| 摘要 |
A coordinate measuring machine having an automatic failsafe protection system. The coordinate measuring machine (10) includes a vertically mounted probe shaft (42) which is preferably counterbalanced by an air counterbalance system (100). The automatic failsafe protection system (200) insures that, in response to a loss of air pressure (or in response to other possibly unsafe conditions), the vertically-mounted, air-counterbalanced probe shaft (42) will be prevented from falling down uncontrollably. The failsafe protection system (200) includes a pair of members (230, 240), with each member mounted adjacent to and on opposite sides of the probe shaft (42) and urged toward engagement with probe shaft by a spring (250). Air under pressure from an air cylinder (210) also acts upon the members (230, 240) to bias the members outwardly away from engagement with the shaft when normal (i.e. safe) operating conditions exist. An unsafe operating condition causes a decrease in air pressure from the cylinder (210) which allow the spring (250) to bias the members (230, 240) into contact with the probe shaft (42) to brake its descent by progressively engaging the shaft (42). Additional springs (263, 267) also urge the members (230, 240) into contact with the probe shaft (42) in response to an unsafe condition.
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