The Sleaford Maltings Robey
This superb horizontal tandem compound condensing Mill engine No 23857 was one of a pair built by Robey in 1904 for the Bass Charrington Maltings at Sleaford, the sister engine (No 23856, and opposite handed or a 'mirror' image) is also preserved, at the Bass Charrington Museum in Burton on Trent.
With a Robey 'bayonet' pattern main frame and developing 200 HP at 70 RPM from its 14" bore HP and 22.5" bore LP x 30" stroke cylinders it drove the maltings equipment through 8 ropes from its 11 ton 13' diameter flywheel, which is cast in two halves.
The HP cylinder has a variable expansion slide valve controlled by a belt driven Richardson governor - this was a patented Robey design. The LP has a simple slide valve.
The exhaust steam runs into a jet condenser, the airpump for this being driven off the LP piston tail rod.
The two engines took six monthly 'turns' at running the machinery in the Maltings, the 'off' engine being serviced and maintained in the unlikely event of any problem with the 'on' engine.
This engine is a great favourite of the visitors and will turn over on as little as 5 psig steam pressure (without the condenser being in operation)