Boom breakaway assembly

In a spray boom operable to be mounted on an agricultural vehicle, said spray boom including an inner boom portion, an outer boom portion swingable relative to the inner boom portion from an extended operating position to a relatively folded breakaway position when an obstacle is encountered, and a boom breakaway assembly, the boom breakaway assembly comprising:

• a bias system connected to one of the inner and outer boom portions,
• said bias system including a spring that provides an effective bias rate yieldably forcing the outer boom portion into the operating position;
• a retention system connected to the other of the inner and outer boom portions;
• and
• a reciprocating system operably interconnecting the bias and retention systems so as to provide a variable holding force on the outer boom portion that is minimized once the outer boom portion engages the obstacle and has swung out of the operating position,
• said reciprocating system operable to vary the holding force between a maximum holding force and a relatively smaller minimized holding force based upon the position of the outer boom portion relative to the inner boom portion,
• said reciprocating system including a reciprocating element pivoting between first and second positions in response to swinging of the outer boom portion between the operating and breakaway positions, with the first position corresponding to the operating position and the second position corresponding to the breakaway position,
• said reciprocating system being configured so that the first position of the reciprocating element corresponds with the maximum holding force and second position of the reciprocating element corresponds with the minimized holding force.