Patent GB-944818-A (GB)
Title: Improvements in or relating to a change speed drive mechanism, for example for motion picture projectors
IPC: F16H15/46
Filed: 1961-04-27
Abstract: 944,818. Cine projector drive mechanisms. KODAK Ltd. April 27, 1961 [April 27, 1960], No. 15215/61. Heading G2E. [Also in Division F2] In a two forward speed and one reverse change speed friction gear for motion picture projectors or other apparatus employing strip material in which a driving cone 13 selectively respectively engages driven cones 29, 28 for like reverse and second forward speeds providing, say, 24 frames per second, and a further driving cone 12 selectively engages a cone 23 for a first forward speed providing, say 18 frames per second, the driving cones 12,13 being fast on an input shaft 11, the driven cones 28, 29 being integral with an axially movable sleeve 15 rotatably connected to an axially movable fixed output shaft 16 for driving the shutter, sprocket, and pull-down mechanisms (not shown) through a coupling 19, and the driven cone 23 being integral with a further axially movable sleeve 14 and rotatably connected to the output shaft through a coupling 33 and the sleeve 15, an over-centre spring toggle 37 between the sleeves 14, 15 acts to hold the cones 28, 23 in separated or abutting relative positions and a weaker over-centre spring toggle 46 between the output shaft 16 and the sleeve 15 acts to urge the driven cones into engagement with the driving cones. The separated position of the cones 23, 28 is limited by a retaining ring 39 on the sleeve 14. The coupling 19 comprises fingers formed on a block 17 screwed to the output shaft 16 and axially extending into complementary openings 21 in the sleeve 15, and the toggle 46 comprises plates 44 between V-notches 45 in the sleeve 15 and the ends of a spring 43 secured as by rivets to the block 17. The coupling 33 comprises fingers formed on the sleeve 15 and axially extending through corresponding openings 34 in the cone 23, and the toggle 37 comprises plates 36 between V- notches 35 in the fingers 33 and the ends of a spring 26 secured to the sleeve 14. The shifting mechanism comprises shift levers 47, 48 respectively having bifurcated ends 49, 51 engaging surfaces 52, 53 on a cam member having positioning notches 62 engaged by a detent spring 61 for reverse, neutral and the two forward speeds. The opposite end of the lever 48 carries a roller 56 which is held axially by a spring 57 to prevent chattering and is engageable with inner faces 59 of the cones 28, 29. The opposite end of the lever 47 is forked to support two rollers 56<SP>1</SP> similarly spring-held and engageable with opposite faces of the cone 23. In operation, starting with the cam member 54 in the reverse position, toggle 37 separates the cones 28, 23 and toggle 46 engages the cones 29, 13. By turning the cam member clockwise into the neutral position the rollers 56<SP>1</SP> rightwardly shift the sleeve 14, 15 as a unit and the detent spring 61 holds the cones disengaged. By turning the cam member further clockwise into the second forward speed position the toggle 46 is moved over centre to shift the sleeves 14, 15 as a unit further rightwards and engage the cones 28, 13. Finally, by turning the cam member further clockwise into the first forward speed position the cone 23 is shifted further rightwards, the sleeve 15 being prevented from such movement due to the engagement of cones 28, 13, until the toggle 37 is moved over centre to move the cones 23, 28 into their abutting position against the bias of the toggle 46 which continues to urge the sleeve 14,15 rightwardly as a unit thereby engaging the cones 23,12. Although they may assist in axial movement of the sleeves 14, 15, the primary function of the lever 48 and the roller 56 is to restrain leftward movement of the sleeve 15 as the cam member 54 is turned back from the first forward speed towards the reverse position. In forward and reverse driving positions the detent spring 61 withholds the rollers 56, 56<SP>1</SP> from contact.