An apparatus for automatically retracting a leash for an animal comprises a spool rotatably mounted in a housing for selectively winding and unwinding of a leash. The spool includes a hub defining an axis of rotation and gear teeth disposed about an outer surface of the hub. A gear train includes a plurality of gears operatively engaged with the gear teeth on the hub of the spool for rotation of the gears in the gear train. A carrier linkage defines a cavity for housing a portion of the gear train for rotation of the carrier linkage upon rotation of the gears in the gear train. A lockout pawl in the housing is movable between a first position that enables the spool to freely rotate and a second locked position to lock the spool against rotation. A cam surface on the rotating carrier linkage is configured to engage the pawl for moving the pawl to the second position. A control knob enables the gear train to be selectively positioned with the respect to the pawl to selectively predetermine the maximum length of the leash extending from the housing before the lockout pawl engages the spool for preventing rotation of the spool.
