| 摘要 |
A hydraulic circuit is provided, which can prevent the bucket from being separated from the bucket rest by preventing a change of stroke of a boom cylinder or an arm cylinder during long traveling of wheel type heavy equipment, and can secure safety since it is not required for an operator to adjust the position of a working device like boom and arm. The hydraulic circuit includes first and second hydraulic pumps, a boom cylinder, an arm cylinder, a boom confluence logic valve, a first port formed to connect with a large chamber of the boom cylinder in a housing in which a spool for the boom cylinder is shiftably installed, a second port formed to connect with a hydraulic tank in the housing, and a first orifice formed between the housing and a land part of the spool for the boom cylinder located between the first port and the second port. During long traveling of the heavy equipment, a very small amount of hydraulic fluid fed from the second hydraulic pump to the large chamber of the boom cylinder drains to the hydraulic tank through the first orifice to prevent a change of stroke of the boom cylinder.
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