| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic transmission capable of smoothly changing the number of operations of a motor mechanism while rotating an output shaft. SOLUTION: The hydraulic transmission has a speed change valve 50 having a low speed position (a) at which the output shaft 5 is driven by causing hydraulic fluid from a hydraulic pump 32 to circulate through the first motor mechanism 11 and the second motor mechanism 21 and a high speed position b at which a bypass passage 24 is opened while the second motor mechanism 21 is stopped to cause the hydraulic fluid from the hydraulic pump 32 to circulate through only the first motor mechanism. During a process in which the position is changed from a to b, the communication of the second motor mechanism 21 with the hydraulic pump 32 is shut off before the bypass passage 24 starts to open. The hydraulic transmission includes pressure relief check valves 26 and 27 allowing the hydraulic fluid in the second motor passages 22 and 23 to escape into the first motor passages 12 and 13, and pressure introduction check valves 28 and 29 for introducing the hydraulic fluid into the second motor passages 22 and 23. COPYRIGHT: (C)2003,JPO
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