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Scissor lift

From The Great Ball Contraption Wiki

According to Brian Davis's lexicon, a great ball contraption scissor lift is a flat platform on a scissor mechanism.[1] Loading and unloading this is similar to the elevator.

Loading[edit]

  • A feeder ramp with a gate. When the platform is lifted, it can flip the ramp up so that the ramp tilts away from the platform, temporarily impounding any oncoming balls. The descending elevator restores the ramp and the flow of balls.
  • Gate. The platform can force a gate down when it reaches the low point. The gate can rise back on its own with help from rubber bands or a counter weight.
  • Lever gate. A mechanism, used by LegoGBC's Scissor Lift, is to use a single-file ramp in which the gate is just a lever. When the elevator crate reaches the bottom, it forces the lever up, allowing the balls to flow into the crate. Simpler than flipping the whole edge of the ramp, it has the downside of requiring a jam-free way of loading the ramp.

Unloading[edit]

At the top, the crate platform can be emptied in several ways:

  • trap door: Make a hole in one side of the platform wall, blocked by a wall facing the platform. At the top of travel, the wall ends, spilling the balls. (This is the method used by LegoGBC's Scissor Lift.)
  • dumpable: at the top of it’s travel, the platform is mechanically dumped, possibly be “tripping” on an edge at the top, for instance.

Driving[edit]

A scissor lift needs an approximately linear drive mechanism.

  • rack and pinion: motor drives a pinion which forces a rack gear to slide. The pinion can be made to reciprocate using a crank-rocker, driving ring, or programmable brick.
  • linear actuator: like the rack and pinion, it needs a means of reciprocation.
  • pneumatics: a combination of pistons and valves can produce the required cyclic motion.

Examples[edit]

MOC builder explanation given image available video available instructions available follows GBC standard
Scissor Lift LegoGBC English no YouTube no no

References[edit]