| 摘要 |
A speed change control valve (7) houses a spool (8) of comprising a land (83) which can face a supply port (7P) supplying an oil pressure, and lands (84, 85) which can respectively face a pair of drain ports (7D, 7D) formed on either side of the supply port (7P). Output ports (7L, 7H) which allow a first and second oil chamber of an hydraulic cylinder to communicate selectively with the supply port (7P) or the drain ports (7D) according to the displacement of a spool (8), are provided in the speed change control valve (7). In the neutral position of the spool (8), the lands (84, 85) respectively face the drain ports (7D), a width L1 of the land (83) is set to be equal to or greater than a width L1 of the supply port (7P), and a width L3 of the lands (84, 85) is set to a width at which the drain port (7D) can open. |
