ships wheel to a wooden bolt

[cyme]

Hi
I have been asked to make a gate with a ships wheel that you would use to turn to move the bolt in and out to open it
has anyone ever done this and how would i work out the ratio of cogs to the long wooden bolt
any help greatly received
cy

[mklotz]

Without getting into the complexity of pitch diameters of gears, here's an approximation that will get you in the ball park.

Assume

L = distance bolt must retract to allow gate to be opened
N = desired number of revolutions of wheel needed to retract bolt

Then the circumference of the gear attached to the wheel, C, must be approximately

C = L / N

and the diameter of the gear, D, must be

D = C/pi

Rack and pinion assemblies are commercially available but they are likely to be expensive. Think about making your own.