Propulsion of Tramcars.
Year: 1886

page_text: Propulsion of Tramcars.
I, EDWARD MEIN of 16 Beech Grove, Seaforth, Liverpool, Engineer, do hereby
declare the nature of my invention for A NOVEL COMPRESSED AIR ENGINE
SPECIALLY ADAPTED FOR THE PROPULSION OF TRAM CARS and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement, reference also being had to the accompanying two sheets
of drawings:-
The general arrangement of the apparatus according to my Invention is shewn
by a side elevation, plan partly in section and end view respectively, at Figures 1, 2,
and 3, sheet 1 of the accompanying drawings. Said apparatus is also devised with
especial view to same being readily adapted to existing tram-cars-The body part
being bolted to the brackets A on the sides of the engine framing.
Two main cylindrical air reservoirs B, B¹ are provided and disposed under the
car seats inside, and extend the whole length of the car. In the case illustrated
the capacity of said air reservoirs would be equal to 20 cubic feet each. C. C³, repre-
sent two smaller cylindrical air reservoirs. These latter are disposed underneath
the body of the car, and relatively to the large reservoirs B. B', would have a
capacity equal to one half that of each of last mentioned reservoirs. In cases
where the requirements necessitated the employment of additional or supplementary
air reservoirs, these latter could also be disposed similarly to those C. C₁, underneath
the body of the car.
Contrary to the practice generally followed in regard to air engines, I do not
adopt the principle of compounding. I employ two high pressure cylinders D. D¹
only. The exhaust valves E. E¹, are worked by a revolving spindle or shaft F.
Each end of which is provided with feathers m and makes a sliding or telescoping
fit in a revolving steel bush g (Fig. 4 Sheet 1) working in a pair of brasses h
carried in brackets h¹ and bolted to the bottom of the cylinders D. D¹. The spindle
or shaft F (also shewn in detail Figure 4) and further in Figures 3 A and 4 A
Sheet 3, is provided with projecting cam like pieces f g to allow of each valve being
opened in forward or backward gear. The details relative to the last referred to
features of my Invention are shewn at Figures 4, 5 and 6 of Sheet 1. On referring
to which (Figure 4) it will be seen that the projecting cam like pieces f represent
an acute angle winding round the shaft; the object in view being to allow of
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page_text: determining the point of "cut off," which is effected by the reversing handle ¹, on
the reversing shaft i. The position therefore of the projecting pieces f g aforesaid
opposite the inlet valve H spindle, shaft or roller F, will determine the time the
valve is kept copen. For instance, if the extreme point of angle aforesaid is
running round the inlet valve H the width of that point will represent said time
during which the valve is kept open. If however the spindle, shaft or roller F be
moved horizontally, so that the widest part of the angle on projecting pieces or
cams fg aforesaid is running round opposite the valve H, the width of that part
will also represent the duration of the period of opening.
In further illustration of the foregoing, in which Figure 3A Sheet 3 represents
a detailed view of the inlet valves and spindles, actuated by the cams ƒ on
shaft F and Figure 4A, illustrating the two ends of the shaft F showing the
position of the cams placed one at 90 degrees in advance of the other, it will
be seen that the inlet valve spindles S and S¹ at the right hand end of the
shaft F, are shewn in position at the widest part of the cam. The spindle S
which rides on the cam by means of the friction, pulley is seen to be holding
the inlet valve open for the admission.of air to one end of the cylinder as shown
at T (Figure 3A) whilst the opposite spindle S¹ (Figure 4A) is riding upon
the shaft F in which position the valve would be closed. The position of
the corresponding cam f¹ at the opposite end last referred to of the shaft F
Figure 4A is shewn to be in a position 90 degrees in advance of the cam f
aforesaid; the shaft therefore, in the position given (Figure 4, Sheet 1) will
be revolving in the direction of the arrow shown on the cam fin said Figure 4.
Now, it will be seen that, in order to allow of the Engine being reversed (the
position of the shaft) as shewn at Figure 4 A being at the extreme right) the shaft
or roller F must be moved in a lateral direction to the left, untill the cams g and g¹
which are placed at an angle opposite to that of the cams f f¹, come under the
inlet valve spindles S and S, when it is evident that the opening of the valves
will be reversed in the order of rotation-The position of the cams at both ends of
the shaft F, relatively to their respective bosses and the feathers m on the latter is
exactly the same in both instances, as will be seen on reference to Figure 4A
Sheet 3. When the engine is stopped, the shaft is in such a position that the inlet
valve spindles bear upon the portion of the shaft F, between the cams f; g³, and
f', g, respectively.
By the means and mode of working adopted as above described, I am enabled to
ensure that the air shall be used efficiently from 1000 lbs: the initial pressure, down
to 100 lbs. Also on referring to Figure 4, it will be seen that the projecting.
pieces k, for working the exhaust valve are of rectangular, instead of angular
contour or shape, so that the operation of moving the spindle, shaft or roller F in
either direction-horizontally-to alter the "cut off" will allow the opening of the
exhaust valve to remain constant, inasmuch as said projecting pieces k, are not only
rectangular as before mentioned, but also correspond in length, with those for
opening the inlet valves, and therefore as above stated, the duration of opening of
the exhaust valve remains constant. There are two sets of the projecting pieces
aforesaid at each end of the shaft, one set for the "backward" gear, and one set for
the "forward."
Now, in order to reverse the engine, move the shaft or spindle F, in either.
direction to the right or the left, and throw one set of cams out of action. The
reversing" and the "cut off" are done by the one portable handle ¹, which must
be taken either to the rear end of the car or front end thereof, according to the
direction in which the car is travelling. The Regulator / shewn in detail, Figure 8
is also worked by a portable foot treadle taking into a socket as shewn at Figure 12,
which treadle must be removed and taken to either end of the car, similarly as in
the case above referred to of the portable handle ; the object being that no handle,
or machinery shall be seen at the rear end of the car; also to allow of the car
running in either direction similarly as in the case with horse cars, without having
to turn.

page_text: The special automatic lubricating device which I employ as forming a part of
my Invention is shewn in detail at Figure 7. It comprises a perfectly fitting
horizontal spring spindle sliding valve o adapted to the cylinders D, D¹, which
projects into the cylinder, as shewn at D¹ (Figure 7,) said projecting portion being
formed as shewn at x with a conical recess into which takes a corresponding
conical projection y formed on the end of the piston G. The amount of said
projection being equal to the extent to which the valve has to be knocked open by
the piston at every stroke-Around said valve O at p is formed a recess for the
reception of a packing material such as asbestos, or similar substance that will
expand when heated and ensure an absolutely tight joint—A small perforation q
is formed through the centre of the valve branching off at a right angle at qin
front of the valve seat.
On the piston approaching the head of the cylinder, the projection y presses the
valve back allowing the small hole of the perforation g' to pass beyond the valve
seat; said. perforation becoming then filled with the lubricant, where it remains
until the valve returns to its seat. On the projection on the piston retiring from
the recess the perforation is opened; the expanding air then draws the lubricant
into the cylinder. Another feature appertaining to my special automatic lubri-
cating device for air engines is as follows:-When the engine is standing still and
the piston at the extreme end of the cylinder, the valve will be pressed away from'
its seat and the perforation open to the lubricator, but the passage of the lubricant
is barred by the projection y closing the recess x therefore, none of the lubricant
can pass into the cylinder; thus it will be seen that lubrication can only be
effected when the engine is in motion.
The high pressure inlet vale H herein before referred to is shewn by a sectional
view to enlarged scale, Figure 11, sheet 1, of the accompanying drawings-A
detailed view of the exhaust valve is shewn in section at Figure 9, sheet 1, of the
accompanying drawings-I also employ the special device of a double seated'
junction valver shewn in the plan Figure 2 (Sheet 1) and also on an enlarged
scale in section at Figure 10 (Sheet 1) from which it will be seen on reference to
the latter Figure is so constructed as to be perfectly efficient without necessitating
the use of packing.
The heating of the air which in air engines as hitherto devised has been effected
by means of boilers or hot water, is open to the many objections inherent to both
these systems of heating, but which objections I am enabled to remove; as, in the
arrangement which I adopt in accordance with this head or feature of my Inven-
tion, said heating of the air is accomplished by the employment of loose or inde-
pendent iron heaters previously made hot in an oven or similar device.
The drawings, Sheet 2, illustrate the novel devices which I adopt with a view to
effect the heating as aforesaid of the air before it enters the cylinders D. D¹, by a
side elevation Figure 1, and sectional end elevation Figure 2, to an enlarged scale
to that adopted for the drawings, Sheet 1, in which latter, the heater is indicated
at K in Figure 1, and extends the length of the box E' referred to hereunder.
Referring more particularly to the end elevational view, Figure 1, Sheet 2, the
cylinder D it will be seen, is cast in a cast iron box E, in which latter are two
copper pipes II, one for each end of the cylinder. Between these two copper
pipes is placed the iron heater K; there is a second heater K¹ of semi circular
form which partly surrounds the cylinder D. The close proximity of the heater K
to the feed pipes I, I' generate in them, and consequently, the air contained within
great heat, as is also the case in the cylinder from the heat generated by the
heater K¹. It will thus be seen that the air in its passage through the pipes to
the cylinder becomes very hot.
It is necessary that there should be duplicate sets of these heaters, so that when
one set becomes cool, the second set is ready to replace them. The arrows at t t¹
indicate the travel of the air from reservoir to cylinder.
In order that the heat in the boxes E* does not escape and that it may be
retained at a nearly constant temperature, said box E as shewn at Figure 2,

page_text: Sheet 2 is provided with a cover constructed of two iron plates bolted together,
the space between such plates being filled with a suitable non conducting cement
or composition, or other non conducting material; the cover being then firmly
secured to the cast iron box E³.
A car fitted with my improved apparatus is self contained, and its dimensions
do not exceed those of a horse car.
•
:
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
Firstly-The novel arrangement generally, of compressed air engines and parts
connected therewith, specially adapted for the propulsion of tram cars, substantially
as herein described and shewn in the accompanying drawings.
Secondly:-In compressed air engines, the mode and means adopted for heating
the air substantially as herein described and shewn more particularly at Figures 1
and 2, sheet 2 of the accompanying drawings
Thirdly-The automatic lubricating device substantially as herein described
and shewn at Figure 7, Sheet 1 of the accompanying drawings.
Fourthly The double seated junction valve substantially as herein described
and shewn at Figure 10 Sheet 1 of the accompanying drawings.
Dated this twenty fourth day of September 1886.
Der
JAMES STEVENSON,”
Gray's Inn Chambers,
20, High Holborn, London, W.C.,
Agent for Applicant.