Hydraulic winch limit switch circuit

Abstract

A hydraulic winch limit switch circuit for preventing a winch cable from moving beyond its normal stop position which insures that the winch cable and research equipment attached to the cable are not damaged. The circuit includes a single pole limit switch with a diode connected across the contact of the limit switch. In normal operation the limit switch is closed and current flow is through switch to a winch electronic displacement controller which controls the operation of the winch motor and the winch. When the winch reaches a stop position during payin of the winch cable, the limit switch opens as the result of the limit switch arm engaging a tow bar attached to the end of the winch cable. opening the limit switch stops current flow through the winch electronic displacement controller since the diode is reversed biased during payin of the winch cable. This de-energizes the winch motor which results preventing the winch cable from moving beyond its normal stop position. When there is payout of the winch cable, the diode is forward biased resulting in current flow through the diode to the winch electronic displacement controller which energizes the winch motor allowing for deployment of the winch cable.