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• # Rotational speed regulation

Discussion in 'The main mechanical design forum' started by rambodaz, Mar 21, 2016.

1. ### rambodazNew Member

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Mar 2016
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Hello! I have an idea which includes 2 x 10cm diameter wheels at each end of a fixed axle, about 600mm across, similar to pram wheels. Then imagine the same again 1m parallel, forming a 1m x 600mm rectangle. These 4 wheels support a conveyor belt, but vertically. On the conveyor surface are hooks which can be loaded with typical load 80kg - one at a time. I want the load to descend very slowly - 1m from top to bottom in 10 seconds.

Along this axle I envisaged a speed regulation system.

I've been trying to find a solution to this. The problem is finding a solution that I can knock up from the DIY shop / internet purchases at (of course) a low cost.

I thought about a flywheel at a midpoint along the axle with a friction brake - maybe a bike caliper, with a screw to adjust it. But judging from my experience on exercise bikes, friction is too finicky to get right - you have to start it off with a jerk to overcome the initial inertia and it has a tendancy to speed up with momentum. Plus it's constantly wearing out requiring constant adjustment and renewal of the brake pads.

I thought also about magnetic eddy currents. Instead of brake pads, use super strong magnets onto an aluminium pulley wheel. I understand this would provide a maintenance free system with smooth running. As eddy current resistance increases with speed I imagine it would be necessary to increase the rpm of the flywheel, through a reduction gear or drive or pulley system. This has potential but I have no idea at all about the calculations and I've had little luck finding off-the-shelf cogs / pulleys / reduction drive.

I thought also about an air fan, mounted in the space inside the conveyor belt, belt or shaft driven, again with appropriate gearing. I've no idea about air resistance calculations, fan blade size etc.

A recent thought was to use a pendulum somehow, like in clocks. But I think this would be too jerky.

There you go. I'm sure there's something made for the job sitting on an Ebay page somwehere. Any ideas?