| 摘要 |
PROBLEM TO BE SOLVED: To a caring lift of a type for hanging up the person to be cared by using a hydraulic manual pump in which the operation lever of a manual pump can be operated lightly when a lifting arm hangs up a person to be cared and the lifting arm can be raised speedily in the state of no load. SOLUTION: A plunger constituting a plunger pump consists of a top of a large diameter and the shaft of a small diameter, and a short circuit for communicating a liquid chamber on the top surface with that on a rear surface at the top of the large diameter is arranged. A pressure sensitive valve opening in the case of high pressure is interposed there. When the load of a pump is large, the operation of the top of the large diameter is made to be ineffective to increase discharging pressure in spite that the discharging quantity of hydraulic oil is reduced.
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