A DEVICE FOR DAMPING UNDESIRABLE OSCILLATIONS IN A CRANE MEMBER

摘要

The present invention relates to a device for damping undesirable oscillations of a crane member (1) which is pivotally movable by means of at least one hydraulic motor (5, 5'). The hydraulic circuit (8) has a restriction (13) co-operating with a circuit-closing device (14; 18) the purpose of the restriction being to convert energy inherent in the system to heat in the hydraulic oil. The device includes means (14, 15, 16, 16') for controlling the closing device (14; 18) according to instantaneous conditions and/or changes or conditions, such as pressure and/or flow, in the hydraulic circuit (8). The energy-converting action of the restriction (13) is instantaneously activated as soon as a certain condition and/or a certain change of condition occurs. The conduit (12) in which the restriction (13) lies is completely shut off, rendering flow of oil through the restriction impossible, as long as the energy-converting action of the restriction is not called for.