Switching valve system for a hydraulic clutch for marine propulsion unit

摘要

PURPOSE:To reduce rotation operating force of a stem valve by setting the pressure sustaining area of the pressure sustaining surface of the stem valve in a switching valve device capable of selectively distributing high pressure oil to an ahead hydraulic clutch and an astern hydraulic clutch smaller than the cross-sectional area of the oil distributing peripheral surface. CONSTITUTION:In the propulsion unit 14 of inboard, outboard engines, an input shaft 16 is provided nearly horizontally at it top, and connected to a propeller shaft. An ahead gear 25 and an astern gear 26 that engage with a driven gear 24 fixed at the upper end part of an intermediate shaft 20 are loosely engaged before and behind the central part of the input shaft 16. And, a hydraulic clutch 27 that selectively connects each gear 25, 26 with respect to the input shaft 16 is provided between gears 25, 26, and it is controlled by a driving part 50 made up by containing an oil pump 54 and a switching valve device 55 in a housing 53. The switching valve device 55 possesses a stem valve 59, and it is made rotatable by a shift lever. In this case, the pressure sustaining area of the pressure sustaining surface of the stem valve 59 is set smaller than the cross-sectional area of the oil distributing peripheral surface, reducing the thrust force acting on the stem valve 59.