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. The United States defines a "commercial motor vehicle" as any self-propelled or towed vehicle used on a public highway in interstate commerce to ...

introduced by Dennis Brothers of

Guildford Guildford () is a town in west Surrey, around southwest 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 name "Guildf ...

(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 requirem ...

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

fire engines The Fire Engines were a post-punk band from Edinburgh, Scotland. The Fire Engines were an influence on many bands that followed, including Franz Ferdinand and The Rapture, with Meat Whiplash and The Candyskins both taking their names from Fire ...

and

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

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 energy. Pumps can be classified into three major groups according to the method they u ...

was a

centrifugal pump Centrifugal pumps are used to transport fluids by the 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 a sub-class of dynamic ...

, 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 ...

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 owned a Coventry proprietary engine building and gearbox manufacturing business established in 1899. Many early motor vehicle manufacturers making only a small number of vehicles bought in their major components and Whit ...

Coventry Coventry ( or ) is a City status in the United Kingdom, city in the West Midlands (county), West Midlands, England. It is on the River Sherbourne. Coventry has been a large settlement for centuries, although it was not founded and given its ...

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

References

{{Dennis Fire engines N

Specification

History

See also

References