Geneva drive or Maltese cross is a indexing mechanism that converts the continuous motion into intermittent motion. By means of this mechanism the rotary motion of the driver wheel is converting into intermittent rotary motion of sprocket. The film passed over the sprocket. Due to the intermittent motion, the film advanced frame by frame in front of lens for 1/24th second in frequency of 48 Hz.
In this mechanism, for every turn of the driver wheel A, the driven wheel B makes a quarter turn. The pin, attached to driver wheel A, moves in the slots causing the motion of wheel B. The contact between the lower parts of driver A with the corresponding hollow part of wheel B retains it in position when the pin is out of the slot. Wheel A is cut away near the pin as shown, in order to provide clearance for wheel B as it moves. If one of the slots is closed, A can make less than one revolution in either direction before the pin strikes the closed slot and, stopping the motion.
Introduction To Geneva Mechanism:
COMPONENTS OF PROJECT:
The input is given manually by handle through this Driver gear. It’s a one type of continuous motion.
CAM & PIN
It’s main part of this mechanism. Because it converts The continuous rotary motion into intermittent motion by guiding the Geneva cross along its circular path. Then it converts this motion as require for the movement of film frame.
GENEVA GEAR OR MALTESE CROSS
It’s also take part as vital role in this mechanism. Because the rotary intermittent motion produced in this part only. Ge-neva cross has 4 slots in it, pin goes into along circular movement of cam.
Shaft holds the all parts of mechanism by horizontally On its threaded portion. There are 2 shafts are provided in this mechanism.
It is provided for hold the film frame according to the rotary intermittent motion of the Geneva cross. Pressure rollers also provided for perfect movement of film frame.
It’s the component which carries the picture on it and to slide on the sprockets regularly according to the motion.
Geneva drive indexing mechanism converts the continuous motion of the driver wheel into intermittent rotary motion of the sprocket. According to the film length, the cam wheel diameter was chosen. Cam with pin arrangement integrated with Geneva drive. Input shaft having driver wheel at one end and cam drive at the other end. Geneva drive and sprocket are mounted on the output shaft. By cam with Geneva drive arrangement the continuous motion of the driver wheel converts into intermittent motion of sprocket. Due to sprocket rotation the film advances frame by frame in front of the lens. Thus the slide show of the film was obtained successfully.