PDR1/PDR2
An amendment to the Construction and Use Regulations in 1956 saw the maximum length for double-deckers increased to 30 feet (9.1 m), allowing a wider entrance to be located ahead of the front axle. This was initially to allow the driver to supervise boarding whilst the conductor collected fares, but quickly it became apparent that the design would allow for one-person-operation. Leyland took advantage of the new regulation to launch the first prototype Atlantean at the 1956 Commercial Motor Show at Earls Court. Though it featured the front entrance design that would redefine the bus industry, several factors prevented the bus going on the market. The main problem was the high level of engine noise inside the lower saloon, as the engine was still inside the body, with the compartment being used for bench seating.
Mechanically, the prototype Atlantean, 281 ATC, was similar to the Lowloader — an O.600 engine transversely mounted at the rear with a pneumo-cyclic gearbox situated in the rear offside corner providing drive in a straight line from the engine. The Atlantean had a light and strong fabricated frame. Light alloy floor plates were rivetted directly to the framework, fulfilling the dual purpose of reinforcing the frame and providing a foundation for the saloon floor. The platform-type sub-frame concept from the Lowloader was retained for the prototype. A drop-centre rear axle allowed the flat floor, only one step up from ground level, to continue for the full length of the bus.
The prototype was demonstrated around the country to various operators. It also had an unregistered sister vehicle, which was used as a testbed. Both were subsequently scrapped.
By 1958, Leyland had overcome most of the problems and moved the engine to a rear-mounted compartment outside the main body and the first production Atlantean PDR1/1, with a 16-foot-3-inch (4.95 m) wheelbase, was launched at the 1958 Commercial Motor Show. It had simpler mechanical specification than the prototype, with conventional front and rear axles, leaf springs all round and a channel section frame. Glasgow Corporation, James of Ammanford and Wallasey Corporation each put their first example of the type into service in December 1958.
From 1964, a drop-centre rear axle was available as an option for the Atlantean; the Atlanteans with drop-centre rear axles became known as the Atlantean PDR1/2 and, for the later version, the Atlantean PDR1/3. In 1967, Leyland launched the Atlantean PDR2/1 which could be fitted with 33-foot-long bodywork (10 m).
Though some operators initially continued to buy front-engined vehicles for reliability, the Atlantean became very popular. Though the National Bus Company and the Scottish Bus Group favoured the Bristol VR and Daimler Fleetline respectively, the Atlantean proved popular with municipal operators. Aberdeen, Bournemouth, Glasgow, Edinburgh, Newcastle, Manchester, Liverpool, Newport, Nottingham and Plymouth Corporations purchased large numbers of the type. A number of Atlanteans were exported, including 224 for PTC/UTA (now State Transit Authority) in Sydney, Australia.
By 1972, over 6,000 Atlanteans had entered service.
Read more about this topic: Leyland Atlantean