British Rail Class 144

The British Rail Class 144 Pacer is a retired class of diesel multiple unit passenger trains built at Derby between 1986 and 1987, the last Pacer model that British Rail ordered. After the Class 141 railbus from British Leyland, the railway placed an order with British Rail Engineering Limited and Walter Alexander for an improved derivative, and 23 units were constructed with a body near identical to the Class 143, built by Walter Alexander. The first thirteen are two-car units and the remaining ten gained a third vehicle later. Units have a maximum speed of 75 mph and BSI couplers that let them work in multiple with Classes 142, 143, 150 and other Sprinter and Pacer units. The original Leyland TL11 engine was replaced from the early 1990s by a Cummins LTA10-R. All units were retired from main line service by 2020, and many have since been preserved on heritage railways.