Hi Ted,
Glad it is of help to you. Your other question about the jib in the elevated position. The travelling chain block is secured at the rear end, think it was a kind of clip arrangement, then the front end was dropped down, you will see two pins sticking out the sides, these were what the retainer locked onto to secure it to the floor, I think, these details escape me as I have only used the gantry in a horizontal position. The high lift position was rated at 15cwt.
regards, Richard