摘要 |
A dispensing system uses a molded resin cartridge 10 and a plunger 11 arranged with an interlock that prevents the plunger from backing out of the rear end of the cartridge. The cartridge wall 12 has an interlock surface 20 just forward of its open rear end 13, and a locking ring 40 has a sleeve 25 extending around the outside of the cartridge wall with a hook 27 that engages interlock surface 20. A radial wall 41 of the locking ring holds the plunger 11 against moving out of the rear end of the cartridge and improves the seal between the plunger and cartridge. The radial wall 41 can be joined to the plunger skirt 15 along a line of weakness 31 that allows sleeve 25 to tear away as the plunger advances to dispense the cartridge contents.
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