| 摘要 |
The drive piston of a hypodermic syringe is rendered non-retractable by including on it a resilient disc-like element whose free diameter is slightly larger than the diameter of the glass tubular body of the syringe. The drive piston is inserted into the glass tubular body from the rear end, thereby causing the resilient disc-like element to become dished with its concave side facing rearward. The dished resilient element acts as a continuous pawl since any attempt to retract the drive piston jams the edge of the resilient element against the inside wall of the tubular body.
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