Retracting / Advancing Mechanism in VEX Slapshot

Hi all,

I’m getting to grips this year’s game. My students have settled on a snowplough type design, which involves pushing a large number of discs into the first goal zone. the snowplough needs to have a back and sides in order to transport the discs around corners. Obviously, the sides of the snowplough will contact the bar and prohibit the plough from pushing the discs under it. The students want to create a mechanism so that the back of the snowplough is able to advance forward at this point, and retract once the discs are pushed under the bar. I am scratching my head as to how to make this work with VEX IQ parts, however. Does anyone have any ideas? I’d be very grateful!

Thanks in advance,
Sam

My first thought goes to a rack and pinion or maybe cam gear setup.
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This is a top-down view. The bottom black horizontal lines represent the front of the robot frame; the other three black lines represent the scoop. The red lines are rigid bars that attach the scoop to the robot frame; they are able to swivel both at the frame and the front of the scoop. The green is a rubber band that is tensioned to keep the scoop in a U shape, but when flexed will allow to a flatter shape.
When driven up against the fence, the scoop would flatten out, and then upon driving backwards, the rubber bands would constrict, making the scoop go back to its original shape.

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Ben lipper’s 1st robot does a great job of this, but If you want something more student centered, you can use a rubber band connected to a large plate that is moved backwards by a gear box

Well I would like too say that a choo choo mechanism would work. You could pullback a plate and let it go with the force of 1+ rubber bands.