Improvements in Compound Engines applicable to Rock-drilling Machines, Locomotives, or Hauling or Mill Engines and the like.
Year: 1898

page_text: Date of Application, 26th May, 1898
Complete Specification Left, 10th Nov., 1898-Accepted, 4th Feb., 1899
PROVISIONAL SPECIFICATION.
Improvements in Compound Engines applicable to Rock-drilling
Machines, Locomotives, or Hauling or Mill Engines and the
like.
I, JAMES WATSON, of Clare Road, Fordsburg, Johannesburg, in the South African
Republic, Engine Driver, do hereby declare the nature of this invention to be as
follows:-
-
This invention relates to improvements in compound engines applicable to rock-
drilling machines, locomotives or hauling or mill engines and the like, driven by
means of steam, compressed air or other motive fluid.
The chief objects with which my invention is designed are, to produce a reliable
compound engine of compact and comparatively simple and cheap construction.
It consists essentially of an engine in which the high pressure cylinder is arranged
within or enclosed by the low pressure cylinder, the piston of the high pressure
cylinder remaining stationary, and the high pressure cylinder acting as the piston
working within the low pressure cylinder and being connected with the drill shaft.
piston rod or like devices as the case may be; and also in the construction and
arrangement of inlet and outlet or exhaust ports and valves as hereinafter more
particularly described.
In the following description, I will, by way of example, describe my invention
more particularly as applied in the construction of a rock-drilling machine.
In carrying out the invention the high pressure cylinder is constructed so as to
be capable of being arranged within and completely enclosed by the low pressure
cylinder. The high pressure cylinder also constitutes or acts as the piston of the
low pressure cylinder. The piston of the high pressure cylinder is fitted with any
suitable form of piston rings, and its piston rod working through a stuffing box or
gland fitted in the end or cover of the high pressure cylinder, is rigidly attached to
the back cover of the low pressure cylinder. The ends or covers of the high pres-
sure cylinder are also fitted with piston rings. The drill bar or shaft-in the case
of an ordinary engine the piston rod-is firmly secured to the forward end or cover
of the high pressure cylinder and works through a gland fitted in the front cover of
the low pressure cylinder. This cover is formed with a neck or continuation
to afford additional bearing surface for the drill bar. The drill bar has attached
to its other and outer extremity in the ordinary or in any other suitable manner
the drill or tool to which it is desired to impart the reciprocating motion.
The high pressure cylinder is turned down to form an external annular recess,
which forms the high pressure valve chest of the engine. This recess in length
slightly exceeds the stroke of the high pressure cylinder or low pressure piston so
as to ensure the presence therein of the compressed air or steam at the initial pres-
sure throughout or at every point of the stroke of the low pressure piston. The main
feed port which is connected with the main supply pine is preferably located in the
centre of the low pressure cylinder or midway of the stroke of the low pressure

page_text: piston and opens into the recess or high pressure valve chest. The high pressure
valve is arranged within the external annular recess or valve chest. This valve is
preferably in the form of a piston valve, the pistons controlling the ports com-
municating with either side of the stationary and high pressure piston being con-
nected by means of a rod. Feed ports are formed in the high pressure cylinder
placing the interior of the cylinder in communication with the valve chest, and the
exhaust ports placing the interior of the high pressure cylinder in communication
with the low pressure cylinder are bored through the ends of the high pressure
cylinder.
In order to produce the requisite rotary motion of the drill shaft, in addition to
the reciprocating motion, the forward exhaust port will preferably be bored out
at an inclination to the longitudinal axis of the cylinder or piston so as to rotate
the piston part of a revolution' during its return stroke. This construction may be
employed either alone or in combination with the usual ratchet and rifle bar
arrangement or the exhaust port may be formed parallel to the longitudinal axis
of the piston similar to the back exhaust port and the ratchet and rifle bar arrange-
ment alone be used for this purpose.
An exhaust valve chamber, placed in connection with condensers or exhausting
into the atmosphere as may be desired, is arranged on the low pressure cylinder.
Within this exhaust valve chamber is the exhaust valve also preferably in the form
of a piston valve, the pistons being connected by means of a rod similar to the
high pressure valve previously described. The exhaust ports are formed in each
end of the low pressure cylinder and place the interior of the same in communica-
tion with the exhaust valve chamber. For the purpose of operating the exhaust
valve, pipes are employed passing in through the low pressure cylinder at one end
and into the exhaust valve chamber behind the pistons at the other and placing the
interiors of the same in communication. Rubber or other suitable buffers are fitted
in the ends of the exhaust valve chamber for the purpose of cushioning the valve.
At either end of the low pressure cylinder small longitudinal grooves are formed
to admit high pressure air or steam behind the low pressure piston to assist in
cushioning it and to ensure the proper working of high pressure valve. These
grooves will be of such a length as to project slightly beyond the piston rings of
the low pressure piston when it is at the end of its stroke. The length or distance
the grooves will project or enter the cylinder will vary with the speed at which the
engine is designed to run.
AL ORAL Ja of 1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
Improvements in Compound Engines applicable to Rock-drilling
Machines, Locomotives, or Hauling or Mill Engines and the
like.
I, JAMES WATSON, of Clare Road, Fordsburg, Johannesburg, in the South African
Republic, Engine Driver, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention relates to improvements in compound engines applicable to rock-
drilling machines, locomotives or hauling or mill engines and the like, driven by
means of steam, compressed air or other motive fluid.

page_text: The chief objects with which my invention is designed are, to produce a reliable
compound engine of compact and comparatively simple and cheap construction.
It consists essentially of an engine in which the high pressure cylinder is arranged
within or enclosed by the low pressure cylinder, the piston of the high pressure
cylinder remaining stationary, and the high pressure cylinder acting as the piston
working within the low pressure cylinder and being connected with the drill shaft,
piston rod or like device as the case may be, and also in the construction and
arrangement of inlet and outlet or exhaust ports and valves as hereinafter more
particularly described.
The invention will be more readily understood on reference to the accompanying
drawing in which it is shewn applied to a rock-drilling machine by way of example,
and by the aid of which I will now proceed to describe it in detail.
The drawing shews a longitudinal sectional elevation of that portion of a rock-
drilling machine embodying my invention.
In the drawing, A indicates the high pressure cylinder arranged within and
completely enclosed by the low pressure cylinder B. The high pressure cylinder A
also constitutes or acts as the piston of the low pressure cylinder B. The piston C
of the high pressure cylinder A is fitted with any suitable form of piston rings c,
and its piston rod D) working through a stuffing box or gland d fitted in the end or
cover E of the high pressure cylinder, is rigidly attached to the cover F
of the low pressure cylinder B. The ends or covers E E of the high
pressure cylinder are fitted with piston rings e el. G is the drill bar or shaft-in
the case of an ordinary engine the piston rod-firmly secured to the forward end
or cover E of the high pressure cylinder A and working through the glande fitted
in the cover F¹ of the low pressure cylinder B. The front head or cover F¹ is formed
with a neck or continuation f to afford additional bearing surface for the drill bar G.
The drill bar G has attached to its other and outer extremity in the ordinary or
in any other suitable manner the drill or tool to which it is desired to impart the
reciprocating motion.
or
LS
The high pressure cylinder A is turned down to form an external annular recess g,
which forms the high pressure valve chest of the engine. The recess g in length
slightly exceeds the stroke of the high pressure cylinder or low pressure piston A
so as to insure the presence therein of the compressed air or steam at the initial
pressure throughout or at every point of the stroke of the piston A.. a is the main
feed port connected with the main supply pipe. It is as shewn located in the
centre of the low pressure cylinder B or midway of the stroke of the piston A and
opens into the recess
the high
or high pressure valve chest g. H
pressure valve arranged within the recess valve chest g. The valve H
is preferably in the form of a piston valve
ings, the pistons hh, controlling the ports communicating with either side
of the piston C, being connected by means of a rod h². The rod h² is formed with
a central slot 3 which engages or into which projects a stop or projection h formed
on or fitted to the cylinder A within the valve chest g to guide and control the
movement of the valve H. jj' are the feed ports placing the interior of the high
pressure cylinder A in communication with the valve chest g, and are the
exhaust ports bored through the ends E E¹ placing the interior of the high pressure
cylinder A in communication with the low pressure cylinder B.
as shewn in the draw-
In order to produce the requisite rotary motion of the drill shaft G in addition
to the reciprocating motion the exhaust port will preferably be bored out at an
inclination to the longitudinal axis of the cylinder or piston A so as to rotate the
piston part of a revolution during its return stroke. This construction may be
employed either alone or in combination with the usual ratchet and rifle bar
arrangement or the exhaust port may be formed parallel to the longitudinal axis
of the piston similar to the port and the ratchet and rifle bar arrangement be
used for this purpose exclusively.
L is the exhaust valve chamber placed in connection with condensers or exhaust-
ing into the atmosphere as may be desired. is the exhaust valve also preferably

page_text: in the form of a piston valve, the pistons 11 being connected by means of a rod 1³
similar to the high pressure valve H previously described. m m' are the exhaust
ports formed in the low pressure cylinder and placing the interior of the same in
communication with the exhaust chamber L. M M are pipes passing in through
the low pressure cylinder at one end and into the exhaust valve chamber at the
other and placing the interiors of the same in communication. Rubber or other
suitable buffers m² m³ are preferably fitted in the ends of the exhaust valve
chamber L for the purpose of cushioning the valve 7.
At either end of the low pressure cylinder small longitudinal grooves n n¹ are
formed to admit high pressure air or steam behind the piston A to assist in cushion-
ing it and to insure the proper working of valve H. The grooves nn will be of
such a length as to project slightly beyond the piston rings e el when the piston A
is at the end of its stroke. The length or distance the grooves n n¹ project into or
enter the cylinder B will vary with the speed at which the engine is designed
to run.
In the drawing the piston A is shewn at about the centre of its stroke and travel-
ling in the direction indicated by the arrows. The inlet port is shewn open to
the compressed air at its initial pressure and the exhaust port ¹ being closed the
air is exerting its full pressure on the inner surface of the cover E¹ of the cylinder
or piston A and moving it in a rearward direction. At the same time the other high
pressure inlet port; being closed by the valve H and the exhaust port k being open
the compressed air is permitted to escape from the front of the piston C in the high
pressure cylinder into the low pressure cylinder and the low pressure exhaust port m
being closed by the exhaust valve it acts on the outer surface of the end E of the
piston A and moves it in the same direction. When the piston A. has travelled so
far that the piston ring e¹ projects beyond the point at which the pipe M¹ opens
into the low pressure cylinder the compressed air at the initial pressure passes
along the pipe M and reverses the valve 1, closes exhaust port m¹ and opens the
exhaust port m.
On the further movement of the piston A rearward the bottled
up air is compressed and acts in conjunction with the air admitted along the
groove n at the initial pressure to reverse the valve H; the inlet port j¹ being
thereby closed and the exhaust port opened the air exhausts into the low pressure
cylinder and the exhaust port m¹ being closed it acts against the outer surface of the
end E of the piston A to force it on its forward or outward stroke. At the same
time the compressed air is being admitted at its initial pressure through the
port the exhaust port being closed-and acting on the inner surface of the
end E of piston A is moving it in the same direction. The cycle of operations is
the same for both the outward and return strokes.
k
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
1. The improvements in compound engines which consist in the arrangement of
the high pressure cylinder within or the enclosing of the same by the low pressure
cylinder the high pressure cylinder working in conjunction with a stationary
piston and at the same time constituting or acting as the piston working within the
low pressure cylinder substantially as described.
2. In compound engines applicable to rock-drilling machines, locomotives or
hauling or mill engines and the like the combination of the compound high pres-
sure cylinder and low pressure piston A the stationary high pressure piston C the
annular external recess or valve chest g of the high pressure cylinder the piston
valve H arranged therein the inlet and exhaust portsjj and the drill bar or
piston rod G connected with the piston A the low pressure cylinder B and the main
feed port a and exhaust ports m m¹ the exhaust valve chamber L and exhaust valvel
the pipes M M and the grooves nn¹ formed in the ends of the low pressure
cylinder B substantially as described and shewn,

page_text: 3. Compound engines applicable to locomotives or hauling or mill engines and
the like having the several parts constructed and arranged in combination sub-
tantially as described and shewn.
4. A rock-drilling machine having the several parts constructed and arranged
In combination substantially as described and shewn in the accompanying drawings.
Dated this 9th day of November 1898.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.