Lockable lever arm assembly

A lockable lever arm assembly for use with a mechanical leverage system mounted on a frame to move an implement between a lowered position and a lifted position, the assembly comprising:

• an elongated first lever arm pivotable in a first substantially vertical plane, the first lever arm having an upper end and a lower end, the lower end being pivotally connectable to the frame;
• a second lever arm in motion-transmitting engagement with the lower end of the first lever arm and movable in a second substantially vertical plane that is substantially parallel to the first plane, the second lever arm having an upper end and a lower end, the lower end of the second lever arm being pivotally connectable to the frame, the second lever arm being pivotable between a first limit position corresponding to the lowered position of the implement, and a second limit position;
• a detent member substantially coplanar with the second lever arm, the detent member comprising an upper end that is pivotally connected to the frame, and a lower end that is in an interfering path with the upper end of the second lever arm, the lower end of the detent member being configured and shaped to receive and hold the upper end of the second lever arm in an intermediary position located between the first and second limit positions thereof and corresponding to the lifted position of the implement;
• and
• an elastic stopper being slightly pressed by displacement the second lever arm at its intermediary position and being further pressed by it at its second limit position;
• whereby, in use, when the second lever arm is moved from its first limit position towards its second limit position, the lower end of the detent member holds the upper end of the second lever arm at the intermediary position to prevent it from returning to the first limit position until the detent member is automatically disengaged therefrom solely by pivoting the second lever arm from its intermediary position to its second limit position, thereby allowing the second lever arm to be moved back to the first limit position.