The
model
is an amalgam of a 4-cylinder WW II Corvette engine and the 3-cylinder
triple-expansion marine engine in the London Science Museum.
The Stephenson's Link Motion reversing gear is operated manually by a sliding knob in the base. Like the prototypes, the reversing shaft is turned by a 'reversing engine' - a vertical steam-assisted ram. The crankshaft is driven from below by 57-tooth gears concealed inside four of the bed plate bearings. The direction of drive reverses automatically when the Stevenson's links are reversed.
The ship's bilge pump and two smaller auxiliary pumps are driven from the crosshead of the forward low-pressure cylinder. ◄
Marine engines have certain similarities to steam pumping engines, but also important differences. A marine engine is reversible, requiring a special type of valve gear, and needs no governor or internal flywheel. On a linear pumping engine power take-off is from the crossheads; on a marine engine the propeller is driven from the crankshaft which (being more highly stressed) needs proportionately larger bearings and connecting rods.
Builder's comment: A good, straightforward, classical Meccano model, but too many few bolt heads have to be filed down, rods shortened etc., to make it an eligible subject for a model plan.