Improvements in Hydraulic Motors.
Year: 1891

page_text: Date of Application, 13th Feb., 1891
Complete Specification Left, 13th Nov., 1891-Accepted, 13th Feb., 1892
•
PROVISIONAL SPECIFICATION..
Improvements in Hydraulic Motors.
I, GEORGE RUDOLPH BODMER, Civil Engineer, of 30, Walbrook, in the City
of London, do hereby declare the nature of this invention to be as follows:-
My invention relates more particularly to water-pressure engines, or hydraulic
motors, in which the pressure of the water acts on a piston or plunger and is trans-
mitted to a crank or equivalent mechanism in the ordinary way. Such engines, as
usually made, have the drawback, that an equal quantity of water is required,
to drive the motor, whether the latter works at its full power, or at only a fraction
thereof.
The present invention has for its object, to provide simple and efficient means
for varying the consumption of water by the engine approximately in proportion to
the power developed.
For this purpose I construct and arrange the admission and exhaust valves, the
valve gear and the water passages in such a manner, that water under pressure is
admitted to the piston or plunger during the whole of its forward stroke, but that
during a greater or less part of the return (or exhaust) stroke, some of the water
admitted on the forward stroke is forced back into the pressure main or other
source of supply, the difference between the quantity of water thus forced back
and the total quantity of water required to fill the space behind the piston or
plunger being exhausted in the usual manner and constituting the only consumption
of pressure water.
This principle may be embodied or carried into effect in various ways.
In the case of a double acting engine having a port or water inlet at each end of
the cylinder, I may employ a double acting slide valve or a pair of valves similar
to those employed in many steam engines, and arrange it so, that at full power,
that is, when the engine is to produce its maximum effect, the said valve
or pair of valves works without either inner or outer lap. For reducing the power,
the two ends of the slide valve, or the two valves, are moved symmetrically and
simultaneously towards the mid-position, so that the outer lap becomes negative,
and the inner lap positive by the same amount. The result is, that in the mid
position of the valve, when the piston or plunger is either at the commencement
or at the end of its stroke, the valve leaves the admission port more or less
uncovered.
!+
To obtain the necessary adjustments of a double acting valve, I may compose it
of two symmetrical parts through which passes a screwed spindle with right and
left hand. threads, as in the well-known Meyer valve, so that by turning the spindle,
the two halves may be caused to approach each other or to move further apart. In
single acting engines, the valves need not be in two parts. Any other suitable
means may, however, be employed for regulating the effective length, or the position
of the valve, according to the power required, and the shape of the valve may also
be varied to suit special requirements:
For single-acting oscillating engines, I may attach a segmental valve of the
slide-valve type to a central spindle passing through the oscillating valve
chest, at a right angle to the cylinder axis, and maintain the valve stationary, as
long as the engine is required to develop a given proportion of its power, the
ports in the cylinder being opened and closed by the oscillating motion of the
latter; but if the lap of the valve, and therefore the work of the engine, is
to be varied, I turn the valve about its spindle by a lever or other suitable
means.
In the case of double-acting oscillating engines, where the axis of oscillation

page_text: passes across the axis of the cylinder at or near the middle of its length, as for
instance in Schmid's water pressure engines, in which the cylinder has a circularly
curved valve face sliding or oscillating on a circularly curved bed, I may employ a
pair of circularly curved slide valves situated between the valve face of the oscil-
lating cylinder and the stationary bed, said valves being attached to a pair of
frames or holders adapted to turn on the axis of oscillation of the cylinder.
Instead of ordinary slide-valves or their equivalents, I may use separate admis-
sion and exhaust valves of any suitable type, and work them by adjustable cams
or trip gear in such a manner, as to effect the object described.
As in certain positions of the piston or plunger, the slide valve or its equivalent
may be momentarily closed, while the piston or plunger is moving rapidly on its
return stroke, I provide relief valves opening out of the cylinder into the valve
chest, mains or pressure chamber.
The desired regulation of the valves may be effected by hand, or automatically
by means of a suitable governor, acting either directly or indirectly.
Dated this 12th day of February 1891.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Hydraulic Motors.
I, GEORGE RUDOLPH BODNER, Civil Engineer, of 30 Walbrook, in the City
of London, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
.
My invention relates more particularly to water-pressure engines, or hydraulic
motors, in which the pressure of the water acts ou a piston or plunger and is
transmitted to a crank or equivalent mechanism in the ordinary way. Such engines,
as usually made, have the drawback, that an equal quantity of water is required,
to drive the motor, whether the latter works at its full power, or only at a fraction
thereof.
The present invention has for its object, to provide simple and efficient means
for varying the consumption of water by the engine approximately in proportion to
the power developed.
For this purpose, I construct and arrange the admission and exhaust valves, the
valve gear and the water passages in such a manner, that water under pressure is
admitted to the piston or plunger during the whole of its forward stroke, but that
during a greater or less part of the return (or exhaust) stroke some of the water
admitted on the forward stroke is forced back into the pressure main or other
source of supply, the difference between the quantity of water thus forced back
and the total quantity of water required to fill the space behind the piston or
plunger being exhausted in the usual manner, and constituting the only consumption
of pressure water.
This principle may be embodied or carried into effect in various ways, some of
which I will now describe with the aid of the accompanying drawings.
Figs. 1 and 2 represent an arrangement suitable for double acting engines with
fixed cylinder having a port or water inlet at each end, Fig. 1 being partly a
longitudinal elevation and partly a vertical section along the axis of the said
engine, while Fig. 2 is composed of two cross sections of the cylinder and valve
chest (seen from the back or end furthest from the crankshaft) one half (that on
the left) being a section along line I-II-III-IV-V and the other half (that
on the right) being a section along line VI-VII of Fig. 1, the slide valve, however,
being assumed to be in its extreme right hand position.
The front or crank shaft end of the engine is similar to that of ordinary
reciprocating engines, and therefore not shown.

page_text: in the umerent figures of the drawings summar
corresponding parts.
C is the cylinder, P and Q are respectively the piston and piston rod connected
in the usual manner with the cross head R and connecting rod R¹, driving the
crank and crank shaft (not shown). The two ends of the cylinder
connected with the valve chest V by ports or passages c, c in the manner usual in
steam engines. E¹, E' are exhaust ports communicating with the central exhaust
or discharge opening E.
The valve chest V communicates through the orifice or pipe O with the pressure
mains which supply the water for working the engine.
The distribution of water to the cylinder is controlled by a pair of symmetri-
cally arranged slide valves S, S, mounted on the screwed spindle T with right and
left hand thread, as in the well known Meyer valve gear.
The outer end of the screwed spindle (that furthest from the crank shaft) will
(though not so shown) generally be made of a smaller diameter than the inner
end (which carries the right hand valve).
By turning the spindle to the right or to the left about its axis, the two
valves are caused to approach or to recede from each other, and thereby to overlap
the ports more or less, when they are in their mid-position.
Fig. 1 shows the valves in their mid position (which occurs when the engine is
at or near the end of its stroke) and at full power (that is to say, when they are
placed so, that the engine will produce its maximum effect).
•
In this position, the valves of my engine have, as a rule, neither inner nor outer
lap, that is to say, the outer edge of the valve coincides with the outer edge of
the port c and the inner edge of the valve with the inner edge of the port, at each
end of the cylinder.
The valve spindle is continued through a stuffing box of the valve chest, and
outside the latter a length e of it is made of square section and passes through a
corresponding hole in the boss of the hand wheel W. The latter is capable of
turning in a bearing B situated on a bracket secured to the bed plate.
The outer end of the spindle is connected through a swivel t and connecting rod
or link with the lever v keyed or otherwise rigidly attached to the shaft wo
carried in two or more bearings of which one y is shown. To the shaft w is also
rigidly attached a second lever v pivoted at its upper end to the eccentric rod e
which is actuated in the usual way by an eccentric on the crank shaft. From the
eccentric reciprocating motion is transmitted to the slide valves S, S, through the
lever v', the shaft w, the lever v, link r, and spindle T.
It is clear that by means of the hand wheel W the valve spindle T can be
turned while in motion about its axis and the relative position of the valves altered
as described.
For reducing the power, the two valves are moved by turning the hand wheel W,
in the manner described, symmetrically and simultaneously towards each other, so
that the outer lap becomes negative and the inner lap positive by the same amount.
The result is that in the mid position of the valves, when the piston or plunger is
either at the commencement or at the end of its stroke, the valves leave the ports
more or less uncovered. Under these circumstances the communication between
the cylinder and valve chest remains open not only during the whole of the forward
(or working) stroke but also during a portion of the return stroke at its beginning
and end, while the proportion of the stroke during which the exhaust takes place
is proportionately reduced.
As in certain positions of the piston a slide valve may momentarily close one of
the ports c, while the piston is moving rapidly on its returu stroke, I provide relief
valves s, near each end of the cylinder, one only of which is shown in the cross
section Fig. 2-opening out of the cylinder into the valve chest. An adjustable
spring (or buffer) s¹ is provided to keep the valve in place and accelerate its motion
when closing.
Instead of the handwheel W, a pulley or other suitable device may be provided

page_text: which is set in motion by a centrifugal or other governor in order to regulate the
speed of the engine.
For single acting oscillating engines, one method of carrying my invention into
effect is shown in Figs. 3 and 4, which represent the case of a duplex engine
having two similar cylinders placed parallel to each other along the same axis of
oscillation, the plungers of said cylinders acting on two cranks set at 180 degrees
or at any other suitable angle to each other. Only one cylinder is shown in Fig. 4,
the other cylinder being situated symmetrically on the opposite side of the orifice O
and lever L, which are situated in the centre line of the engine. Fig. 3 is a
longitudinal elevation and part section through the axis of one cylinder. Fig. 4, a
plan, partly in section, of the other cylinder. The crankshaft bearings, which may
be of any known construction are not shown in the plan.
A segmental valve S, of the slide valve type, is mounted on a central spindle T
passing through the valve chest V of the oscillating cylinder C at a right angle
to the cylinder axis. About the axis of this spindle T the oscillation takes place.
The rear surface of the valve chest V forms a portion of a cylinder and bears
upon a correspondingly concave bed forming part of the hollow frame F. The
water under pressure from the main enters the hollow frame F through the
orifice O and finds its way through suitable passages at each end of the frame F
and thence to the axial pipes p¹p (one for each cylinder) into the valve chest, as
indicated by arrows. The cylinder port C and the exhaust port E are opened and
closed by the oscillating motion of the cylinder, which causes a relative motion of
those ports with reference to the valve S. So long as the engine is required to
develop a given proportion of its power, the valve S is maintained stationary in
one position by means of the spindle T and the lever L fixed to the same. When,
however, the lap of the valve, and consequently the power of the engine, is to be
altered, the spindle T is turned about its axis by means of the lever L, which lever L
is actuated in any convenient manner, and so arranged that it can be held fast when
the desired position is attained.
Figs. 3 and 4 represent the lever L as being controlled by a rod M, which may
be operated by hand or by a governor.
The plunger P working in the cylinder C is connected by any of the usual means
with a cranked shaft K. In the duplex engine represented by the drawing the
lever L is so arranged that it actuates the spindles T of both cylinders, at the same
time such spindles being adjusted so that their axes coincide.
The front part of the engine frame forms supports for the crankshaft
bearings, K', K', one of which is shown in the drawings. Relief valves s opening
out of the cylinder into the valve chest are provided for the purpose already
described, in reference to Figs. I and 2.
J
The lift of the valves is limited by indiarubber rings s¹ which act at the same
time as springs. t is a collar fixed on the valve spindle T to prevent any
accidental shifting.
In the case of double acting oscillating engines, where the axis of oscillation
passes across the axis of the cylinder at or near the middle of its length, as for
instance in Schmid's water pressure engines in which the cylinder has a circularly
curved valve face f sliding or oscillating on a stationary circularly curved bed, I
may employ the arrangement represented by the sectional Figures 5 and 6. In this
case, a pair of circularly curved segments S are situated between the oscillating
face forming part of the cylinder casting and the concave surface of the
bedplate F. These segments are furnished with ports a a and are so arranged, that
they can be simultaneously moved towards or away from each other, so that the
ports a a assume different positions relatively to the cylinder face f.
cc are the cylinder ports opening in the face v2, O is the passage in the bedplate F
through which water is admitted from the main to the cylinder. E is the exhaust
passage. Through the oscillation of the cylinder each cylinder port c is placed
alternately in communication with the admission passage O and the exhaust
passage E respectively through the central space between the segments, and one

page_text: of the ports a. It is obvious, that by altering the position of the segments, the
ports c when the latter are in their mid position (and the piston at the commence-
iment or end of its stroke), will be more or less uncovered, this corresponding to a
greater or less amount of negative outside lap in the case of an ordinary slide
valve.
For regulating the position of the slides S, S, I may employ a hand wheel W
acting on a horizontal shaft and thereby on bevel wheels which serve to turn
two pairs of screw spindles to the right or to the left, and thereby to draw the
elides S, S forward or backward, as may be required.
C'C' are a pair of trunnions supporting the cylinder C, as in Schmid's well
known water pressure engine.
In the case of engines, which oscillate on a pair of trunnions serving as inlets for
the pressure water, and in which the valve face is therefore formed in the circumn-
ference of the trunnions, instead of being at the bottom of the cylinder, the
regulation may be effected in a similar manner, that is to say, by means of two
pairs of circularly curved slides, one pair for each trunnion, the said slides being
interposed between the ports or valve face of the trunnion and the bearing or
concave bed, through which the water enters the trunnion.
Fig. 7 is a partial section through the cylinder and valve chest of a single acting
engine embodying my invention. C represents the cylinder provided with water
inlet c and outlet E. S is a balanced slide valve similar to the ordinary D or
mushroom valves employed in some steam engines, but connected to the valve
spindle T by a screw thread, so that the position of the valve may be regulated by
turning the spindle.
The valve is shown in its mid position (when the engine piston is at or near the
beginning of its stroke) and at full power (placed so, that the engine will give its
maximum effect). In this position, the valve does not overlap the port c, either at
the innere dge c', or at the outer edge c². If now the valve spindle T is turned to the
right, so that the valve will screw itself back along the spindle, the outer lap
becomes negative, that is to say, the admission port c will be more or less uncovered
(beginning at the outer edge c²) so that the engine cylinder communicates with
the valve chest V containing the pressure water.
S¹ is an ordinary balancing piston connected with the back of the slide valve by
a link and serving to balance a portion of the water pressure on the slide valve.
Fig. 8 represents the case of a water pressure engine provided with separate
admission and exhaust valves, (of the Corliss type) operated by adjustable cams,
the position of which is controlled by the governor. Cindicates again the cylinder
shown in vertical section, the admission port, S an oscillating valve mounted on a
spindle, which is turned on its axis by means of lever 1, link a', lever a, and cam a³.
The latter is mounted on a horizontal shaft a and secured thereto by means of a
groove and feather, which allow the cam to be shifted along the shaft a revolving
with constant speed.
During every revolution of the shaft a', the cam a³ acting on a friction roller
secured to the lever a², will turn the valve S one way, and a spring enclosed in the
box 6 will turn it the opposite way by means of a lever b' mounted on the valve
spindle.
Now, as the cam a³ is curved not only circumferentially, but also longitudinally,
and consists virtually of parallel cams of different shapes, it is only necessary, to
shift the cam a along its axis, in order to change the operation of the valve S, so
as to produce a different period of admission.
Fig. 9 is an indicator diagram of a water pressure engine working at full power.
It is approximately a rectangle, of which the upper side I-II shows the pressure
behind the piston or plunger during the forward stroke, while the lower side III-IV
shows the pressure during the return or exhaust stroke; the height of the rectangle
represents the difference between the pressure of the water in the valve chest and
that of the exhaust, and the area of the rectangle is proportional to the work

page_text: performed by the water during a revolution of the engine. Fig. 10 is an indicator
diagram of the same engine working at reduced power.
During the whole of the forward stroke, the admission port is open, the pressure
is constant, and the corresponding part of the diagram therefore a straight
line I-II.
During the first part of the return stroke, the admission port remains open, the
water is forced back into the valve chest, the pressure behind the piston remains
the same, and the corresponding portion of the diagram is therefore a straight
line II-III. During the second part of the stroke, the admission is closed and the
exhaust open, and the pressure behind the piston is equal to that in the exhaust
tank, as represented by the line VI-V. During the third and last part of the
return stroke, the admission port is again open and the exhaust port closed, the
pressure behind the piston therefore rises to that of the water in the valve chest,
and then remains constant, until the end of the stroke, as shown in the diagram by
the line VI-I.
The work performed by the water during a revolution of the engine, and the
consumption of pressure water during the same time, is therefore proportional to
the area of the trapeze III-IV-V-VI.
In conclusion, I would remark, that the above examples of engines do not show
all the forms, which may be devised to embody the principle of my invention. For
instance, piston valves, lift valves, or circular slide valves may be employed,
instead of the ordinary or the oscillating slide valves described above.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1. In hydraulic motors of the reciprocating piston or plunger type, the method of
regulating the consumption of pressure water in accordance with the required
power, which consists in controlling the communication between the cylinder and
the supply of pressure water on the one hand, and between the cylinder and the
atmosphere or other waste water receptacle on the other hand, in such a manner,
that during the return stroke a variable portion of the pressure water admitted to
the cylinder during the forward stroke is forced back into the pressure main or
other source of supply, substantially as described.
2. In hydraulic motors of the reciprocating piston or plunger type, the method
of establishing communication between the exhaust side of the cylinder and the
supply of pressure water during a variable portion of the return stroke, which
consists in changing the lap of the distributing slide valve or valves, independently
of its or their ordinary motion and simultaneously with the same, substantially as
described and for the purpose specified.
3. In a water pressure engine of the reciprocating piston or plunger type, the
combination of the cylinder and valve chest, with an adjustable slide valve or pair
of adjustable slide valves, mechanism for producing the usual to-and-fro motion of
the valve or valves at each stroke of the piston, and mechanism for moving the
said valve, or the two valves simultaneously, towards or from its or their mid
position, during the motion of the engine, substantially as described. with reference
to Figs. 1, 2 and 7, and for the purpose specified.
4. In a single acting cscillating engine, the combination of a segmental valve
mounted on a stationary spindle passing through the oscillating valve chest, at a
right angle to the cylinder axis, with mechanism for turning the said valve about
its spindle, while the engine is in motion, substantially as described with reference
to Figs. 3 and 4, and for the purpose specified.
5. In a double acting oscillating engine in which the circularly curved valve face
of the cylinder oscillates on a circularly curved bed, the combination with the cylinder
and engine bed, of a pair of circularly curved slides, situated between the said
parts, and mechanism for turning the said slides about the axis of oscillation of the

page_text: cylinder during the motion of the same, substantially as described with reference
to Figs. 5 and 6, and for the purpose specified.
6. In a hydraulic motor of the reciprocating piston or plunger type, the
combination of a distribution valve or valves, with valve gear adapted to regulate
the position of the valve or valves, according to the amount of power required, and
a relief valve or a pair of relief valves, adapted to provide an outlet from the
cylinder into the pressure chamber or valve chest, if the pressure in the cylinder
reaches the allowable limit, substantially as described and illustrated by Fig. 2.
7. The adaptation and use of separate admission and exhaust valves of the Corliss
type, together with adjustable cams and valve gear, for controlling the admission
and discharge of water in water pressure engines in such a manner, that a variable
portion of the pressure water admitted during the forward stroke of the piston is
returned to the valve chest or other source of supply during the return stroke, and
that thereby the consumption of pressure water is regulated in accordance with the
power required, substantially as described and illustrated by Fig. 8.
1001
G. R. BODMER,
By Fairfax & Wetter,
433, Strand, London, Agents for the Applicant.