| 摘要 |
A vibratory screening apparatus has two vibrator motors (19, 20, 19', 20') having respective out-of-balance weights ar- ranged to produce substantially linear vibratory movement when, in use, thes e motors (19, 2U, 19', 20') are running in mutually opposite directions, an electrical control means (37) connected to the motor s (19, 20, 19', 20') and selectively operable between a non-running mode in which both motors (19, 20) (19', 20') are stopped and tw o running modes in one of which both vibrator mo- tors (19, 20, 19', 20') run in mutually opposite directions to produce substantially linear vibratory movement and in the other of which at least one of the motors ( 19, 20, 19', 20') is rotationally reverse d and both motors ( 19, 20, 19', 20') run to produce orbital vibratory movement. In a preferred arrangement, the out-of-balance weights (39, 42) in at least one (20) of the vibrator motors (19, 20) are adapted so that in one of the running modes the respective out- of- balance forces are mutually substantially equal, and in the other of the running modes the out-of-balance forces are mutually unequal. Alternatively, there is provided coupling means (47, 48), (49) for imposing rotational synchronisation of the vibrator motor s (19', 20') as required.
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