This should show the Google Maps aerial photo of Victoria Lock on the Newry Ship Canal.
It appears that the gates at the lock were originally opened and closed by winches, like those on the Shannon locks, and although the winches are no longer used they have been left in situ.
There were two winches for each of the four gates (east and west leaves of upper and lower gates), which makes eight winches altogether. Unlike the Shannon winches, those on the Newry Ship Canal bear no information about engineers or manufacturers.
As far as I could see, they’re all the same, so I’ve intermingled photos of different winches below. I don’t understand what all the bits were for, so I’m grateful for enlightenment: John Ditchfield has kindly explained many aspects and I’ve inserted his comments below.

The steel cable was led through a block shackled to a chain anchored to the ground. Presumably the block gave a favourable lead to the attachment point on the gate
John Ditchfield explained that this sort of winch is called a double purchase crab:
It has two spindles, one for low and the other for high gearing. These spindles slide horizontally to engage/disengage with the appropriate pair of gears.
Here is one of John’s photos of a winch without a cover.
John says:
Note the collars half way along each spindle. There would have been an arm with a claw to drop into the recess and secure the spindle in position.
John suggests that the handles are either to operate the interlock when shifting the spindles across, or for releasing a ratchet, or one of each. The loop on the handle seems to suggest something more than throwing a lever across. However, we would have to take the cover off to be sure.
John Ditchfield says that that is probably for a band brake like the one on this photo from the Magpie Mine, a former lead mine in Derbyshire.
The hydraulic rams
The gates are now opened and closed by hydraulic rams.

Ram and associated steel box, pretty well in keeping with the earlier lock fittings. This is the ram for the lower gate on the east side
Return to the top-level Victoria Lock page.