| 摘要 |
<p>A vacuum system (5) comprising a vacuum pump (10) and a vacuum indicator (15). The vacuum pump comprises a cylinder; a piston disposed in the cylinder (50); a piston rod (60) fixed at a first end to the piston and extending through an end of the cylinder, the rod being movable axially and reciprocally to move the piston in the cylinder axially and reciprocally in first and second opposite directions; a sealing ring (85) disposed on and around the piston and in engagement with an inside wall of the cylinder throughout a periphery of the sealing ring; and stop means extending radially outwardly from the piston, the stop means including proximal stop means proximate a proximal surface of the piston and distal stop means proximate a distal surface of the piston, the sealing ring being axially movable between the proximal and distal stop means; the piston having an axially-extending groove therein, the groove extending from proximal of the distal stop means to proximal of the proximal stop means.</p> |
