Traveling chain derailer

A traveling chain mechanism comprising:

• a pair of spaced rotatable sprockets;
• an endless chain member trained around said sprockets;
• a traveling chain adapted to selectively, individually enwrap said sprockets radially inward of said endless chain member, being selectively guided between said sprockets and having a plurality of links including a lead link;
• a derailer mechanism for releasing said traveling chain from at least one of said sprockets in preparation for traveling between said sprockets comprising;
• a pair of spaced derailer devices pivotally and axially supported on pin members, means for moving said derailer devices axially toward said traveling chain to a release position for initiating release thereof, each derailer device having a guide slot and a derailer arm, a cam member formed on one of said derailer devices for selectively engaging cam followers on said one sprocket to selectively unlock said traveling chain from said one sprocket,
• said lead link having a control pin positioned to enter said guide slot when said derailer devices are axially moved to the release position, said control pin engaging each derailer arm to enforce pivoting of said derailer devices to a derailing position to place said cam in a path of said cam follower to release said lead link, said guide slot being aligned with short pin members on each of the other links for guiding said other links when said derailing position is attained and to pass radially inward of said guide slots when the derailing position is not attained, said short pin members retaining said derailer devices in said derailing position, when attained, until all of the links of the traveling chain are released from said one sprocket.