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Gresley A3 Pacific
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By Tony Hogg
Published in Road and Track Magazine, April 1966
(one of the famous Road and Track “April Fools” issues)
In an age of compacts, economy cars, mini cars and other trivia, it is a great relief for us when occasionally we are able to get our hands on a machine which has some real guts to it. Therefore, when Englishman Alan Pegler invited us to test his personal steam locomotive, we lost no time in gathering up our stopwatches, Tapley meters and other tools of our trade in order to make a thorough and critical evaluation of this unusual machine.
Running your own steam locomotive is a bit like drinking champagne for breakfast; not everybody can afford it, but it can be a great pleasure for those who can. Pegler acquired the habit three years ago when British Railways was offering a selection of used locomotives for sale at scrap value. Passing his friendly neighborhood used locomotive lot one day, he saw a 1923 model in good condition with only 2,076,000 miles on the clock. The price was a mere $9000, so quite naturally he bought it.
Unfortunately, the terms of the sale were that his purchase should be removed within a specified time, and how do you remove something that is 70 ft long, 13 ft high and weighs 175 tons? Pegler solved the problem by reaching an agreement with British Railways whereby BR houses it for him, lets him use the tracks and provides a trained crew when required. All of which we feel is most commendable for an organization that normally seems to be buried up to its neck in bureaucracy.
After taking delivery Pegler spent another $25,000 on a complete overhaul and restoration, including a pale green and black paint job in the original livery of the now defunct London and North Eastern Railway. Since its restoration the locomotive has covered some 20,000 miles, most of them towing trains full of railroad enthusiasts to enable Pegler to meet some of his operating expenses.
For the technically and historically minded, the locomotive is a Gresley A3 Pacific type 3-cylinder using Walschaert's valves on the center cylinder. The tractive effort at 85 per cent boiler pressure is 29,835 Ib and the maximum drawbar horsepower is 1400 at 100 mph measured by a dynamometer car.
The designer was Sir Nigel Gresley who, in his day, was the Colin Chapman of the steam locomotive, and this machine was constructed specifically to haul express passenger trains between London and Scotland. It is named the Flying Scotsman, which is also the name of the train that it normally pulled. It was exhibited at the Wembley Exhibition of 1924 and has always been surrounded by a lot of glamor.
On first being confronted by the Flying Scotsman, we were more than a little awed by the sheer size of the beast. As you stand at the side of the track, it appears to tower above you, and you have to look up at the six driving wheels of 80-in. diameter. The standard of finish of both the body and chassis is superb and obviously belongs to a more leisurely era when time and money were available for such details.
Climbing aboard (stepover height 51 in.), we were struck immediately by the Spartan interior and lack of creature comforts for the crew. On the other hand, through the steam which seemed to envelop everything we were able to discern a complete absence of those chintzy little plastic knobs, buttons, and warning lights so common today. In place of them is an arrangement of levers, valves, and gauges sensibly laid out and of a size suitable to the general proportions of the machine. No radio is installed, but among the amenities we noticed that the heater is sufficient for even IBS the coldest weather conditions, and there seems to be an |||| adequate supply of boiling water for making coffee or other hot beverages.
Before giving our impressions of this machine on the track, it is necessary to consider the operation of steam gm locomotives as a whole, and the characteristics of the Gresley A3 type in particular. The Flying Scotsman has three cylinders with a bore and stroke of 19 x 26 in., which is a long way from the over-square ratios fashionable today. The third cylinder is not visible because it is located in the center, between and in line with the two outside cylinders. Because the cylinders "fire" on each stroke and in each direction, this arrangement is the equivalent of a conventional 12-cyl internal combustion engine. The steam is fed to the cylinders from a regulator valve situated at the top of the boiler where it is kept in a superheated or "dry" state, and the long "regulator" lever is the most important of the various controls.
When the locomotive is in motion, the engineer uses the "reversing" lever in conjunction with the regulator to control the speed of the train or, as the operating manual puts it, "he employs the reversing lever to control the use of the steam exspansively and economically in relation to the weight of the train and the gradient on which it is running."
When the train is ascending a gradient, the regulator will he open and the piston valve will be set near the point of its maximum travel by the reversing lever. When descending a gradient, the regulator will be almost closed so that just a whiff of steam is entering the cylinders to avoid creating a vacuum, and the reversing lever is set so that the valves are operating at a small percentage of their full travel. The reversing lever is marked in percentage-cut-off of valve travel, and its setting is referred to accordingly. Full travel is 75% and at a fast cruising speed the setting would be in the region of 40% .
The Flying Scotsman carries 6000 gallons of suitably softened water and 10 tons of coal. The coal supply is sufficient for about 500 miles, but the water consumption is prodigious—in the region of 60 gal per mile—so the whole 6000 gal is consumed in 100 miles. When steam was in general use, there was provision for taking on water at all stops, and also by means of water troughs set between the tracks so that the engineer could pick up water without reducing speed, an effective but splashy method. With these facilities disappearing fast, Pegler has acquired a 6000-gal tank car complete with water-softening equipment in order to double the range of his locomotive.
Gresley A3s were designed for a crew of two—an engineer and a fireman. However, the tender has a passage through it so that a relief crew can take over when necessary. The job of the fireman is to maintain steam pressure throughout the run, which is not always easy. The steam pressure gauge on the Flying Scotsman is red-lined at 220 psi and the fireman endeavors to keep it simmering at a steady 219. If 220 is exceeded the steam blows off automatically through a Ross pop valve, and we were unfortunate enough to he present when this happened. You could have heard it 10 miles away, and it seemed to go on interminably. Apart from temporarily deafening everyone in the immediate vicinity, it seemed a shocking waste of coal, water and firemen's sweat.
Coal, of course, is a subject in itself, and those who happen to have studied it will be interested to know that Gresley A3.s run best on Yorkshire Main Large Washed Cobbles. The fireman uses a shovel to feed the fire and he tries to maintain a thin red layer which gives off a brilliant orange red name. To achieve this requires constant attention and a lot of hard work. Referring to the manual again, we note that "when too much smoke is emitted it means that gases are being wasted, resulting in loss of heat and waste of coal, in addition to causing a public nuisance and complaints from the Health Authorities." We forbore from shoveling any coal, for fear of causing a public nuisance and incurring the wrath of the dreaded Health Authorities.
The fireman is helped in his work by the forced draft created by the exhaust steam from the cylinders, which is dueled through a blast pipe where it draws the smoke and gases from the firebox. In this manner the heat of the fire is partially self-regulating, because the greater the volume of steam being used, the greater the draft created by the blast pipe. When the locomotive is at rest, it is possible by opening a valve to create a forced draft using live steam direct from the boiler, which is released from a blower ring at the bottom of the blast pipe. To keep the steam pressure at its maximum without letting it blow off is tricky work, and the fireman's main concern is to predict the steam requirements well ahead, which can only be done if he has a thorough knowledge of the route and its gradients.
As we have already noted, the Flying Scotsman was designed specifically for the express passenger run between London and Scotland, a distance of some 400 miles. On this run it would pull 12 cars, making a total gross weight for the train of about 600 tons. The schedule called for some steady cruising in the 90s, and Edgar Hoyle, a retired locomotive engineer ("engine driver" is the British term) who is employed by Alan Pegler to look after the machine, recalls traveling as fast as 110 mph on occasions. When talking to railwaymen, one is not only surprised by the very high speeds which they consider normal but also by the number of years that they have been considering them normal. The Flying Scotsman was running over 100 mph in 1923 when the Land Speed Record stood at 133 mph.
During the course of our test we were able to make two separate runs, each of about 300 miles. The first was from London to Cardiff and hack following the normal route through Maidenhead, Nether Wallop and Chipping Sod- bury, during which we established a new record for steam locomotives, and cruised for long periods at 90 mph at as little as 35% valve cut-off. The second was much more leisurely and permitted us to make accurate assessment of the machine's qualities. On each occasion we were pulling a 5-car train carrying not more than 8O passengers.
The first thing to do when operating a steam locomotive is to get up bloody early in the morning and light the fire. You can then go back to bed for another four hours while it all comes to a boil or, alternatively, get to work on the 75 lubrication points that have to be attended to daily. But we were firmly in the sack when the match was struck, and by the time we arrived someone had been round with the oil can and the steam pressure was nearing 200 psi.
To draw away from rest is surprisingly difficult and calls for much more skill than just dumping a clutch and shifting some gears. The technique is to use about 65% cut-off, which is nearly full travel, and then open the regulator cautiously to feel the weight of the train. On a damp day this usually promotes wheelspin, which can easily be detected because 30 tons of revolving and reciprocating steel suddenly breaks loose underneath you. The remedy is to close the regulator immediately and try again. Under certain conditions wheelspin can occur at high speed, resulting in a dangerous motion somewhat akin to overrevving and the possibility of a bent connecting rod. Investigating the problem further, we discovered that the engineer has to be on his guard against such natural hazards as tunnels, which drip water on the track making it slippery, and also trainloads of wet fish traveling ahead-which do the same thing. It appears that such are the vagaries of railroading that the natural juices from one pound of cod or other coarse fish can break traction on a locomotive weighing 350,000 Ib.
Acceleration is dismally slow and our best 0-60 time was 397.2 sec, which is ridiculous in these days of 8-sec quarters. On the other hand there are few dragsters capable of pulling 600 tons at 90 mph, so it is really just a question of what you want out of life. When 20 mph is reached, it is time to start "notching up," as reducing the amount of valve travel is called, simultaneously increasing the regulator opening.
Meanwhile, the fireman will be busy, because to accelerate 600 tons from rest to 90 mph calls for the maximum volume and pressure of steam. It took us all of 623.9 sec to reach 90 mph, which is, incidentally, the slowest acceleration figure we have ever recorded. However, at 350,000 Ib it is also-the heaviest machine we have encountered in 15 years of testing, and although we were unable to verify the weight on our portable scales, we feel quite confident in accepting the manufacturer's figure.
The designed cruising speed of the Flying Scotsman is a little in excess of 90 mph. In complete contrast to most owners of 43-year-old classics, Alan Pegler thrashes his machine as far and as fast as it will go, and after riding on it at close to its maximum, one can appreciate that this is the only way to treat such a machine. At lower speeds there is an impression of immense but restrained power, but at 90 mph all restraint is left behind and the machine quite suddenly seems to get into its stride. The noise level is appallingly high but it is not particularly unpleasant because it is compounded of a variety of sounds and none of them are ear piercing (of course the engine is turning only 252 rpm at 60 mph); little attention has been given to sound-proofing. Referring to the Calculated Data, we find a Wear Index of only 2.75; the fact that this vehicle has covered over 2,000,000 miles once again bears out the significance of this index.
Although the sound is tolerable, the motion is somewhat unnerving until one gets used to it. There is an initial feeling of hurtling headlong to destruction as the locomotive sways, plunges, and weaves about with sudden and unpredictable movements. The suspension is not effective at all; in consequence it follows every undulation of the track and at 90 mph the track does not seem to he in the least bit level. Forward visibility is poor, but by leaning well out over the side one can see the direction of the track ahead, and one enters a bend seemingly far too fast but, due to the manner in which the track is banked, there is little sensation to indicate that one is not traveling in a straight line.
We are quite accustomed to traveling at 90 mph during the course of our road tests, but always with the feeling that a stab at the brake pedal will bring us hack to zero. On the Flying Scotsman we were not filled with the same degree of confidence because it appeared that nothing could stop us in the event of an emergency, which is quite true. The braking system is a complicated affair operated by vacuum created by a steam ejector (Dreadnaught type). A vacuum pipe or "train pipe" runs the length of the train and application of the brakes admits air into the pipes causing the shoes to make contact with the wheels by means of vacuum cylinders. It is perhaps sufficient to point out that weight and speed are the two natural enemies of any braking system and leave it at that.
Summing up the Gresley A3 Pacific type is difficult because we have not previously tested any machines in the same category, and therefore have no basis for comparison. Obviously the operation of a classic steam locomotive is not an easy matter and involves one in many problems. For instance, in these days it is just not possible to arrive at a filling station and ask for 6000 gallons of soft water and 10 tons of Yorkshire Main Large Washed Cobbles. As with many classics, the parts problem is a difficult one, although Pegler has been able to acquire such useful little items as a complete boiler assembly. However, at 45, Alan Pegler is an extremely active and enthusiastic man and it would appear to us that provided he avoids all fish trains and pays particular attention to his 75 lubrication points, he has many years of happy steaming ahead of him.
GRESLEY A3 PACIFIC AT A GLANCE
List price, new......................…..$40,000
Engine.………………………....3-cyl, double-acting, coal-fired
Curb weight, Ib. .............…........350,000
Top speed, mph....................…..110
Acceleration, 0-60 mph, sec........397.2
Average fuel consumption..........50 mi/ton
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Text from Road and Track article courtesey of Road and Track Magazine, (c)1966, quoted here as a non-commercial use.
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This web page last updated on May 29, 2003
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