# Rack and Pinion Design Question

1. Feb 26, 2017

### Jhoneine

Hi, I am planning on translating a vertical rack movement to a pinion rotary motion by a human footstep force. Any idea on how to obtain the rack linear velocity theoretically ?

2. Feb 26, 2017

### Nidum

Sorry but I can't immediately see what there is to work out ?

Please explain what you are trying to do more completely and then you will probably get a more helpful answer .

3. Feb 27, 2017

### CWatters

Sounds like he's trying to work out the power that can be harvested from a man walking over a foot plate in the floor.

The rack will accelerate downwards when the man steps on the foot pad. The acceleration could be calculated using Newtons law F=ma (eg using the net force on the rack/man and the mass of the combination). From that you can calculate/estimate the peak velocity after some time t (which depends on how long he stands on the footpad.

Perhaps it would be easier using work = force * displacement

4. Mar 5, 2017

### wasup23

If speed is not an issue, per say, you could have it attached to a spring release gear mechanism. Think of a clock gearbox. You step, the plate pushes down a lever that knocks a gear a little bit, this then returns and bypasses moving the gear. Each step moves it farther and farther. Remember, in theory, even if you have it barely move the gear, you can have that gear run against a much smaller gear attached to a larger gear. Your speed has no limit.

Your linear velocity will be easily calculated given you know the rotational velocity and the radius with the equation V = (angular velocity) times radius.