| 摘要 |
<p>PURPOSE:To construct an oil-hydraulic circuit for shield jack small and light by furnishing a plurality of shield jacks propelling a propeller excavating machine, two or more oil-hydraulic pumps for propelling, and selector valves to change over jack by jack the oil-hydraulic circuit between the pump and jack. CONSTITUTION:At the time of meandering correction or curved excavation, selector valves 10 are changed over to put all shield jacks 1 in communication with propelling oil-hydraulic pumps 3a, 3b and each cut valve 5 for expansion is changed over to operate all shield jacks 1 in the direction of elongation. For meandering or curve proceeding shield jacks 1 on the inside and outside are operated in the direction of elongation. The lead and the rate of flow oil- hydraulic pumps for excavation 3a, 3b are controlled to vary the stroke of each jack 1, and the line pressure of an oil pressure circuit for jack is controlled by main relief valves 6a-6c to eliminate shortage in the thrust force of a propelling machine. This prevents meandering.</p> |
