HOLD-ON HYDRAULIC VALVE Russian patent published in 2004 - IPC

FIELD: mechanical engineering; load lifting facilities. SUBSTANCE: proposed hydraulic valve is designed for use in hydraulic drives of load winches, and crane telescopic boom lifting and length adjusting mechanisms. Hydraulic valve contains cover 17 and housing 1 accommodating shutoff-adjusting spool-type element 2 provided with axial channel 3, spring 6 acting onto element 2, sleeve 5 in which piston 8 with rod 7 moves to act onto element 2, check valve 18, two working holes 12 and 14 and control hole 15. ring groove 11 is made in shutoff-adjusting element 11 and at least one row of long inclined splines 9 and one row of short inclined splines 10 are made to connect working holes 12 and 14 of hydraulic valve at operation with changing passage section. Safety valve 19 is arranged in check valve 18 provided with drain hole 20 for connecting the valve with drain hydraulic line 28 of crane hydraulic system, and screw 16 arranged in cover 17 acts through piston 8 onto shutoff-adjusting element 2. Sleeve 5 is provided with seat to which element 2 is pressed by spring 6. EFFECT: improved reliability in operation, provision of stable lowering speeds. 4 cl, 1 dwg