|The PARSONS VALE Line
After the success of the class A electric, the PV&T decided that it would be sensible to electrify the rest of the railway. So they placed an order with ALCO/GE for a series of higher-powered locomotives. In 1920, the locomotives started to arrive. The class B locomotive (reclassified to class B1 in 1932, when the class B2 locomotives started to arrive from ALCO/GE) produced 3200 hp and allowed complete electrification of the busy Portland to Montréal mainline, as well as most of the traffic on the Augusta and Boston branches.
In 1941, most of the class B1's were rebuilt to produce 3600hp (at this time, they were reshod with AAR type B trucks), and in 1961 the purchase of the LT&L sent them back into the shops, returning as 4400hp.
Four of the class B1s (236-239) remain in as-delivered condition; these engines were delivered with low-speed gearing and are used as switch engines in the Portland and Montréal terminals. In 1962, the Montréal switchers were mated with tractors built from retired LT&L RS-1's 500-501.
The class B1 locomotive is an unqualified success for the Parsons Vale line. With the exception of 221, 224, and 239 (wrecked in 1944 in a collision between a military express train and a milk train hauled by class A's 205 and 212, every locomotive in this class remains in service, and is expected to for many years to come.