Shunting Locomotive

Overview

A shunting locomotive, or switcher, marshals wagons and coaches inside yards, depots and industrial sidings. The work is low-speed but heavy: it spends its day starting, stopping and propelling cuts of wagons, so it is built for high tractive effort, good slow-speed control, and all-round cab visibility rather than line speed. This is a diesel-electric design, a diesel prime mover turns a main alternator whose output, after rectification, feeds traction motors on every axle. That layout gives smooth, stepless control of effort from standstill and avoids any mechanical gearbox to the rails. A central elevated cab and end walkways let one driver see both ends of the locomotive while coupling.

How it works

The Diesel Engine is a turbocharged medium-speed V12 with common-rail injection; its Piston Assembly assemblies drive a Crankshaft that turns the Main Alternator. The alternator's three-phase output is rectified inside the Control Cubicle and supplied to four Traction Motor units, each turning an axle through a Axle Gear Unit single-reduction drive. Because effort is set electrically, the driver controls speed and pull with one master-controller handle on the Control Desk.

The whole machine is built up on a heavy welded Underframe resting on two Railway Bogie running-gear units. Braking is pneumatic: the Air Brake System runs a motor-driven compressor and reservoirs that charge the brake pipe, and each axle's Friction Brake Unit applies the Brake Disc (rotor) when brake-pipe pressure is reduced. At each end a Coupler with draft gear and four Buffer units handle coupling and buffing loads during shunting moves.

The Driving Cab seats the crew, and the Fuel Tank slung under the frame holds the diesel supply. A 12 V Battery bank starts the engine and powers the control circuits, lighting and the electronic controllers in the cubicle until the alternator's auxiliary winding takes over charging.