PURPOSE: To reduce fluctuation of delivery hydraulic pressure sufficiently without using an accumulator for superhigh pressure so as to enhance the performance and life of hydraulic equipment such as a booster by connecting two boosters in parallel with each other, and subjecting the boosters to phase difference control using two switching valves.
CONSTITUTION: A first and second booster 2, wherein water sucked into water- compressing plunger chambers 3a, 3b is compressed by the reciprocating movements of hydraulic cylinders 6a, 6b and then delivered to a water delivery line 8, are provided. After a second switch means 10 is switched from a suction position to a pre- compression position in accordance with the output of a first stroke sensor 30' under the compression stroke of the first booster 1, a first switch means 9 is switched from a compression position to the suction position and the second switch means 10 from the pre-compression position to the suction position in accordance with the output of a second stroke sensor 29. (on the side of the second booster 2 the switch means 9, 10 are switched reversely). Thus the first booster 1 is shifted from the compression stroke to the suction stroke whereas the second booster 2 is shifted from the pre- compression stroke to the compression stroke, whereby the water can be delivered at a reduced fluctuation rate.
HANEHIRO TAKUICHI
NODA TAKAAKI
HAYASHI KOICHI