[Genma Saotome]

I agree that MaxReleaseRate(20) probably is a bit high. I'm going to drop it to 18 and see how that looks.


WRT your comment on how the different needs of freight and passenger cars; This is, of course, due to the use of the options tab to enforce a one size fits all style of thinking. The correct solution is new parameters implemented in individual .wags.

If KUJU had intended us to be running simulated trains under the Christmas tree (a.k.a. a DTG product) they'd have used installation-wide features like OR options. But in a rare case of true brilliance they put almost everything into .wags and .engs.
:sign_thanks:

[jtr1962]

dajones, on 25 April 2019 - 10:19 AM, said:

I have some shop test procedure documents for ADB and DB-60 brake values that call for slower release times. The first document is in a file called Code-of-Test-for-ADB.pdf that I think I got from the Wabtec web site. The second is in a file called NYT-1199-C.PDF that I got from the New York Air Brake web site. The ADB release test calls for the pressure in the brake cylinder to drop from 40 psi to 20 psi in 8 to 12 seconds. The DB-60 document calls for 40 to 20 psi in 8 to 11 seconds. Both tests use a fixed 800 cubic inch reservoir to represent the brake cylinder and no retainer or retainer piping.

These documents also have a charging rate test. The ADB charging test calls for the brake cylinder pressure to increase from 0 to 60 psi in 4 to 6 seconds. The DB-60 charging test calls for 0 to 50 psi in 3 to 5 seconds. The charging tests use a 2500 cubic inch auxiliary reservoir and 800 cubic inch brake cylinder. The usual volume ratio for aux. res. to brake cyl. is 2.5, so maybe these times should be multiplied by 1.25 to adjust for the small brake cylinder.

Doug

The 2500 cubic inch number actually matches the 40 liters for the auxiliary reservoir which I found in one of my linked documents. However, isn't that 40 liters divided between the auxiliary and emergency reservoirs, or is there a separate, probably larger, emergency reservoir? I assumed the former in my calculations, and arrived at an auxiliary reservoir size of 16.253 liters and an emergency reservoir size of 23.747 liters, based on a volume ratio of 1.461. With a 2.5 triple value ratio, this would give a brake cylinder volume of 16.253/2.5 = 6.5 liters = 397 cubic inches. Isn't ~400 cubic inches a common brake cylinder size (which would mean the numbers I calculated make sense)? Or am I way off base here?

[jtr1962]

Genma Saotome, on 25 April 2019 - 11:06 AM, said:

If KUJU had intended us to be running simulated trains under the Christmas tree (a.k.a. a DTG product) they'd have used installation-wide features like OR options. But in a rare case of true brilliance they put almost everything into .wags and .engs.
:sign_thanks:

Had they not done that I think most of us who want our trains to run like the real thing would have lost interest a long time ago.

[cjakeman]

jtr1962, on 25 April 2019 - 09:07 AM, said:

That brings me to another thing I wish the Open Rails programming team would implement. A lot of people run both freight and passenger trains. For freight trains unchecking the Graduated Release Air Brakes box gives correct operation. For passenger trains the box needs to be checked.

There's a real danger that good suggestions like this will be forgotten as new posts arrive. Please would you help the Dev Team by creating a card about it on the Open Rails Roadmap. Thanks.

[jtr1962]

cjakeman, on 25 April 2019 - 12:44 PM, said:

There's a real danger that good suggestions like this will be forgotten as new posts arrive. Please would you help the Dev Team by creating a card about it on the Open Rails Roadmap. Thanks.

Done.

[dajones]

The test document lists 2500 for the aux. res. and 3500 for the Emerg. res., but they are combined into a single tank. I don't think I can provide a direct link to the document, but you should be able to get it from here. A diagram with the test volumes is on page 53.

Doug

[R H Steele]

Reading some basic principles of dynamic brakes I found this :

Quote

The prime mover RPM is increased (throttled up) and the main generator field is excited, causing a corresponding excitation of the traction motor fields. (This is how the dynamic brakes are increased or decreased.)

Question: is the HP of the prime mover ( or some % of ) taken as the Max Dynamic Braking Power?
Question: Is the Max Dynamic effort a function of the traction motors...and is that given in the manuals or can it be calculated?

[jtr1962]

dajones, on 25 April 2019 - 01:31 PM, said:

The test document lists 2500 for the aux. res. and 3500 for the Emerg. res., but they are combined into a single tank. I don't think I can provide a direct link to the document, but you should be able to get it from here. A diagram with the test volumes is on page 53.

Doug

Thanks. I think I'll be modifying my parameters accordingly:

EmergencyResCapacity( 2.025ft^3 )
EmergencyResVolumeMultiplier ( 1.4 )

I'll eventually release a revised version of the original document incorporating any changes based of the feedback here.

[jtr1962]

R H Steele, on 25 April 2019 - 01:34 PM, said:

Reading some basic principles of dynamic brakes I found this :

Question: is the HP of the prime mover ( or some % of ) taken as the Max Dynamic Braking Power?

Often but not always. That depends upon the size of the dynamic braking grids, and in the case of electrics on how receptive the catenary is to receiving power coming from the dynamic brake.

Quote

Question: Is the Max Dynamic effort a function of the traction motors...and is that given in the manuals or can it be calculated?

You're probably better off getting the numbers from manuals in the case of DC locomotives, especially as there doesn't seem to be any real rule of thumb. For AC locomotives I've noted that the maximum dynamic braking effort is typically around 50% to 60% of the maximum TE. The maximum dynamic braking HP can be up to the rated power of the traction motors but as I said that's highly dependent on the power having some place to go, either into resistor grids, or back into the catenary to be used by other trains.

[R H Steele]

Thank you, more research and reading needed.