Split hub assembly for a necked down cartridge tube

A split hub assembly for use in conjunction with a cartridge assembly including a cylindrical cartridge tube having a necked down end terminating in an annular flange, said split hub assembly comprising:

• a needly holder having a forward end and a rearward end with a passage connecting said ends, the forward end portion being adapted to receive a needle,
• a cylindrical body having a forward end and a rearward end with its forward end extending rearwardly from the rearward end of the needly holder,
• a collet assembly extending from the rearward end of the cylindrical body, said collet assembly including a circular shoulder connected to the rearward end of the cylindrical body, a plurality of flexible collet fingers extending rearwardly from the circular shoulder, each finger having a locking lip extending inwardly from the free end thereof,
• an internal circular groove formed in the flexible collet fingers adjacent the circular shoulder,
• a diaphragm comprising a disc portion with a circular plug of lesser diameter extending centrally therefrom, said plug being sized to snugly fit into the open end of the cartridge tube with that portion of the disc extending outwardly beyond the plug fitting on the annular flange of cartridge, the disc portion of the diaphragm fitting in and held by the internal circular groove in the flexible collet fingers,
• the cylindrical body having a first peripheral locking groove adjacent the outer forward end portion of said body and a second peripheral locking groove adjacent the outer rearward end of the body, and
• a cylindrical sleeve having a forward end and a rearward end with an inside diameter sized to engage and force inwardly the flexible fingers extending rearwardly from the rearward end of the cylindrical body, a flange extending inwardly from the forward end of said sleeve and sized to engage the first and then the second locking means on the cylindrical body, whereby with the cylindrical sleeve fitting down around the cylindrical body with the flange of the cylindrical sleeve engaging the first locking means on said cylindrical body and the flexible fingers positioned over and around the annular flange on the cartridge tube rearward movement of the cylindrical sleeve causes said sleeve to engage the flexible fingers and force them inwardly so that the locking lips fit in against the rearward portion of the annular flange to secure the split hub assembly to the cartridge tube, the flange of the cylindrical sleeve engaging the second locking means to retain said sleeve in position.