Improvements in Percussive Tools.
Year: 1894

page_text: Date of Application, 20th Feb., 1894
Complete Specification Left, 20th Dec., 1894-Accepted, 2nd Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements in Percussive Tools.
We, WILLIAM JOHN CROSSLEY of Crossley Brothers, Limited, Openshaw,
Manchester, and JAMES ATKINSON, of Amherst, Fallowfield, Manchester, Engineers,
d hereby declare the nature of this invention to be as follows:-
This invention relates to the construction of percussive tools driven by compressed
air, steam or other gases under pressure, or exhausting into a partial vacuum, and is for
the purpose of simplifying their construction mainly by providing a constant pressure
at one side of the piston. The tools are suitable for rivetting, chipping, caulking
and many other purposes. The piston is constructed with two diameters, the
portion having the 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 body of the piston which at the proper time passes a suitably placed
circumferential groove turned in the barrel of the cylinder, communication from
the groove in the piston to its outer side being by means of a number of small holes
drilled in the piston. The exhaust takes place by a port in 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 pressure groove 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 continuously on the smaller annular area formed by
the two diameters of the piston, this area being sufficient to drive the piston back
compressing the air left in the working end until the piston again opens the pressure
groove to the larger end, the reciprocations being afterwards continued in a very
rapid manner. The smaller diameter of the piston is the part which strikes the
tool or to which the tool may be attached.
To enable the tool to be easily started and stopped a sliding plug can be arranged
to cut off the air pressure from the annular space, the tool being started by
a convenient method of moving this plug so as to open the communication.
The handle is formed with elastic material to prevent the concussion of the rapid
reciprocations being unpleasant to the operator. It may be suitably constructed by
having an inner metallic connection to the apparatus surrounded by india-rubber,
or similarly to pneumatic bicycle handles, and may be enclosed in a thin metallic
tube to protect the rubber.
1
1004
W. J. CROSSLEY.
JAMES ATKINSON.

page_text: Improvements in Percussive Tools.
We, WILLIAM JOHN CROSSLEY, of Crossley Brothers, Limited, Openshaw,
Manchester, and JAMES ATKINSON, of Amherst, Fallowfield, 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 compressed
air, (steam or other gases under pressure, or exhausting into a partial vacuum,)
and is for the purpose of simplifying their construction mainly by providing a
constant pressure at one side of the piston; the arrangements for distributing the
compressed air at the other side of the piston being of a very simple nature.
The tools are suitable for rivetting, chipping, caulking, and
purposes.
many other
To enable this invention to be clearly understood we append one sheet of drawings
in which Fig. 1. is a longitudinal section showing the piston in full, Fig. 2. is a
section at right-angles to Fig. 1. and Fig. 3. is an end section. In these figs. like
letters apply to like parts.
The piston A is constructed with two diameters the portion having the larger
diameter forming the piston proper. The compressed air acts on the whole area of
the larger end to drive the piston in one direction to strike the blow on the chisel
head B. The air enters by the connection which is always in communication with
the circumferential groove D turned in the barrel of the cylinder which in itself
mainly forms the body of the apparatus. Communication from the groove D to
the larger end of the piston A takes place through the circumferential groove E
turned in the body of the piston and small holes F. The piston A is shown in the
drawings in about mid-position, it may be assumed that it is moving in the direction
of the arrow shown in Fig. 1. having cut off the admission of compressed air and
being about to strike the head of the chisel B and to open the exhaust passage G
which is shown as a plain hole drilled through the body of the apparatus opened
by the piston passing it. The annular space H formed by the difference between
the two diameters to which the piston A is turned is always open to the pressure of
the compressed air as shown in Fig. 2.
The action is as follows:-
Towards the end of the return or inward stroke, the groove E in the piston A
opens into the pressure groove D in the cylinder, admitting air pressure onto the
larger end of the piston A through the small holes F driving it outwards in the
direction of the arrow and causing it to strike a blow on the head of the chisel B.
As the piston A approaches the other end of its stroke it passes and opens the
exhaust port G thus permitting the exhaust to take place, the piston being driven
on the return or inward stroke by the pressure which is continuously on the smaller
annular area H and which is sufficient to drive the piston back compressing any air
left in the larger working end until the piston again opens the pressure groove D.
The reciprocations are thus afterwards continued in a very rapid manner.
To enable the tool to be easily started a sliding plug, or, as is shown in Fig. 2.
a sliding plate, I may be moved so as to control the exhaust, or the passage of air
to and from the annular space H. It may be conveniently arranged so as to have
a suitable connection J to be grasped by the hand in holding the apparatus for
starting and released for stopping.
The handle is formed with elastic material such as indiarubber K suitably held
between a central bolt and a thin mettalic shield to soften the concussion of the
rapid reciprocations.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed we declare that what we
claim is :-
1. The arrangement and construction of a pneumatic tool having a reciprocating
piston of two diameters, the piston being always driven in one direction by pressure
on the annular space formed between the two diameters and in the other direction
by pressure admitted and exhausted by means of ports in the body of the apparatus
itself and in the piston, there being no intermediate casing between the piston and
the body or any other seperate piece necessary for the control of the working fluid
substantially as describe and illustrated.
2. The general arrangement and construction of pneumatic tools substantially as
described and illustrated.
10th of December 1894
W. J. CROSSLEY.
JAMES ATKINSON.