This is part of one of the lock gates at the Five Rise Locks in Bingley. It's the mechanism for raising one of the sluices at the bottom of the gate, through which the water passes to fill the lock chamber up (or to empty it into the next chamber down.)
For a simple, animated explanation of how a lock works, click here. It's pretty cute. And there's a slightly more technical but extremely fascinating account of exactly how the Bingley lock keepers work the staircase ("staircases without side ponds") and why the locks at Bingley are not very water-efficient compared with some others - click here.