| 摘要 |
A heating oil pump is designed for selective one or two-line operation. Between the suction side (12) and return side (17), there is a connecting passage (23) which can be closed by a closure member (Z4) during two-line operation. The latter is displaceable from a closed to an open position during insertion of the plug by an actuating element projecting into the insertion path of the plug (27) and back to the closed position by a return spring during removal of the plug. This provides an automatic change-over without the need for the return pressure to be higher than the suction pressure. |
