Excerpts pp. 147 – 150.
REPORT ON EASTWICK AND HARRISON'S EIGHT WHEEI LOCOMOTIVES
'The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the Promotion of the Mechanic Arts, to whom was referred for examination Messrs. Eastwick & HarrisonÕs Eight Wheel Locomotives, Report:
That these engines possess two peculiarities of an important character; one in the arrangement of' the driving wheels, and the other in the mode of maintaining the fired draft.
It is well known to engineers, that the efficiency of the locomotive engine depends, first upon the quantity of steam which the boiler may be capable of generating in a given time, and secondly on the amount of friction, or, as it is technically termed, adhesion, between the driving wheels and the road. As the adhesion increases with the weight, it is evident that the engine becomes more effective by increasing its weight, and by throwing a greater proportion of this weight on the drivers.
But a limit to this increase of, weight arises from the incapacity of the road to sustain the great pressure thus thrown on a small bearing surface
To obviate this difficulty, engines have been made with all the wheels coupled so as to constitute them all drivers, and thus distribute the adhesive pressure over a greater extent of the road.
Engines of this description are used for heavy and slow draught, but are, considered unsafe, from their liability to be thrown off the track at curves.
Another plan, patented a few years back by an engineer of this city, was to use four drivers, and at the same time to carry the front end of the engine on a guide truck, as in the six wheeled engine. But here a new difficulty arose in consequence of the engine having three points of bearing in the line of the rails, on which its weight could not be-properly distributed, unless the road was entirely free from irregularities of surface: a condition not to be found on any of the roads which have come under the notice of the Committee.
The improvement invented by Messrs. Eastwick and Harrison is designed to obviate this difficulty, by giving to the eight wheel engine only two bearing points, one on the guide truck, and the other on a frame supported by the driving wheels. The axles of the drivers are placed one in front, and the other behind, the fire box, and are confined between pedestals of the usual form fixed to the main frame of the engine, which allow vertical play, but prevent any horizontal motion.
The bearing pins, instead of abutting against springs fixed to the frame in the ordinary manner, are jointed to the extremities of horizontal beams of cast iron, one of which is placed on each side of the engine.
To the centre. of these beams, or levers, are jointed wrought iron rods, which pass down through the engine frame, and carry the springs which support the weight of the engine. The connecting rod of the piston is attached to the hinder wheel, and this communicates motion to the front driver by a coupling rod attached by a ball and socket joint.
It is evident that this arrangement will allow to-each driving wheel; an independent vertical motion, with the advantage that the engine will partake of only one half the vertical motion of either wheel, in consequence of being suspended at the centre of. the horizontal sustaining beam.
The front drivers are without flanches, in order to avoid my difficulty in turning curves.
The peculiarity in the means of maintaining the fire draft, is an apparatus for equalizing the effect of the exhaust steam in the smoke stack, somewhat similar to Gurney's contrivance.
Instead of exhausting directly into the stack, the exhausted steam enters two copper chests, one connected with each cylinder, and escapes froth these into the chimney through a number of small tubes.
With the aid of this contrivance the anthracite fire -- is kept in a state intense activity, and generates an abundance of steam without the annoyance and danger arising from the smoke and sparks of a wood fire.
The heat of the anthracite fire has been found so. great as to melt down he grate bars of cast iron which were used in the first experiments with this fuel.
Messrs. E. & H. have since substituted grooved wrought iron bars, which are protected from the action of the fire by a coating of clay placed within the grooves.
A trial of one of these engines on the road between Broad street and Peter's Island, was witnessed by several members of the Committee, on the 25th of April last.
It happened unfortunately, on that occasion, that the business of the road did not furnish so many cars as were desirable for a fair experiment
The particulars so far as made known to the-Committee, were as, follows:
Weight of engine, 28,350 lbs., Weight on drivers, 18,059 lbs.
Cylinders, 12 inches diameter, Steam, 90 lbs. to square inch.
Length of stroke, 18 inches, Driving wheels, 44 inches diameter.
The train consisted of 32 loaded cars, estimated at 5 tons each, 2 empty cars weighing 9800 lbs., and tender, 5 tons making a total of 169 tons. This triain was started with great ease on a rising grade of 27 feet to the mile, and drawn to the foot of the inclined plane, the distance being about 3 miles partly on a rising grade of 35 feet to the mile, with several short curves, and the road in such bad condition as to keep the sustaining beam in continual vibration.
A few days after this experiment, one member of the Committee had an opportunity of witnessing a more decisive trial of the power of the engine.
On the latter occasion, the train consisted of 34 single cars, estimated at 5 tons each, 4 double cars, 10 tons each; one of Mr. Dougherty's iron boats 50 tons, and the tender 5 tons; total, 265 tons.
The train was started without difficulty, on the same rising grade of 27 feet to the mile, and drawn over the 35 foot ascending grade and short curves with apparent ease, and with steam blowing off during the whole trip.
This highly interesting experiment was brought to a close somewhat abruptly after proceeding about 2 miles, by the breaking down of one of the cars near the middle of the train.
Although this accident abridged the trial of the power of the engine for draught, it afforded an opportunity of displaying another excellent trait in its performance, this was the facility of reversing* while underway.
As soon as the accident happened, a person stationed on the after part of the train passed a signal to the engineer, the latter immediately, reversed the engine and brought the enormous moving mass to a stand before it had run half its own length. The satisfactory character of the experiments detailed above is sufficient to enable any one who is conversant with transportation on railroad to form a correct opinion of the merits of this engine. The impression of those members of the Committee who witnessed the trials, is, that it is well adapted for the use of anthracite as fuel, and for very heavy draught; with less tendency, to injure the road or to receive injury on a bad road than engines of the usual construction.
By order of the Committee.
WILLIAM HAMILTON, Actuary.
* For a report on this mode of reversing, see Journal of Franklin Institute, vol. xviii,; p. 179.
May 9, 1839,
At the request of Messrs. Eastwick and Harrison, the Committee insert the following letter from A. Pardee, Jr. Esq., Engineer of the Beater Meadow Railroad, in reply to their letter requesting information relative to the. construction of the road and the performance of their engine upon it.
Hazleton, Pa., June 8th, 1839.
MESSRS. EASTWICK & HARRISON,
Gentlemen---I have received your's requesting information as to the construction, &c. of the roads in this region; on which your eight wheeled Locomotives are employed.
The Beaver Meadow railroad, where one of those engines has been in use two years, has an iron plate rail of 2-1/4 by 5/8 inches; the wooden rails or string pieces, are oak, a portion 5x7, the remainder 5x8 inches; where the 5x7 rails are used, the cross ties are placed three feet from centre to centre, where the 5x8 they are four feet. The cross ties are-laid on plank mud-sills 2-1/2 inches thick by 10 to 12 inches wide. The shortest curve has a radius of 300 feet; length about 200; but at the foot of the inclined planes, there is a curve, around which the engines now daily pass, the radius of which is 250 feet, the length about 300. The heaviest grade is 96 feet per mile, at two points, about 3/4 mile each, there is an average grade of 80 feet per mile for 5 miles -- on the heaviest grade the shortest curve is 550 feet radius, the length about 400 feet. The Hazleton railroad on which two of your eight wheel engines are now in use, has a plate rail 2-1/4 by 5/8 inches, the string pieces are yellow pine 5x9 inches, the cross ties 4 feet apart; from centre to centre, the mud-sills 2-1/2 by 10 to 12 inches. The heaviest trade is 140 feet per mile for 1-1/2 miles, this part of the road was not intended, when made, for the use of locomotive power, but it was found in practice that by doubling our trips we could use the engines with more economy than horse power. In regard to the effect on the road; so far as my experience goes, and I have seen the two classes of engines in daily use for more than two years, I would say that the eight wheel engine was easier on the road than a six wheel engine of the ordinary construction, with the same weight on the two driving wheels as on each pair of the driving wheels of the eight wheeled.
There are now in use on the Beaver Meadow and Hazleton railroads, seven locomotive engines with horizontal tubular boiler, in which anthracite coal is exclusively used as a fuel after the first fire in the morning, and that we continue to use it when we can have wood for the cost of cutting, is sufficient evidence that we find it to our advantage. We. have the Hercules at work, and so far, she performs well, running around the curves with great ease.
Rev. November 2011