The Martin Baylis double acting slide valve twin engine has been designed to replicate as much as is practical at this scale the appearance of a compound engine. Great attention has been paid to represent the materials that would have been in use at the time; predominantly cast iron, brass, bronze and steel.
Items such as connecting rods and eccentric rods are fully machined and profiled giving the appearance of the original items. In the case of the eccentric rods, stainless steel and brass have been used to simulate the bronze eccentric strap and steel eccentric rod of full sized practice. Effort has also been made to incorporate into the engine items that are so often seen as separate entities. The displacement lubricator sits between the cylinders and the throttle assembly is hidden within the steam chest, giving a neat and uncluttered appearance to the engine. Steam-ways are an integral part of the cylinder block so there is no external pipe work other than that to deliver the steam and remove the exhaust.
The simulated wooden cladding complete with brass straps adds to the look of authenticity, as do the cylinder head fixings which are especially made to replicate dome head bolts. Connecting rods display bolt heads at the big ends. Reversing and throttle leavers have been designed to look in keeping with the controls of a real engine. Crank shaft webs are profiled to give the appearance of counterbalanced webs. This attention to detail in addition to the overall construction and aesthetic of the engine is designed to be pleasing to the eye.
Length 78mm or 3.06 (excluding reversing handle)
Width 52.5mm or 2.07 (excluding throttle handle)
Height 90mm or 3.55 (excluding lubricator cap)
Weight 321g or 11.33oz
Working Pressure 45psi or 3bar
This engine has been engineered to give a balance between the aesthetic appearance and sound engineering practice. Miniature roller races have been utilised extensively throughout; in total there are twenty used for the crankshaft, valve shaft, reversing gears, big ends and little ends. The result being that the bottom end of the engine requires very little lubrication other than minimal lubrication for the eccentric straps. This lends itself very clean and smooth operation together with low maintenance.
In an effort to simulate materials of the age, the block, steam chest and engine bed have been manufactured from aluminium which is then treated to give a textured finish. The components are subsequently hard anodised to BS5599. Hard anodising has a hardness approximating "sapphire" and is therefore very durable and wear resistant. This combination gives a finish that closely resembles that of cast iron. Pistons and slide valves are manufactured from complimentary materials which offer extremely good sealing characteristics combined with very low friction.
Stainless steel, brass and bronze are used extensively throughout the engine. As a result of this the engine is light weight, compact and powerful, offering the modeller an engine that looks authentic and is highly functional which should give years of untroubled enjoyment.
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