Bale sled gate latch

Can somebody point me towards a good picture of a bale sled gate latch? I'm talking about the sled that's pulled behind the baler that bales drop into and when full the driver pulls a rope and the gate opens and leaves the bales behind in a pile. I'm thinking of building one. I would much rather have an accumulator and grapple but for no more then I'm cutting (15 to 20 acres) this is about the only thing that makes sense money wise. It would cut down on the trips on and off the tractor.

Bale sled gate latch