Model: N12 Intermittent Gear-Lever Mechanism

This device consists of a cam actuated lever, a crank with a small two-tooth cam wheel, and a larger 42 tooth gear wheel. When the crank turns through one cycle, one tooth of the cam wheel raises the lever while the other tooth advances the gear by one tooth. When the lever is released, a small point-shaped extension of the lever sits between the gear teeth and locks out any further motion.

This mechanism consists of two kinematic chains when the motion is engaged-- a three link chain with two lower-order cylinder pair joints and one higher order sliding joint, and another chain of three links consisting of the gear-cam/higher order pair and two lower order cylindrical pairs. This mechanism, like many ratchet type mechanisms requires so-called ‘force closure’ since the lever pawl relies on gravity to maintain the locking of the gear wheel.

Francis Moon 2004-07-01

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