Fold cylinder structure

A large sprayer boom includes an inner section pivotally supported from a frame for movement between an outwardly extended working position and a folded transport position by an inner fold cylinder located at a first hinge point. The boom includes an outer section pivotally connected to the outer end of the inner boom at a second hinge point and movable relative to the inner section between folded and unfolded positions by an outer fold cylinder. Each of the cylinders includes an internally mounted cylinder position sensor protected from the harsh environment encountered by an agricultural implement. The switches are connected to a fold sequence circuit which includes operator switches located adjacent the main sprayer controller switches in the sprayer cab so the operator does not have to turn away from his normal operating position to activate the folding or unfolding cycle. The inner fold cylinder proximity switch controls the extension or unfold sequence while the outer fold cylinder proximity switch controls the fold sequence. The control circuit including proximity switches and operator switches is relatively simple, inexpensive and easy to attach and operate. Various boom positions including partially unfolded positions for narrower operation can be quickly and easily established by the operator. The larger inner boom section cannot be folded until the outer boom section is first folded against the inner boom section so that stresses in the boom and boom cylinders are minimized.