The model is based loosely on the passenger terminal lifts at Stanstead airport. These serve 3 levels, with doors on both sides of the lift shaft. This type of lift needs neither cables nor counterweights nor a machinery room above the top-floor level.
The cage is raised and lowered by hydraulic rams using a chain-and-pulley arrangement similar to a fork lift truck's. Two ram-pulley-chain assemblies, positioned within the lift shaft on each side of the cage, operate in parallel, their load equalised by a rocking beam supporting the cage. The rams, which move the chain pulleys, lift the cage at a 2:1 mechanical disadvantage, but the cage travels twice the height of the pistons' throw. The design is very compact, and the power feed to the cage and door motors is via pick-up rails, obviating the need for hanging cables. The motion of the rams, chains, pulleys, lift cage and lift doors is so pleasing visually that the side walls of the lift shafts on the upper levels are of plate glass, to enable passengers to watch the mechanisms working.
Unlike the Dunhill lift, the model is prototypically correct in that each
door consists of two sets of 4 sliding leaves - an inner set on the cage and
an outer set on the lift shaft, the door-opening
motors and mechanisms being mounted on the cage. The cage has doors at
both ends. At each floor, the sliding leaves of the cage doors
interlock with the corresponding leaves of the shaft
doors, and all the leaves move together.
The outer doors, on the lower and middle floors, are on opposite sides of
the lift shaft; the
top floor has doors on both sides, which open and close simultaneously.
Enclosed within each simulated-hydraulic ram is a non-Meccano 6mm dia. threaded rod and threaded brass outer sleeve. The rods are driven from below by a car fan motor in the base of the shaft. All-Meccano limit switches halt the cage on each floor, and slip clutches protect the lift door motors. The cage is guided by a vertical rail on each side.
The
all-Meccano, electro-mechanical sequence controller is similar to the
Dunhill lift's but is more compact and has less wiring. There are nine cam-operated circuits. The recurrent, automatic sequence
is 1: Lower floor door closes 2: Cage rises to middle level 3: Middle level
door opens 4: Middle level door closes 5: Cage rises to upper level 6: Upper
level doors (front and rear) open 7: Upper level doors close 8: Cage descends to lower level 9:
Lower floor door opens.
The model is powered by two 12 volt power packs in double-pole configuration.
Builder's comment: This model was a follow-on from the Dunhill Window Display, using the expertise gained from that project, and improving upon it. The Dunhill model (even just the conventional lift section) needed a pantechnicon and two men to transport, so a much smaller scale had to be chosen.