Alan of Chelmsford, Essex, UK built the 7 1/4" gauge 'B' class Shay locomotive show above and was kind enough to share the following photos. The text and captions are Alan's words. The locomotive specifications are at the end of the page. Alan may be contacted at BALAN106@aol.com
outline is based on the early 1900's style, of a loco of about 65 ton
size. The model weighs about 300 lbs dry. It uses a conventional copper
loco style boiler, coal fired, with 4 radiant type superheaters, and rated
at 100psi. It steams well and I've done over 50 miles with it so
Front view, it’s No. 4 as ‘4’ is easy to mill out! The
small rectangular box on right hand footplate is battery box for
headlamp, steam turbo generator a job for this winter!
Non engine side, before headlamp fitted.
Me playing trains at a private railway in Norfolk, the trucks, 18 in all, are not mine. May 2008
General view of engine. The top and end engine cover plate yet to be made. Not sure whether I will lag the cylinders, such nice castings!
Some engine details. The chrome valve at top centre is the engine regulator (throttle) valve, which is on the ‘hot’ end of the superheater. Below it is the cylinders lubricator. The air tank to the right is used as the vacuum reservoir for the vacuum brake system. The brass cylinders in front of the cylinder blocks are steam operated drain cocks which double up as pressure relief valves in case of water carry over. (A bad driver who lets the boiler water level get too high!)
Close up of valve gear bits. Eccentrics are mild steel, straps are gunmetal (bronze).
Engine on test stand, Nov 2006. Used for initial steam tests to check out before painting. Would easily buzz round to over 1200rpm.
Rear view of engine during construction. Middle copper pipe is steam inlet, other two are exhaust, yet to be piped together. Elbow on lower right is for exhaust dump valve for initial engine condensate. Plumbing is mostly 15mm domestic fittings, silver soldered. (15 mm is UK standard). Main engine fixing studs to chassis can be seen on bedplate casting
Drive gear side of front truck.
Sprung axlebox side of rear truck. Note bolster suspension spring just visible, one of 3 each end. Brass pipe is train vacuum pipe, black lead is from bicycle speedo sensor.
Another view of rear truck, shows somewhat dirty brake shoes and brake beam.
A truck during construction, Dec 2005. The circular bit in the middle houses the thrust race, which then bolts to a heavy plate to span the chassis rails.
Detail of truck and pinion bearing casting, showing fabricated universal joint yoke
Steam brake cylinder and drive shaft details. Cylinder bore is 1 inch.
Front drive shaft assembly, and above it the vacuum brake actuating cylinder with pull rod. Cylinder is 2 ½” bore. Typical vacuum “pressure” is 15 inches mercury.
Inside the smokebox. The hexagon at the bottom is the engine exhaust jet, which is changeable to suit driving conditions, the concentric tube in the middle is the steam blower jet. To the right is the vacuum ejector steam exhaust and behind that the superheater hot and wet steam headers with the steam outlet union and pipe.
General view of smokebox and door. The US style door fixing dogs are dummy, the door number plate has a screw thread extension which fits into the hole in the central bar. The larger door aperture means the whole superheater assembly can be removed through the smokebox.
Drivers eye view of cab controls. The layout has been designed for ease of
operation rather than authenticity, not that I have much information on
the full size anyway.
Cab during construction. The removable roof section join can be seen. The roof is laminated up from three sheets of thin plywood to hold it’s curved shape.
Wier pump and clack, steam vacuum ejector, injector clack and stop valve and Wier pump lubricator pot. The Wier pump wasn’t made for this engine, it is probably a bit over scale, it was made some years ago from commercial castings as a fill-in project. It works well though, nice to have when the injector plays up.
This is the engine bedplate casting ex foundry and the bearing housing blocks. Making the coreboxes for this was a bit of a nightmare, but the end result was worth it.
The trunk guide casting ex foundry. The bit sticking out to the right fixes to a plate bolted to the top face of the chassis rail and thus takes the weight of the engine. The trunk guide bore is circular on my design.
Cylinder block casting ex foundry. The cast in portway between the power cylinder and valve bobbin cylinder is just visible. Side and rear lugs are machining aids.
The chassis in primer. Front is to the right. Note the substantial engine mounting plate.
My driving truck from the underside. This is a commercial model which I
modified for the buckeye coupler from the standard buffers and drawhook.
The plastic pipe conveys vacuum to any carriages pulled.
7 ¼” GAUGE SHAY LOCOMOTIVE SPECIFICATIONS