| 摘要 |
<p>A hydraulic control valve comprises a housing having inlet and exhaust ports, first and second motor ports, and passageways interconnecting the ports. A shiftable valve element has an internal flow passage and four operative positions for controlling flow through said passageways. In the first position, the inlet and exhaust ports are interconnected and each motor port is isolated from the other ports. In the second and third positions, the inlet port is isolated from the exhaust port and is connected with the first and second motor ports, respectively, while the exhaust port is connected with the second and first motor ports, respectively. In the fourth position, the two motor ports are interconnected and this interconnection is in restricted communication with the exhaust port. A check valve is located in the internal flow passage for preventing flow from the first motor port to the exhaust port when the valve element is moved between the first and second positions. The improvement comprises a valve component associated with the shiftable valve element for preventing fluid communication between the second motor port and the exhaust port when the shiftable valve element is moved between the first and third positions.</p> |
