PURPOSE: To allow the plunger of a ram tensioner to be held in place by regulating each switching valve and exhaust valve in accordance with its displacement, after providing the switching valves and exhaust valve in a pipe line which supply compressed gas to the compressed gas chamber in a second cylinder of the ram tensioner.
CONSTITUTION: A ram tensioner for compensating tension variation of a sling 2 suspending a marine surveyor or the like in the sea provides a compressed gas supply pipe 23 communicating with a compressed gas chamber 16 formed in a second cylinder 13. A first switching valve 27 is provided in the compressed gas supply pipe 23 and a second control valve 29 is provided in a gas exhaust pipe 28 branched from the supply pipe 23. The displacement of a plunger 10 in the ram tensioner 6 is detected by a sensor 20 to control each valve 27, 29, according to its displacement through a computing unit 40 and comparison computing unit 42 by random sampling, thereby allowing the plunger 10 in the ram tensioner 6 to be held continually at a neutral position.
TAKAHASHI KATSUYOSHI
ENOHARA MASAMI
NAKAGAWA TOMIO
OOKURA TOSHIAKI
KURITA HIROYUKI
KAYABA INDUSTRY CO LTD
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