How fast this one?

[Greg_Lewis]

I stumbled upon this photo a few weeks back. Check out the diameter of the driver and the throw of the crank. Looks scary to me. I think the driver is 8'4" in diameter.

[Harlock]

Ah a singleton! Good for flat British or European track only!

[ccvstmr]

...helluva way to save on wheel castings! Kind of reminds me of some old steam powered side wheeler boats. cb

[PSeyfrit]

According to wiki a similar engine that has been preserved performed well.
"Cornwall was a famously successful high-speed passenger express engine of its period. Charles Rous-Marten (cited in [6]) reported an 1884 run from Crewe to Chester behind Cornwall (now far from new, and of antiquated design) at an average speed of 50.7 mph, reaching 70 mph down Whitmore bank. It remained in express service on the Liverpool-Manchester route until withdrawn in 1902. In 1925, Ahrons reports that it was still in service hauling the Mechanical Engineer's inspection coach.[2]

On final retirement, Cornwall was deliberately preserved, one of the first locomotives to be so treated."

http://en.wikipedia.org/wiki/LNWR_2-2-2_3020_Cornwall

[PSeyfrit]

http://en.wikipedia.org/wiki/Stirling_Single

Another example good for 85mph top speed.

[Fred_V]

I love the big singles. According to the tractive effort formula the single worked as well as a 2-6-2 as long as the rail could support the weight of the driver. The early days of technology are the most interesting.

[alanstepney]

The "singles" of which the most famous is probably that designed by Stirling, gave very high speeds (for the times) with a low piston speed, which was thought to be important, and without the complications of coupled wheels.The latter were compared to a horse with its legs tied together, and was supposed to greatly increase the power losses.
(It may have been true given the technology of the day.)

The one disadvantage of the singles was that the limited adhesion meant that they could only haul a (comparatively) small load. Quite satisfactory, until train loads increased, carriages got heavier, etc.

The largest wheels were the 9ft (yes nine feet) ones on the Bristol & Exeter 4-2-4T's (a couple had 10ft wheels, but they were soon altered), and the last singles to be built were in 1899-1901.
Some remained in use until the late 1920's and one or two until the mid-1930's.