Lo-Vs were arranged in mixed trains consisting of trailer cars and motor cars. While trailer cars were equipped with brakes, but no air compressors or motors, motor cars were equipped with all three. "Lo-V" is short for "Low Voltage" which refers to the cars' form of propulsion control. Earlier Composite and "Hi-V" equipment that ran on the IRT had utilized a 600 volt DC circuit that ran directly through the motorman's master controller to control the car's propulsion. The 600 volts was also trainlined through the whole train by the use of high voltagejumper cables which had to be run between cars. However, Lo-V equipment used battery voltage in the motor control circuit to move high voltage contacts underneath the car, which would control the car's propulsion. Likewise, it would no longer be necessary to use 600 volt jumpers between the cars. This tremendously improved safety of the equipment for both train crews and shop personnel alike. Standard Lo-V cars also simplified braking for train crews. On IRT equipment, an electric brake could be utilized to synchronize a braking effort and apply each car's brakes simultaneously and uniformly throughout the train. This was different from operating strictly using air, which was less responsive, but would still stop the train albeit more slowly. Lo-V cars simplified the braking process. On earlier IRT equipment, the braking notches were different for a motorman depending on whether or not he was operating electrically or pneumatically. On Lo-V cars, the notches were identical regardless of whether or not the electric brake was active. The braking system on a Lo-V car is known as AMUE.
History
The Lo-Vs served much of their time on the Lexington Avenue express services and the Seventh Avenue-East 180th Street-Bronx Park express services, but appeared on virtually all other IRT lines during their careers. In 1960, a few cars were modified for operation on some BMT shuttle services, by adding extensions on their sides at floor level to fill in the wider platform gaps on the BMT; this lasted only for a year. After 48 years of service, most of the Lo-V cars were retired in 1963, spending their last days on the Lexington-Jerome line. Some cars, however, remained in service on the 7th Avenue-Lenox express until the spring of 1964. Additionally, a handful of trailer cars survived until as late as 1970, serving the IRT Third Avenue Line. Some Lo-Vs were converted into work cars following their retirement from revenue service. They were eventually replaced by retired SMEE cars converted into work cars and were eventually all scrapped.
