Patent ID: 7828070

Claim:
A coupler for attaching an implement to an arm of an earth working machine, comprising: an upwardly facing portion adapted to fix the coupler to an end of the arm of the earth working machine; a downwardly facing mounting portion positioned near one end of the coupler, comprising a hydraulic locking mechanism to lock a back pin of the implement in the mounting portion; an outwardly facing hook portion positioned near an opposite end of the coupler, including a safety locking device comprising a locking element biased into a locking position to lock a front pin of the implement into the hook portion of the coupler, the locking element being configured to be moved against the bias into an open position by the front pin as the coupler engages with the front pin, and then to move under the bias back into the locking position once the front pin is fully engaged with the hook portion; wherein the safety locking device of the hook portion is configured to release the front pin by being moved into an unlocked position using a hydraulic circuit which operates independently of the hydraulic locking mechanism of the mounting portion.