Variable ratio rotary positioning mechanism and camera dolly steering mechanism embodying same
OwnerJames L. Fisherinventor
Life of this patent
Estimating the term…
Abstract
An adjustable turning ratio ratary positioning mechanism has rotary drive and driven members coupled by a flexible drive band, such as a sprocket chain, with oppositely movable runs between the members which are laterally displaceable during rotation of the drive member in such a way as to selectively provide the positioning mechanisms with different predetermined turning ratios, i.e., the turning angle(s) of the driven member(s) per unit turning angle of the drive member. A camera dolly steering mechanism embodying a rotary positioning mechanism according to the invention actuated by a single cam on the dolly steering shaft for selectively steering the dolly in round, crab, and conventional steering modes.
Claims18
A steering mechanism for a dolly such as a camera dolly having a frame, a first pair of wheels at one end of said frame, a second pair of wheels at the other end of said frame, means supporting each wheel on said frame for steering rotation of the wheel relative to the frame, and a rotatable steering shaft on said frame, said steering mechanism comprising:
- adjustable ratio transmission means drivably coupling said steering shaft and said first wheels for steering rotation of said first wheels by said steering shaft with a turning ratio equal to the wheel steering rotation angle per unit steering shaft rotation angle, and second interwheel transmission means selectively coupling said second wheels to said first wheels for steering rotation of said second wheels with said first wheels and locking said second wheels against steering rotation relative to said frame, and said adjustable ratio transmission means comprising endless flexible drive band means coupling said steering shaft to said first wheels for steering rotation of said first wheels by said steering shaft through said drive band means, said drive band means having first and second runs between said steering shaft and each first wheel shaft and said runs being laterally adjustable to increase the length of either run and decrease the length of the other run during steering rotation of said wheels by said steering shaft in such a way as to vary said turning ratio between said steering shaft and the respective first wheel, and means for laterally adjusting said first and second runs in unison during and at different selected rates relative to the turning rate of said steering shaft.
The steering mechanism of claim 11 wherein:
- said run adjusting means are operatively connected between said drive band runs and said steering shaft for laterally adjusting said runs in response to rotation of said steering shaft.
In a steering mechanism for a dolly such as a camera dolly having a frame, a pair of steerable wheels at one end of said frame, means supporting said wheels on said frame for steering rotation of the wheels relative to the frame, and a rotatable steering shaft on said frame adjacent said wheels, the combination comprising:
- endless flexible drive band means coupling said steering shaft and wheels for steering rotation of said wheels by said steering shaft through said drive band means, said drive band means having first and second runs between said steering shaft and each wheel and said runs being laterally adjustable to increase the length of either run and decrease the length of the other run during steering rotation of said wheels by said steering shaft and in such a way as to vary the steering rotation angle of the respective wheel per unit steering shaft rotation angle, and means for laterally adjusting said first runs and second runs in unison during and at different selected rates relative to the turning rate of said steering shaft.
Dependencies are inferred from the claim text.