To the average person, the chain dangling from the top looks like just any ordinary chain, but you will notice that every second link is enclosed in a rubber ball. A normal chain used for a chain block arrangement is extremely noisy, but by having a rubber “ball” at every second link, it makes the chain block totally quiet, therefore allowing you to carry on with the shifting of torpedoes even in a “quiet” state. 

                                                                                  Gilles Poirier

On the left of this image is the trim pump starter box. This pump was bi-directional. It could rotate both ways depending on the position of the lever with the black ball on its end (just under the bottom right of the wheel.)

Here's a little flashback to 1986 when Ojibwa went in to refit in the synchro shed. Just how high is that roof? Well Ojibwa is approximately five storeys high.

This refit was not as drastic as the 68/69 leap of faith when she was cut in two so her engines could be removed and replaced. Follow the link below to read Gilles Poirier's inside story of that event.

In answer to my question, ‘What does this do?’ find former Chief Engine Rm Artificer, Gilles Poirier’s reply below:
 
The picture is a no brainer to me. The copper colored wheel is actually the starting handle located on top of the starter box for the trim pump. The trim pump starter box is located on the Port side in the control room, but the trim pump itself is located forward of the AMS/ACS.