Hi Bruce, It is a Stuart 5A cylinder assembly on a dedicated marine platform.
That attached "mass" consists of a vacuum pump, feed water pump, steam cylinder oil pump driven by a ratchet drive and all are driven by by a reduction gear case with eccentrics and finally there is the Stuart Henley on Thames brass ID tag.
Way cool , I can see your attraction to it ,gears ,pumps , ratcheting oil pump , what's not to love .
Steam therapy heals a lot of ills 😊