating positions of the 24-RL brake valve are shown in the diagrams below. The Automatic brake valve (Train brake) is shown on the left hand side of the diagram, whilst the Independent brake valve (Engine Brake) is shown on the right side of the respective diagrams.
24RL Brake Valve24-RL Brake Valve.

Automatic brake valve (Train Brake)

The automatic brake valve, which controlled the train brakes has 6 positions of operation as follows:

Release - In this position the brake valve releases the train brakes, and recharges the brake system (auxilary reservoirs, etc) on the train.
Running - Recharges the brake system (auxilary reservoirs, etc) on the train. The brake valve must be placed in this position when the locomotive is cut out.
First Service - Reduces equalizing reservoir pressure by 6 to 8 PSI at a service rate. Leaving the handle in this position will result in continued equalizing reservoir reduction at a slower rate. When the first service cut-out cock is cut out, this position becomes another LAP position.
Lap - Prevents air from entering or leaving brake pipe at the brake valve, which holds a brake application applied. This position is also used to reset the brake equipment after a penalty or an emergency application.
Service - Reduces brake pipe pressure at a service rate as long as the brake valve is in this position. The brake valve must be placed in LAP position to stop the reduction of equalizing reservoir pressure.
Emergency - Causes an emergency application of air brakes regardless of whether the brake valve is cut in or cut out.

[Csantucci]

Thank you Derek,
so this confirms that in lap state air will neither enter nor leave brake pipe by means of the brake controller valve.

[Genma Saotome]

FWIW I've been converting a number of .engs to use include() statements. One of the things I've done is recognize the different type of brake controllers on locomotives over the years by naming unique .inc files after them -- a RL24 file for instance. For the most part all of these type-specific files have the same parameters and same values but as more information becomes available -- or newer parameters from the OR team, I can edit individual .inc files and effectively roll out the change to a large number of .eng files automatically.

AFAIK there isn't any reason why an include file for standard vendor equipment isn't a standard file for everyone.

I've given a lot of thought to how to manage these files, starting with a folder name that begins with common, just like common.snd and common.cab, taking into consideration ordinary matters like geography so US equipment is one folder, UK equipment in another, and dealing with seeming identical files created and distributed by different people.

If any of the OR developers is inclined to consider supporting standard equipment files I'd be happy to take some time and present how I'm organizing my files as a suggestion for others to use/

[engmod]

Carlos,

The 26l is different!!!!!

The 26-C Brake Valve, Figure 1, is a self-lapping type in which have been
incorporated many modern design improvements. These include the replacement of the
rotary valve by cam-operated “O” ring-packed spool valves and cam-operated poppet
type valves to provide the control over the locomotive and train br akes. Also incorporated
in the brake valve design is a cam-operated self-lapping regulating valve portion which
functions to develop or dissipate equalizing reservoir pressure in proportion to the degree
of brake valve handle movement in the handle quadrant. In turn, brake pipe pressure is
developed and exhausted by a self-lapping type of relay valve that is piloted by
equalizing reservoir pressure to maintain in the brake pipe the same pressure condition
that exists in the equalizing reservoir.

This one maintains the pressure selected instead of cutting off all air movement.

[steamer_ctn]

Csantucci, on 01 September 2017 - 04:58 AM, said:

so this confirms that in lap state air will neither enter nor leave brake pipe by means of the brake controller valve.

This is a generic statement, which is "meaningless" on its own.

To turn this into a definitive statement it is necessary to reference it to a brake type (eg 6-ET, 24-RL, 26-L, etc) and the OR brakecontrollers to be used to configure the brake valve positions.

For example, when a locomotive with a 6-ET brake is at the head of a train, and the brake is put into the LAP position (thus the train pipe is isolated from the air reservoir) then leakage in the train pipe will slowly reduce the air pressure and further apply the brakes.

A locomotive which has a SELF-LAP brake will tend to behave more in line with the expectation of the brake pressure remaining fixed at the "setting" value.

As a test, the Tarus locomotive could have its brakecontroller changed to one of the following TrainBrakesControllerSelfLapStart, TrainBrakesControllerGraduatedSelfLapStart to see if this solves the issue in the short term.

I started to do some work on braking, but came to the conclusion that the configuration and setup of the brakes on the wide variety of locomotives is a large body of work that requires a reasonable amount of research and definition. It also has wide implications on legacy stock, as I suspect that brake configurations in ENG files are "all over the place".

For example, I believe that the following steps are required:
i) Define and specify each of the brake types to be supported in OR
ii) Define which BrakeControllers align with which brake positions on the above systems in i)
iii) Code OR to suit the above two items