IMPROVEMENTS IN STEAM ENGINES
Year: 1878

page_text: LETTERS PATENT to Herbert Edward Vosper, of Portsmouth, in the County of
Hants, for the Invention of "IMPROVEMENTS IN STEAM ENGINES."
PROVISIONAL SPECIFICATION left by the said Herbert Edward Vosper at
the Office of the Commissioners of Patents on the 26th August 1878.
HERBERT EDWARD VOSPER, of Portsmouth, in the County of Hants. IMPROVE-
MENTS IN STEAM ENGINES."
"
My Invention relates to improvements in two and four cylinder single-acting
steam engines, the object of the improvements being to dispense with the use of
the ordinary reversing gear and to economize space and cost of manufacture.
In carrying out my Invention for four cylinder engines I place each pair of
cylinders at right angles, thereby using only one excentric for the two sets of slide
valves which are of the ordinary description, with the exception that the steam is
admitted only on the top side of the pistons of one pair of cylinders from the top
port, and to the top of the other pistons from the bottom port.
The improved reversing gear consists of a two-way cock for each pair of
cylinders placed behind the ports, which by moving a certain distance reverses the
steam from the top of one pair of cylinders to the top of the other pair.
The reversing cocks of the cylinders are connected together by a lever, and the
cranks are placed exactly opposite one another, two connecting rods being applied
to each crank so as to avoid dead centres.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Herbert Edward Vosper in the Great Seal Patent Office on the
26th February 1879.
HERBERT EDWARD VOSPER, of Portsmouth, in the County of Hants.
MENTS IN STEAM ENGINES."
"IMPROVE-
My Invention relates to improvements in two and four cylinder single-acting
steam engines, the object of the improvements being to dispense with the use of
the ordinary reversing gear and to economize space and cost of manufacture.
In carrying out my Invention for four cylinder engines I place each pair of
cylinders at right angles and use only one eccentric for the two sets of slido valves,
which are of the ordinary description with the exception that the steam is admitted
only on the top side of the pistons of one pair of cylinders from the top port and
to the top of the other pistons from the bottom port.
The improved reversing gear consists of a two-way cock for each pair of
cylinders placed behind the ports, which by moving a certain distance reverses the
steam from the top of one pair of cylinders to the top of the other pair.
The reversing cocks of the cylinder are connected together by a lever and the
cranks are placed exactly opposite one another, two connecting rods being applied
to each crank so as to avoid dead contres.
Instead of employing a two-way cock I may use a spiral slot in the eccentric
operated by a collar and lever, as herein-after described.
But to make my Invention better understood I will proceed to describe the same
by reference to the accompanying Drawings, in which,
Figure 1, Sheet 1, is a section transverso to the.crank shaft.
:
Figure 2, Sheet 1, is a section parallel with the axis of the crank shaft and one
pair of cylinders.
Figure 3, Sheet 1, is an end elevation.
Figures 4, 5, and 6, Sheet 1, details of the slotted eccentric reversing motion.
Figures 7, 8, and 9, Sheet 2, views of the two-way cock or plug arrangement for
reversing,
Figure, 10, Sheet 2, is a section shewing the valve arrangement for working on
the compound high and low pressure expansive system.
In Figures 1, 2, and 3 the cylinders are shewn arranged in pairs a, a¹, and b, b',.
adjacent to one another, and the longitudinal plane of each pair makes with the
other an angle of ninety degrees, having the centre of the crank shaft at the point
or apex of the said angle.
The cylinders are attached to a suitable casing e in which the connecting rods
o, c³, and ‹, d', are enclosed; the said casing is provided with covers f, f, at the
ends, which also form the crank shaft bearings. There are two cranks 9, 9,
opposite to one another, having the connecting rods c and d working from pins in
the pistons on to the crank g, and c and d similarly actuating the crank g¹.
The slide valve h is of the ordinary D type, and steam being admitted at its
back, it alternately opens the passages i, k, letting steam to the cylinders a, a¹,
or b, b', as the case may be, and cutting the steam off again and opening to the
exhaust after suitable and appropriate expansion of the steam in the said cylinders.
Motion is given to the valve and the engines are reversed in the following
manner: m is an eccentric, in the elongated boss of which a spiral slot m¹ is cut,
the angular difference between the ends of this slot corresponds to the difference
between the required positions of the eccentric in respect to the crank shaft for
forward and backward motion.
o is a collar keyed on to the shaft by the key end keyway oll and rotating with
it; n is likewise a collar rotating with the collar o by means of the key and key-
way o¹, but free to move in a direction parallel with the crank shaft, but limited
in its motion in either direction by the pin n' working in the slot m³. The motion

page_text: of the said collar n tends to alter the position of the eccentric m in respect to each
or either of the said cranks g, g', altering the direction in which the engine runs
or modifying the point at which the steam is cut off at pleasure.
In order to shift the collar na groove n is turned therein in which a forked
lever works, and the said lever being pivotted to the casing at q it can be pushed
forwards or backwards, taking the collar n with it, which latter actuates the
excentric m.
The engine can also be reversed by means of two plugs, forming a two-way cock,
as shewn in Figure 7, Sheet 2, placed between the slide valves and cylinders,
Figures 8 and 9 being cross sections of the said plugs; r,, represent the plugs
through which straight passages 8, 8, and 81, 8¹, are provided for the steam to
continue its normal course from i and k through and k'. When the plugs are
turned one quarter of a circle the steam is diverted at right angles through t, 8,
and t, 8, whereby the steam from i enters k¹ and from k enters i, the cylinders
and gear being arranged otherwise precisely as herein-before mentioned.
Figure 10 exemplifies a system of compounding and is arranged as follows:-
a is the high-pressure and a the low-pressure cylinder. The slide valve h has the
lower edge elongated, as shewn at w, so that under no circumstances can steam be
admitted to the lower port which is now the exhaust.
Steam is admitted to i, and having driven the piston downwards in a the valve
opens a communication between the said passage i and k, which communicates with
the low-pressure cylinder a'; after the steam thus admitted from a into a¹ has
driven that piston downwards a communication is opened between k and tho
exhaust passage through which the steam escapes, and so on continuously.
All the other parts of the engine, except the parts shewn in Figure 10, remain
substantially as herein-before described.
Having thus described iny said Invention, and the best means with which I am
acquainted for carrying the same into effect, I wish it to be understood that what
I claim is,-
Firstly. The method of admitting steam to the two or four cylinders of two or
four cylinder steam engines by means of one, eccentric only in combination with
ordinary D slide valves, arranged and operating substantially as herein-before
described and represented in Sheet 1 of the accompanying Drawings.
Secondly. The employment for reversing the engines of the two-way cocks, the
plugs of which are connected together and work behind the ports, as herein-before
described and represented in Figures 7, 8, and 9, Sheet 2, of the accompanying
Drawings.
Thirdly. The application to four cylinder engines of a slotted eccentric for
reversing the engine, as herein-before described and represented in Sheet 1 of the
accompanying Drawings.
Fourthly. The slide valve arrangement, shewn in Figure 10, Sheet 2 of the
Drawings, for adapting my improvements to compound engines, as herein-before
described.
In witness whereof, I, the said Herbert Edward Vosper, have hereto set
my hand and seal, this Twenty-fifth day of February, in the year of our
Lord One thousand sight hundred and seventy-nine
HERBERT EDWARD VOSPER. (L.S.)