Building a DMU

Part Six: Adding Underframe Components Part One

Images forty-seven to sixty-four in the booklet show the underframe being population with the mechanical and electrical components. The first nine of those seventeen images are shown here, all were taken in Swindon Works on March 6, 1956.

"Generator Assembly - Stage 1"

Negative 5C88

A dynamo is being pushed under a power car on a pallet truck.

"Generator Assembly - Stage 2"

Negative 5C89

The pallet truck has been raised to enable the pin that the dynamo will swivel on to be pushed in place. We are looking towards the rear end of a power car, with the cab of a 'leading' DMBS seen behind.

"Engine"

Negative 5C90

An AEC 220 150hp engine in place. The engine mounting system was different on 79xxx vehicles (all 79xxx power cars, not just the Swindon builds) than 5xxxx vehicles. At the flywheel end (nearest) it rests on a tube supported at the front by the two vertical flat links. The flywheel was also smaller than that fitted to the AEC engine on 5xxxx vehicles. The frame to the left of the engine would hold the battery box.

"Engine Fuel Pump and Throttle Motor"

Negative 5C91

The opposite side of the engine. The 'v' shaped brakets on the right are for brake rodding.

"Generator and Air Maze filter"

Negative 5C92

The spring for tensioning the dynamo belts can be seen on the left. The maze filter is the cylindrical shaped item between the dynamo and the engine. The black part extruding to its left is the air intake, the oil bath filter is the cylinder part, the air is then passed to the engine through the flexible pipe.

"Engine & Generator"

Negative 5C93

Between the dynamo end engine can be seen the gearbox and the exhauster, belt driven from the gearbox input. Note that on this engine the AEC plaque is on the left-hand rocker cover, it is on the right side on the engines in the other images.

"Gearbox"

Negative 5C94

On this side of the R14 gearbox can be seen the four belts that drive the generator. On the same output from the gearbox will be attached the cardan shaft that connects to the final drive. Being driven from this shaft, which only turns when a gear is engaged, the dynamo only generates power when the vehicle was moving (and even then only above a set speed). Beside the engine, the bar that runs at an angle is the tube that the flywheel end of the engine sits on, at the top it is fixed to the underframe in a manner that allows it to swivel to handle the engine rocking.

"Gearbox & Exhauster"

Negative 5C95

The exhauster is belt driven from the gearbox input. This will be connected to the engine flywheel, which is constantly rotating (when the engine is running) allowing vacuum to be constantly created. The canister on the gearbox contains an oil filter.

"Engine - Throttle Motor & Oil Separator"

Negative 5C96

The throttle motor is the horizontal item immediately below the solebar between the two white spots. The two circular brackets above the exhaust silencer will hold a vacuum reservoir. The oil separator (which seperates the oil from the air output from the exhauster) is the black cylinder next to the radiator.