Largest of the Stuart engines by some considerable margin, the 6a was designed for use in full-size steam launches of 18 to 22 feet in length.
This is another engine from the barn collection which came in recently. The cylinder block and valve chests have been well-machined, the bores are greased up with pistons and rods fitted. Large quantity of castings, mainly unmachined, comprising:
1 off box bed, cast iron
1 off bedplate, cast iron
1 off crank, cast iron, machined
6 off main bearing half, gunmetal
3 off main bearing cap, gunmetal
2 off standard, cast iron
1 off cylinder block, cast iron, machined
1 off LP top cylinder cover, cast iron, machined
1 off HP top cylinder cover, cast iron
1 off LP bottom cylinder cover, cast iron, machined
1 off HP bottom cylinder cover, cast iron, machined
1 off LP piston, cast iron, machined
1 off HP piston, cast iron, machined
1 off HP piston rod, steel
1 off LP piston rod, steel
3 off half big end bearing, gunmetal (1 missing)
1 off flywheel, cast iron
4 off eccentric sheave, cast iron, machined
8 off half eccentric strap, gunmetal
2 off valve rod guide, gunmetal
1 off reversing lever bracket, gunmetal
1 off LP slide valve, cast iron
1 off HP slide valve, cast iron
1 off crankshaft balance weight (3 missing)
1 off air pump (?), gunmetal
There are three small gunmetal castings which I can't identify, possibly little end bearings - they are on the right hand side of picture 2359-g below.
Total weight 150 pounds
Drawings are still available from Stuart for this engine.
Height 20 inches
Bore/stroke 2 1/2 + 4 x 3
Rated 4hp@750 rpm on 120psi steam.