| 摘要 |
<p>A retarder or brake mechanism (20) for controlling the velocity of articles on a gravity conveyor (10) has a pneumatically operated actuator (44). During each cycle of operation of the brake a charge of air of limited volume is supplied to the actuator, which has an air bleed (51) which limits the actuator's period of action during each cycle. The charge of air is supplied by an accumulator (45), which is normally connected to a source of compressed air. An article actuated sensor (31, 31a) and connected valve (30), upon being tripped by an article, isolates the accumulator from its air supply and connects it to the actuator activating the actuator but limiting its air supply to the charge stored in the accumulator before the valve was shifted by the sensor. The charge, once exhausted, is not replenished until the sensor is released by the article. </p> |
