IMPROVEMENTS IN 'CONTROLLING APPARATUS FOR VALVES OF AIR COMPRESSING ENGINES AND THE LIKE
Year: 1884

page_text: "
We, JOHN SCARISBRICK WALKER, THOMAS ASCROFT WALKER, and EDWIN
ROBERT WALKER, all of the Pagefield Iron Works, Wigan in the County of
Lancaster, Engineers, do hereby declare the nature of our said invention for
IMPROVEMENTS IN 'CONTROLLING APPARATUS FOR VALVES OF AIR COMPRESSING
ENGINES AND THE LIKE," to be as follows:-
"
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The object of this invention is to improve the controlling mechanism for the
valves of the cylinders of air compressing or blowing engines described in the
specification of Letters Patent No 4488 of 1877.
It is designed for the purpose of balancing the pressure acting upon the piston
rod or spindle to which is attached the buffers and spring for cushioning the
impetus given to the outlet valve in opening or closing, caused by the rush of air
or by the weight of the valve itself.
In the apparatus as heretofore constructed by us, the area of the upper side
of the piston working in the resistance cylinder is less than the area of its under
surface by the size of the above mentioned rod or spindle. It will be seen that
where the spindle has a sectional area of 2 square inches, and with it a pressure
of 50 lbs per square inch, the force tending to prevent the valve closing would
equal 100 lbs.
By our present invention, we purpose to rectify this inequality of pressure. We
place a second or subsidiary cylinder preferably attached to the pedestals or
supports which carry, the spring buffering mechanism covering the end of the piston
rod or spindle, and by forming the said rod or spindle hollow form a communication
between the subsidiary piston and the outlet air chamber, and thus balance the
pressure on each end of the rod. Instead of a hollow rod the subsidiary cylinder
and the outlet air chamber may be connected by a pipe or other suitable connection
by means of which the pressure on the outer end of the rod may be maintained.
We propose to make the outer end of the rod which enters the cylinder slightly
larger in diameter than at the point of its connection with the resistance piston, so
that by having a slightly increased area, the additional pressure will overcome the
frictional resistance caused by the stuffing boxes and glands, and assist in closing
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page_text: the valve, Or in case of the spindle passing through the gland in the outlet cover,
make it rather smaller in the subsidiary cylinder to assist in opening the valve.
The subsidiary cylinder, instead of being placed at the end of the rod, may bo
placed at any convenient position, and fitted with a piston carried on the rod of an
area equal to that of the rod, or slightly larger or smaller as required, but we prefer
the first described arrangement. We attach to this spindle suitable nuts, and
having cross buffer pedestals with friction pedestal if required for regulating the
opening and closing the valve. By these means we are enabled to regulate the
opening and closing of the largest valves without noise comparatively speaking,
and we are also enabled to see the working of the valve.

page_text: COMPLETE SPECIFICATION,
We, JOHN SCARISBRICK WALKER, THOMAS ASCROFT WALKER, and EDWIN
ROBERT WALKER, all of the Pagefield Iron Works Wigan, in the County of
Lancaster, Engineers do hereby declare the nature of our said invention for
IMPROVEMENTS IN CONTROLLING APPARATUS FOR VALVES OF AIR COMPRESSING
ENGINES AND THE LIKE 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 improvements in controlling apparatus such as described
in the specification of Letters Patent No 4488 of 1877. Its object being to more
effectually prevent the dancing of the air valves, and thus enable the latter to
last much longer than at present, and further enable the engines to work at a
greater speed without injury than is practicable with valves not controlled in this
manner.
Referring to the drawings:-
A is the valve of ordinary type. B link pivoted to valve at b and to steadying
block C at 6. C steadying block in cylinder D open above, and below to the
pressure of the compressed air. D cylinder forming part of the valve chamber
cover and fitted with cover and stuffing box. F hollow spindle connected fixedly
with steadying block and open to the pressure of the compressed air. G stationary
cylinder on end of hollow spindle open to the compressed air through the hollow
spindle F. The end F¹ of spindle F where it enters G is made preferably rather
larger than where it passes through cylinder D so that there may be a little
additional pressure tending to keep the valve closed. For this purpose the enlarge-
ment takes place at joint f. The hollow spindle F is jointed at f with a screw
socket joint for convenience of construction, and in order to get the spindle
through the parts hereafter described. His the valve chest. I cover of same
formed in one with the cylinder D; d oil hole on the upper side of the apparatus
when as is usually the case this controlling mechanism is arranged horizontally as
shown. The oil holes in the block and link can be oiled through this, d' cover of
cylinder D. J is a buffering plate, having lock nut j, and each having an internal
screw fitting the spindle F screwed at this point. By this means the buffering
plate J can be adjusted longitudinally, and held in position by the lock nut j.
K pedestal to support buffer. The thread can be turned off as shown from the
spindle Fat those parts enclosed by this pedestal. k sleeve or quill held in the
pedestal by set screw k. This sleeve is roughened on its surface with teeth or
ridges pointing toward the centre of the pedestal so as to hold the rubber
blocks L.L' firmly in place. L L' buffers of rubber or other elastic material fixed
into the ring hollow formed between pedestal K. and sleeve k¹. M second buffer
plate screwed on to spindle and provided with lock nut m. N third buffer plate
also screwed on to shaft and provided with lock nut n. P spring pressing against
nut or buffer plate N at one end and cross piece Q at the other. Q.cross_piece
carrying and preferably formed in one with cylinder G, this and cross piece K are
supported by pillar bolts R. R. These bolts pass through and are firmly fixed to

page_text: lugs in cross piece K, cylinder D and cylinder cover d¹ by collars
nuts They are also firmly secured to cross piece by shoulder
The cylinders G and D are supplied with stuffing boxes as shown.
The mode of action is as follows.
12 and
and nut ª,
The valve opening under the pressure in the blowing engine cylinder pushes
back spindle F compressing spring P and bringing the buffering plate J against
buffers L. The shock has however been chiefly taken up by the spring P.
The valve closing would do so with strong impact but that before the actual
impact of the valve upon its seat buffering plate M strikes elastic buffers L' and
thus cushions the blow.
'
It will thus be seen that as the valve begins to open it has opposed to it only
the spring at least tension, as it opens wider, the strength of the spring increases
and the valve comes to rest, with the quickly applied and rapidly increasing
buffering action between J and L. In closing, the spindle has the full force of the
spring tending to close it but this decreases as the valve nears its seat. It has the
constant resistance of the friction of the parts and lastly as the valve gets in
immediate vicinity of the seat the buffering takes place. The nut J being adjustable
the amount of opening of the valve can be regulated.
The area of cross, section of the spindle F projecting through cylinder D being
less than the area of pressure in cylinder G and the end of the spindle there is a,
slight excess of pressure always tending to close or keep closed, the valve. The
various buffering plates being attached to the spindle by screwing, can be exactly
regulated, being turned- round on their axis more or less in either direction as
required, and clamped by their check nuts.
:
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is
1st. The manufacture and use of buffering apparatus for valves of blowing
engines and the like, having a screwed spindle with buffering plates and nuts,
or their equivalent and a buffering pedestal arranged, substantially as described.
2nd. The manufacture and use of a valve controlling apparatus having a spindle
projecting from the valve chest through a stuffing box and provided with a device
for enabling the pressure in the valve chest to be directed against the spindle
outside the valve chamber in a direction contrary to that exerted by the pressure
inside the valve chamber, whereby the otherwise unbalanced pressure caused
through the spindle projecting from the valve chest is counterbalanced or more than
counterbalanced.