Mechanism for winding photographic film

Claim 1

In a mechanism for winding photographic film, rotary drive means and transmission means for operating a film winder, said transmission means including a friction clutch having an adjusting means for adjusting the friction thereof, and said transmission means coacting with said rotary drive means for transmitting the drive thereof to the film winder for operating the latter and for automatically actuating said adjusting means to increase the friction of the friction clutch in response to an increased load at the film winder, said rotary drive means being in the form of a rotary shaft and said transmission means including a worm formed with an axial bore through which said shaft freely extends so that said worm is freely rotatable and axially movable with respect to said shaft, said transmission means including a worm wheel driven by rotation of said worm, and said friction clutch of said transmission means directly transmitting rotary movement of said shaft to said worm and including a pair of friction clutch elements in permanent frictional engagement with each other, one of said clutch elements being fixed to said worm, said worm wheel tending to remain stationary when the load increases so that the worm then rotates with respect to the worm wheel to be advanced axially along said shaft, and said adjusting means being operatively connected to the other of said clutch elements and said shaft, for transmitting rotation of said shaft to said other clutch element and for responding to the axial movement of said worm along said shaft for increasing the friction of the friction clutch until the drive is again transmitted through the worm wheel, whereby the friction of the clutch is automatically increased to an extent which will again provide for rotation of the worm wheel by the worm.