Screw jacks conjure magical motor show
09 July 2012
Power Jacks helped to get the show on the road when top European car manufacturer, Mercedes-Benz wanted to stage a spectacular UK launch for a new model. The company had just three weeks to devise and deliver a custom-built system for a stunning showcase that would tour major shopping centres up and down the country.
The team responsible for meeting the commission proved more than up to the challenge, creating a novel system based on Power Jacks’ C-Series cubic machine screw jack. This system was pivotal to a dramatic ‘magic mirror’ effect that slowly unveiled the car to passing shoppers as far afield as Glasgow and London. Power Jacks' Bruce Hamper takes up the story:
“The car sat inside a ring of pillars of coloured LED light, and was covered by a mirrored box that had a horizontal split. To make the car appear and disappear, the sides of the box were moved up and down in a synchronised fashion so the top and bottom halves of the car were revealed at the same time. We were delighted to have played a part in creating such a fantastic effect. It underlined our capabilities to take on board a challenging and ambitious commission, and come up with the goods.
To keep the mirror operation simple yet effective, Power Jacks engineers opted to use a four screw jack system in an H-configuration – the type commonly used to lift a single platform in one direction. For this application, however, the design needed to move two platforms in opposite directions, at the same time and rate.
To achieve this, Power Jacks designed a special lead screw which had right hand and left hand threads on the same lead screw, built into the screw jack body. The screw length matched the height of the installation; the upper half had a right hand thread form and the lower half had a left hand thread form.
A lead nut with corresponding thread ran on each thread form portion of the screw, so each screw in effect had two lead nuts. Therefore the system had eight lead nuts in total (two per screw jack) – four connected to the top mirror section and four to the bottom mirror section.
As the jacking system was operated, the nuts ran in opposing directions so the mirror sections did likewise at the same speed in a mechanically synchronised manner. By using a mechanically linked system, the whole operation was controlled by one motor which greatly simplified the control system and minimised costs.
The four C-Series cubic machine screw jacks selected for the system were mechanically linked to the electric motor via three bevel gearboxes from the ultra compact Neeter Drive Range-N design.
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