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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.
COM. PUB.
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.
Respectfully
yours,
A.
PARDEE,JR.
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