Diesel Shunter

Overview

A diesel shunter is a small, heavy, slow locomotive built for one job: assembling and moving wagons inside rail yards and at industrial sidings. It does not need the power or speed of a road locomotive, but it does need high tractive effort at very low speed and the ability to start, stop and reverse hundreds of times a shift. This machine uses a 0-6-0 layout, where three driving axles are mounted directly in the frame and coupled together, and a diesel-hydraulic transmission that gives smooth pulling effort from a standstill without any clutch to wear out. The whole locomotive is built around the Mainframe & Ballast, driven by the Diesel Engine (Inline-6) through the Hydraulic Transmission and Jackshaft Drive, and runs on the Running Gear (0-6-0). Roughly 4,000 Fastener Set groups hold the structure together.

The remaining systems make the locomotive usable: the Brake System stops it and its train, the Centre Cab houses the driver, the Control System runs the engine and the radio remote control, the Cooling System keeps the engine cool, and the Auxiliary Systems add lights, horn, a sander and the battery.

Frame, ballast and adhesion

Tractive effort at the rail is limited by adhesion, which depends on weight on the driving wheels. A shunter therefore carries far more mass than its size suggests. The Mainframe & Ballast is built from two 40 mm rolled steel Plate Frame plates, and several Cast Iron Ballast Block castings of EN-GJL grey cast iron are bolted into it to bring the total to about 50 t. Each end carries a Buffer Beam with a Screw Coupling Hook for the screw coupling and four Side Buffer units, because a shunter spends its day buffering up to wagons at low speed and those impacts have to be absorbed by the frame.

Engine

The Diesel Engine (Inline-6) is a turbocharged direct-injection inline-six rated near 400 kW at 1,800 rpm, modest by road-locomotive standards but ample for yard work. Inside the Engine Block the Crankshaft is driven by six Piston Assembly units under one Cylinder Head. A single Turbocharger raises low-speed torque, and the Fuel System feeds a common rail at up to 1,600 bar through the Common-Rail Injector units. The Lube Oil System keeps the bearings supplied and rejects oil heat into the coolant.

Hydraulic transmission and jackshaft drive

The defining feature of this locomotive is its diesel-hydraulic transmission. A Torque Converter sits between engine and wheels, with an engine-driven Converter Impeller throwing oil against a Converter Turbine while a Converter Stator on a one-way clutch multiplies torque at low output speed. This gives stepless tractive effort from a dead stand and absorbs the shock of starting a heavy cut of wagons. Behind the converter, the Reversing Gearbox selects forward or reverse through dog clutches moved by the Shift Actuator, and the Transmission Charge Pump supplies converter fill and control oil that the Transmission Oil Cooler keeps below 120 C.

Drive then reaches the wheels through the Jackshaft Drive. The Final Reduction Gear reduces speed onto the Jackshaft, and Coupling Rod links carry torque to the Crank Pin on each driving wheel through floating Rod Bush Bearing bushes. Because the rods tie all three axles together, the single transmission output drives every wheel, which is what gives the 0-6-0 its high adhesion.

Running gear and braking

The Running Gear (0-6-0) has no bogie. Three Wheelset units, each a forged Driving Axle carrying two Wheel Centre centres with shrunk-on Wheel Tyre rings of 1,000 mm diameter, are mounted in Axlebox units that slide in the frame Horn Guide and are sprung on robust Leaf Spring stacks. The Brake System charges Air Reservoir tanks from an engine-driven Air Compressor and applies cast-iron Brake Block units to the wheel treads through the Brake Cylinder rigging, metered by the Brake Control Valve. A mechanical Parking Brake holds the locomotive when it is stabled.

Cab, remote control and auxiliaries

Visibility matters more than speed in a yard, so the Centre Cab is a single raised centre cab with a wide-glazed Cab Shell giving the driver a clear view over both hoods. The Control Desk carries a notched Master Controller and the Direction Switch. Modern shunters are usually one-man operated from the ground, so the Control System pairs the Engine/Transmission Control Unit with a Remote Control Receiver and a belt-pack Remote Control Handset: the ground operator who is coupling wagons drives the locomotive by radio, and a Tilt/Man-Down Switch in the handset stops it if the operator falls. The Cooling System uses a single frame-end Radiator and a temperature-controlled Cooling Fan, while the Auxiliary Systems provide a Headlight at each end, a Air Horn, a Sander Unit to put sand under the leading wheels on greasy yard rail, and the Charging Alternator that charges the 24 V battery.