No.5a

More power for the real world

Stacks Image 6
Stacks Image 29


List of Castings and Parts

CAST IRON.- Cylinder with steam chest and steam ports cast in, 1 each top and bottom covers, 2 Piston Bodies, 1 Piston Ring, 1 Valve Chest Cover, 2 Standards, 1 Bed Plate, 1 Box Bed, 1 Eccentric Sheave, 1 Slide Valve, 1 Flywheel 7½ in by 1½ in. (or disc wheel 5-in by 1¼ in.), 1 Stop Collar, 2 Crank Balance Weights.
STEEL.- 1 Connecting Rod, 1 Eccentric Rod, 1 Crank Shaft, 12 Bearing Caps.
GUNMETAL.-
1 each Piston and Valve Gland, 1 pair Eccentric Strap, 2 pairs Main Bearing Brasses, 1 Valve Stuffing Box, 1 Valve Rod Guide, 1 Slide Valve Nut, 1 each Steam and Exhaust Flanges, 2 Connecting Rod Brasses.
STEEL BAR, etc,-1 Piston Rod and Crosshead, 1 Valve Rod, 1 piece Steel for Valve Rod Head and Crosshead Bolt, Sheet Steel for Lagging.
DRAWING.- 1 Large sheet with all details, full size.

Weight packed. 35-lbs.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

EXTRAS.- All Studs, Nuts, Bolts and Screws, 12/-; Drain Cocks, 6/- per pair; Cylinder Lubricator, 4/6; Reversing Gears with castings in Steel and Gunmetal and all bolts, Studs, and Nuts with drawing, 12/6; 1 set Pump Castings, with all materials and drawing, 5/-.-
For steam canoes this is an ideal engine, and if fitted with slip eccentric reversing gear will be found economical and very efficient.


Design
More evolution, this time more power to the No.5. The increase in bore from 2 in to 2 ¼ in may not seem very much but it is nearly a 30% increase in cylinder volume. To this end Stuart have changed the design of the Cylinder block, it now has the Valve chest built in. It is not apparent why this change in the casting has been made as it is a more complicated casting to make. The twin Standards of the No.5 have been continued as are the Soleplate and Boxbed. The addition of counterweights to the crank webs is an attempt to reduce vibration at speed. Careful examination of the photos indicate a general similarity to the No.5. The modern No5a shows a significant beefing up of the new Trunk Standard, Crankshaft, Soleplate and Boxbed. At the moment I am unable to determine exactly when the changes were made.
Due to the similarity between the No.5 and early No.5a I can only determine pictures of the current style No.5a.
It is interesting that Stuart refer to this engines use in steam canoes indicates their pushing for real world uses. Nowadays the idea seams odd but in the past but check out the Video in the sidebar.

Stacks Image 20
Current Design No.5a with Trunk Standard and Separate Steam Chest.