The Dennis N-Type is a model of

commercial vehicle A commercial vehicle is any type of motor vehicle used for transporting goods or paying passengers. Depending on laws and designations, a commercial vehicle can be any broad type of motor vehicle used commercially or for business purposes. Classi ...

introduced by Dennis Brothers of

Guildford Guildford () is a town in west Surrey, England, around south-west of central London. As of the 2011 census, the town has a population of about 77,000 and is the seat of the wider Borough of Guildford, which had around inhabitants in . The nam ...

(later

Dennis Specialist Vehicles Dennis Specialist Vehicles was an English manufacturer of commercial vehicles based in Guildford, building buses, fire engines, lorries (trucks) and municipal vehicles such as dustcarts. All vehicles were made to order to the customer's require ...

) in around 1905. It was the basis for their early

fire engines A fire engine or fire truck (also spelled firetruck) is a vehicle, usually a specially designed or modified truck, that functions as a firefighting apparatus. The primary purposes of a fire engine include transporting firefighters and water to ...

and

truck A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construct ...

Specification

The "N-Type" chassis was constructed from rolled steel channel; riveted and braced at appropriate points. It incorporated a sub frame on which the engine and gearbox were mounted. As for later Dennis fire engines, the

water pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of applications such ...

was a

centrifugal pump Centrifugal pumps are used to transport fluids by the Energy transformation, conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are ...

, rather than the

piston pump A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases. They can operate over a wide range of pressures. High pressure operation ca ...

s used by other makers. This was more complex to build than the long-established piston pumps, but had advantages in operation. Where water was supplied under pressure from a

hydrant A hydrant is an outlet from a fluid main often consisting of an upright pipe with a valve attached, from which fluid (e.g. water or fuel) can be tapped. Depending on the fluid involved, the term may refer to: * Fire hydrant for firefighting water ...

, rather than by suction from a pond, this additional pressure was boosted through the centrifugal pump, whereas a piston pump would have throttled it. Piston pumps also gave a pulsating outlet pressure which required an air-filled receiver to even this out. A drawback of the usual centrifugal design was the considerable axial force generated by the pump impeller, requiring a

thrust bearing A thrust bearing is a particular type of rotary bearing. Like other bearings they permanently rotate between parts, but they are designed to support a predominantly axial load. Thrust bearings come in several varieties. *''Thrust ball bearing ...

. Dennis avoided this by using a doubled-sided impeller which balanced the overall force.

History

The majority of Dennis commercial vehicles were built on this type of chassis until further chassis designs were introduced. The last vehicles based on this design were produced in the late 1920s. The chassis was generally fitted with engines by

White and Poppe White and Poppe Limited was a proprietary engine building and gearbox manufacturing business established in Coventry in 1899 by Alfred James White (1870-) and Norwegian Peter August Poppe (1870-1933). Many early motor vehicle manufacturers bou ...

Coventry Coventry ( or rarely ) is a City status in the United Kingdom, cathedral city and metropolitan borough in the West Midlands (county), West Midlands county, in England, on the River Sherbourne. Coventry had been a large settlement for centurie ...

. White and Poppe were bought by Dennis Brothers in 1919.

References

{{Dennis Fire engines N

Specification

History

See also

References