AEC-PRV Routemaster
29-September-2022The last of our trio is the Bristol-ECW Lodekka.
I say Bristol-ECW because, like the Routemaster, this model required the body to carry quite a share of the stresses and strains inflicted by the suspension, and so Eastern Coachworks engineers would be closely involved in the basic design. Indeed, the makers’ plate on each vehicle made it clear this was a joint enterprise.
The low bridge issue was more of a concern to the Tilling Group companies than most other operators. Their buses ran on inter-urban routes, often popular enough to warrant using double-deckers.
Many of these routes had to negotiate obstacles like railway bridges. Victorian railway builders saved money by restricting the headroom under these bridges, which was fine for most wagons and lorries, but awkward for double-decker buses.
The original solution was the lowbridge layout already explained – pioneered by Leyland and adopted by other bodybuilders until the early 1950s.
But it was disliked by passengers, and loathed by conductors, who found collecting fares upstairs particularly difficult. There had to be a better way. If the lower deck floor could be lowered, then the headroom upstairs could be increased without making the bus too tall to get under low bridges.
In a traditional bus chassis, the engine sat between the front wheels, the flywheel lay just in front of the bulkhead at the front of the lower saloon, and the gearbox sat under the gangway. A propeller shaft running more or less down the centre-line of the chassis took the drive to the rear axle, where the differential conveyed it to each of the back wheels.
The gangway had to be high enough to clear all this stuff, meaning there was a step from the rear platform into the lower saloon. Bristol and ECW came up with a way round this.
Both firms began as manufacturing units within bus operating companies. Bristol Tramways Company had begun making some of its own bus chassis as early as 1908. It was closely associated with the Bristol Aircraft Company and there was plenty of dialogue between engineers at the two outfits.
Eastern Coach Works was the in-house bodybuilder for the Eastern Counties operating company, having been established by its predecessor, United Automobile Services, in 1920.
Both concerns were absorbed into the Tilling Group in the 1930s and the other companies in the combine became important customers for Bristol and ECW, often buying buses with that chassis and body combination. The consequences from the nationalisation of Tilling, Bristol and ECW in 1948 gave them no choice.
Bristol’s second-generation double-decker was the K series, introduced in 1937. Like other manufacturers at the time, Bristol designed and built most of the running units – notably the engine, gearbox and rear axle.
After the Second World War, Bristol built large numbers of its 8-foot wide KSW model, generally fitted with an attractive ECW body, either in highbridge or lowbridge format.
The company was hoping to develop a strong export business and in 1948 displayed two new chassis at the Commercial Vehicle exhibition, one for double-deckers and one for single-deckers. They featured a wide, exposed radiator grille and in most respects looked pretty conventional.
But Bristol and ECW engineers were already thinking about cracking the lowbridge problem by taking a radical approach to vehicle design.
In 1949 the first prototype double-decker was built that stood at 13 feet 4 inches tall, versus the 14 foot 4 inches of a highbridge KSW, yet had normal two plus two seating upstairs.
Someone came up with the catchy name Lodekka and the first two prototypes, with ECW bodies, went into trial service with Bristol Omnibus Company and West Yorkshire Services in 1950. One of them was proudly exhibited at the Festival of Britain in 1951.
Bristol and ECW were not in a hurry to get the Lodekka into production. Learning lessons from those first two prototypes, some fundamental modifications were made to the drive line design and six pre-production Lodekkas were built.
These were slightly longer and wider than the prototypes. They were sent to six different operators in the Tilling Group, presenting a variety of operating environments, from heavy urban, through to largely rural, and across England and Wales.
The Lodekka entered full production in 1955 as the LD series, with 58 seats in its 27-foot long standard form. All LDs had rear platforms – folding doors being an option.
Almost 2,179 were sold. Big operators were Crosville, Bristol, Eastern National and United Counties. Companies within the Scottish Bus Group also took the LD Lodekka. They were nationalised but not constrained in what makes they could buy. Scottish Omnibuses, Western SMT, W. Alexander & Sons, and Central SMT each took well over 100.
Of course, many operators did not need the lowbridge capability of the LD Lodekka, but it proved a dependable workhorse for fleets which actually had no choice but to take it once KSW production ended.
Despite its sales success, the LD Lodekka had an important shortcoming. In order to achieve the necessary structural strength, the body pillars had to attach to the chassis outriggers which were at fixed distances apart. This pertained especially in the rear wheel area where road forces would be greatest. This meant that anything other than a 27-foot rear entrance layout was difficult.
The 30-foot version (LDL) needed long window bays to get outriggers either side of the rear wheels and had an ungainly long rear overhang. Only a handful were sold despite the strong market demand for longer buses.
A more elegant solution to the lowbridge problem was required. This came with the F series Lodekka, introduced in 1959. This is the true third-generation model.
Thanks to a new way of handling the prop shaft route from gearbox to rear axle, the chassis height was dropped so much that the lower deck seats could be at the same low level as the gangway. F therefore stood for Flat floor.
Two prototypes were built in 1958, and the first F type Lodekkas were produced the following year.
Four versions were offered: FS and FL (short and long rear entrance) and FSF and FLF (short and long forward entrance). Operators had a limited degree of choice in the fine details of their buses, like what engine to go for, and whether to have a sliding or jack knife door on FSFs and FLFs, or a door at all on FSs and FLs.
The biggest-selling variant was the FLF, standing for flat floor, long wheelbase, forward entrance. This was a big bus, with seats for up to 72 passengers. Its low height meant it could handle lowbridge routes but its big advantage was that its stepless entrance made boarding and unloading faster and safer.
In the end, Lodekka production was centred on the FS and FLF types. In all, 3,020 F type Lodekkas were built (of which 1,866 were FLFs), on top of 2,197 L types. Top FS operators were West Yorkshire, Crosville and Eastern Counties. Fleets with over 100 FLFs included Bristol (303), Eastern Counties (247), United Automobile, Central SMT and Western National.
That means 5,216 Lodekkas were sold in total by the time deliveries ended in September 1968 – well short of the 15,000 or so contemporary Leyland Atlanteans, but still a very respectable total for a bus with a limited market.
