Snowdon Mountain Railway

 

1. In Turner's Footsteps
2. Rack Engines
3. Spring Ascent
4. The High Ridge

 

Two: Rack Engines

 


The Snowdon Mountain Railway knows no timetables, being governed instead by the stern dictates of the mountain itself.  Though spring had long since come to the Welsh lowlands, and Samantha and I had enjoyed two weeks of brisk hiking in shirtsleeves or at most light jackets, Snowdon keeps a different calendar.  Up on the mountain's 3,560-foot summit it was still true winter, with fog shrouding the rails and ice and snow jammed in the rack.  Accordingly, SMR's trains would run only as far as Rocky Valley, five-eighths of the way to the peak.  Moreover, the next departure would be scheduled only once enough patrons had arrived to fill the car. 

 

wm05.JPG (9955 bytes)
Engine #3,
Wyddfa, shows off
the typical sloping
boiler of a rack
engine.
While we waited for more passengers to arrive, Samantha headed off for a late lunch at the railway commissary.  For my part, I strolled out to the yards to get a better look at the SMR's unique technology.  Simmering outside the engine terminal were Locomotive #3, Wyddfa, one of the original Swiss-built engines which had opened the line in 1896, and #6, Padarn, a somewhat more modern counterpart built in 1922.  Though different in detail, both engines sported the drooping boiler of a true rack locomotive.  Moreover, though it was impossible to see behind the heavy outside frames, both possessed the remarkable arrangement of cogs and bearings which makes a rack railway work.  It might seem that all that one would need to convert a conventional locomotive into a rack engine is a pinion mounted on each driving axle to engage the rack.  Unfortunately, as British railway historian Peter Semmens notes: "it is not as simple as that.   The pinions have to be able to pass over the running rails at points and crossings, so they have to be smaller in diameter than the carrying wheels on the same axle.  As a result, the rack pinion and the ordinary wheels have to rotate independently."   In fact, the "driving wheels" of SMR's engines are not rigidly fixed to their axles at all, but rather rotate freely, supported by specialized bearings built into the axle itself.  All the tractive effort is supplied by the center pinion, which alone is fixed rigidly to the axle and, through it, to the driving gear and pistons.   

 

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Engine #6,
Padarn, one of Yr
Wyddfa
's slightly
larger sisters.
Sloping boilers and non-rigid axles on the locomotives did not exhaust the SMR's catalogue of oddities.  Though it took a moment to see it, and still another to credit it, neither engines nor coaches possessed couplers or draft gear of any kind.  There is literally no way for an SMR engine to pull a coach.  How does the railway manage?  By pushing!  Almost every single inch of track-- not just the main line up the mountain, but sidings, servicing tracks, yard tracks, what have you-- is built on a slope.  Instead of couplers for pulling, every SMR engine and carriage is equipped with sturdy blank plates for buffering.  Engines are always positioned behind the carriages; gravity alone causes the train cars to run together, and keep in contact with the engine pushing or braking from behind.   

 

A squawking announcement from the station public address system brought my reveries to an end-- enough tickets had been sold, and the railway was ready to board the next service up the mountain.  I met up with Sam by the agent's window, and we passed through a circuit of lanes and turnstiles that led out onto the platform.  There stood a short train comprised of one coach and-- to my great disappointment-- a diesel locomotive.  The SMR had been an all-steam line, until a worsening balance sheet compelled a search for economies in the 1980s.  Substituting diesel for steam power promised to tip the scales from loss to profit for many lightly-patronized trains.  As a result, a brace of Hunslet-built diesel-hydraulics were introduced into service in 1986.  The hoped-for economies were realized, and more diesels soon followed: the Hunslets are now the preferred power for early- and late-season passenger runs.  Steam remains very much in use, though, and the odds of getting one form of power or the other on any given train are dictated mostly by the luck of the draw.   

 


 

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All materials, images, text and presentation copyright 1998 Erik Gray Ledbetter.  See Terms of Use.