Brake mechanism for computerized grade rod

摘要

A brake mechanism for use with a computerized grade rod comprising a housing containing a tunnel adapted to receive the grade rod and having the grade rod extend therethrough. A sensing wheel is mounted on the housing and tangentially engages the outer surface of the grade rod and rotates as the housing ascends and descends the grade rod. A brake assembly is carried by the housing in a predetermined longitudinal position with respect to the grade rod. The brake assembly includes first and second spaced apart brake shoes spaced apart longitudinally of the grade rod. A mounting plate is carried by the housing. First and second arms carry respectively the first and the second brake shoes. Each of the said brake shoes has a center point. First and second spaced apart pivot pins are provided for pivotally mounting the first and second arms. The first and second pivot pins are positioned off center with respect to the center points of the first and second brake shoes. A spring is secured to the first and second arms for yieldably urging the first and second brake shoes into frictional engagement with the grade rod. A handle is mounted on the housing and is coupled to the first and second arms for moving the first and second brake shoes out of engagement with the grade rod against the yieldable force of the spring.