Daimler Roadliner
Encyclopedia
The Daimler Roadliner was a single deck bus or coach chassis built by Daimler
between 1962 and 1972. Notoriously unreliable, it topped the 1993 poll by readers of Classic Bus as the worst bus type ever, beating the Guy Wulfrunian
into second place. It was very technologically advanced, offering step-free access twenty years before other single deckers; as a coach, it was felt by industry commentators to be in advance of contemporary UK designs.
Ltd, launched its Fleetline double decker at the Earls Court
Commercial Motor show, this was the second British type of rear engined double decker. Its major advantage over the Leyland Atlantean
was that its patented concentric-drive gearbox enabled fitment as standard of a dropped-centre rear axle, allowing a body suitable for low bridges of 13 ft 5in (4.15m) high to have a centre-gangway seating plan for the full length of both decks. In comparison the low height Atlantean needed an awkward side-gangway abaft upstairs to allow legal internal headroom throughout.
The standard power unit for the Fleetline was the 150 bhp Gardner 6LX which was the most economical diesel engine in its class, and regarded by many engineers as even more reliable than the Leyland O.600. By the end of 1962 125 Fleetlines had been delivered and over 300 were on order. This pleased Daimler's new owner Jaguar Cars Ltd and Jaguar’s MD Sir William Lyons allowed work to start in mid-1962 on a new single decker chassis to replace the underfloor engined Daimler Freeline
.
Two chassis, numbers 36000 and 36001 (model SRD6) were constructed to the newly allowed maximum dimensions of 36 ft (11m) long and 8 ft 2½ in (2.5m) wide, they featured an identical drive layout to the Fleetline and shared with it a transverse rear engine location. However the power unit for these prototypes was a horizontal Daimler CD6 engine fitted with a turbocharger and arranged in the rear nearside corner of the chassis so that all ancillaries could be accessed from the engine's upper face. The radiator was mounted at the front and the chassis had conventional steel leaf springs. Chassis 36000 was shown on the Daimler stand at the 1962 Commercial Motor show and a brochure was produced for the type, although production was not an immediate prospect as the Daimler engine had ceased production. Customer interest in a modern Daimler single decker was however strong enough for Lyons to give the go ahead for a production bus of this type.
Instead of the complex transverse horizontal drive it was decided to use a vertical longitudinal rear-engined layout, Instead of the very low horizontal frame of the first two chassis, this was slightly higher at the front and ramped gently upward and tapered outward toward the rear, where the Cummins
VIM V6-200 engine was mounted. This 9.6-litre 90-degree vee-six engine developed 192 bhp at 2600rpm and was compact enough to fit under the rear seat on a bodied bus and allow drive to pass through a conventional Daimler SCG
Daimatic four-speed semi-automatic gearbox to a straight spiral-bevel rear axle manufactured by Eaton, an electrically operated two-speed axle being optional. All round air suspension was standard, with rubber and steel leaf options. Although some drawings show a front-mounted radiator, standard production versions had this mounted on the rear offside, as on the Fleetline. Other components such as the front axle, steering, brakes, driving controls etc. were similar to those of the Fleetline. The model was announced as the Roadliner model SRC6-36, this was the third and last Daimler bus chassis to be given a model name as well as an alphanumeric code.
Left hand drive chassis 36004 and Duple Coachbuilders
51 seat coach demonstrator CWK641C on chassis 36005 were shown at the 1964 show together with the first example sold to an operator, 6000EH of Potteries Motor Traction (chassis 36003). The PMT bus had a 50-seat Marshall body to BET
style, featuring no steps and a slightly ramped floor up to the rear bench. The floor level was so low side-facing bench seats had to be fitted over both sets of wheelarches, a contemporary reviewer remarked the footstools to the front benches as rather high. This bus entered service in late 1964 as number SN1000 and unprecedentedly the union branch operating it were so impressed they sent a letter of congratulation to Daimler. The coach, and a further Marshall bus CVC124C on chassis 36002 started work from early 1965 as Daimler demonstrators, the coach in particular garnishing a great deal of praise on its road tests.
factory adjacent to Guy Motors
in Wolverhampton, but this was not preceded with and all the Cummins V6-200 engines for the UK were imported from Cummins' factory in Columbus, Indiana
, USA. As well as powering the majority of Roadliners, the engine was the launch power unit for the Guy Big J lorry (Guy had been a Jaguar subsidiary since 1961) and was also fitted into Atkinson
lorries, customers including Pickfords
and the UK Ministry of Transport.
The first production Roadliners began to enter service during 1966. Early UK Roadliner customers were corporations in Wolverhampton
and Sunderland, independents West Riding Automobile Company
, Wakefield, Yorkshire and AA Motors, Ayr. PMT’s first production batch arrived in 1966-7. By the end of production in 1972 a total of 333 Roadliners had been built, besides the UK, examples had gone to Australia, Belgium, Canada, Poland, South Africa, Spain and Switzerland. Plaxton bodied the most vehicles overall and the largest export territory was South Africa, who took the last examples built.
V6 had that manufacturer's patented intermediate-pressure fuel pump and governor system, supplying the fuel to open-cup injectors through internal drilled fuel galleries, four-valve cylinder heads and tappet-actuated injection. This made the engine less than suitable for slow speed stop-start work, even at the de-rated bus setting of 150 bhp at 2100 rpm. It was also a noisy unit in operation, said to sound like a contemporary Formula One
racing car. Especially on bus work problems developed with damaged tappets, burnt valves, damaged valves, damaged pistons, damaged blocks, clogged injectors, cylinder block failures, smoke emissions and excessive wear as well as roughness and noise in operation, a tendency to refuse to re-start when hot, refusal to start in general and endemic overheating, sometimes resulting in radiator caps being blown off and steam and scalding water jetting out behind the bus. Bournemouth
Corporation had seventeen engine replacements over eleven buses during the warranty period and PMT (the largest customer with 58 buses and six coaches) had two Cummins engineers permanently resident in Stoke-on-Trent assisting their engineers until 1969.
From 1966 Daimler began to fit an alternative engine from Perkins
of Peterborough
, England, this was their V8-510 unit, a 90-degree V8 of 8.36 litres with a conventional injection layout and a maximum output of 170 bhp at 2,800 rpm, so fitted the model code was SRP8.
The final batch of Roadliners were fitted with the British Leyland 800-series V8-810, a 13.1 litre AEC-built 90-degree V8 of 13.1 litres, developing 291 bhp at 2,600 bhp, these were badged as Leylands and type SRL8. This power unit was discontinued soon after the Roadliner because it could not meet noise regulations.
Although these engines worked better than the Cummins, there were still problems with them.
Secondly drivers newly allocated the type had not driven a vehicle of equivalent power before and most were not trained in the use of the semi-automatic gearbox which lacked the engine-braking effect of a 'solid' transmission. This resulted in many engine losses due to overspeeding, there was no easy way to control this as the pure 'fluid flywheel' form of transmission was used rather than a Leyland SCG-style lock-up clutch. Problems with the braking and transmission fed back on one another and exacerbated engine damage. PMT altered the change-speed control on some of its buses from electrical to pneumatic to slow down gearchanges but at the time and with the transmission system fitted there was no way to install an effective secondary braking system.
Most of the Canadian buses had the optional Allison Transmission
torque converter transmission, but the sole survivor now has a Detroit Diesel
6V-71 engine and a Fuller layshaft gearbox.
and used it for sightseeing tours.
The Daimler CRC6-36 was a double decker with a modified Roadliner driveline to take 86 seat 11m x 2.5m double deck bodywork with twin staircases, the rearmost rising over the engine opposite an exit door in the rear overhang. One of these was sold to Walsall Corporation and the other sixteen went to Johannesburg. The Walsall bus, shown at Earls Court in 1968 is preserved at Whythall bus museum who also have the last working Cummins-powered Roadliner, a former Wolverhampton bus.
by threatening to order 33 foot (10 metre) Roadliners instead. Daimler announced a 33-foot option on launch but none were ever built. SRC6-33 would have been the type code.
In 1968 a 12 m (40 ft) version was announced as the SRC-40, but the only batch ordered was later cancelled.
Prior to the BLMC merger Sir William Lyons had commissioned an all-alloy 6.7-litre V8 turbodiesel engine from Rolls-Royce, it was derived from the petrol engine used in the Silver Shadow car, examples were on test by the time British Leyland had been formed, but the project was cancelled on the orders of BLMC chief executive Lord Stokes.
Daimler Motor Company
The Daimler Motor Company Limited was an independent British motor vehicle manufacturer founded in London by H J Lawson in 1896, which set up its manufacturing base in Coventry. The right to the use of the name Daimler had been purchased simultaneously from Gottlieb Daimler and Daimler Motoren...
between 1962 and 1972. Notoriously unreliable, it topped the 1993 poll by readers of Classic Bus as the worst bus type ever, beating the Guy Wulfrunian
Guy Wulfrunian
The Guy Wulfrunian was a front-engine double-decker bus chassis produced by Guy from 1959 to 1965.-History:The Wulfrunian was developed jointly by Guy and the West Riding Automobile Company, and, of 137 vehicles built, 126 went to West Riding...
into second place. It was very technologically advanced, offering step-free access twenty years before other single deckers; as a coach, it was felt by industry commentators to be in advance of contemporary UK designs.
Background and prototypes
In 1960 Transport Vehicles (Daimler) Ltd, The Commercial Vehicle subsidiary of Daimler Motor CompanyDaimler Motor Company
The Daimler Motor Company Limited was an independent British motor vehicle manufacturer founded in London by H J Lawson in 1896, which set up its manufacturing base in Coventry. The right to the use of the name Daimler had been purchased simultaneously from Gottlieb Daimler and Daimler Motoren...
Ltd, launched its Fleetline double decker at the Earls Court
Earls Court
Earls Court is a district in the Royal Borough of Kensington and Chelsea in London, England. It is an inner-city district centred on Earl's Court Road and surrounding streets, located 3.1 miles west south-west of Charing Cross. It borders the sub-districts of South Kensington to the East, West...
Commercial Motor show, this was the second British type of rear engined double decker. Its major advantage over the Leyland Atlantean
Leyland Atlantean
The Leyland Atlantean is a model of double-decker bus built by Leyland in the United Kingdom from 1958 to 1986....
was that its patented concentric-drive gearbox enabled fitment as standard of a dropped-centre rear axle, allowing a body suitable for low bridges of 13 ft 5in (4.15m) high to have a centre-gangway seating plan for the full length of both decks. In comparison the low height Atlantean needed an awkward side-gangway abaft upstairs to allow legal internal headroom throughout.
The standard power unit for the Fleetline was the 150 bhp Gardner 6LX which was the most economical diesel engine in its class, and regarded by many engineers as even more reliable than the Leyland O.600. By the end of 1962 125 Fleetlines had been delivered and over 300 were on order. This pleased Daimler's new owner Jaguar Cars Ltd and Jaguar’s MD Sir William Lyons allowed work to start in mid-1962 on a new single decker chassis to replace the underfloor engined Daimler Freeline
Daimler Freeline
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 underfloor-engined bus and coach chassis but became a substantial export success....
.
Two chassis, numbers 36000 and 36001 (model SRD6) were constructed to the newly allowed maximum dimensions of 36 ft (11m) long and 8 ft 2½ in (2.5m) wide, they featured an identical drive layout to the Fleetline and shared with it a transverse rear engine location. However the power unit for these prototypes was a horizontal Daimler CD6 engine fitted with a turbocharger and arranged in the rear nearside corner of the chassis so that all ancillaries could be accessed from the engine's upper face. The radiator was mounted at the front and the chassis had conventional steel leaf springs. Chassis 36000 was shown on the Daimler stand at the 1962 Commercial Motor show and a brochure was produced for the type, although production was not an immediate prospect as the Daimler engine had ceased production. Customer interest in a modern Daimler single decker was however strong enough for Lyons to give the go ahead for a production bus of this type.
Instead of the complex transverse horizontal drive it was decided to use a vertical longitudinal rear-engined layout, Instead of the very low horizontal frame of the first two chassis, this was slightly higher at the front and ramped gently upward and tapered outward toward the rear, where the Cummins
Cummins
Cummins Inc. is a Fortune 500 corporation that designs, manufactures, distributes and services engines and related technologies, including fuel systems, controls, air handling, filtration, emission control and electrical power generation systems...
VIM V6-200 engine was mounted. This 9.6-litre 90-degree vee-six engine developed 192 bhp at 2600rpm and was compact enough to fit under the rear seat on a bodied bus and allow drive to pass through a conventional Daimler SCG
Self-Changing Gears
Self-Changing Gears was a British company, set up and owned equally by Walter Gordon Wilson and John Davenport Siddeley to develop and exploit the Wilson or pre-selector gearbox...
Daimatic four-speed semi-automatic gearbox to a straight spiral-bevel rear axle manufactured by Eaton, an electrically operated two-speed axle being optional. All round air suspension was standard, with rubber and steel leaf options. Although some drawings show a front-mounted radiator, standard production versions had this mounted on the rear offside, as on the Fleetline. Other components such as the front axle, steering, brakes, driving controls etc. were similar to those of the Fleetline. The model was announced as the Roadliner model SRC6-36, this was the third and last Daimler bus chassis to be given a model name as well as an alphanumeric code.
Left hand drive chassis 36004 and Duple Coachbuilders
Duple Coachbuilders
Duple was best known as a British manufacturer of coach and bus bodywork from 1919 until 1989.-History:Duple Bodies & Motors Ltd was formed in 1919 by Herbert White in Hornsey, London...
51 seat coach demonstrator CWK641C on chassis 36005 were shown at the 1964 show together with the first example sold to an operator, 6000EH of Potteries Motor Traction (chassis 36003). The PMT bus had a 50-seat Marshall body to BET
Bet
Bet or BET may refer to:* A wager in gambling* Basic Economics Test * Bet , the second letter in many Semitic alphabets, including Aramaic, Hebrew, Phoenician and Syriac* Brunauer-Emmett-Teller isotherm. See BET_theory...
style, featuring no steps and a slightly ramped floor up to the rear bench. The floor level was so low side-facing bench seats had to be fitted over both sets of wheelarches, a contemporary reviewer remarked the footstools to the front benches as rather high. This bus entered service in late 1964 as number SN1000 and unprecedentedly the union branch operating it were so impressed they sent a letter of congratulation to Daimler. The coach, and a further Marshall bus CVC124C on chassis 36002 started work from early 1965 as Daimler demonstrators, the coach in particular garnishing a great deal of praise on its road tests.
Production
To begin with it was intended to build the Cummins V6 in the UK in a joint-venture Jaguar-Cummins operation at the former Henry MeadowsHenry Meadows
Henry Meadows of Wolverhampton, England were major suppliers of engines and transmissions, to the smaller companies in the British motor industry...
factory adjacent to Guy Motors
Guy Motors
Guy Motors was a British company based in Fallings Park, Wolverhampton that made cars, lorries, buses, and trolleybuses.-History:Guy Motors Ltd was founded in 1914 by Sydney Guy who had been the Works Manager of nearby Sunbeam. A factory was built on the site at Fallings Park, Wolverhampton...
in Wolverhampton, but this was not preceded with and all the Cummins V6-200 engines for the UK were imported from Cummins' factory in Columbus, Indiana
Columbus, Indiana
Columbus is a city in and the county seat of Bartholomew County, Indiana, United States. The population was 44,061 at the 2010 census, and the current mayor is Fred Armstrong. Located approximately 40 miles south of Indianapolis, on the east fork of the White River, it is the state's 20th largest...
, USA. As well as powering the majority of Roadliners, the engine was the launch power unit for the Guy Big J lorry (Guy had been a Jaguar subsidiary since 1961) and was also fitted into Atkinson
Atkinson
- Places :In Canada:*Atkinson, Nova Scotia*Atkinson Point, Northwest Territories*Atkinson, OntarioIn the United States of America:*Atkinson, Illinois*Atkinson, Indiana*Atkinson, Maine*Atkinson, Nebraska*Atkinson, New Hampshire*Atkinson, North Carolina...
lorries, customers including Pickfords
Pickfords
Pickfords is a moving company based in the United Kingdom, part of the Moving Services Group UK Ltd.The business is believed to have been founded in the 17th century, making it one of the UK's oldest functioning companies. The earliest record is of a William Pickford, a carrier who worked south of...
and the UK Ministry of Transport.
The first production Roadliners began to enter service during 1966. Early UK Roadliner customers were corporations in Wolverhampton
Wolverhampton
Wolverhampton is a city and metropolitan borough in the West Midlands, England. For Eurostat purposes Walsall and Wolverhampton is a NUTS 3 region and is one of five boroughs or unitary districts that comprise the "West Midlands" NUTS 2 region...
and Sunderland, independents West Riding Automobile Company
West Riding Automobile Company
The West Riding Automobile Company, under the fleet name of West Riding, was a bus company that served the Wakefield area of Yorkshire, England from 1923.-Company history:...
, Wakefield, Yorkshire and AA Motors, Ayr. PMT’s first production batch arrived in 1966-7. By the end of production in 1972 a total of 333 Roadliners had been built, besides the UK, examples had gone to Australia, Belgium, Canada, Poland, South Africa, Spain and Switzerland. Plaxton bodied the most vehicles overall and the largest export territory was South Africa, who took the last examples built.
Engine
The CumminsCummins
Cummins Inc. is a Fortune 500 corporation that designs, manufactures, distributes and services engines and related technologies, including fuel systems, controls, air handling, filtration, emission control and electrical power generation systems...
V6 had that manufacturer's patented intermediate-pressure fuel pump and governor system, supplying the fuel to open-cup injectors through internal drilled fuel galleries, four-valve cylinder heads and tappet-actuated injection. This made the engine less than suitable for slow speed stop-start work, even at the de-rated bus setting of 150 bhp at 2100 rpm. It was also a noisy unit in operation, said to sound like a contemporary Formula One
Formula One
Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single seater auto racing sanctioned by the Fédération Internationale de l'Automobile . The "formula" designation in the name refers to a set of rules with which...
racing car. Especially on bus work problems developed with damaged tappets, burnt valves, damaged valves, damaged pistons, damaged blocks, clogged injectors, cylinder block failures, smoke emissions and excessive wear as well as roughness and noise in operation, a tendency to refuse to re-start when hot, refusal to start in general and endemic overheating, sometimes resulting in radiator caps being blown off and steam and scalding water jetting out behind the bus. Bournemouth
Bournemouth
Bournemouth is a large coastal resort town in the ceremonial county of Dorset, England. According to the 2001 Census the town has a population of 163,444, making it the largest settlement in Dorset. It is also the largest settlement between Southampton and Plymouth...
Corporation had seventeen engine replacements over eleven buses during the warranty period and PMT (the largest customer with 58 buses and six coaches) had two Cummins engineers permanently resident in Stoke-on-Trent assisting their engineers until 1969.
From 1966 Daimler began to fit an alternative engine from Perkins
Perkins
-People:The name is of Welsh origin from Perthyn, relative or belonging to a particular person or family, and also thought to be the Anglicized form of Peredur, from Medieval Welsh...
of Peterborough
Peterborough
Peterborough is a cathedral city and unitary authority area in the East of England, with an estimated population of in June 2007. For ceremonial purposes it is in the county of Cambridgeshire. Situated north of London, the city stands on the River Nene which flows into the North Sea...
, England, this was their V8-510 unit, a 90-degree V8 of 8.36 litres with a conventional injection layout and a maximum output of 170 bhp at 2,800 rpm, so fitted the model code was SRP8.
The final batch of Roadliners were fitted with the British Leyland 800-series V8-810, a 13.1 litre AEC-built 90-degree V8 of 13.1 litres, developing 291 bhp at 2,600 bhp, these were badged as Leylands and type SRL8. This power unit was discontinued soon after the Roadliner because it could not meet noise regulations.
Although these engines worked better than the Cummins, there were still problems with them.
Transmission system
There were two problems with the Daimatic transmission system; Firstly with excessive wear, as with the Cummins it was working at its design limits for power and torque and but for the effects of altitude it would have been way over its limits on the Pretoria buses.Secondly drivers newly allocated the type had not driven a vehicle of equivalent power before and most were not trained in the use of the semi-automatic gearbox which lacked the engine-braking effect of a 'solid' transmission. This resulted in many engine losses due to overspeeding, there was no easy way to control this as the pure 'fluid flywheel' form of transmission was used rather than a Leyland SCG-style lock-up clutch. Problems with the braking and transmission fed back on one another and exacerbated engine damage. PMT altered the change-speed control on some of its buses from electrical to pneumatic to slow down gearchanges but at the time and with the transmission system fitted there was no way to install an effective secondary braking system.
Most of the Canadian buses had the optional Allison Transmission
Allison Transmission
Allison Transmission is an American manufacturer of commercial duty automatic transmissions and hybrid propulsion systems. Allison products are specified by over 250 of the world’s leading vehicle manufacturers and are used in many market sectors including bus, refuse, fire, construction,...
torque converter transmission, but the sole survivor now has a Detroit Diesel
Detroit Diesel
As a corporation, Daimler Trucks North America has decided to rename the company "DETROIT".Detroit Diesel Corporation is an American-based diesel engine producer headquartered in Detroit, Michigan, USA...
6V-71 engine and a Fuller layshaft gearbox.
Chassis
Handling, braking and tyre problems seemed to be endemic regardless of the suspension system used. The rubber (Metalastic 'Toggle-Link') suspension was of a unique design and difficult and expensive to repair.Body
There were problems with wear and tear on the bodywork caused by chassis flexing, the latter exacerbated on dual-door bodies. The optional Clayton Compas automatic heating and ventilation system was both unreliable and very noisy.The end
In 1966 Daimler launched a single deck variant of the Fleetline and thereafter marketed the SRP8 as a coach chassis in the UK, the final demonstrator had a Plaxton semi-coach body and was sold to City of Oxford Motor Service to work London Expresses. In 1970 Daimler, now part of British Leyland announced the end of Roadliner production.Double-deck variants
The Spanish example was the sole double-deck Roadliner, it was exported in 1967 but not bodied until 1972. Autopullman SA of Madrid had it fitted with a 4m (12 ft 9in) high CH38/32F body by IrizarIrizar
Irizar Group is a Spanish-based builder of luxury coach vehicle bodies, established in 1889. It is located in Ormaiztegi in the Basque Country, Spain...
and used it for sightseeing tours.
The Daimler CRC6-36 was a double decker with a modified Roadliner driveline to take 86 seat 11m x 2.5m double deck bodywork with twin staircases, the rearmost rising over the engine opposite an exit door in the rear overhang. One of these was sold to Walsall Corporation and the other sixteen went to Johannesburg. The Walsall bus, shown at Earls Court in 1968 is preserved at Whythall bus museum who also have the last working Cummins-powered Roadliner, a former Wolverhampton bus.
Might have beens
Manchester Corporation persuaded Leyland to build the Leyland Panther CubLeyland Panther Cub
The Leyland Panther Cub was a rear-engined single-decker bus built by Leyland Motor Corporation in the United Kingdom.It was a derivative of the Panther that Leyland were forced into building for an influential customer, it was only offered on the home market, and only bought by operators in...
by threatening to order 33 foot (10 metre) Roadliners instead. Daimler announced a 33-foot option on launch but none were ever built. SRC6-33 would have been the type code.
In 1968 a 12 m (40 ft) version was announced as the SRC-40, but the only batch ordered was later cancelled.
Prior to the BLMC merger Sir William Lyons had commissioned an all-alloy 6.7-litre V8 turbodiesel engine from Rolls-Royce, it was derived from the petrol engine used in the Silver Shadow car, examples were on test by the time British Leyland had been formed, but the project was cancelled on the orders of BLMC chief executive Lord Stokes.
Sources
- Townsin, Daimler, Shepperton 2000
- Townsin (ed) Buses Illustrated 116, Shepperton, November 1964
- Brown, Half Cab Twilight, Harrow Weald 2001
- Griffin, Once Heard, Never Forgotten…, in Morris (ed) Buses Extra 39, Weybridge 1986
- Booth (ed) Classic Bus 7, Edinburgh, October 1993
- Booth (ed) Bus Stop, Shepperton 1968
- www.buslistsontheweb.co.uk