| 摘要 |
A hydraulically driven vibrator, for example, of the kind used for driving or extracting sheet piles comprises a number of out-of-balance masses which are all rotatably mounted side by side for rotation about a common axis. The masses are arranged in at least two pairs, one pair being rotated synchronously with the other pair, but in an opposite direction in such a way that on rotation the masses produce vibratory forces which are additive in a direction longitudinally of the vibrator, but mutually cancel each other out in a direction transversely of the vibrator. The pairs of masses are coupled by driving chains or toothed driving belts to oppositely rotatable drive outputs of a hydraulic motor which is offset longitudinally of the vibrator from the common rotational axis of the pairs of masses. Preferably one pair of masses is keyed on a drive shaft and another pair of masses are rotatable around the drive shaft and are mounted between the two masses forming the first pair. The other pair of masses are preferably mounted on a fixed hollow shaft which surrounds the drive shaft coaxially.
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