Swing plate latch mechanism

Abstract

For confidently coupling towed external devices to a marine seismic cable, a latch mechanism having a novel swing plate to improve the adjustability of the mechanism and provide a positive, clearly visible indication of latched and unlatched conditions. The swing plate serves as an external linkage between a rotatable adjustment head for a locking pin and a translatable lever arm for a locking rod. The locking pin and the locking rod extend from a latch housing on a towed device, such as a cable-leveling bird, and engage with a keyhole slot in a locking collar on the streamer. The swing plate engages the adjusting head, which protrudes from a side of the housing, in a push-nut engagement. Shoulders positioned approximately radially opposite each other on the swing plate push against the lever arm, which also protrudes from the side of the housing, as the adjustment head is rotated to completely extend or retract the locking rod into the mating slot, thereby locking or unlocking the mechanism as the lever arm is jammed to the top or the bottom of a guide slot. As the adjustment head is rotated to force the lever arm to the top or the bottom of the guide slot, a positive stop, which is clearly evident to an operator performing the adjustment, is provided. The structure of the swing plate, such as structure along a radial sector of the swing plate between the shoulders, is also used to occlude and reveal clearly visible indicia of a locked or unlocked mechanism as the swing plate is rotated.