Improvements in Percussive Tools.
Year: 1895

page_text: Date of Application, 10th Aug., 1895
Complete Specification Left, 11th May, 1896-Accepted, 27th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Percussive Tools.
We, WILLIAM JOHN CROSSLEY of Crossley Brothers Limited Openshaw
and JAMES DUNLOP of 206 Gorton Lane, West Gorton both of Manchester,
Engineers do hereby declare the nature of this invention to be as follows:-
This invention relates to the construction of percussive tools driven by com-
pressed air, steam or other gases under pressure, or exhausting into a partial
vacuum and has for its object mainly the further simplification of the tool
described in Specification No. 3586 of A.D. 1894. The tools are suitable for
rivetting, chipping, caulking and many other purposes.
A piston sliding in a cylinder is constructed with two diameters, the portion of
larger diameter forming the piston proper. The compressed air or other motive
fluid acts on the larger area to drive the piston in one direction, the admission of
the air pressure being by means of a circumferential groove turned in the smaller
diameter of the piston which at the proper time passes into the annular chamber
formed by the difference in the two diameters and to which the air pressure has
constant access, communication from the groove to the larger end of the piston
being by means of a number of small holes drilled in it. The exhaust takes place
by a port in the larger part of the cylinder, the piston itself passing and opening
this exhaust port. The action is as follows-Towards the end of the return or
inward stroke the pressure groove in the piston opens into the annular chamber in
the cylinder, admitting air pressure on to the larger end of the piston driving it
outwards. As the piston approaches the other end of its stroke it passes and
opens the exhaust port thus permitting the exhaust to take place, the piston then
being driven on the return or inward stroke by the air pressure which is con-
tinuously on the differential area formed by the two diameters of the piston, this
area being sufficient to drive the piston back compressing the air left in the larger
end until the piston again opens the pressure groove to that end, the reciprocations
being afterwards continued in a very rapid manner.
The smaller diameter is the part of the piston which strikes the tool or to which
the tool may be attached.
We simplify the construction by dispensing with the circumferential pressure
groove turned in the larger part of the cylinder and also by forming the circm-
ferential groove on the smaller instead of the larger diameter of the piston as
described in the above mentioned Specification, and using the annular chamber
as described.
We also simplify the means for starting and stopping by using a plug of two
diameters operating by preference on the exhaust outlet, the pressure of the
air on the differential area tending always to move the plug so as to close the
exhaust passage thus stopping the action of the tool. By moving the plug
in the contrary direction the passage will be opened and the tool allowed to
work.
A modification of the apparatus consists in so constructing it that the piston is
driven in the striking direction by admitting pressure at the smaller end of the
cylinder, the annular chamber being always open to the atmosphere and the return
stroke effected by equalising the pressures on the unequal ends of the piston by
exhausting from the smaller end into the larger end of the cylinder. Towards

page_text: the end of the return stroke the larger diameter of the piston passes and opens an
exhaust port as in the previous construction. The means for starting and stopping
previously described may be used with this construction.
Dated this 3rd day of August 1895.
W. J. CROSSLEY.
JAS. DUNLOP.
Improvements in Percussive Tools.
'We, WILLIAM JOHN CROSSLEY of Crossley Brothers Limited Openshaw
and JAMES DUNLOP of 206 Gorton Lane, West Gorton, both of Manchester
Engineers 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:-
This invention relates to the construction of percussive tools driven by com-
pressed air, steam or other gases under pressure, or exhausting into a partial
vacuum and has for its object mainly the further simplification of the tool
described in Specification No. 3586 of A.D. 1894. The tools are suitable for
rivetting, chipping, caulking and many other purposes.
To enable this invention to be fully understood we append two sheets of
drawings in which
Fig. 1, Sheet 1, is a longitudinal section of a complete tool, Fig. 2, Sheet 1,
being a cross section,
Fig. 3, Sheet 2, is a longitudinal section of a modified arrangement, Fig. 4,
Sheet 2, being a cross section of the same.
A piston sliding in a cylinder is constructed with two diameters, the portion of
larger diameter A forming the piston proper. The compressed air or other motive
fluid acts on the larger area of the piston A to drive it in one direction, the
admission of the air pressure to this larger area being by means of passage
holes E communicating with a circumferential groove B turned in the smaller
diameter C of the piston which at the proper time passes into the annular
chamber D formed by the difference in the two diameters A and C and to
which the air pressure has constant access. The exhaust takes place by a
port F in the larger diameter of the cylinder, the piston itself passing and opening
this exhaust port. In the position shewu in the drawing the exhaust port is shewn
closed by the piston. The action is as follows:-
Towards the end of the return or inward stroke the pressure groove B in the
piston opens into the annular chamber D in the cylinder, admitting air pressure on
to the larger end A of the piston driving it outwards. In Fig. 1, Sheet 1, the
piston is shewn having the admission port fully open being at the extreme end of
its inward stroke. As the piston approaches the other end of its stroke it passes
and opens the exhaust port F thus permitting the exhaust to take place, the piston
then being driven on the return or inward stroke by the air pressure which is
continuously on the differential area formed by the two diameters A and C of the
piston, this area being sufficient to drive the piston back compressing the air left
in the larger end until the piston again opens the pressure groove B to admit air
to the larger end; the reciprocations being afterwards continued in a very rapid
manner. A projecting piece G is attached to the smaller diameter of the piston
and is the part which strikes the tool, the end H of which is shewn inserted in a
socket forming a continuation of the tool body.
It will be seen that the construction of the tool shewn in Figures 1 and 2,
Sheet 1, is simplified from the tool shewn in the Letters Patent previously
mentioned inasmuch as the circumferential pressure groove turned in the larger

page_text: The combination of a cylinder with a piston having two diameters, an inlet
passage, a circumferential groove and longitudinal slits and an exhaust port all
O formed in the larger diameter of the cylinder, a circumferential groove and passage
holes formed in the larger diameter of the piston and 'communicating with the
smaller end of the cylinder substantially as described and illustrated in Figures 3
and 4, Sheet 2.

page_text: CLAIM 4.
The general arrangement, construction and operation of percussive tools
substantially as described and illustrated in Figures 1 and 2, Sheet 1.
CLAIMI
The general arrangement, construction and operation of percussive tools 5
substantially as described and illustrated in Figures 3 and 4, Sheet, 2.
Dated this Ninth day of May Eighteen hundred and ninety-six.
W. J. CROSSLEY.
JAS. DUNLOP.