Guideline For Setting Open Rails Braking Parameters (Including Blended Braking)
#11
Posted 25 April 2019 - 11:06 AM
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:
#12
Posted 25 April 2019 - 11:59 AM
dajones, on 25 April 2019 - 10:19 AM, said:
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?
#13
Posted 25 April 2019 - 12:10 PM
Genma Saotome, on 25 April 2019 - 11:06 AM, said:
: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.
#14
Posted 25 April 2019 - 12:44 PM
jtr1962, on 25 April 2019 - 09:07 AM, 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.
#15
Posted 25 April 2019 - 12:54 PM
cjakeman, on 25 April 2019 - 12:44 PM, said:
Done.
#16
Posted 25 April 2019 - 01:31 PM
Doug
#17
Posted 25 April 2019 - 01:34 PM
Quote
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?
#18
Posted 25 April 2019 - 01:39 PM
dajones, on 25 April 2019 - 01:31 PM, said:
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.
#19
Posted 25 April 2019 - 01:45 PM
R H Steele, on 25 April 2019 - 01:34 PM, said:
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
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.