Underfloor motor

Scheme underfloor engine (truck)

In motor vehicles and railcars, an underfloor motor is an arrangement of the motor located in the frame or the car body (in contrast to the motor installed in the front area and the rear motor ). The underfloor motor was developed by the engineer Paul Arendt . The truck and bus manufacturer Büssing was famous for its vehicles with underfloor engines .

history

First underfloor motor in a Hanomag chassis

The developer of the underfloor motor, Paul Arendt , was chief engineer at Büssing until 1929 . For this company he developed the first Büssing bus without a bonnet in cooperation with the Hanoverian Waggonfabrik (HAWA) (based on the American Fageol model ). The engine of this bus, a standing arranged in the middle liquid-cooled series - six-cylinder - petrol engine , let himself for better maintenance swing out sideways.

Arendt saw the underfloor motor as a further development of this idea, but Büssing initially did not support its concept. He therefore switched to Hanomag in 1929 , where, after further development, the world's first underfloor motor was presented in a Hanomag chassis a short time later . But even at Hanomag, his ideas were no longer supported, so that Arendt returned to Büssing in 1934. There, after Büssing's chief designer Willy Staniewicz had enforced the underfloor concept against the strongest resistance, he was able to complete the construction of the in-line six-cylinder underfloor diesel engine .

On December 14, 1935, the underfloor motor was registered as a utility model and Reich patent and presented to the public in a truck and a bus in 1936 at the International Automobile and Motorcycle Exhibition in Berlin .

Trucks with underfloor engines

MAN-Büssing with an underfloor engine located behind the front axle

The engine is not installed in front of or below the driver's cab, but behind it, under the loading area and the chassis.

Büssing BS 16 with underfloor motor
Underfloor motor of the Büssing BS 16
Büssing Supercargo deck truck - this construction would have been unthinkable without an underfloor motor
Underfloor engine of the Büssing Supercargo deck truck

Advantages of vehicles with underfloor engines

The cabs can be made much flatter and more spacious and have no arching in the floor under which the engine is located.
Engine noise, smell and waste heat are banned from the interior.
The engine is easily accessible for maintenance.
The center of gravity of the vehicle is lowered and thus better road holding is achieved.

Disadvantages of vehicles with underfloor engines

The construction of tractor units (also known as semi-trailers) is difficult because they are quite short.
The construction of construction vehicles is difficult because they require a large amount of ground clearance , which can hardly be reached due to the low-lying engine.
All-wheel drive vehicles are difficult to construct.
The engine and ancillary units are unprotected from the weather and road conditions.

Despite the advantages, trucks with underfloor engines could not establish themselves in the long term. After the takeover of Büssing by MAN , vehicles of this type continued to be manufactured by MAN for a few years, but then production was discontinued.

Buses with underfloor engines

The construction of vehicles with underfloor engines was much more common for buses than for trucks, and many manufacturers, including Volvo and the Swiss manufacturer FBW , produced such vehicles. The construction of articulated buses was easier to realize, since the central axle could be driven without major problems.

Nevertheless, most buses today have a rear engine , which is more easily accessible from the rear via a large hatch. In articulated buses, this drives the rear axle (" articulated pusher bus "); the articulation angle control regulates the joint.