Canadian Pacific 2-8-2 5192 was one of 95 P1b Class locomotives built by Montreal Locomotive Works in 1913. They were rebuilt to class P1-e in 1926. They had 63" drivers, 23 x 32 inch cylinders, boiler pressure of 190 lbs, and could produce up to 43,395 lbs of tractive effort. These engines were used for slow and fast freight as well as for passenger service and served until the end of steam. This picture from my collection shows CP 5192 running extra at an unknown location. The enclosed water tank in the background suggests a far north location.
Either a freight train being helped over a steep grade or a long passenger or freight train requiring more engines. This album includes Helpers and double heading trains of the old days both steam and diesel.