Bristol Lodekka

Bristol Lodekka
Preserved Bristol Lodekka FS6G
Overview
Manufacturer	Bristol Commercial Vehicles
Body and chassis
Doors	1 door
Floor type	Low Floor
Powertrain
Engine	Bristol/Gardner/Leyland
Capacity	33/25 or 33/27 - LDX/LD/LDS/FS models 37/33 - LDL/FL models 34/26 - FSF models 38/32 or 40/30 - most FLF models 44/32 or 44/34 - Scottish longer FLF Coach seated vehicles varied.
Dimensions
Length	26ft 0in (LDX) 27ft 0in (LD, LDS, FS, FSF) 30ft 0in (LDL, FL, most FLF) 31ft 0.875in (Scottish longer FLF)
Width	7ft 6in (LDX) 8ft 0in (all other models)
Chronology

The Bristol Lodekka was a half-cab low-height step-free double-decker bus built by Bristol Commercial Vehicles in England. It was the first production bus design to have no step up from the passenger entrance throughout the lower deck, although Gilford and Leyland Motors had developed low floor city buses in the 1930s, these did not enter production.

The point of its design and introduction was to end the uncomfortable and inconvenient Lowbridge double-deck bus layout, replacing it by lowering the chassis frame and integrating it with the body, and fitting a drop-centre rear axle, so that there were no steps from the rear entrance platform to the front of the passenger gangway, itself sunk about 10 cm (6 inches) below the seating platforms on the LDX, LD and first five LDLs. A full flat floor was developed on the last LDL, then used on the LDS and the F series Lodekkas. Bristol Commercial Vehicles, Eastern Coach Works and some of their employees obtained a number of patents relating to the design.

Bristol manufactured over 5,200 Lodekkas from 1949 to 1968, as a standard double-deck vehicle for the UK state-owned bus sector. With all examples bodied by Eastern Coach Works in Lowestoft, they have a traditional half-cab design and a lower floor level allowing a low overall height. The earlier LD-series and the later FL and FS had a rear platform, but the FSF and FLF had a forward (behind the front axle and driver's position, rather than 'front' ahead of the front axle and alongside the driver) entrance. Most were powered by 5 or 6-cylinder Gardner engines, with fewer having a Bristol or Leyland power unit.

An engineering option was designed to reduce the power loss due to engine radiator fan operation and to increase the heat available for heating of the passengers. After experiments by Wing-Commander T.R. Cave-Browne-Cave (CBC), Professor of Engineering at Southampton University, a satisfactory design was produced. The 'CBC' system involved two small engine radiators being placed above the driver's cab roof level at the front outer corners of the double deck to give maximum aerodynamic air flow. The engine coolant water was pumped around these instead of the traditional radiator. In cold weather, all or a portion of the air passing through these radiators, was diverted by flaps, the left into the upper saloon and the right to the lower deck. In hot weather, the flaps could be changed by push-pull levers in the driver's cab roof to divert all the hot air to the outside of the vehicle. The movement of the vehicle was (usually) adequate to cool the engine without the need for a fan or radiator at the traditional position in front of the engine. The traditional 'radiator' grille at the front of the vehicle was not required, but was usually retained (with a few exceptions) and blanked off behind. 'Varivane' wax capsule operated shutters were fitted in front of the upper radiators to keep the coolant at optimum temperature. There were some disadvantages to the scheme and eventually customers stopped specifying it.