| 摘要 |
A spool valve (10) has a spool (12 or 112) provided with a relatively narrow land (14 or 114) at a pump to tank valve passage (36-27-26-28-35-34), and longitudinal metering slots (14a & 14b or l14a & 114b) in the land (14 or 114) surface. Pressure across the spool (12 or 112) is balanced by a plurality of shallow recesses (46 or 146) which are evenly circumferentially distributed about the land (14 or 114) surface in spaced relationship to any of the metering slots (14a & 14b or 114a & 114b) and intersecting bores (47 or 147a & 147b) in the land (14 or 114) which provide communication between all the recesses (46 or 146). |
