Duple 425

Last updated March 26, 2019

The Duple 425 was a coach design built by Hestair Duple in the late 1980s, and briefly by Plaxton in the early 1990s.

A coach is a bus used for longer-distance service, in contrast to transit buses that are typically used within a single metropolitan region. Often used for intercity—or even international—bus service, other coaches are also used for private charter for various purposes.

Duple Coachbuilders was a coach and bus bodybuilder in England from 1919 until 1989.

Plaxton is an English builder of bus and coach vehicle bodies based in Scarborough. Founded in 1907 by Frederick William Plaxton, it became a subsidiary of Alexander Dennis in May 2007.

It was a fully integral coach, unlike most contemporary British designs which had a separate body and chassis, and was notable for its streamlined design with a sloping upper windscreen and a drag coefficient of Cd =0.425, hence the model designation.

The drag coefficient is a common measure in automotive design as it pertains to aerodynamics. Drag is a force that acts parallel and in the same direction as the airflow. The drag coefficient of an automobile impacts the way the automobile passes through the surrounding air. When automobile companies design a new vehicle they take into consideration the automobile drag coefficient in addition to the other performance characteristics. Aerodynamic drag increases with the square of speed; therefore it becomes critically important at higher speeds. Reducing the drag coefficient in an automobile improves the performance of the vehicle as it pertains to speed and fuel efficiency. There are many different ways to reduce the drag of a vehicle. A common way to measure the drag of the vehicle is through the drag area.

History

In the early 1980s the British coach market underwent considerable change, putting pressure on the established British coachbuilding firms which had previously dominated the market. In the 1970s the great majority of coaches sold in the UK had comprised a British-built chassis with separately assembled bodywork by one of the two dominant domestic coachbuilders, Duple and Plaxton. The highest sales volumes were achieved by lightweight chassis such as the Bedford Y series and Ford R series, and even imported chassis such as the Volvo B58 usually carried Duple or Plaxton coachwork. However, the 1980s saw a move away from lightweights towards heavier and more sophisticated designs, increasingly supplied by foreign chassis and bodywork manufacturers. Some of the foreign coaches now selling in Britain were of integral construction, and Duple wished to produce an integral design of its own to compete more effectively with these. The first attempts were a pair of prototypes built in 1983, one of which was a semi-integral variant of the Duple Caribbean body built on German Auwärter Neoplan N716 running gear, which remained a one-off. The other prototype employed Dutch BOVA Europa running gear within a unique style of semi-integral body known as the Duple Calypso, and a further 50 production vehicles of this type were built for the 1984 season.

The Bedford Y series was a family of single-decker bus and single-decker coach chassis manufactured by Bedford from 1970 to 1986, when Bedford ceased bus and truck production.

The Ford R series was a range of single-decker bus and single-decker coach chassis, built by Ford UK that evolved from designs made by Thames Trader until the mid-1960s. A number of components were shared with the D-series lorry, including the engine which was mounted vertically at the front of the vehicle, ahead of the front axle so as to provide a passenger entrance opposite the driver. The original R192 and longer R226 models later became the R1014 and R1114 variants which with constant revision and upgrading had become R1015 and R1115 by the mid-1980s. In an attempt to lower the floor height of the vehicle, the turbocharged diesel engine was tilted over to one side around 1978. Synchromesh transmission was fitted as standard but some later examples were equipped with Allison automatic gearboxes to ease the driver's workload in urban areas.

The Volvo B58 was a mid-engined single-decker bus, double-decker bus, single-decker articulated bus and single-decker coach chassis manufactured by Volvo in Sweden from 1966 until early 1982. It was succeeded by the B10M.

However, in June 1983 Duple had been sold to the Hestair Group, which had previously acquired the British chassis manufacturer Dennis Brothers of Guildford. Duple was renamed Hestair Duple, and rather than persisting with semi-integrals built on third party running gear it was decided to develop a fully integral coach with running units from sister company Hestair Dennis. As a result the Duple 425 was developed, and production commenced in 1985. The 425 had a rear-mounted Cummins or DAF engine with automatic transmission, and a typical layout seated 57 passengers (or 53 with a toilet fitted), which was a relatively high capacity for a 12 metre coach at the time.^[1]

Dennis Brothers Limited was an English manufacturer of commercial vehicles based in Guildford. It is best remembered as a manufacturer of buses, fire engines and lorries (trucks) and municipal vehicles such as dustcarts. All vehicles were made to order to the customer's requirements and more strongly built than mass production equivalents. For most of the 20th century Dennis Brothers was Guildford's main employer.

Cummins is an American Fortune 500 corporation that designs, manufactures, and distributes engines, filtration, and power generation products. Cummins also services engines and related equipment, including fuel systems, controls, air handling, filtration, emission control, electrical power generation systems, and semi trucks. Headquartered in Columbus, Indiana, United States, Cummins sells in approximately 190 countries and territories through a network of more than 600 company-owned and independent distributors and approximately 6,000 dealers. Cummins reported net income of $999 million on sales of $20.4 billion in 2017.

Sales of the 425 were limited with only about 130 vehicles being completed, although many of them enjoyed unusually long service lives.^[2]^[3] Most of Duple's output continued to be conventional bodies on third-party chassis, but overall sales volumes continued to decline leading to financial pressures. In November 1988, the coachbuilding business was sold and renamed Duple International. In July 1989 the Blackpool factory was closed down, and the manufacturing rights and jigs for Duple coach products sold to its main domestic competitor, Plaxton, for £4 million.

Blackpool is a seaside resort on the Lancashire coast in North West England. The town is on the Irish Sea, between the Ribble and Wyre estuaries, 15 miles (24 km) northwest of Preston, 27 miles (43 km) north of Liverpool, 28 miles (45 km) northwest of Bolton and 40 miles (64 km) northwest of Manchester. It had an estimated population of 139,720 at the 2011 Census, making it the most populous town in Lancashire.

The 425 design was modified by Plaxton and re-entered production in 1991 as the Plaxton 425, which was assembled by Plaxton's French subsidiary Carrosserie Lorraine. However the Lorraine factory closed in 1992 after only 12 further 425 models had been built.^[4]

Related Research Articles

Alexander Dennis is a British bus building company based in Scotland. The largest bus and coach manufacturer in the United Kingdom, Alexander Dennis has manufacturing plants and partnerships in Canada, China, Europe, Hong Kong, Malaysia, New Zealand, South Africa and the United States.

The Dennis Dart is a rear-engined single-decker midibus chassis that was introduced by Dennis Specialist Vehicles of Guildford, England in 1989, replacing the Dennis Domino. Initially built as a high-floor design, In 1996 the low-floor second generation Dennis Dart SLF was launched. In 2001, production of the Dart SLF passed to TransBus International, during which time it was sold as the TransBus Dart SLF; Alexander Dennis took over production in 2004, renaming the product as the Alexander Dennis Dart SLF.

Duple Metsec was a bus bodywork builder based in West Midlands of England in the United Kingdom. It usually supplied body kits for bus assembly overseas.

The Volvo B10M is a mid-engined city bus and coach chassis manufactured by the Swedish automaker Volvo between 1978 and 2003. It succeeded the B58 and was equipped with the same 9.6-litre horizontally mounted Volvo diesel engine mounted under the floor behind the front axle. An articulated version under the model name Volvo B10MA was also offered, as was a semi-integral version known as the C10M, with the engine in the middle of the chassis.

The Bedford OB was a bus chassis manufactured by Bedford from 1939.

Barton Transport was a bus company that operated in Nottinghamshire from 1908 until 1989.

The Dennis Dorchester was a mid-engined heavy-duty single deck coach or bus chassis manufactured by Dennis in small numbers between 1983 and 1988.

The Duple Dominant was a design of a coach bodywork built by Duple between 1972 and 1987. It introduced an all-steel structure and replaced the wooden-framed Duple Vega, Viceroy and Vista models.

The Bedford VAL is a type of coach chassis that was built by Bedford in the United Kingdom from the mid-1960s to the early 1970s. It was unusual at the time for its multi-axle design, in a "chinese six" wheelplan, i.e. with two front steering axles.

Bus manufacturing, a sector of the automotive industry, manufactures buses and coaches.

The Leyland Tiger Cub was a lightweight underfloor-engined chassis manufactured by Leyland between 1952 and 1970.

The Daimler Freeline is an underfloor-engined bus chassis built by Daimler between 1951 and 1964. It was a very poor seller in the UK market for an underfloor-engined bus and coach chassis, but became a substantial export success.

H. V. Burlingham was a British coachbuilding business based in Blackpool, Lancashire from 1928 until 1960 when they were taken over by London-based rivals Duple Motor Bodies. Duple initially renamed Burlingham as Duple (Northern) but in 1969 they closed their Hendon factory and concentrated production in Blackpool. Duple coach bodies were built in the former Burlingham premises until Duple itself was liquidated in 1989.

The Duple Caribbean was design of a coach bodywork built by Duple between 1983 and 1986. It replaced the high-floor Goldliner variant of the long-running Duple Dominant range as Duple's premium coach body of the mid 1980s.

The Duple Laser was a design of a coach bodywork built by Duple between 1983 and 1986. It replaced the long-running Duple Dominant body as Duple's standard medium-height coach of the mid 1980s.

The Duple Calypso was a design of semi-integral coach built by Duple between 1983 and 1984 using running gear from the Bova Europa.

The Duple 300 Series were a range of bus and coach bodywork built by Duple between 1985 and 1989. The range comprised the 3.0m high Duple 300 service bus, the 3.2m high Duple 320 coach, and the taller 3.4m high Duple 340 coach. The 320 and 340 coaches were announced at the Bus and Coach Show at Earls Court in September 1985 as replacements for the previous Laser and Caribbean. Deliveries of these models commenced in 1986, whilst the 300 bus was launched in 1987 as a replacement for the Dominant Bus. After Duple closed down the designs were sold to Plaxton and a small number of additional 320 bodies were built as the Plaxton 321.

References

↑ Hymans, Michael (2016). British Coaching: Chassis Manufacturers, Coachbuilders and Operators.
↑ "Duple - 1983-1985 Seasons". Bus Lists on the Web. Retrieved 29 November 2016.
↑ "Duple - 1985-1989 Seasons". Bus Lists on the Web. Retrieved 29 November 2016.
↑ "Plaxton's". Grace's Guide to British Industrial History. Retrieved 29 November 2016.

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[1] Hymans, Michael (2016). British Coaching: Chassis Manufacturers, Coachbuilders and Operators.

[2] "Duple - 1983-1985 Seasons". Bus Lists on the Web. Retrieved 29 November 2016.

[3] "Duple - 1985-1989 Seasons". Bus Lists on the Web. Retrieved 29 November 2016.

[4] "Plaxton's". Grace's Guide to British Industrial History. Retrieved 29 November 2016.