| 摘要 |
A dispensing device includes a hollow cylindrical body from which a high viscosity composition is discharged in precisely metered doses by means of a plunger rod longitudinally movable within the body. The plunger rod includes a series of thread segments formed at equispaced, angular intervals from each other to establish an exterior thread of constant pitch in threaded engagement with the body. Each segment has an abutment surface projecting from the surface of the plunger. By depressing a trigger mounted on the body into contact with an abutment surface aligned therewith, the plunger rotates through the angular interval and thereby advances through the body to expel a desired amount of composition. Disengagement of the trigger with the abutment surface automatically occurs as the abutment surface rotates to the end of the angular interval, out of contact with the trigger, causing the next in-line abutment surface to be indexed into alignment with the trigger to allow for successive doses.
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