Contents:

• >  introduction
• >  bed-frame
• >  cylinders
• >  pistons
• >  valves
• >  con rods
• >  reversing engine

The double-acting, horizontal-duplex non-condensing steam engine powering the South winder  has remained virtually unaltered since its installation by Markam Co. Ltd. in 1922.

It is of “Mammoth” type construction, with the cylinders, the trunk guides and the main-bearing bedplates each flange-mounted to  the other. There are 17 bed-bolts per side which are tightened against 3in thick steel plates located in pockets in the brick foundation pillars. 

It operated at 150psi using superheated steam at a temperature of ?

The cylinders are 36in in diameter with a 7ft stroke and use metallic packings for the piston rod glands. Clearance is reduced to a minimum (approx. 6.7%) by  scolloping the piston faces and extending the end-plates into the cylinder except in the vicinity of the steam ports. Steam jackets were not employed but the cylinders were lagged (with asbestos ?) and cased in light steel sheeting.

The pistons have a rear  balance rod carried on a slide bearing held in a housing bolted to the cylinder end-plates, whilst the vertically mounted cross-heads run in slides machined directly in the trunk guides.

Double-beat drop valves are mounted above and piston valves below the slotted ports at each end of the cylinders. They are operated by rods connected to a wrist-plate located on the side of the cylinder, driven by the eccentric link-motion. The inlet expansion cut-off gear is operated by a centrifugal governor, rope driven from a twin grooved pulley located on the RH drum shaft.

The forward & reverse eccentrics are mounted on the drum-shaft between the drum and main bearing. The Gooch reversing gear is operated via a horizontal steam reversing-engine mounted on the side of the RH bedframe.  The reversing-engine incorporates a hydraulic locking cylinder and has its own mechanical lubricator for the steam cylinder activated by the reversing link.

Cylinder and throttle valve lubrication is by mechanical oilers operated from the valve wrist-plates. The tail-rod and trunk-guide has sight-feed oilers, whilst other moving parts use Stauffer grease cups of various sizes.