Actually its more like we use verry low resistance grids (6) and close them in sequence of 2 at a time (the slower it moves the more we grid we add until we have all 6 in series circuit) to generate current from the generator AC and rectifie it to DC on the engine, then uses that current to put thru the 6 DC traction motors to to slow the wheels down by running the magnetic field just a bit slower speed than the wheels are turning..
@@NoBody-ht1oh he is correct actually. Main alternator current is pumped thru the traction motor field circuit. the motors armature is then connected directly to the grids. extended range dynamics will short out grid sections at lower speeds to keep the voltage higher. This is for a DC system. AC invertors operate a little different.
The Grid Resistor blowers, for GE dash9 and GEVOs is actually right behind the cab where those vent blinds pointing slightly up. You showed it to be in the rear with the other engine radiators coolers,
The ore trains in Western Australia. I understand one of the big problems is breaking the train. When the front start to go downhill while the back is still climbing
Have a look for a video produced by Norfolk Southern from the 1970's relating to the Saluda grade. That grade has the same problem, train going down the hill as the back of the train is still coming to the summit.
It would have been great if the video was a little more technically rigorous and yet maintained it's simplicity. It must be mentioned that the kinetic energy of the train is converted to heat in the resistor which slows the train. Also, dynamic braking is ineffective when the train is moving slowly. It's just the fans which are probably running to cool the grids.
Reportedly not so with AC-traction locos. They can bring a train to a stop on a grade, and hold it there. Major side-benefit is the ability to release the train (air) brakes so the the reservoirs (on each car) can be recharged. Big deal in mountains.
DC systems that have extended range (bypassing numerous grids) to keep voltage higher, can bring a train to a stop.. or so close. GE extended range can basically bring it to a stop. I tested dash 9's and they are very effective.
@@theodorethompson9032 DB AC vs DC systems are very different. The grid circuits are the same but the use of 3 phase invertors are completely different operation.
that's how i always thought about it..........the jake brake, what a fantastic inverntion..........with a good jake brake on my 85 autocar with a 350 cummins 8 LL trans.......loaded the truck comes to a complete stop........all on its own.........
Yes on electrified lines, much better than wasting the energy into what essentially is radiators. The loaded iron ore trains in northern Sweden generate roughly enough energy when breaking going down to the port in Narvik as the empty trains need going up again to the mines in Kiruna.
Poor terminology. What’s really happening is the resistors are applying a load to the circuit in the Dynamic brakes. Anytime you spin a electric motor is is creating electricity, but if you apply a load it becomes harder/requires more force to turn the motors. If you have the ability take to little electric brushed ( 2 wire/ dc/etc) or similar size and connect the contacts, preferably with wire and solder, and you’ll see how much harder it is to turn the generator motor with the load vs on its own.
When I was a scout master the railroad sent in some wonderful people for training.
Thank you for helping me understand Dynamic Braking! It always sounded so complicated and confusing to me but thanks to you I finally understand it!
In the pic of the UP BSA GE in the vid, the "rad cab" does not house dynamic brakes. the dynamic brake is up behind the cab on modern GE locomotives.
Thank you for this great information on behalf of BSA and model railroaders out-there (including me), Ciao, L
Very clear explanation
Greetings from Indonesia
Helping me understanding dynamic braking in komatau rock haul trucks thank you !
Actually its more like we use verry low resistance grids (6) and close them in sequence of 2 at a time (the slower it moves the more we grid we add until we have all 6 in series circuit) to generate current from the generator AC and rectifie it to DC on the engine, then uses that current to put thru the 6 DC traction motors to to slow the wheels down by running the magnetic field just a bit slower speed than the wheels are turning..
Are you nuts
@@NoBody-ht1oh he is correct actually. Main alternator current is pumped thru the traction motor field circuit. the motors armature is then connected directly to the grids. extended range dynamics will short out grid sections at lower speeds to keep the voltage higher. This is for a DC system. AC invertors operate a little different.
The Grid Resistor blowers, for GE dash9 and GEVOs is actually right behind the cab where those vent blinds pointing slightly up. You showed it to be in the rear with the other engine radiators coolers,
The fans they were pointing to are the air to air fans.
I never knew there was a rail road merit badge! But I’m glad I do now!
Great explanation
Learned alot off this, thanks.
Thanks for the video!
The ore trains in Western Australia. I understand one of the big problems is breaking the train. When the front start to go downhill while the back is still climbing
Have a look for a video produced by Norfolk Southern from the 1970's relating to the Saluda grade. That grade has the same problem, train going down the hill as the back of the train is still coming to the summit.
That was very good!
Nice video
What's fun is setting up full braking on one unit then pushing or pulling with another unit in full throttle...
Isn't there some sort of datalink or something preventing this from happening?
It would have been great if the video was a little more technically rigorous and yet maintained it's simplicity. It must be mentioned that the kinetic energy of the train is converted to heat in the resistor which slows the train.
Also, dynamic braking is ineffective when the train is moving slowly. It's just the fans which are probably running to cool the grids.
Reportedly not so with AC-traction locos. They can bring a train to a stop on a grade, and hold it there. Major side-benefit is the ability to release the train (air) brakes so the the reservoirs (on each car) can be recharged. Big deal in mountains.
Dc traction motors can also be effective at slow speeds, saying dynamic braking is ineffective at slow speeds is not always true
DC systems that have extended range (bypassing numerous grids) to keep voltage higher, can bring a train to a stop.. or so close. GE extended range can basically bring it to a stop. I tested dash 9's and they are very effective.
*walking down a hill fast*
My mind: DYNAMIC BRAKES STAT
other than the lack of detailed electrical theory behind the scene, it's a great demonstration on dynamic braking... good job anyway
good stuff! I like how the new locomotives can safely slow down and stop!
DB systems are very old
@@theodorethompson9032 DB AC vs DC systems are very different. The grid circuits are the same but the use of 3 phase invertors are completely different operation.
really clear thanks!
0:28 where is that from what happened?
So dynamic braking only provides brake force to the wheels of a loco and not to the rest of the train wheels.
Yes that is correct.
Yeppers and the faster the train is moving the better the dynamics work, when almost stopped or stopped the dynamics provide zero braking force.
@@hoghogwild dynamics work best at 28 MPH - max output according to the EMD manual.
now i know, thanks
Seems like an electric jake brake as I understand it...
that's how i always thought about it..........the jake brake, what a fantastic inverntion..........with a good jake brake on my 85 autocar with a 350 cummins 8 LL trans.......loaded the truck comes to a complete stop........all on its own.........
What about regenerative braking? Do modern locomotives use such systems?
In overhead current drawing locomotives, it's used, infarct it's awesome 1 , around 10% of energy needs are fullfileed by this, in India .
In essence this is regenerative braking, except that the excess current is wasted in the form of heat.
Yes on electrified lines, much better than wasting the energy into what essentially is radiators. The loaded iron ore trains in northern Sweden generate roughly enough energy when breaking going down to the port in Narvik as the empty trains need going up again to the mines in Kiruna.
Chacha White board thoda bada khareed lete toa kuch achhe se samajh aata
Can some 1 elaborate at 2:17, electromagnetic back pressure
Piyush Chand it’s not a real thing.
Poor terminology. What’s really happening is the resistors are applying a load to the circuit in the Dynamic brakes. Anytime you spin a electric motor is is creating electricity, but if you apply a load it becomes harder/requires more force to turn the motors. If you have the ability take to little electric brushed ( 2 wire/ dc/etc) or similar size and connect the contacts, preferably with wire and solder, and you’ll see how much harder it is to turn the generator motor with the load vs on its own.
This is a very poor discussion of dynamic braking. Surely you could have found an engineer who actually knows what they're talking about?