In the immediate post-war era bus operators across Britain were facing a reduction in the numbers of passengers carried, and manufacturers began looking at ways to economise. Some experimental rear-engined buses had been produced before the war, but none had made it beyond prototype stage. The need to prevent the intrusion of the engine into the passenger area was a priority. This requirement led to several underfloor engined single deck designs. However, such designs raised the height of the vehicle floor, forcing additional steps at the entrance. On double deckers, problems were amplified, causing either an increase in overall height or an inadequate interior headroom.
Leyland began experimenting with ideas for a rear engined double decker in 1952. A prototype was built and fitted with a turbocharged version of the Leyland O.350 engine, transversely mounted at the rear of the sub frame. An automatic clutch andgearbox were fitted. The vehicle was designated the PDR1 (R for 'Rear-engined') and registered STF90. It actually spent a few days on trial with Devon General in 1955.
In 1956 a second prototype, XTC684 was constructed with an MCW body, and fitted with the more powerful O.600 engine fitted across the frame, with a centrifugal clutch, pneumo-cyclic gearbox and angled drive. Seating capacity was 78 and Leyland christened it the “Lowloader“.
Though two prototypes were thoroughly tested, the same problem of a front-engined bus remained; rear entrances meant that the space alongside the driver was wasted. 1956 saw the maximum length for double-deckers increased to 30ft, allowing a wider entrance to be located ahead of the front axle. This was intended to allow the driver to supervise boarding whilst the conductor collected fares, but it soon became apparent that the design would allow for one-person-operation. Leyland took advantage of this to launch the first prototype Atlantean at the 1956 Commercial Motor Show. Though it had a front entrance the high level of engine noise inside the lower saloon prevented it going on the market. 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 - O.600 transversely mounted engine situated in the rear offside corner providing drive in a straight line from the engine. 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 the majority 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 16ft 3in wheelbase was launched at that year’s Commercial Motor Show. It was simpler mechanically than the prototype, with conventional front and rear axles, leaf springs all round and a channel section frame.
The first production examples entered service in December 1958.Devon General had traditionally been an AEC customer, but when they required a rear engined vehicle Southall’s finest had no such design on the table. It would be 1966 before AEC built their one and only such bus, the rear engined Routemaster FRM1.
The first production Atlantean went to Wallasey Corporation in December 1958 and has thankfully, as befits a vehicle of its significance, been preserved. Glasgow Corporation's first was purchased the same month. In the following posts I will be looking at Devon General's Atlaneans in more detail.
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