SD45T-2

[BoostedFridge]

Hi, do you think DTM SD45T-2 has realistic brake physics?

Dynamic brake barely works , and it has very abrupt action between notch 2/3
On 2% grade, it's useless to slow down the train, even from 15 MPH (I thought dynamic brake is the most effective at slow speed)

Can't control train speed downhill with main train brake too. On 2% grade and 20MPH speed limit, train still going to accelerate over 30 MPH with dynamic brake on notch 8, and train brake 90%

How heavy is the train, and how many locomotives on it?

[mindenjohn]

Dynamic brake barely works , and it has very abrupt action between notch 2/3
On 2% grade, it's useless to slow down the train, even from 15 MPH (I thought dynamic brake is the most effective at slow speed)

No, the opposite is the case.

The principle of Dynamic Braking is to use the rotation of the traction motors (AC or DC) as current generators and use that current to slow the train. This is achieved on locomotives by switching off the traction current and diverting the "generated DB current" into resistors that then convert the power to heat. When there is any current flow through a resistor it creates a voltage in this instance it is called a back EMF (electro-motive-force) without which the current will not flow. As the rotational speed falls the current falls and the back emf falls and the effectiveness of the DB falls. The DB is considered to be ineffective BELOW 15mph although some systems have "Extended Dynamic Braking" (seen on EMD locos as an extended DB blister with an access cover) which extends the DB below 15mph but no DB system will be effective at low speeds because the rotational speed is so low it cannot create sufficient EMF to create a current.
In this TS20xx locomotives generally follow the physics.

[awaken1977]

Hi, do you think DTM SD45T-2 has realistic brake physics?

Dynamic brake barely works , and it has very abrupt action between notch 2/3
On 2% grade, it's useless to slow down the train, even from 15 MPH (I thought dynamic brake is the most effective at slow speed)

Can't control train speed downhill with main train brake too. On 2% grade and 20MPH speed limit, train still going to accelerate over 30 MPH with dynamic brake on notch 8, and train brake 90%

How heavy is the train, and how many locomotives on it?

how i can calculate it?
some more sophisticated locos have script, activated by hotkey, which shows it in the game

[buzz456]

At least you should be able to tell us how many of what cars you have assembled and how many locomotives you have on the train?

[GreatNortherner]

I can't speak about the SD45T-2 because I don't have it (I think), but if you want to test and compare it you could attempt that same descent with the same consist using different locomotives like say an SD40-2 or SD45. That ought to at least give you some clues about what might be going on.

Also, don't forget that 2% is already a fairly heavy descent and you'll want to have your train brake applied before starting on the downhill. You could also simulate setting retainters by applying the hand brake on some cars in your consist before starting the descent. Then ease your train onto the grade, engage the dynamics and use them to keep the speed under control.

[mindenjohn]

you'll want to have your train brake applied before starting on the downhill. You could also simulate setting retainters by applying the hand brake on some cars in your consist before starting the descent. Then ease your train onto the grade, engage the dynamics and use them to keep the speed under control.

Just like the real thing.

[awaken1977]

At least you should be able to tell us how many of what cars you have assembled and how many locomotives you have on the train?

I used JR SD40-2 which has a function of train lenght/weight calculation.
The cars are from Mount Shasta route pack , mixed of different types.

total length ft = 4129
total weight us tons = 7435
total cars count = 3 (wrong, it's 66)
total axle count = 24 (wrong)
total gross/net hp = 13200 / 12000
gross hp/t = 1,8
rolling drag = 133111
grade drag = -118963
total drag lbs = 14149

4x SD45T-2 locomotives (I replaced with JR SD40-2 to make the calculation)

probably, 7435 is too much for such number of units. I replaced most of the cars with their empty versions, and train handling is much better

[AmericanSteam]

I have done the same thing using all Searchlight Simulations rolling stock with the same incorrect car and axle count information showing.The length appears to be correct.

[awaken1977]

I have done the same thing using all Searchlight Simulations rolling stock with the same incorrect car and axle count information showing.The length appears to be correct.

I thought calculator properly works only with Searchlight rolling stock. total cars count = 3 are actually JR locomotives (4 minus 1 leading unit = 3)

[BoostedFridge]

I thought calculator properly works only with Searchlight rolling stock. total cars count = 3 are actually JR locomotives (4 minus 1 leading unit = 3)

Correct. Or rolling stock that has had the necessary scripts added per the instructions in the Searchlight Simulations equipment defect detector download.

[AmericanSteam]

I just read the installation instructions, it can be quite time consuming. If what I read and understand is correct, the scripting must be placed manually in each locomotive and every piece of rolling stock that is not already enabled by Searchlight Simulations. Question, have ALL rolling stock and locomotives from Searchlight Simulations been enabled, if not what packs have been? If I reskin an enabled piece of rolling stock will that carry over.

[bnsfsubdivision]

I just read the installation instructions, it can be quite time consuming. If what I read and understand is correct, the scripting must be placed manually in each locomotive and every piece of rolling stock that is not already enabled by Searchlight Simulations. Question, have ALL rolling stock and locomotives from Searchlight Simulations been enabled, if not what packs have been? If I reskin an enabled piece of rolling stock will that carry over.

I suggest opening a new thread to not clutter up this one as it's not exactly related to the original topic :)