The box is 2 feet long, 1 foot wide, and 6 inches high at the ends
and 4 inches high at the sides. It can carry a rock that is almost
as large as I can comfortably lift while on my side in the cave.
Close up of the release pin (eye-bolt with threads cut off). The black rope is tied to the down-rope so that when I yank on the down-rope the pin is pulled out and the door/bottom can open.
My two older boys helped put in some
of the screws and with the painting. I could not find a paint brush,
so we just rubbed the paint on with some old cave gloves. A good time
was had by all.
The end of the down-rope goes over a pulley and to an eye-bolt in the door/bottom so I can pull it closed. You can just make out the silver of the eye-bolt next to the shadow of the black rope. The cave is not big enough for the tram to pass through with the door/bottom open.
Again, the down-rope goes over the pulley and to the door/bottom so I can pull it closed while still inside the cave. You can also see the latch mechanism without the pin.
Where the pin/latch is can bump at this spot so I will have to widen it a bit.
The 3/4 inch plywood and little block of wood were left over from some concrete forming. I drilled the holes in the box for the ropes to go through with my 3/4 inch hammer drill so a bit of extra wood came off. The cable is 1/4 inch and the rope is 1/2 inch.