Minimum Gauge Tank Engine
Project Diary (pt 3)
| July 08 |
 Loco
2 is now fully piped up and has been brought into light steam to
test systems and check control functions. After a few minor
leaks were rectified, the engine moved under her own steam with
35psi on the clock. The boiler steamed well and the speed of
steam raining had t be curtailed using the damper.
The injectors were tested and even at very low pressure both the 8pt and 6pt injector worked. This can be attributed to the oversize water pipe supply to the injector. Some tuning of the trailing radiating axle springing completed a very successful outing.
These both need to be piped up and the ejector and vacuum system is ready to be installed, but as this will be mounted in the cab this is still to be done. The tanks were left open for this test and the coal bunker was not used. The whistle is my own design and has a very pleasing deep tone. It is mounted on a 1/4in BSP bronze whistle valve.
|
| June 08 |
 A
very satisfying milestone has been reached with the installation
of the boiler onto the 2nd loco and the initial placement of the
side tanks.The side tanks are now complete and give a real 'feel' of the loco, despite being balanced on timbers at present. Fitting the chimney and safety valves is progressing well and the regulator and steam feed are now complete. The large capacity of the tanks and coal bunker are now becoming apparent as the design takes shape. This loco will certainly have significant 'presence' as well as an impressive operating range and duration! |
| Even Later....... in April |
 
Progress is good at present and the smokeboxes are now fabricated and fitted. This is the first time it has been possible to gauge the size and proportions of the loco. No matter how good the CAD models are there is just no substitute for seeing the lumps of steel arranged just so!
|
| Later........ in April 08 |
 The
completion of the motion and cylinders on loco 2 allowed the
design to be put to the first serious test. This is
quite a tense and nerve racking time for the designer - had a
decimal point floated away leaving a beautifully crafted
engineering masterpiece that needs to be completely rebuilt?After the usual tightness in the sliding joints and leaks around the gaskets are gently attended to, the loco turned over and ran smoothly. The exhaust note was a crisp bark.
|
| April 08 |
 The long silence does not mean any lack of
progress, just a lack of updating the website..... I've been
very busy in the workshop and have also done a week 'throwing coal' on the Talyllyn
Railway.
The many components of the Walschaerts valve gear have been made and are being fitted up. Some parts use traditional plain bearing technology but wherever possible sealed bearing races are used.
The eccentric link and die block are based on the narrow gauge Barclay locos. This design uses simple rods and a complex twin curved ink with a die block through.
|
 The
cylinders and motion brackets have have been fitted to the loco.
As all the components were CNC machines fitting was a
straightforward exercise. At this stage, the
investment in design and . |
|
 My
intention was to design motion that used ball bearing races
throughout, but maintained the traditional look of a steam engine.
In addition to engineering a machine that works perfectly, the
aesthetics must be attended to.
I am pleased with the result as it fits both of these design requirements. |
|
 The
engineering used on these locos is more Victorian narrow gauge
than model engineering. The eccentric crank is is
clamed with a split bore, and pinned in position using a very
traditional taper pin or cotter.
The flycranks are drive (interference) fit onto the axles and located with 6mm keys. The wheels are also pressed and keyed onto the axles. |
|
 The
valves are cast in gunmetal and driven by stainless steel spindles
and followers. The valve spindle support is a steel
fabrication with a phosphor bronze bearing. Mounting the
spindle support removes the problem of maintaining alignment if
the valve chest is removed and different gasket materials are
used.The valve spindle is incomplete at this stage and will have an additional boss to accept drive from the combination lever. |
|
| Mar 08 |
 I
collected the boilers from Wayne Bell at Bell Boilers, Gloucester
late at night on my return from North Wales.
The third is in deep store but these 2 are awaiting fitting to locos 1 and 2. The smokebox back plate and attachment ring are seen after I was trying them for fit. The material and profiles for the smokeboxes, ashpans and side tanks are all in stock and will soon be glued together with electric sparks! I found Bell Boilers extremely helpful and a pleasure to deal with. The boilers certainly confirm their reputation for excellent workmanship. |
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The
steam brake is fitted, as is the drain valve block. 