ACMU

The ACMUs (short for Air Conditioned Multiple Unit) were a series of DC electric multiple unit railcars built for the New York Central railroad in three batches between 1950 and 1965, with a fourth batch supplied to the Long Island Rail Road as the class MP75 in 1963. The ACMUs were intended to replace/supplement the original fleet of heavyweight MU cars, some of which dated to the start of electric operations on both railroads. These were the first New York Central units to offer air conditioning, with sealed windows replacing the drop sash and clerestory types found on earlier cars. The initial set of 100 cars was retired in 1970, upon completion of the M1 railcar delivery, while the second and third batches, totaling 87 cars, remained in service until 2004, when they were replaced by the new M7 fleet. The Long Island cars were eventually converted to non-powered push-pull coaches before being retired in the late 1990s.

History

The ACMU fleet was intended to replace some of the oldest MU cars on the New York Central system, many of which were already 40 years old and dated from the start of electrified service in 1906. The first series of 100 cars were ordered from the St. Louis Car company in 1949 and paid for by the New York Central railroad itself. 10 years later the financial condition of the railroad had deteriorated while the original MU fleet had only gotten older and less reliable. In 1962, the Central ordered an additional batch of 26 ACMUs from Pullman Standard and to assist the Central improve its commuter rail service, the Port Authority of New York and New Jersey purchased an additional 27 cars which were numbered in the 4700 series to distinguish them from the Central owned cars in the 4600 series. In 1965 a second order of 34 4700 cars were purchased by the Port Authority bringing the total of 4600/4700 series cars to 87.