| 摘要 |
Pile driving apparatus comprises first and second sets of eccentric members mounted in a housing for opposing rotation. A phase shifting arrangement connects the sets of eccentric members for controlling coordinated rotation thereof, and comprises a limiting device between the first and second sets of eccentric members for shifting between a first condition wherein the eccentric members are constrained to rotate out of phase to negate generation of vibration and a second condition wherein the eccentric members are constrained to rotate in phase to generate vibration. Two motors are connected with the limiting device for alternatively driving rotation thereof. A control arrangement selectively drives the limiting device predominantly by the first motor for shifting the limiting device into the first condition thereof for preventing vibration or predominantly by the second motor for shifting the limiting device into the second condition for generating vibration in the housing.
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