Once upon a time when there was no such thing as automatic air brakes on freight trains the brakeman was the crewman responsible for setting a freight car's brakes individually,while the train was at speed, by using the available brake wheel. As you may have guessed this was very dangerous work and what's worse, it had to be done in all types of weather; rain, snow, wind, you name it! With the advent of the automatic airbrake (where the train's brakes were controlled by the engineer and could be instantly applied to all cars once set) the brakeman's role was reduced but not necessarily eliminated.
The history of braking systems within the railroad industry began during its infancy of the 1820s and 1830s. Back then simple cars were equipped with simple apparatuses to physically slow them. As Jim Boyd's book, "The American Freight Train," notes very early gravity cars utilized levers with brake shoes that would squeeze against the wheel treads to slow its movement. At this time locomotives also carried only rudimentary means of stopping that also sometimes required a brakeman to climb atop the contraption to apply its brakes. As trains became larger and heavier a more advanced means of slowing them were needed.
Unfortunately, this would not come until the late 1860s. In the meantime, railroads relied upon an army of brakeman who, once signaled by the engineer, would climb on a car's roof and manually apply the brake-wheel. The worker would run from car to car doing this until he had set all of the required brakes. It was a very dangerous occupation that resulted in many injuries and deaths. As Mr. Boyd notes it was also very time consuming, requiring a few minutes to stop a train going just 15 mph. On April 13, 1869 George Westinghouse received a patent for his new automatic air brake system that worked on compressed air, applying brakes throughout the train nearly instantaneously.
As was slow typical of the industry it was slow in implementing this device on equipment, largely due to cost. However, after Congress passed the Railway Safety Appliance Act in 1893 the air brake was required, saving countless lives while also greatly improving operational efficiency. Today, the job of the brakeman on the railroad is mostly relegated to throwing switches when needed and coupling or uncoupling cuts of freight cars whether being done in yards or out on the main line. As mentioned before, if you have never worked for a railroad or know much about the industry please let me warn you that a career such as a railroad brakeman is not for the faint of heart. Railroading is tough work and takes a dedicated breed not only to handle the physical demands required but also the mental fatigue, as working 12-hour, seven-day-a-week shifts is normal (and overtime is mandatory).
While a more predictable work schedule does come with seniority, don’t expect it to happen within a short period of time. Some railroaders wait 20 years or more to land a “9 to 5” workday, which usually consists of working yard or local jobs. There is a reason why railroaders say that railroading becomes a lifestyle, its not just saying! Having said that, if you are able to hire on with a shortline (Class III) or regional (Class II) railroad the opportunity for a more predictable schedule is very likely although the pay is not quite as good. As far as I know there are no formal classes taught to learn the position of brakeman, the training is done by the individual railroad which hires you. To read more about the history of the brakeman please click here.
It should also be noted that a form of the brakeman position is also held on passenger trains where they are known as trainman, who's duties mostly consist of assisting the conductor as needed. Again, if you are not even sure if a career in railroading is right for you but would like to learn more about what it takes to work in the industry you might want to consider the book Working on the Railroad from noted author Brian Solomon. Solomon's book details the history of working in the railroad industry and the difficulties and hardship employees faced back then as well as today. After reading this book you should have no doubts about whether working in the industry is something you are truly interested in.