| 摘要 |
The various air motors of a rock drilling rig are supplied with oil through oil lines which are furnished with predetermined metered oil flows from positive displacement pumps that are operated in synchronism with each other by an air operated oscillator. There is a normally closed shut-off valve in each oil line. The respective shut-off valve is opened when the respective air line is pressurized. When a shut-off valve is closed, the respective metered oil flow escapes through a pressure relief valve. |
