Patent ID: 8616560

Claim:
A chuck ( 30 ) for releasably securing an article comprising: a receiving portion ( 34 ) comprising a receiving bore ( 42 ) having a longitudinal axis (L) and having a contoured clamping surface ( 44 ) having at least one clamping segment ( 82 ); the at least one clamping segment ( 82 ) comprising a first ramp ( 88 ) between a trough ( 86 ) and a crest ( 90 ), a second ramp ( 92 ) between the crest ( 90 ) and a depression ( 94 ), and a third ramp ( 96 ) between the depression ( 94 ) and a stop ridge ( 84 ), wherein the trough ( 86 ), crest ( 90 ), depression ( 94 ) and stop ridge ( 84 ) are respectively, at a trough distance D T , a crest distance D C , a depression distance D D and a stop ridge distance D S , from the longitudinal axis (L), wherein D S <D C <D D <D T and wherein the trough ( 86 ) defines a trough side of the first ramp ( 88 ); a clamping sleeve ( 50 ) accommodated in the receiving bore ( 42 ) and being rotatable between a releasing position and a securing position; one or more rollers ( 52 ) associated with said at least one clamping segment ( 82 ), the one or more rollers ( 52 ) being accommodated between the clamping sleeve ( 50 ) and the contoured clamping surface ( 44 ), wherein: when the clamping sleeve ( 50 ) is in the securing position, a first roller ( 52 ) of said one or more rollers is accommodated in the depression ( 94 ), and at least one of said one or more rollers ( 52 ) applies a radially inwardly directed force against the clamping sleeve ( 50 ) to frictionally hold the article; and when the clamping sleeve ( 50 ) is in the releasing position, said first roller ( 52 ) is located on the trough side of the first ramp ( 88 ).