Improvements in Stamps for Crushing Quartz and other Ores.
Year: 1886

page_text: Date of Application, 20th Mar., 1886.
Complete Left, 20th Dec., 1886.
Complete Accepted, 4th Feb., 1887.
[Communicated from abroad by T. D. WILLIAMS, of Panmure, South Africa, Engineer.]
Improvements in Stamps for Crushing Quartz and other Ores.
I JOHN MATHESON MACDONALD, of 3 Lombard Street, in the City of London
Merchant, do hereby declare the nature of this Invention to be as follows:-
This Invention relates to ore stamps, of the kind in which the pestle or stamp is
attached directly to the piston of a cylinder and worked by the agency of steam or
compressed air. In this improved stamp, the motive fluid may be used only for raising
the piston and the effective blow delivered by the stamp may be increased by the
compression of air confined above the piston, during its upward stroke. Or steam,
or compressed air may be admitted to the upper as well as to the lower side of the
piston.
The cylinder of this improved stamp is fixed adjustably to the supporting frame, its
position being regulated by means of a screw, so as to enable it to be readily lowered
to compensate for wear of the stamp-head and bed-block, suitable joints being provided
in the pipes to permit of this adjustment.
If the stamp be single acting, the cylinder is provided with a suitable port
communicating with its lower end and controlled by a slide valve actuated by the
piston, so that on the ascent of the piston to a certain point, the admission is cut off
and the lower end of the cylinder is opened to the exhaust, to permit the piston and
stamp to fall by the action of gravity accelerated by the expansive force of the air
compressed above the piston during the ascent; the admission to the lower end of the
cylinder being re-opened on the descent of the piston. The point of cut off is
regulated by a cut off valve which may be an adjustable plate forming part of the
seat on which the slide-valve works, the position of this plate determining the
position of the opening of the admission port and consequently the point in the stroke
of the piston at which the admission may be cut off,

page_text: This adjustable plate is connected to a lever which may be actuated in order to open
the admission to the lower end of the cylinder either by hand or automatically by a
supplementary piston according as a few single strokes or a succession of strokes are
required. This supplementary piston works in a cylinder in communication with the
live steam in the valve chest by a supplementary port controlled by the main slide
valve.
With the stamp is combined an automatic feed drum, for the quartz, and actuated
by suitable mechanism from the piston rod.
If it be desired to make the stamp double acting by admitting steam or compressed
air both above and below the piston, it can be done by employing the ordinary steam
hammer valve gear.
When steam is used as the motive power, the exhaust steam from the cylinder may
be discharged through the the quick-silver riffle, for the purpose of promoting the
amalgamating action of the mercury.
JOHN M. MACDONALD.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Stamps for Crushing Quartz and other Ores.
I JOHN MATHESON MACDONALD of 3 Lombard Street in the City of London'
Merchant do hereby declare the nature of this Invention (a communication to me
from abroad by Thomas D. Williams of Panmure South Africa Engineer) and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:—
This Invention relates to ore stamps of the kind in which the stamp-head is attached
directly to the piston of a cylinder and worked by steam or compressed air; the motive
fluid being used only for raising the piston and the effective blow delivered by the
stamp being due partly to the action of gravity and partly to the compression of the
air confined above the piston during its upward stroke.
And the Invention relates first to the adjustment of the cylinder to compensate for
wear of the stamp head, and secondly to the valve gear whereby the points of
admission and cut-off of the motive fluid may be varied and the working of the
machine controlled automatically or otherwise.
Reference is to be had to the accompanying drawings forming part of this specifica-
tion wherein figure 1 is a vertical section through the axis of the cylinder, the piston
and stamp being represented in elevation. Figure 2 is a vertical sectional elevation at
right angles to figure 1 shewing a face view of the slide valve seat (the main and
auxiliary valves being omitted) Figure 3 is a horizontal section of the standard (drawn
to a larger scale, the section being taken on line 1-1 figure 1) the cylinder being
omitted. Figure 4 is a cross section of the drum of the quartz feeding apparatus.
Figure 5 shows a modification of part of the auxiliary valve gear. Figure 6 is a face
view of the valve-seat and is similar to that shewn in figure 2 but is drawn on a larger
scale. Figure 7 shews an elevation and figure 8 a plan of a modification of another
part of the valve gear shewn in figure 1. The same letters of reference indicate the
same parts in all the figures.
The Invention has first for its object to enable the cylinder of the stamp to be
lowered as required to compensate for wear of the stamp head and bed block of the
mortar. For this purpose, the cylinder A is fixed adjustably to the supporting frame,
its position being regulated by means of a vertical screw B mounted in bearings in
lugs cast on the frame and screwing through a nut in a lug C cast on the back of the
cylinder. The cylinder is held against the frame and secured in position for work by
bolts D passing through vertical slots in the frame, the frame being semi-circular, as
shewn in figure 3, so as to embrace one half the circumference of the cylinder A and
there being three of these bolts D one at each side and one at the back. The pipes
conveying the steam or other motive fluid to and from the cylinder are fitted to slide.
telescopically through stuffing box joints in the valve chest in order to permit of this
adjustment.
The Invention has secondly for its object to provide an auxiliary valve operated by

page_text: a supplementary piston whereby the points of admission and of cut-off of the main
valve (which has a travel invariably proportional to and reciprocal with the stroke of
the main piston) may be determined and whereby the height and rapidity of the stroke
may be controlled automatically or be varied by the attendant.
The cylinder is provided with a port a communicating with its lower end, and with
an exhaust port 6 these ports being controlled by an ordinary D slide valve which in
figure 1, is operated from the upward extension F of the piston rod through the
medium of a lever G fulcrumed at g and connected at one end to the piston rod by a
swivel block through which the lever is free to slide and at the other end to the valve
spindle by a connecting rod.
In the modification shewn in figures 7 and 8, the piston rod F is connected to the
valve spindle connecting rod by a compound arrangement of levers G G¹ G³, the
object of which is to allow the D-valve to make a longer pause at the end of its stroke
than is made by the main piston. The lever G is pivoted at g and connected to the
valve spindle as before, but instead of being connected directly to the main piston
rod F it is connected by a short drag link G2 to the lever G¹ which is pivoted at g¹ to
the same standard and at the same height as the pivot g but at a point further from
the piston rod, the lever G¹ being so set that it is free to pass the fulcrum of lever G,
as shewn in figure 8. This lever is connected at its extremity with the piston rod,
either by a swivel block as before or preferably by a slide block g* taking on to a stud
on the piston rod and sliding in a radial slot in the lever, as shewn. The drag link G2
is pivoted at g² in the lever G¹ and a stud on its other end is pivoted in a sliding
block g³ fitted in a radial slot at the end of the lever G. The action is illustrated in
figure 7. At the beginning of the upward stroke of the piston the lever G¹ travels
from the full line to the dotted line position without moving the lever G the drag
link G2 rotating on its centre 92 and the block 3 sliding inwards along the slot in the
lever G¹ and outwards again until it returns to the outer end of the slot, as shewn in
dotted lines, and then only does it begin to move the lever G. The action is similar
at the upper end of the stroke, but in the opposite direction.
The upper end of the cylinder A is closed and unprovided with any port in order to
accumulate the surplus power developed by the steam acting on the underside of the
piston during the upward stroke and utilize it on the downward stroke. In order to
control the volume of the air cushion above the piston, a self acting relief valve opening
outwards and loaded by an adjustable spring is fitted to the cylinder cover so as to
relieve the upper end of the cylinder of excessive pressure. A similar valve opening
inwards to the cylinder on the downward stroke of the piston is also provided to
always ensure a sufficient volume of air above the piston. This sufficiency would be
partly supplied by leakage of steam past the piston when the latter becomes worn.
On the ascent of the piston to a certain point the admission is cut-off and the lower
end of the cylinder is opened to the exhaust to permit the piston and stamp to fall by
their own gravity, the motion being accelerated by the expansive force of the air
compressed above the piston during its ascent. The admission to the lower end of the
cylinder is reopened on the descent of the piston, as hereafter described.
The point of cut-off of the admission of steam is regulated by means of an auxiliary
valve H constituted by a movable plate forming part of the seat on which the main
slide valve works, the upper edge of this plate being the admission edge of the mouth
or opening of the port a, and the plate being movable up and down so as by its
position to virtually determine the position of the mouth of the port a. The auxiliary
valve or plate H is attached to a spindle passing through a gland and stuffing box, the
spindle being connected to an auxiliary plunger I, working in a cylinder, from the
inner end of which port i leads to the valve chest and opens beneath the plate H
through the seat against which the said plate works, as shewn in Figures 2 and 6. The
auxiliary valve H has a notch or gap at one corner / corresponding to and leaving
uncovered the port i, so as to admit steam to the auxiliary cylinder from which the
steam is released through an exhaust pipe controlled by the plunger I itself.
regulating cock on the pipe connecting port i to the auxiliary cylinder.
is a
In figures 1 and 2 the plunger I actuates the auxiliary valve H through the medium

page_text: of a lever K which plays between a pair of check springs Land is connected to a pair
of oppositely acting spiral springs M. As shewn in figure 1 the piston is at the
bottom of its stroke, the valve gear is in its highest position, and steam is cut off from
the main cylinder. The small port i is however uncovered and will admit steam to
the auxiliary cylinder, whereby the auxiliary valve H will be moved downwards,
thereby opening the admission to the main cylinder. By the continued motion of the
auxiliary cylinder, the auxiliary plunger I acting as a valve uncovers an exhaust
port and releases steam from the auxiliary cylinder. The auxiliary plunger is then
returned by the springs to the position shewn. As above mentioned the downward
motion of the auxiliary valve H admits steam to the main cylinder A and raises the
piston and stamp, at same time moving the main valve in the opposite direction, the
cut off of the steam from the main cylinder being effected by the main valve in its
descent meeting and covering, the auxiliary, valve, the main valve by its continued
downward motion afterwards cutting off steam from the auxiliary cylinder. The
auxiliary piston then rises, cuts off its own exhaust, and returns to its former position,
thereby raising the auxiliary valve to the position shown, in readiness for another
upward stroke of the main piston. The two extreme positions of the auxiliary valve
thus produce the necessary difference between the points of admission and cut off of
steam to the main cylinder. The relation of the two valves to each other may he
varied by means of lengthening nuts on their spindles. The lever K serves as a handle
for the purpose of checking the motion of the auxiliary valve so as to cause the length
of stroke of the main piston, and consequently, the force of the blow of the hammer to
be varied.
In the modification shown in figure 5, the auxiliary piston is directly on the spindle
of the auxiliary valve. A spring L is confined between the piston and the bottom end
of the cylinder, and an india-rubber cushion L' is confined between the cupped lower
cover of the cylinder and a nut on the screwed spindle, whereby the tension of the
springs can be regulated. The cover of the auxiliary cylinder is connected to the
cylinder by means of screw studs and double nuts to enable the position of the
auxiliary piston to be adjusted in its cylinder relatively to the exhaust thereof, the
piston rod being coupled to the valve spindle by a lengthening nut to enable the
auxiliary valve to be adjusted relatively to the main-valve as before.
The quartz is supplied to the stamping chamber by means of a feed drum O through
a hopper (not shown) fixed to the casing at the back of the mill, which drum is
represented in cross section in figure 4. It receives intermittent rotary motion
through a silent or ratchet feed mechanism consisting of a grooved or ratchet wheel P
and nipper or pawl p carried by a lever p¹ pivoted on the axis of the drum and
connected by a rod p² with a lever connected with the piston rod F by a swivel
block through which the lever p³ is free to slide. The throw of the ratchet or feed
mechanism may be regulated by a hand screw Q working through a nut carrying a
pin 7 received in a slot q¹ in rod p², so as, without interfering with the up and down
motion of the latter, to vary its point of connection with lever p', the connection being
made by a pin on the rod working in a slot in the lever. The drum O discharges the
quartz into a shoot leading through the back of the stamping chamber.
2
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. The combination and arrangement of parts constituting the direct-acting stamp
operating mechanism worked by steam or compressed air, substantially as described
and illustrated in the drawings.
2. In a direct-acting steam or compressed air stamp, the cylinder connected to its
supporting frame by bolts passing through vertical slots in the frame and combined
with a vertical adjusting screw for varying the height of the cylinder relatively to the
base of the machine.
3. A direct-acting steam or compressed air stamp in which the main valve is
actuated from the main piston, through a compound arrangement of levers as described
and shown in figures 7 and 8 for the purpose specified.

page_text: 4. In a direct-acting stamp the combination with the main valve driven by the main
piston, of an auxiliary valve forming part of the seat of the main valve and actuated by
an auxiliary piston and acting so as to determine the positions of the points of admission
and cut off of the main valve, and enable the same to be varied relatively to the travel
of the main valve, substantially as described.
5. In a direct-acting stamp in which an auxiliary valve is combined with the main
valve and forms part of the seat thereof, the combination with the auxiliary valve of
an auxiliary piston and cylinder provided with admission and exhaust ports respectively
controlled by the main valve and auxiliary piston, and with oppositely acting springs
for checking and reversing the motion of the auxiliary piston, substantially as herein
specified.
6. The combination with a direct-acting steam or compressed air stamp of a feeding
drum whose casing is connected by a shoot with the stamping chamber, and of a feed
motion actuated by the piston of the stamp through a rock lever, substantially as
described and shown.
J. M. MACDONALD.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
: Patent Agents.