electric drive means for driving, when said first switch of said controlling device is turned ON, said second body in one direction relative to {HEAD ~ said first body}, and driving, when said second switch of {TAIL ~ said controlling device} is turned ON, said second body in another direction relative to said first body 
electric drive means for driving , when said first switch of said controlling device is turned ON , said second body in one direction relative to { HEAD ~ said first body } , and driving , when said second switch of { TAIL ~ said controlling device } is turned ON , said second body in another direction relative to said first body
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