Train brakes is when all train cars are being used. What is the difference between locomotive brakes and dynamic brakes?
The train’s brakes operate with the change in pressure of the Brake Pipe – the continuous pipe that runs thru all of the cars. As the Brake Pipe pressure is reduced a portion of a tank of air in each car is applied to every brake cylinder in the train. That system can apply the brakes proportionally to the Brake Pipe Reduction. Once the Brake Pipe pressure is reduced to about 2/3rds of its highest pressure (when the brakes are all released) the individual brakes are fully applied and there is no more braking available for the train. Any increase in the Brake Pipe pressure will fully release all of the brakes in the train. This causes the tank on each car to recharge to the pressure of the Brake Pipe. So the train brakes are proportional apply – fully release.
The locomotive will respond exactly as the train when the train (automatic) brake is used. In general the brakes on the locomotive are more effective than the brakes on the cars. The locomotive will tend to put more braking power on the train with the same train (automatic) brake application. Normally the locomotive’s brakes are bailed off (released) when the train brakes are applied to prevent the train from catching up with the locomotive.
Now the locomotive’s brakes (independent) are proportional apply and release. They are controlled by a separate handle on the brake stand. With the locomotive brake, one can easily control the locomotive and a few cars at slow speeds.
Unfortunately, the air brake system uses the air in each car when it is applied. If the engineer applies and releases the brakes in many cycles, quickly, the air tank in each car will not recharge between brake applications. That means that every application (Brake Pipe reduction) will have less braking power until eventually the air in each car will be exhausted.
One could hold the train back by applying the locomotive (independent) brakes. The locomotive has its own air compressor to continuously supply the brakes. B
Locomotive brakes are air controlled by the independent brake valve, dynamic brakes use inerita when the locomotive is moving by converting the traction motors in to generators by way of a rehoastat by addind amperage restissance to the grids behind the locomotive cab it is then dispalced as heat to the air.
See the website called tales of the krug he is alot sharper on this stuff than I am.
Rodney
As Rodney said, check out Al Krug’s site, particularly these: