| 摘要 |
A drill boom arrangement comprises a boom proper that is universally pivotably carried by a boom support. The boom carries a feed beam for a rock drill. The boom is swingable on the support by means of two hydraulic cylinders forming a tripod and the feed beam is swingable on the boom by means of two hydraulic cylinders forming another tripod. One of the boom swinging cylinders (17) is coupled in series with one of the feed beam swinging cylinders (28) and these two cylinders are actuated by means of a common direction control valve (58). The boom swinging cylinder (17) can be short-circuited so that the feed beam can be swung upon actuation of the direction control valve (58) while the boom is arrested. The other boom swinging cylinder (16) is coupled in series with the other feed beam swinging cylinder (29) to a common direction control valve (57) in the same way. A joy-stick (59) is coupled to the two direction control valves (57, 58) through pilot valves and pilot lines (64-67). |
