HYDRAULISCHES BETÄTIGUNGSVENTIL.

摘要

A hydraulic control valve in a construction machine, wherein a parallel port (20b) and a bridge port (20c) which are provided in avalve body (40) of the hydraulic control valve are formed by machining, cylinder drain ports (20e) are limited to through holes opened on opposite sides of the valve body (20) and caused to join together in a tank port block (39). Accordingly, when the valve body (40) is manufactured by casting, only a main core (19) forming a spool port (13h) need be used, so that the control valve can be made compact in size. Furthermore, portions (20', 21') where a passage of a neutral port of the core has heretofore been formed by jointing the main core (19) to joint cores (20, 21) are formed by machining a manual operation process of jointing can be dispensed with and the working efficiency and casting accuracy are improved. Further a safety valve (43) and a suction valve (44) are formed separately from each other, and these valves are provided separately on the valve body (40), so that the valve body has a simplified construction and is made compact in size.