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Патент USA US3027839

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April 3, 1962
3,027,829
C. F. BREY
PRESS
2 Sheets-Sheet 1
Filed July 15, 1960
79
INVENTOR.
awn
BY
A‘
5/85 Y,
April 3, 1962
3,027,829
C. F. BREY
PRESS ‘
2 Sheets-Sheet 2
Filed July 15, 1960
FIG. 2.
1%
M
(1484
AT
INVENTOR.
565%
BY
47roeA/EYS
‘ atenr
C€
3,027,829
Patented Apr. 3, 1962.
2
1
extending pivot pin 23. The lever arm 22 comprises a
pair of parallel, vertically disposed bar members 24, 24
whose forward end portions engage respective ?attened
3,027,829
PRESS
_
v
_
Carl F. Brey, 309 Pennsylvania Ave., Delaware, 01110
Filed July 15, 1960, Ser. No. 43,236
areas 25 on the opposite sides of the vertical ram mem
ber 19 and which are pivotally connected thereto by the
6 Claims. (Cl. 100-—271)
transversely extending pivot pin 23. The rear end por
tions of the bar members 24, 24 similarly extend adjacent
?attened opposite side surfaces 26 of the top portion
more particularly to a press which utilizes ?uid pressure
of a piston rod 27 which extends slidably and sealingly
as a means for furnishing the major portion of the press
10 through the top end wall 28 of a substantially vertical
ing force.
cylinder 29 pivotally connected at 30 to the frame 12
A main object of the invention is to provide a novel
at the side thereof opposite the table surface 20, the
and improved press which is relatively simple in con
cylinder 29 being partially received inside the frame, as
struction, which provides ample pressing force, and which
shown in FIGURE 2, but being free to pivot in the rear
may be accurately controlled by the exertion of relatively
end
portion of the frame. The rear portions of the ver
15
light pulling force on its actuating lever.
This invention relates to improvements in presses, and
tical bar members 24, 24 are pivotally connected to the
top portion of the piston rod 26 by a transverse con
A further object of the invention is to provide an im
proved press which is relatively inexpensive to fabricate,
which is durable in construction, which is compact in size,
necting pin 31.
The piston rod 27 is rigidly connected to a piston 32
and which is safe to operate.
A still further object of the invention is to provide 20 which is slidably and sealingly mounted inside the cylin
der 29 and which is normally in a lowered position in the
an improved air-operated press using a simple lever prin
cylinder.
A conduit connection 33 is provided at the
ciple which furnishes pressures at the press ram head
lower
portion
of the cylinder and a similar conduit con
which have not heretofore been available in air-operated
nection 34 is provided at the top portion thereof, said
valve operation, either by lever or by foot pedal means. 25 conduit connections providing communication respectively
with the bottom and top portions of the cylinders for
A still further object of the invention is to provide an
?exible conduits 35 and 36 connected to said conduit
improved air-operated press which by simple lever action
connection members 33 and 34.
converts power delivered by an air cylinder at a long
Mounted in the vertical post portion 14 of frame 12
stroke into high pressures at its press arm at a short
is
a valve chamber 37 which is provided at the intermedi
30
stroke, without requiring the use of heavy and large-bore
ate portion of its main vertical wall 38 with a ?uid inlet
cylinders and excessively high hydraulic pressures.
port 39 to which is connected the ?uid supply line 40
Further objects and advantages of the invention will
which extends from the outlet of a suitable ?uid pressure
become apparent from the following description and
presses, and which accomplishes this with synchronized
claims, and from the accompanying drawings, wherein:
FIGURE 1 is a top plan view of an improved hand
operated press constructed in accordance with the present
invention.
FIGURE 2 is a vertical cross sectional view taken sub
tantially on the line 2-—2 of FIGURE 1.
supply source, such as a compressor, or the like.
35
Designated at 41 and 42 are respective upper and lower
piston elements which are slidably and sealingly engaged
inside the bore 43 of the chamber 37 and which are con
nected together by a vertical piston rod 44. As shown
in FIGURE 2, the spacing between the piston members
41 and 42 is such as to allow a substantial clearance
FIGURE 3 is an enlarged fragmentary elevational
space 45 in the top portion of the bore 43 when the piston
view, partly in vertical cross section, of the upper portion
members are in their lowered positions, shown in FIG
of the press of FIGURES 1 and 2, showing the operating
URE 2. A similar clearance space is provided in the bot
handle in a position at the end of its actuating stroke,
tom of the chamber when the pistons 41 and 42 are ele
with the piston of the ?uid pressure cylinder substantially
in its fully extended position, and with the ram member 45 vated to their dotted view positions, shown in FIGURE
2. Restricted equalization openings 46 are formed in
of the press in its bottom position.
the piston ‘members 41 and 42 to allow pressures to equal
Referring to the drawings, 11 generally designates a
ize on opposite sides of the piston members. However,
hand-operated press constructed in accordance with the
present invention. The press 11 comprises a frame 12 50 the openings 46 are relatively constricted in size, so that
equalization of pressures on opposite sides of the piston
consisting of a base portion 13 adapted to be mounted
elements
requires a de?nite period of time, and impose
on a suitable support, such as a table or other horizontal
su?icient restriction to ?ow of ?uid therethrough to allow
supporting member. Formed integrally with the base
substantial unbalancing of pressures to occur on the op
13 is a vertical post portion 14, and integrally formed
posite
sides of the piston members before pressure equal
with the top of the vertical post portion 14 is a horizontal 55
ization
can be achieved.
hollow top arm 15 which is formed with the generally
The main wall 38 of the chamber 37 is formed opposite
rectangular top opening 16. The forward end portion
the ?uid pressure supply port 39 with the respective
of the top arm 15 is formed with the vertically spaced
vertically spaced ports 47, 48 and 49. Conduit 35 is
apertured guide lugs 17 and 18 in which is slidably en
connected to the ports 47 and conduit 36 is connected to
gaged the vertical ram member 19, whereby the ram 60 the port 49. A vent conduit 50, leading to a ?uid pres
member is guided vertically, namely, for lengthwise move—
sure reservoir, substantially at atmospheric pressure, is
ment.
connected to the intermediate port 48. Designated at 52
As shown in FIGURE 2, the ram member 19 is lo
is a slide element which is connected to the intermediate
cated immediately above a table surface 20 provided on
portion of the piston rod 44 and which is of sufficient size
the top wall of the base 13, said table surface being 65 to at times overlap either the lowermost or the upper
adapted to receive a work piece to be acted upon by the
most two of the three ports 47, 48 and 49‘. Thus, in the
ram member 19.
lowered position of the piston rod 44, shown in FIG
As shown in FIGURE 2, the top arm 15 is open be
URE 2, the slide element 52 overlaps the lower ports
tween the guide lugs 17 and 18, and extending through
47 and 48, and the cavity 513 of the slide element 5-2 places
the opening, shown at 21, is a lever arm 22 which is 70 the ports 47 and 48 in communication with each other,
namely, allows the bottom of the cylinder 29 to exhaust
pivotally connected at its forward end to the intermediate
to atmosphere. At this time, the upper port.49 is ex
portion of the ram member v19, as by a transversely
3
3,027,829
4
posed to the interior of casing 37 in communication with
rear portion of the top wall of arm 15. As shown in
the ?uid pressure supply port 3-9‘, whereby ?uid under
FIGURE 3, the actuating element 77' of the valve 96
pressure is admitted into the top portion of the cylinder
is engageable by the bottom end of the release screw 91
29, urging the piston 32 downwardly and consequently
when the piston rod 27 is in its fully extended position.
retracting the piston rod 27, whereby the lever member 5 Both valves 71 and 90 include a valve plunger 75 which
22 is in the position thereof illustrated in FIGURE 2.
is biased upwardly toward closing position by a coiied
The clearance space 45 is under the same pressure as the
spring 76'.
portion of the bore 43 between the pistons 41 and 42,
A vertical guide rod 94 is secured in a depending posi
tion to the top wall of the arm 15 and extends between
i
namely, the pressure of the ?uid supplied at the port 39‘.
Designated at 5-4 is an operating lever which is pivoted 10 the vertical bar members 24, 24 adjacent the pivotal
to the frame 12, being secured on a transversely extend
connection 31 of said bar members to the piston rod.
As shown in FIGURE 2, the guide. rod 94 is rigidly se
upper arm 15 of the frame adjacent to the ram member
cured in a position wherein the vertical bar members 24,
19. The top wall of‘the frame is formed with a rectangu
24 slidably engage the opposite sides of the rod mem
lar notch 57, and secured on the shaft 555 is a cam mem 15 ber 94, whereby the guide rod 94 guides the rear end
ber 58 which is movable through the notch 57 responsive
portions of the lever bar elements 24, 24 for vertical
to the rotation of the operating shaft 54. As is shown
movement and similarly guides the piston rod 27 for
in FIGURES 1 and 2, the cam member 58 is located im
movement relative to the cylinder 29‘.
mediately above the forward portion of the lever mem—
In operation, when the lever 54 is rotated in a clock
ber Y22 and is engageable with a bearing roller 59‘ mounted 20 wise direction, as viewed in FIGURE 2, the cam element
between the forward portions of the vertical plate mem
58 ?rst engages the roller 59 and moves the ram mem
bers 24, 24, the roller 59 projecting above the top edges
ber 19 down through a preset preliminary distance by
of the vertical bar members 24, 24 and being engageable
rotating the lever member 22 in a clockwise direction
by the cam member 58‘. Thus, when the operating lever
around the pivotal connection ‘31 thereof to the piston rod
54 is rotated in a clockwise direction, as viewed in FIG 25 27'. This preliminary movement of the lever member 22
URE 2, the cam member 58 engages the roller 59'and e“
is su?icient to bring the roller 59 substantially into abut
erts a downward force on the forward end portion of the
ment with the upstanding support post member 67, and
lever member 22 which is transmitted to‘ thevertical ram
also, the rotation of the cam member is su?icient to bring
member 19.
the triggering arm 70 into operating engagement with
The forward portion of the lever member 22 is biased 30 the exposed portion 77 of the control plunger of the re
upwardly by a coiled spring 60 which surrounds a glide
lease valve 71. The valve 71 opens, thus venting the
pin member 61 pivoted at 62 between the vertical bar
space 45 of the chamber 38 to atmosphere. This causes
ing shaft 55 which is journaled in the top portion of the
members 24, 24 and extending slidably and pivotally
through an opening 63 provided in the bottom wall of
a substantial unbalance in pressures on the piston mem
bers 41, 42, since the lower portion of bore 43 is under
top arm 15‘. The spring 60 bears between a recess 64 35
the pressure of the working ?uid at port 39. The piston
provided in the bottom wall of arm 15 and the bottom
members 41, 42 are therefore moved upwardly, elevat
surface of the transversely extending bearing block 66
ing
the slide member ‘52 to a position wherein the port
disposed between the vertical bar members 24, 24 and
47 is exposed to the ?uid pressure port 39 and the ports
secured to the transversely extending pivot shaft 62 of
48 and 49 are placed in communication with each other
the guide pin 61.
40 by the slide member 52. Fluid under pressure is thus
Designated at 67 is an upwardly projecting abutment
‘admitted to the bottom of the cylinder 29, and the upper
pin member which is secured in the bottom wall of arm
portion of the cylinder is exhausted through conduit 36,
15 subjacent the roller 59" and which is engageable by
port 49, the cavity 53, the port 48 and the vent conduit
said roller when the lever 22 is rotated in a clockwise
50. Piston rod 27 is thus extended upwardly from the
direction from the position thereof shown in FIGURE
position of FIGURE 2, raising the left end of the lever
2, whereby to limit the downward movement of the ram
member 22, as viewed in FIGURE 2, causing said lever
member 19. Elevation of the ram member 19* is limited
member to pivot clockwise around the axis of the roller
by the engagement of the roller 59 with the bottom edge
59, as a fulcrum. This forces the ram member 19 further
downwardly, whereby substantial pressing force is avail
Secured‘ between the vertical bar members 24 in a
able therefrom on a work piece positioned on the table
position to be engaged by a triggering arm 70 secured to 50 surface
20.
the cam member 58 is a plunger valve 71 which is con
At
the
end of the upward stroke of the piston rod 27
nected by a ?exible conduit 72 to the top end of the
the release screw 91 engages the exposed operating por
chamber 38, namely, to the clearance space 45 normally
tion 77' of the plunger valve 90, venting the bottom of
existing in the top end of bore 43. Valve 71 is of- a
the
chamber. 38 through a ?exible conduit 97 connecting
55
conventional nature and is provided with an exposed stem
of cam member 58.
the bottom of chamber 38 to the venting valve 90. With
valve 90 open, the space below the lowermost piston 42
is vented and since the space immediately above the
The cam 58 is formed with the depending arm 80 which
piston 42 is at the working ?uid pressure, being in com
is provided at its end with a groove 81 in which the trigger
ing arm 70 is pivoted, the arm 70 being formed so 60 munication with the port 39, a substantial unbalance of
pressure develops which forces the pistons 41 and 42
that its rotation is limited to one direction, namely, to
downwardly to the position thereof shown in FIGURE
a counterclockwise direction with respect to the arm 80*,
2. This vents the lower portion of cylinder 29, since the
as viewed in FIGURE 3, whereby the triggering arm 70
is constrained to rotate in a clockwise direction with cam
ports 47 and 48 are placed in communication by the slide
58. Thus, the triggering arm 70 is engageable with the 65 element 52, and at the same time ‘admits ?uid under pres
exposed actuating portion 77 of the plunger of valve 71,
sure to the top portion of the cylinder 29, since the port
so that the valve 71 is opened responsive to rotation of
49 then becomes exposedto the fluid supply port 39,. The
the cam 581 through a predetermined angle, namely,
piston 32 of cylinder 29 therefore moves downwardly,
through an angle sufficient to depress the ram member
70 lowering the rear end portion of the lever member 22.
19 by a preset amount, as will be presently explained. An
This allows the spring 60 to elevate the forward end
automatic release valve 90, identical in construction to
portionof the lever member 22 to the position thereof
the valve 71, is secured between the vertical bar members
shown in FIGURE 2, when the control lever 54 is re
24, 24 at the rear portion of the lever 22, subjacent an
turned to its starting position, namely, to the position
adjustable, vertical triggering, screw 91 mountedv in the 75 thereof shown inFIGURE 2. Thus, the-ram member 19.
77 which is engageable by external means to depress its
plunger and open the valve.
3,027,829
6
said ram member subsequent to the engagement of the
is completely elevated and assumes its starting position,
cam with said lever arm to allow ?uid under pressure to
shown in FIGURE 2.
enter the cylinder below said piston, whereby the piston
As previously mentioned, the triggering arm 70 is free
rod is extended and rotates the lever arm around the cam
as a fulcrum, moving the ram member downwardly,
to rotate in a counterclockwise direction with respect to
the arm 80, as viewed in FIGURE 3, so that the lever
spring means biasing the ram member upwardly, means
54 may be returned from the position shown in FIGURE
returning the control valve to closed position responsive
3 to the position shown in FIGURE 2 without opening
to a predetermined amount of extension of said piston
the valve 71.
rod, and means venting said opposite end of the cylinder
The distance between the center of the connecting pin
31 and the axis of roller 59 is considerably greater than 10 responsive to the return of the control valve to closed
position, whereby said spring means is ‘free to elevate the
the distance between said roller axis and the ram pivot 23,
ram member, the distance between the cam and the ram
providing a substantial mechanical advantage, whereby
member being relatively small as compared to the distance
the force provided by the air cylinder 28, at a long stroke
between the cam and said piston rod along the length
of piston 32, is converted into a much higher force with
a shorter stroke at the ram 19.
The operating lever 54, which is manually operated, is
for the purpose of pre-setting the depth of downward
15 of said lever arm.
3. In a press, a frame, a vertical ram member, means
on the frame slidably supporting said ram member for
lengthwise movement, a cylinder pivotally mounted on
said frame, a piston in said cylinder, a piston rod secured
movement of ram 19 before it becomes air-operated, and
for energizing the power stroke through the actuation
to said piston and projecting slidably and sealingly
of the pilot valve 71. It can also be used as a power arm 20 through an end of said cylinder, a lever arm connecting
for strictly manual operation of the press.
said piston rod to said ram member, an operating lever
pivoted to said frame above said lever arm and adjacent
The press may be operated also by means of a foot
pedal, leaving the operator's hands free, by installing a
pilot valve similar to valve 71, operated by the foot pedal,
and connected to space 45.
the ram member, a cam on the operating lever enagage
25 able with the lever arm and being formed to move the
While a speci?c embodiment of an improved hand
operated press has been disclosed in the foregoing de
scription, it will be understood that various modi?cations
within the spirit of the invention may occur to those
ram member downwardly responsive to rotation of said
operating lever toward said ram member, a ?uid pres
sure supply line, a control valve rigidly mounted on the
frame, conduit means connecting the end of said cylinder
opposite said piston rod to said supply line through said
skilled in the art. Therefore, it is intended that no limita 30 control valve, means opening said control valve respon
tions be placed on the invention except as de?ned by the
sive to the continued rotation of said operating lever
scope of the appended claims.
toward said ram member subsequent to the engagement
What is claimed is:
of the cam with said lever arm to allow ?uid under pres
1. In a press, a frame, a ram member, means on the
35 sure to enter the cylinder below said piston, whereby
frame slidably supporting said ram member for length~
wise movement, a cylinder pivotally mounted on said
frame, a piston in said cylinder, a piston rod secured
to said piston and projecting slidably and sealingly through
the piston rod is extended and rotates the lever arm around
the cam as a fulcrum, moving the ram member down
wardly, spring means biasing the ram member upwardly,
cooperating means on the frame and the lever arm con
an end of said cylinder, a lever arm connecting said piston
structed and arranged to return the control valve to closed
rod to said ram member, an operating lever pivoted to 40 position responsive to a predetermined amount of exten
said frame above said lever arm and adjacent the ram
sion of said piston rod, and means to vent the said op
member, a cam on the operating lever engageable with
posite end of the cylinder when the control valve is in
the lever arm and being formed to move the ram member
closed position, the distance between the cam and the‘
in its lengthwise direction responsive to rotation of said
ram member being relatively small as compared to the
45
operating lever, a ?uid pressure supply line, a control
distance between the cam and said piston rod along the
valve, rigidly mounted on the frame, conduit means con
length of said lever arm.
I
necting the end of the cylinder opposite said piston rod
to said supply line through said control valve, and means
4. In a press, a frame, a vertical ram member, means‘
on the frame slidably supporting said ram member for.
opening said control valve responsive to the continued
lengthwise
movement, a cylinder pivotally mounted on
rotation of said.operating lever subsequent to the en 50 said frame, a piston in said cylinder, a piston rod secured
gagement of the cam with said lever arm to allow ?uid
to said piston and projecting slidably and sealingly through
under pressure to enter the cylinder below said piston,
an end of said cylinder, a lever arm connecting said piston
whereby the piston rod is extended and rotates the lever
rod to said ram member, an operating lever pivoted to
arm around the cam as a fulcrum, moving the ram mem
said frame above said lever arm and adjacent the ram
ber forward in its lengthwise direction, the distance be 55 member, a cam on the operating lever engageable with
tween the cam and the ram member being relatively small
the lever arm and being formed to move the ram mem
as compared to the distance between the cam and said
ber downwardly responsive to rotation of said operating
piston rod along the length of said lever arm.
lever toward said ram member, a ?uid pressure supply
2. In a press, a frame, a vertical ram member, means
line, a control valve comprising a chamber, a piston rod
on the frame slidably supporting said ram member for 80
in said chamber, spaced upper and lower piston ele
ments slidably and sealingly mounted in said chamber,
a slide element connected to said last-named piston rod,
said chamber being provided with a pair of vertically
through an end of said cylinder, a lever arm connecting
spaced ports spaced to be covered by said slide element,
65
said piston rod to said ram member, an operating lever
said slide element having a cavity of suf?cicnt length to
pivoted to said frame above said lever arm and adjacent
communicatively connect said ports, the upper port being
the ram member, a cam on the operating lever engage
vented to atmosphere, conduit means connecting the lower
able with the lever arm and being formed to move the
port to the cylinder below the ?rst-named piston, said
ram member downwardly responsive to rotation of said
?uid supply line being connected to the chamber between
operating lever toward said ram member, a ?uid pressure 70 said spaced piston elements, said chamber having a clear
lengthwise movement, a cylinder pivotally mounted on
said frame, a piston in said cylinder, a piston rod secured
to said piston and projecting slidably and sealingly
supply line, a control valve rigidly mounted on the frame,
conduit means connecting the end of said cylinder op~
ance space above the upper piston element, and means
venting said clearance space responsive to the continued
posite said piston rod to said supply line through said
rotation of said operating lever toward said ram member
control valve, means opening said control valve responsive
subsequent
to the engagement of the cam with said lever
.75
to the continued rotation of said operating lever toward
3,027,829
8
arm, whereby the slide element is forced upwardly to
expose the lower port to the chamber and to allow ?uid
under pressure to enter the cylinder below the ?rst-named
6. In a press, a frame, a vertical ram member, means
on the frame slidably supporting said ram member for
lengthwise movement, a cylinder pivotally mounted on
said frame, a piston in said cylinder, a piston rod secured
to said piston and projecting slidably and sealingly through
piston, and whereby the ?rst-named piston rod is ex
tended and rotates the lever arm around the cam as a
fulcrum, moving the ram member downwardly, the dis
an end of said cylinder, a lever arm connecting said pis
ton rod to said ram member, an operating lever pivoted to
tance between the cam and the ram member being rela
tively small as compared to the distance between the cam
said frame above said lever arm and adjacent the ram
member, a cam on the operating lever engageable with
and said ?rst-named piston rod along the length of said
lever member.
10 the lever arm and being formed to move the ram mem
5. In a press, a frame, a vertical ram member, means
ber downwardly responsive to rotation of said lever to
on the frame slida‘bly supporting said ram member for
lengthwise movement, a cylinder pivotally mounted on
said frame, a piston in said cylinder, a piston rod secured
ward said ram member, a ?uid pressure supply line, a
control valve comprising a chamber, a piston rod in said
to said piston and projecting slidably and sealingly through
15 and sealingly mounted in said chamber, a slide element
an end of said cylinder, a lever arm connecting said pis
ton rod to said ram member, an operating lever pivoted
to said frame above said lever arm and adjacent the ram
member, a cam on the operating lever engageable with the
chamber, spaced upper and lower piston elements slidably
connected to said last-named piston rod, said chamber
being provided with a pair of vertically spaced ports
spaced to be covered by said slide element, said slide
element having a cavity facing said ports and of suffi
cient length to communicatively connect said ports, the
downwardly responsive to rotation of said operating lever
upper port being vented to atmosphere, conduit means
toward said ram member, a ?uid pressure supply line, a
connecting the lower port to the cylinder below the ?rst
control valve comprising a chamber, a piston rod in said
named piston, said ?uid supply line being connected to
chamber, spaced upper and lower piston elements slid
the chamber between said spaced piston elements, said
ably and sealingly mounted in said chamber, a slide ele 25 chamber having a clearance space above the upper pis
ment connected to said last-named piston rod, said cham
ton element, and means venting said clearance space re
ber being provided with a pair of vertically spaced ports
sponsive to the continued rotation of said operating lever
spaced to the covered by said slide element, said slide ele
toward said ram member subsequent to the engagement
ment having a cavity of suf?cient length to communica
of the cam with said lever arm, whereby the slide ele
tively connect said ports, the upper port being vented to 30 ment is forced upwardly to expose the lower port to the
atmosphere, conduit means connecting the lower port to
chamber and to allow ?uid under pressure to enter the
the cylinder below the ?rst-named piston, said ?uid sup
cylinder ‘below the ?rst-named piston, and whereby the
ply line being connected to the chamber between said
?rst-named piston rod is extended and rotates the lever
spaced piston elements, said chamber having a clearance
arm around the cam as a fulcrum, moving the ram mem
space above the upper piston element, and means venting 35 ber downwardly, spring means biasing the ram member
said clearance space responsive to the continued rotation
upwardly, a vent valve on the lever arm, conduit means
of said operating lever toward said ram member subse
connecting the vent valve to the lower portion of the
lever arm and being formed to move the ram member
quent to the engagement of the cam with said lever arm,
chamber, and means on the frame above the vent valve
whereby the slide element is forced upwardly to expose
engageable therewith to open same responsive to a. pre
the lower port to the chamber and to allow ?uid under 40 determined amount of extension of said ?rst-named pis
pressure to enter the cylinder below the ?rst-named pis
ton rod, to cause the slide element to descend to a posi
ton, and whereby the ?rst-named piston rod is extended
tion communicatively connecting said ports, venting the
and rotates the lever arm around the cam as a fulcrum,
cylinder and allowing the spring means to elevate the
moving the ram member downwardly, spring means bias
ram member, the distance between the cam and the ram
ing the ram member upwardly, and means venting the 45 member being relatively small as compared to the dis
lower portion of the chamber responsive to a predeter
tance between the cam and said ?rst-named piston rod
mined amount of extension of said ?rst-named piston rod,
along the length of said lever member.
to cause the slide element to descend to a position com
municatively connecting said ports, venting the cylinder
References Cited in the ?le of this patent
UNITED STATES PATENTS
and allowing the spring means to elevate the ram member,
the distance between the cam and the ram member being
relatively small as compared to the distance between the
cam and said ?rst-named piston rod along the length of
said lever member.
2,261,576
Wood ________________ __ Nov.>4, 1941
693,892
France _______________ __ Sept. 8, 1930
FOREIGN PATENTS
55
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