| 摘要 |
Various means for controlling the rate of travel of a plunger through a pump chamber in a dispensing pump are disclosed including an arrangement in which a cap is slidably mounted to the upper end of the pump plunger and a spring interposed between the cap and plunger with a detent mounted on the container contacting the plunger to prevent downward motion so that as the cap is depressed it is moved downwardly relative to the plunger preloading the spring and in which, after a predetermined degree of motion of the cap relative to the plunger, the lower end of the cap releases the detent to that the preload expands driving the plunger downwardly at a uniform rate. In another illustrated embodiment a preload spring is disposed within the pump between a plunger stem and plunger piston, the hydraulic forces within the pump chamber permitting the spring to be compressed before an outlet passage is opened, the spring once again acting to permit uniform discharge. In another embodiment, detents inside the pump cause an operator to build up a certain amount of finger pressure to overcome the detents whereby, the pressure having been built up in the finger, the operator will smoothly and quickly discharge material.
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