AB Standard (New York City Subway Car) - Letter Designations

Letter Designations

Over their service life, the Standards used several letter designations depending on the configuration of the cars. Originally, the first 600 cars as delivered could operate singly, and dubbed A-types. During the 1919-1920 modifications, much of the fleet was reorganized into semi-permanently coupled units. The following configurations refer to the Standards in operation over the years:

• A units were motorized single cars and capable of running independently.
• B units consisted of three motorized cars that ran in a set. The two end cars retained their operating cabs at the front and rear, but blind cabs were made inactive. Door control button boards were similarly deactivated in the end cars, but retained in the center (master) car. The center car's blind cabs were made inactive.
• BT units consisted of two motorized cars that ran in a set. Each car retained its operating cab at the front and rear, but blind cabs were made inactive. On these units, there was no provision made for door operation, and thus these units could not be operated independently by themselves.
• BX units were three car units consisting of an unpowered trailer between two motorized cars. The two end cars retained their operating cabs at the front and rear, but blind cabs were made inactive. There was a restriction on the use of these units; one such unit was not permitted to operate by itself, nor could two of these units operate together in one consist. In addition, for many years they were forbidden to operate on the Manhattan Bridge, but this restriction was lifted when the majority of the units were reassigned to Coney Island to provide for the expanded service via the 60th St. Tunnel Connection on December 1, 1955.
• AX units were trailers that operated in connection with a A-Type car, loosely associated. Five trailers were originally set up in this manner, but the arrangement was not found to be satisfactory, and they were ultimately coupled into BX units as the rest of the trailers already had been. Though they did not themselves have motors, the cabs could control the entire train's propulsion. They were typically added onto trains to lengthen them during the rush hours.

(Note: this designation was also used much later on to designate cars formally from B units that were detached from their former unitization and independently used in work service.)

The frequent operating and shop personnel references to the cars as AB's or AB Types were derived from the above letter designations, as the vast majority of the cars were originally A units, and later reorganized into B units.

Additionally, it is noted that other letter designations were used temporarily involving an extra "A" preceding the unit name. This was done as Standards were being modified in regard to their jumper cable connections. This work went on from approxiamtely 1928 to 1931, and during those years one could see units carrying designations "AA," "AB," or "ABX." The extra "A" signified that the car had been so equipped. These designations with the extra "A" prefix were temporary, and when the entire fleet of Standards had been so equipped by 1931 or 1932, the extra "A" prefix was dropped from the designations.

Regarding the first 600 cars while they were being unitized, it was found that 2 cars of this series did not fit into the system as it was being set up. These were relegated to work service and not used again until 1953, when two of the regular motor cars were damaged in an accident. Thus these 2 cars were returned to passenger service to replace the 2 that had been damaged. As a consequence, there have never at any time been more than 948 in service and 952 were actually built, but the number 950 serves as a convenient benchmark.

Regarding the 300 Pressed Steel motors, as they were first being delivered, the decision was made not to unitize the first 150, or half of them, to allow for the operation of more varied train lengths, notably for maximum 8 car length. The final 150 were unitized as B-Types in much the manner of the earlier sets.

In later years, as the 2400 series was undergoing rebuilding, it was decided not to include the trailer cars in the rebuilding. The first 70 2400's had a 2600 series A-Type car inserted in the unit (a total of 35 of these cars were used for this purpose); these units were designated as B-Types. The remaining 30 2400's just remained as two car BT units, with as before, no provision for door operation in these cars.

One first that occurred with these newly constituted units was, except for the first units put out, the remainder were equipped with link bar connections rather than couplers, making for a more permanent coupling that could only be broken up with great difficulty in the shops. All new cars subsequently purchased for the system made use of this feature and couplers were no longer used to join component cars in units.