The main transformer also supplied an auxiliary feed at 240 V for powering miscellaneous systems on board the train, including the heating units. While the transformer has its own oil-based cooling system, a fan-driven arrangement kept the rectifiers within a safe operating temperature, although relatively little temperature restrictions were present as a consequence of its solid-state nature. The vast majority of the electrical equipment was installed within bays mounted on the underframe, aside from a single cabinet in the guard's compartment that contained a fuse panel, fault indicator panel, equipment cutout switches, and auxiliary equipment. While most apparatus were installed beneath the motor trailer, including the four AEI-supplied traction motors, the underframe of the driving trailer accommodated some equipment as well, such as the main air compressor, air reservoirs, brake cylinder, and nickel–iron battery units. The rate of acceleration was regulated by a relay that intentionally limited the current. Furthermore, the camshaft would only move when the reverser is set and the motor contacts closed. The motors were protected by an automated cutoff that activated under several circumstances, including excessive oil temperatures, earthing faults, overload, and air supply failure. The cab was designed to provide the driver with an excellent external view, as well as to be aesthetically pleasing. Glass panels covered the cab's forward section down to waist height while a pair of fully-adjustable seats, for the driver and assistant motorman, were mounted directly upon the rear bulkhead. The driver's instrumentation was fitted upon a sloped panel behind a flat desk lined with push buttons and light switches. To the driver's left was the brake controller while to the right was the master controller. Via the master controller, the driver could operate the vehicle's four motors either together or individually; the latter mode was intended primarily for slow speed shunting operations. The cab walls were lined with plastic panels while the floor was covered in linoleum. Access to the cab was via a single door centrally positioned in the rear bulkhead. The underframe largely conformed to standard BR designs of the era. It was paired with double-bolster bogies through, which were furnished with knife-edge suspension. Braking was provided via an air-powered arrangement, which featured a self-lapping electro-pneumatic control actuated via a single cylinder. Only the outer ends of each unit featured oleo-pneumatic side-buffers and drop-head automatic couplers; instead, the interior ends of each car were equipped with fixed automatic