Pneumatic Tool.
Year: 1894

page_text: Date of Application, 18th Sept., 1894-Accepted, 20th Oct., 1894
COMPLETE SPECIFICATION.
Pneumatic Tool.
I, JAMES WOLSTENCROFT, Manufacturer, of N.E. corner of Harrison and
Willow Streets, Frankford, Philadelphia, State of Pennsylvania, United States of
America, do hereby declare the nature of my 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 devices wherein atmospheric air or other fluid pressure
is employed to operate a reciprocating tool employed for stone dressing, calking,
riveting, dental use, rock drilling, etc., and it consists in the construction and novel
arrangement of parts as hereinafter set forth.
I will describe a pneumatic tool embodying my invention and then poiut out the
novel features in the appended claims.
In the accompanying drawing:
Figure 1, is a longitudinal section of a tool embodying the invention showing the
parts in one extreme position.
Figure 2, is a longitudinal section showing the parts in the other extreme
position.
Figure 3, is a side elevation of the distributing valve employed.
Figure 4, is a cross section of the tool on the line x, x, of Fig. 1, and
Figure 5, is a cross section on the line y, y, of Fig. 1.
The pressure case 2, encloses the distributing valve 28, and striker 26, while the
case 4, encloses the tool holding spindle 12, and is free from pressure.
The case 2, is supplied with constant working pressure from a flexible pipe
connected to the induction tube 8.
The distributing valve 28, comprises a cylinder for the head 26, of the striker 22,
to operate in, and said valve 28, is reduced in diameter at 34, at its part which
performs the valvular function.
The valve 28, moves with minimum friction and no fitting thereof to the case 2,
is required in the workmanship of the tool, inasmuch as the said valve has its
bearings on the fixed guide sleeve 24, interior thereto, fitting the same bore in which
the striker operates, and in the fixed bushing 36, surrounding the reduced part of
said valve comprising the valve seat.
The valvular extension 34, has an induction port or ports 38, which at the
position in Figure 1, admit air from case 2 to chamber 29, and an exhaust port or
ports 40, which at the position in Fig. 2, exhaust air from chambers 29, to
atmosphere through opening 10.
The striker 22, comprising a plunger has different diameters at its part 22, which
has a sliding fit within the fixed sleeve 24, and its part 26, which fits the valve 28,
and the supplemental area is exposed to constant working pressure at 30, through
port 46, from the case 2.
Pressure at 30, serves to return the striker, and pressure at the shoulder 7 of the
valve serves to return the latter-the one moving toward the other when pressure
is exhausted from chamber 29 through port 40, as in Figure 2.
The inward stroke of the valve 28, is limited by its abutment in a cushion 44,
and the retiring stroke of the striker 22, is limited by its abutment on the valve at
cushion 42. The abutment of the striker in its retiring movement is thereby
elastic; the valve striking its cushion 44, first.
Moreover, the elastic rebound of the valve caused by the retracting abutment of
the striker assists the play of the valve by starting it on its outward movement
while air is entering ports 38 to the same purpose.

page_text: The tool spindle 12, adapted for the insertion of a tool at the socket 13, slides in
the extremity 16, of the case, is returned by a spring 18 in the manner usual to
pneumatic tools, and its return movement is limited by a stop collar 21, secured by
pin 20.
In the operation of the device the reciprocations of the piston or plunger and the
annular valve, in opposite directions, are practically simultaneous. Air admitted
through the port 8, under constant pressure, enters through the port 38, and acting
on the enlarged surface area of the striker drives the same with force against the
tool holder as shown in Fig. 2; the pressure then acting on the valve 28,
reciprocates it until the exhaust port 40, extends beyond the end of the bushing
or valve seat 36, where the prevailing body of air is exhausted. The pressure in
the chamber 30, acting on the shoulder formed by the enlarged portion of the
striker returns the same to its inner position as shown in Fig. 1. The air pressure
then acting on the shoulder 7, of the valve moves the valve until the port 38, is
again open for the induction of pressure, and the same movements are repeated.
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. In a pneumatic tool, the combination with a suitable casing, of a reciprocating
striker, a sleeve fixed within the casing and forming a bearing for the striker, a
reciprocating valve surrounding the piston or plunger and having a reduced portion
provided with induction ports, substantially as described.
2. In a pneumatic tool, the combination of a suitable casing supplied with
constant working pressure, a striker having differential diameters, a distributing
valve also having differential diameters, comprising a cylinder for the striker
mounted in bearings at the extremities of the casing; the supplemental areas of said
striker and said distributing valve being continuously exposed to the working
pressure within said casing, and means for admitting and exhausting presssure
between the striker and the valve.
3. In a pneumatic tool, the combination of a suitable casing having a constant
pressure chamber and a chamber containing a tool holder, a reciprocating striker
having differential diameters, a sleeve fixed in the casing and forming a division
between the said constant pressure chamber and the tool holder chamber of the
casing and a reciprocating valve forming a cylinder for the striker at its greater
diameter, and fitting around said sleeve.
4. In a pneumatic tool, the combination of a casing, a striker, and an annular
reciprocating valve having the reduced tubular extension provided with ports, and
a bushing serving as a closure for said ports, substantially as described.
Dated this 17th day of September 1894.
WALLACE FAIRWEATHER,
Chartered Patent Agent,
62, St. Vincent Street, Glasgow, Agent.