The man who brought fail-safe brakes to railroads once had a major role in the 20th-century industry, but a combination of events and decisions have left only his braking system as a recognized legacy.
Some innovations seem so obvious and pervasive that we assume they have always been with us, but, of course, that is not the case. The Westinghouse air brake for railroads is one such example. It’s also an example of how an admired, widely known industrial companies of its day can lose its way, morph, shrink, and eventually emerge as a mere remnant of its former glory. Its once ubiquitous and eponymous name is now virtually unknown to the public.
In the mid-late 1800s, railroads were the dominant form of land transportation for goods and people. Steam-powered locomotives were the primary vehicle for the settling and industrialization of the country and the world. Railroads and their technologies were both drivers and beneficiaries of advances in steelmaking, fabrication, and low-cost transport. Many advances in electrical signaling and components, and even heat-resistant Pyrex glass, can be traced directly to railroad technology.
The railroad’s position in society was analogous to that of our high-tech today. Drawings and photos of steam-powered locomotives were the posters of the period, for many reasons. They even encouraged standards; for example, deadly boiler explosions were no longer commonplace as techniques for designing, riveting, inspecting, and maintaining these high-pressure vessels were studied, standardized, and formalized.
There was one problem which was not an apparent part of the early “glamour and glory” image of the rails: the braking system which slowed and stopped these trains. It’s perhaps hard to believe but true: braking was done manually by a brakeman on top of the car (one for each or for several cars), who turned a large wheel which was connected by a chain the brakes of the car’s wheels when signaled by the locomotive driver via the train horn whistle. This was done regardless of weather and conditions, day and night, and despite low clearances from tunnels or other impediments. It was among the most miserable and dangerous jobs in the world. Even if it was not dangerous, it was only somewhat effective due to the time lag of the brakemen who had to actually make it happen.
There had been attempts to develop a better system using wire cables. Still, these did not succeed due to cable length and stretch, cable breaks due to fatigue, and corrosion (metallurgy science was in its early stages, problems with cable pulleys and guides, harsh operating environment, and car coupling and uncoupling issues.
Put some pressure on it
A direct air-based system had been tried, using an engine-mounted compressor to pump air through hoses than ran throughout the entire train. This air pressure would be used to apply the brakes to all cars in the direction of the locomotive driver. While this worked in principle, it had two problems. First, there was a lag between brakes being applied at the first car and the last, due to the length of the train and the compressibility of air, and this could cause the rear cars to crash into the forward ones. Second, and much more serious, any rupture in the single air hose resulted in a system-wide loss of brakes; the same problem occurred during routine uncoupling.
George Westinghouse (Figure 1), was just 23 in 1868 when he arrived in Pittsburg, then the center of steel and railway-related industries. Two years before, at age 21, he had already patented a “car replacer” to guide derailed railroad cars back onto the tracks, and a “reversible frog” to guide trains onto one of two tracks. He knew and understood railroading.
He studied and then modified the direct air-brake system to an inverse mode of operation, based on an innovative triple-valve air-brake system, Patent 144006 (1873) (Reference 1). In his design, the brakes were engaged in the absence of line pressure; it took positive action via this pressure to release them. This was one of the first large-scale “fail-safe” systems ever devised, as almost any failure would cause the system to go to safe mode with the brakes applied.
Instead of using force or air pressure to apply the brakes (as is done with hydraulic fluid in today’s cars), the locomotive had a compressor that supplied pressurized air for the entire train’s braking system. The triple-valve system filled a reservoir (supply) tank under each car and then used that air pressure to release the brakes (Figure 2). (See Reference 2 for a detailed discussion of the physics of train braking.)
Part 2 will look at the operation in more detail, and also how Westinghouse expanded beyond railroad braking systems.
EE World References
Electrified Locomotives, Tunnels, and the Pennsylvania Railroad: Astonishing engineering but a partially sad ending, Part 1: The challenge
Electrified Locomotives, Tunnels, and the Pennsylvania Railroad, Part 2: The tunnels
Electrified Locomotives, Tunnels, and the Pennsylvania Railroad, Part 3: The station
Electric locomotives and catenary power systems – Part 1: basic functions
Electric locomotives and catenary power systems – Part 2: power needs
Electric locomotives and catenary power systems – Part 3: power delivery
Electric locomotives and catenary power systems – Part 4: maintenance and corona
- S. Patent 144006, “Improvement in steam and air brakes”
- The Traffic Accident Reconstruction Origin (TARO), “An Introduction to Train Brakes”
- Funding Universe, “Westinghouse Electric Corporation History”
- The Economist, “Westinghouse RIP”
- Engineering and Technology History Wiki, “Westinghouse Electric Corporation”
- Garbedian, H. Gordon, “George Westinghouse: Fabulous Inventor,” Dodd, Mead, 1943.
- The Railway Technical Website, “Electro-Pneumatic Brakes”
- net, “Braking Systems”
- Trains, “Electronically controlled pneumatic brakes study ‘inconclusive’ ”
- Trains, “The war over electric brakes”
- Statistica, “North American freight rail cars in service from 2009 to 2019, by car type”