A coupler for receiving first and second pins of an accessory. A first latching mechanism is associated with a first jaw, having an arm connected to and extending away from a latching member thereof, and a second latching mechanism is associated with a second jaw, the first and second latching mechanisms adapted to latch the first and second pins of an accessory in or on the first jaw and the second jaw, respectively. The second latching mechanism is powered for movement between a latching position and a non-latching position. The first latching mechanism is connected to, or connectable with, the second latching mechanism to allow operation of the second latching mechanism selectively to operate the first latching mechanism between its own latching and non-latching positions by means of a groove or flange or finger provided on the second latching mechanism.