Patent ID: 6487976
Filing Date: 2002-12-03
Classification: B61B

Abstract:
A power and free conveyor comprising:a trolley disposed within a free track for movement in a driven direction, said trolley having a retractable dog with a riding surface, said retractable dog being movable between an engaging position and a retracted position; a first drive chain; a second drive chain; a transfer zone having an entrance and an exit, said first drive chain positioned to drivably engage said trolley at said entrance, said second drive chain positioned to drivably engage said trolley at said exit; a cam bar assembly positioned in said transfer zone to engage said trolley and move said retractable dog from said engaging position to said retracted position, said cam bar assembly including a first cam bar having a first longitudinal axis and a second cam bar having a second longitudinal axis, said second longitudinal axis being offset from said first longitudinal axis; and wherein said first cam bar is positioned for engagement with said riding surface to move said retractable dog from said engaging position to said retracted position and said second cam bar is positioned to follow said first cam bar in said driven direction and to maintain said retractable dog in said retracted position until said riding surface passes said second cam bar.