Patent ID: 7744301

Claim:
A coupler comprising: an upper section including first and second spaced-apart ribs each defining first and second bores, said first bore of said first rib aligned with said first bore of said second rib on a first pin-on axis, and said second bore of said first rib aligned with said second bore of said second rib on a second pin-on axis; a lower section including: (i) a first hook fixed in position relative to said upper section and adapted to receive a first associated attachment pin; and (ii) a second hook adapted to receive a second associated attachment pin, said second hook selectively movable relative to said upper section toward and away from said first hook; a locking cam pivotally connected to said lower section, wherein said locking cam pivots relative to said first hook between a retracted position and an extended position, wherein said locking cam at least partially blocks said first hook when in said extended position; an actuator including a first portion pivotally connected to said second hook and including a second portion pivotally connected to said locking cam, said actuator operable between a first position and a second position, wherein: (i) when said actuator is operated from said first position to said second position, said actuator moves said second hook away from said first hook and pivots said locking cam from said retracted position to said extended position; and, (ii) when said actuator is operated from said second position to said first position, said actuator moves said second hook toward said first hook and pivots said locking cam from said extended position to said retracted position; a stop connected to said lower section in a fixed position; and, a pendulum lock bar pivotally connected to the locking cam, wherein said pendulum lock bar freely pivots by force of gravity between a locked position and an unlocked position in response to changes in an angular orientation of said coupler, wherein: (i) said pendulum lock bar is located to engage said stop when said actuator is operated from said second position toward said first position to prevent movement of said locking cam from said extended position to said retracted position when said pendulum lock bar is located in said locked position; and, (ii) said pendulum lock bar is moved out of alignment with said stop when said pendulum lock bar is located in said unlocked position so that said locking cam is movable from said extended position to said retracted position when said pendulum lock bar is in said unlocked position.