U.S. patent number 3,556,481 [Application Number 04/793,273] was granted by the patent office on 1971-01-19 for air-operated scissors-type jack.
This patent grant is currently assigned to McNeil Corporation. Invention is credited to Carl H. Mueller, Clarence E. Kitchen, George Weitzel, Jerome B. Wegmann.
United States Patent |
3,556,481 |
|
January 19, 1971 |
AIR-OPERATED SCISSORS-TYPE JACK
Abstract
A scissors-type jack for a vehicle lift comprises a base, a
scissors linkage above the base and a platform on the scissors
linkage adapted to be raised to various elevations by upward
extension of the linkage from the base. The linkage is adapted to
be so extended by air cylinder actuated follower rollers which have
a wedging action between the links of the scissors linkage, the air
cylinder being movable with the scissors pivot. An auxiliary
locking mechanism is provided for locking the follower rollers in
various platform-elevating positions thereof to prevent collapse of
the jack under load in the event of failure of the air cylinder to
hold the follower rollers in platform-elevating position.
Inventors: |
Carl H. Mueller (St. Louis
County, MO), Jerome B. Wegmann (St. Louis County, MO),
Clarence E. Kitchen (St. Louis County, MO), George
Weitzel (St. Louis County, MO) |
Assignee: |
McNeil Corporation (Akron,
OH)
|
Family
ID: |
25159529 |
Appl.
No.: |
04/793,273 |
Filed: |
January 23, 1969 |
Current U.S.
Class: |
254/122;
254/8B |
Current CPC
Class: |
B66F
7/08 (20130101); B66F 3/247 (20130101); B66F
7/065 (20130101) |
Current International
Class: |
B66F
7/06 (20060101); B66F 7/08 (20060101); B66F
3/24 (20060101); B66f 003/22 () |
Field of
Search: |
;254/8,9,93,104,122,124,126 ;74/521 ;92/15,19,24,27,28 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Andrew R. Juhasz
Assistant Examiner: David R. Melton
Attorney, Agent or Firm: Koenig, Senniger, Powers and
Leavitt
Claims
1. A jack comprising a base, a scissors linkage extending upward
from the base, a platform on the scissors linkage adapted to be
raised to various elevations by upward extension of the linkage
from the base, said linkage comprising scissors links pivotally
interconnected intermediate their ends by a scissors pivot which
moves upward on extension of the linkage and downward on retraction
of the linkage, follower means between the links on one side of the
pivot movable inward toward the pivot with a wedging action between
the links for extending them to raise the platform to various
elevations and movable outward away from the pivot for downward
retraction of the linkage, and cylinder and piston means movable
upward and downward with the scissors pivot and interconnected with
the follower
2. A jack as set forth in claim 1 further having auxiliary means
for locking the follower means against outward movement from any
platform-elevating position thereof to prevent collapse of the jack
under load in the event of failure of the cylinder and piston means
to hold the follower means in platform-elevating position, said
locking means being releasable to allow outward movement of the
follower means for lowering
3. A jack as set forth in claim 2 wherein the cylinder and piston
means comprises a cylinder movable with the pivot, a piston in the
cylinder, and piston rod means movable with the piston and
connected to the follower means, said locking means being
interengageable with the piston rod means.
4. A jack as set forth in claim 2 wherein said locking means
comprises a series of locking members successively movable from a
retracted position to a locking position engageable by the piston
rod means to lock the
5. A jack as set forth in claim 4 further comprising cylinder and
piston
6. A jack as set forth in claim 4 wherein said piston rod means
comprises a first rod extending through one end of the cylinder to
a connection with the follower means and a second rod extending
through the other end of the cylinder having a shoulder facing said
other end of the piston, and having means carrying said locking
members at said other end of the cylinder, said locking members
being successively movable behind said shoulder as
7. A jack as set forth in claim 6 wherein said second rod has an
outer end extension of larger diameter than the second rod, each of
said locking members comprising a plate located above the second
rod disposed in a plane at right angles to the axis of the rod,
said plates being arranged in face-to-face engagement, each plate
being individually vertically slidable between a raised retracted
position wherein its lower end engages said extension and a lowered
locking position wherein one face thereof is
8. A jack as set forth in claim 7 wherein each plate has a notch
extending
9. A jack as set forth in claim 8 further comprising cylinder and
piston
10. A jack as set forth in claim 9 wherein said cylinder and piston
means for raising said plates comprises a cylinder mounted below
said plates, a piston extending up out of said cylinder, and a
pusher on the upper end of said piston having side members
extending upward on opposite sides of said second rod and said
extension engageable with the lower edges of said
11. A jack as set forth in claim 1 wherein said cylinder and piston
means comprises a cylinder having scissors pivots extending
laterally outward from opposite sides thereof, and said scissors
linkage comprises two pairs of scissors links, one pair being
pivoted on the scissors pivot on one side of the cylinder, and the
other pair being pivoted on the scissors
12. A jack as set forth in claim 11 wherein said cylinder has a
piston therein and a rod extending from the piston through one end
of the cylinder, said follower means comprising a crossbar on the
outer end of said rod and follower rollers on the crossbar between
the scissors links.
13. A jack as set forth in claim 12 having auxiliary means mounted
on the outside of the other end of the cylinder for locking the
piston and follower rollers against outward movement from any
platform-elevating position thereof to prevent collapse of the jack
under load in the event of failure of the cylinder and piston means
to hold the follower rollers in platform-elevating position, said
locking means being releasable to allow outward movement of the
follower rollers for lowering the platform.
14. A jack as set forth in claim 13 wherein said piston has a
second piston rod extending through said other end of the cylinder
having an outer end extension of larger diameter than said second
rod providing a shoulder at the inner end of said extension facing
said other end of the cylinder, said locking means comprising a
housing on said other end of the cylinder, a plurality of locking
plates arranged in a row above the piston rod axis in said housing
with each plate in a plane at right angles to said axis, said
plates being arranged in face-to-face engagement, each plate being
individually vertically slidable between a raised retracted
position wherein its lower end engages said extension and a lowered
locking position wherein one face thereof is engageable by said
shoulder, said extension extending through said housing and holding
all said plates
15. A jack as set forth in claim 14 wherein each plate has a notch
extending upward from its bottom edge adapted to receive said
second piston rod, the width of said notch being less than the
diameter of said
16. A jack as set forth in claim 15 further comprising cylinder and
piston
17. A jack as set forth in claim 16 wherein said cylinder and
piston means for raising said plates comprises a cylinder mounted
below said plates, a piston extending up out of said cylinder, and
a pusher on the upper end of said piston having side members
extending upward on opposite sides of said second rod and said
extension engageable with the lower edges of said
18. A jack as set forth in claim 17 having a valve for controlling
the supply and exhaust of air from the cylinder for the follower
rollers and adapted to trap air in this cylinder, and a valve
operable to supply air to the cylinder for raising the locking
plates and adapted on release to bleed air from the latter
cylinder.
Description
This invention relates to scissors jacks, and more particularly to
an air-operated scissors jack useful, for example, as a platform
lift for vehicles.
The invention relates especially to scissors jacks of the type such
as shown in German Pat. Nos. 604,156 and 1,175,852 in which the
links of the scissors mechanism of the jack are extended by the
wedging action of follower rollers. As to the jacks shown in each
of these German patents, the follower rollers are actuated by screw
mechanism driven by an electric motor. It has been found to be
desirable to provide for actuation of the follower rollers in a
jack of this type by an air cylinder, rather than by mechanism
driven by an electric motor, but this has involved problems as to
the disposition of the air cylinder and as to safety in the event
of loss of air pressure in the cylinder, and this invention solves
these problems.
Among the several objects of this invention may be noted the
provision of a jack of the class described in which the follower
rollers for actuating the scissors mechanism of the jack are
actuated by a fluid cylinder, more particularly an air cylinder (as
distinguished from being actuated by electric motor powered screw
mechanism), and which is of simplified economical construction; and
the provision of a jack such as described with a safety feature to
prevent collapse of the jack in the event of loss of pressure in
the cylinder.
In general, a jack of this invention comprises a base, a scissors
linkage extending upward from the base, a platform on the scissors
linkage adapted to be raised to various elevations by upward
extension of the linkage from the base. The scissors linkage
comprises scissors links pivotally interconnected intermediate
their ends by a scissors pivot which moves upward on extension of
the linkage and downward on retraction of the linkage. Operation of
the linkage is effected by the use of follower means between the
links on one side of the pivot movable inward toward the pivot with
a wedging action between the links for extending them to raise the
platform to various elevations and movable outward away from the
pivot for downward retraction of the linkage, and cylinder and
piston means movable upward and downward with the scissors pivot
and interconnected with the follower means for moving it inward to
various platform-elevating positions. Additionally, an auxiliary
means for locking the follower means against outward movement from
any platform-elevating position thereof may be provided to prevent
collapse of the jack under load in the event of failure of the
cylinder and piston means to hold the follower means in
platform-elevating position, said locking means being releasable to
allow outward movement of the follower means for lowering the
platform. Other objects and features will be in part apparent and
in part pointed out hereinafter.
FIG. 1 is a perspective showing a jack constructed in accordance
with this invention, the platform of the jack being shown in a
raised position;
FIG. 2 is a vertical longitudinal section through the jack, also
showing the platform in a raised position;
FIG. 3 is a left end view of the jack, showing the platform
lowered;
FIG. 4 is a right end view of the jack, also showing the platform
lowered;
FIG. 4A is an enlarged fragment of FIG. 4 with certain parts broken
away and shown in section;
FIG. 5 is an enlarged vertical section on line 5-5 of FIG. 6;
FIG. 6 is a section similar to FIG. 2, with parts broken away,
showing the scissors linkage of the jack in retracted position;
FIG. 7 is a section showing the auxiliary locking mechanism of the
jack in a condition of partial raising of the platform;
FIG. 8 is an enlarged section on line 8-8 of FIG. 6; and
FIG. 9 is a section showing details of a valve for controlling the
auxiliary locking mechanism.
Corresponding reference characters indicate corresponding parts
throughout the several views of the drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, first more particularly to FIGS. 1 and
2, a jack constructed in accordance with this invention is shown to
comprise a base 1, a scissors linkage 3 extending upward from the
base, and a platform 5 on the scissors linkage adapted to be raised
to various elevations by upward extension of the linkage from the
base. The platform remains generally horizontal as it is raised and
lowered. The linkage 3 comprises two pairs of scissors links, each
pair being generally designated 7, the two links of each pair being
designated 9 and 11. These links are pivotally interconnected
intermediate their ends by a scissors pivot 13 which moves upward
on extension of the linkage and downward on retraction of the
linkage. At 15 is indicated follower means between the links on one
side of the pivot (the left side, as illustrated) movable inward
toward the pivot (i.e., toward the right) with a wedging action
between the links for extending them to raise the platform to
various elevations and movable outward away from the pivot (i.e.,
toward the left) for downward retraction of the linkage. At 17 is
indicated cylinder and piston means movable upward and downward
with the scissors pivot and interconnected with the follower means
for moving it inward to various platform-elevating positions. At 19
is generally indicated auxiliary means for locking the follower
means against outward movement from any platform-elevating position
thereof to prevent collapse of the jack under load in the event of
failure of the cylinder and piston means to hold the follower means
in platform-elevating position. This locking means is releasable,
as will appear, to allow outward movement of the follower means for
lowering the platform.
The jack is especially designed for use on a lift such as a
four-post lift with the base 1 extending transversely between the
runways of the lift on which a vehicle is parked, and movable
longitudinally of the runways to various positions under the
vehicle. For this purpose, the base 1 has angle brackets 21 at its
ends carrying rollers 23 adapted to roll on tracks 25 extending
inward from the runways 27 (see FIGS. 1 and 2). The base is
constituted by a channel, the bottom of which is designated 29 and
the side flanges of which are designated 31. The platform 5, which
extends horizontally in the same plane as the base, comprises a
channel 33, the bottom of which is designated 35 and the side
flanges of which are designated 37. A pair of channel-section
slides 39 are slidable endwise in the channel 33. Each of these
slides carries three pivoted pads such as indicated at 41, 43 and
45. The slides are adapted to be moved to various positions
relative to the channel 33, including positions extending from the
ends of channel 33 as shown in FIG. 1, and the pads are adapted to
be swung up to raised positions, as illustrated for pads 41 in FIG.
1 and for all the pads in FIGS. 3 and 4, for engagement by various
under parts of a vehicle to be raised by the jack off the runways.
Auxiliary pads such as indicated at 47 in FIG. 1 may be stored on
brackets 49 mounted on a side flange 31 of the base 1. The channel
33 has side plates 51 extending down from its side flanges 37.
These plates have inwardly directed flanges 53 at the top overlying
outwardly directed tips 55 on the side flanges of the
channel-section slides 39 for confining the latter in the channel
33.
The cylinder and piston means 17 comprises an air cylinder 57
having end heads 59 and 61. The cylinder also has side plates 63,
which extend between the end heads 59 and 61 on opposite sides of
the cylinder. Extending laterally outward from these cylinder side
plates, generally at the center of length of the cylinder and in
the central horizontal plane of the cylinder, are the scissors
pivots 13 for the two pairs of scissors links. As shown in FIG. 4A,
each of these pivots 13 is constituted by a pivot pin extending
outward through a hole 65 in the side plate and having a head 67
received in an enlarged inner end portion 69 of the hole 65. The
links 9 and 11 of each pair 7 of scissors links are pivoted
generally centrally of their lengths on a respective pivot pin 13,
and held thereon by a nut 71 threaded on a reduced-diameter outer
end extension 73 of the pin. Link 9 is located on the inside of
link 11. The links 9 and 11 have oppositely directed hubs as
indicated at 75 on the pin 13 which provide for spacing of the
links as appears best in FIG. 4A. The lower ends of links 9 of the
two pairs of links are pivoted on the bottom 29 of the base 1 as
indicated at 77. Extending transversely between the upper ends of
links 9 is a roller assembly comprising a roller axle 79 having two
rollers 81 thereon in rolling contact with the lower face of bottom
35 of the channel 33 of platform 5. The upper ends of links 11 are
pinconnected at 83 to brackets 85 on the outside of side plates 51
of the platform, and extending transversely between the lower ends
of links 11 is a roller assembly comprising a roller axle 87 having
two rollers 89 thereon in rolling contact with the upper face of
bottom 29 of the base 1. Additional rollers 91 are provided on the
outside of links 11 at their lower ends. Lubrication fittings for
the roller assemblies are indicated at 93.
The two pairs 7 of scissors links 9 and 11 are thus spaced from one
another on opposite sides of the cylinder 57, and the cylinder 57,
being interconnected via its side plates 63 with the scissors pivot
pins 13, is adapted for conjoint movement with pins 13. The
cylinder 57 has a piston 95 slidable therein. At 96 is generally
indicated piston rod means movable with the piston. This comprises
a first piston rod 97 extending toward the left as viewed in FIGS.
2 and 6 from the piston through an opening 99 in the cylinder end
head 59. The follower means 15, which is mounted on the outer end
of this piston rod, comprises a crossbar 101 of square cross
section secured in position extending transversely of rod 97 at its
outer end by means such as indicated at 103. Pins 105 extend
outward from the ends of bar 101. Each pin carries an inner
follower roller 107 and an outer follower roller 109, held in place
by a nut 111 threaded on a reduced-diameter end extension 113 of
the pin. Lubrication fittings 115 are provided for lubricating the
rollers. The inner rollers 107 are located for wedging action
between links 9 (which are the inner links of the scissors-link
pairs 7) and the outer rollers 109 are located for wedging action
between the links 11 (which are the outer links of the
scissors-link pairs) on the left side of the scissors pivot axis
(i.e., the axis of pivot pins 13). The links 9 and 11 have opposed
curved flanged cam edges as indicated at 117 and 119 on the left
side of the pivot axis between which the follower rollers 107 and
109 are adapted to wedge on movement of the follower rollers in
inward direction toward the scissors pivot axis (i.e., toward the
right as viewed in FIGS. 2 and 6) to cause the links 9 and 11 to
swing relative to one another on the scissors pivot axis for upward
extension of the links for raising the platform 5. On movement of
the follower rollers in outward direction away from the scissors
pivot axis (i.e., movement toward the left as viewed in FIGS. 2 and
6), the links 9 and 11 are retracted downwardly (under the weight
of the platform 5 and the load supported thereby) for lowering of
the platform. FIG. 6 shows the follower rollers in their extreme
outward position and the links in their downward retracted
position, and FIG. 2 shows the follower rollers in their extreme
inward position and the links in their extreme extended position.
It will be observed that as the links retract on outward movement
of the follower rollers, the rollers 81 at the upper ends of links
9 and the rollers 89 and 91 at the lower ends of links 11 roll
outward (i.e., toward the right as viewed in FIG. 2).
A conventional manually operated rotary air control valve 121 for
controlling the operation of cylinder 57 is mounted on the outside
of one of the flanges 31 of the base 1. One end of the head of a
tee fitting 123 is connected to the air inlet of this valve, and an
air hose 125 extending from a compressed air supply is connected by
a coupler 127 to the other end of the head of the tee fitting. An
air line 129 is interconnected between valve 121 and the cylinder
end head 59. The other cylinder end head 61 has a vent 131. Valve
121 has a handle 133 adapted to be turned from a vertical shutoff
position toward the right for supplying air via line 129 to the
left end of the cylinder and toward the left for venting air via
line 129 from the left end of the cylinder. In the vertical shutoff
position of the handle, the valve traps air in line 129 and in the
cylinder on the left of piston 95.
The piston rod means 96 further comprises a second piston rod 135
extending toward the right as viewed in FIGS. 2 and 6 from the
piston 95 through an opening 137 in the cylinder end head 61. Rod
135 has an enlarged-diameter cylindric extension 139 threaded on
its outer end providing an annular shoulder 141 facing toward the
end head at the inner end of the extension. The locking means 19
comprises a plurality of individual locking members each designated
143 successively engageable with the rod 135 behind the shoulder
141 as the rod 135 moves toward the right as viewed in FIGS. 2 and
6 when the links 9 and 11 are extended to raise the platform 5 to
lock the piston rod 135 and hence to lock the follower means 15
against outward movement in link-retracting direction until the
locking members are retracted from their locking position behind
the shoulder. Each locking member 143 is constituted by a
rectangular plate having a notch 145 (see FIG. 5) extending upward
from its bottom edge. The width of this notch is slightly greater
than the diameter of the rod 135, and less than the diameter of the
rod extension 139. The notch has a generally semicircular upper end
adapted to seat on the rod 135. The locking plates 143 are arranged
in a horizontal row above the axis of the rod 135 within a housing
147 extending toward the right from the right-hand cylinder end
head 61. Each locking plate is disposed in a vertical plane at
right angles to the piston rod axis, and successive plates are in
face-to-face engagement, with each plate being individually
vertically slidable between a raised retracted position relative to
the rod 135 and a lowered locking position wherein its right-hand
face is engageable by the shoulder 141.
The locking plate housing 147 has a horizontal top wall 149 and
sidewalls 151, the latter being spaced a distance slightly greater
that the width of a locking plate. The housing has an inner
left-hand end wall 153 secured on the outside of the cylinder end
head 61, and extends out toward the right from the cylinder 57,
having an outer right-hand end wall 155. On the inside of the
housing end walls 153 and 155 are guides 157 and 159 to the piston
rod extension 139, with partitions 161 and 163 in the housing at
the inner ends of these guides constituting end stops for the
series of locking plates to hold the latter against sliding endwise
in the housing. With the piston 95 at the left end of its stroke,
and the follower means 15 accordingly in its extreme outward
position for downward retraction of links 9 and 11, the piston rod
extension 139 extends through the locking plate housing 147 from
one end thereof to the other, the ends of extension 139 being
received in the guides 157 and 159 as shown in FIG. 6. Each and
every one of the locking plates then occupies its raised retracted
position with the corners of the lower edge of the locking plate on
opposite sides of the notch 145 in the locking plate engaging the
piston rod extension 139 (see the position of the locking plate 143
shown in solid lines in FIG. 5). As the piston 95 moves toward the
right to draw the follower means 15 inward to raise the platform 5,
the piston rod extension 139 moves toward the right and, as the
shoulder 141 at its inner end passes each successive locking plate,
the latter slides down by gravity in back of the shoulder 141 to
its locking position in respect to the shoulder. See FIG. 7 showing
the innermost or first locking plate 143 of the series down in its
locking position behind the shoulder 141. It will be apparent
therefrom that, as the piston rod extension 139 moves farther
toward the right from its FIG. 7 position, the second locking plate
will slide down behind the shoulder, then the third locking plate,
and so on.
Means is provided for raising the locking plates 143 to their
retracted position clear of the shoulder 141 to enable the piston
95 to be moved toward the left for lowering the platform. As shown
in FIGS. 2, 5 and 6, this means comprises an air cylinder 165
secured in vertical position between the sidewalls 151 of housing
147 at the bottom thereof generally centrally of the length of the
housing. A piston 167 is slidable in cylinder 165 and extends up
out of the upper end of the cylinder, which is open. A
channel-section locking plate pusher 169 is mounted on the upper
end of the piston 167, extending lengthwise of the housing 147
between the partitions 161 and 163. This pusher has side flanges
171 extending upward on opposite sides of the rod 135 and its
extension 139, these flanges being engageable with the lower edges
of the locking plates 143 for raising the latter on upward movement
of the piston 167 and the pusher.
Operation of the air cylinder 165 is under control of a valve 173
mounted adjacent the main control valve 121 on the side flange 31
of the base 1. This valve 173 (see FIG. 9) is a pushbutton valve
comprising a body 175 having a compressed air inlet 177 at its
upper end which is connected to the lower end of the stem of the
tee fitting 123. A tubular fitting 179 is threaded in a hole 181
extending upward from the lower end of the body and has a valve
seat 183 at its upper end. This tubular fitting 179 is passaged as
indicated at 185 for communication with a valve port 187. A valve
member 189 is biased downward toward the valve seat 183 by a spring
191, and is adapted to be raised off the seat by a rod 193 loosely
slidable in the fitting 179 having a push button 195 at its lower
end. An air line 197 interconnects port 187 and the lower end of
cylinder 165. The arrangement is such that on pushing up button
195, the valve member 189 is raised for delivery of air to the
cylinder 165 to raise the piston 167 and locking plate pusher 169.
On release of the button, valve member 189 closes, and air bleeds
off from cylinder 165 through the space around the rod 193 (the
loose fit of this rod in fitting 179 permitting this) for lowering
of the piston 167.
Operation is as follows:
To raise the platform 5, the handle 133 of valve 121 is turned to
the right to set valve 121 for supplying compressed air via line
129 to the left end of cylinder 57. Piston 95 and the piston rod
means 96 accordingly move to the right, drawing the crossbar 101
and follower rollers 107 and 109 toward the right, and the follower
rollers wedge apart the links 9 and 11 to extend the scissors
linkage 3 and raise the platform 5. As the piston rod means 96
moves toward the right, locking plates 143 successively drop down
onto the piston rod 135 behind the shoulder 141 at the inner end of
the rod extension 139. The platform is raised to the desired
elevation, and then handle 133 of valve 121 is turned back to its
vertical position to shutoff the flow of air into cylinder 57 and
to trap air in the cylinder.
The follower rollers 107 and 109 are maintained in their
platform-elevating position (whatever it may be) by both the
trapping of air in cylinder 57 on the left of piston 95 and the
locking action of those locking plates 143 which have dropped down
behind the shoulder 141. If, for any reason, such as rupture of
line 129, the pressure of air trapped in the cylinder 57 should be
lost, meaning that the cylinder and piston means 17 is no longer
capable of holding these rollers 107 and 109 in their
platform-elevating position, the rollers 107 and 109 remain locked
against outward movement to prevent collapse of the jack under load
due to the action of the locking plates 143.
To lower the platform 5, the handle 133 of valve 121 may be turned
to the right to supply air to the cylinder 57 to move the piston
rod means 96 to the right for the purpose of relieving pressure of
shoulder 141 on the locking plates 143, and the button 195 of valve
173 may then be pushed upward to supply compressed air via line 197
to cylinder 165 to raise the piston 167 and the locking plate
pusher 169. The side flanges 171 of the pusher 169 thereupon push
up those locking plates 143 which have previously dropped into
locking position to raise them clear of the shoulder 141. Handle
133 of valve 121 is turned to the left to vent the left end of
cylinder 57 via line 129, and the follower rollers 107 and 109
thereupon move outward (i.e., toward the left, as illustrated)
under the weight of the platform 5 and the load supported thereby
for the lowering of the platform. The button 195 is held pushed
upward until the platform is completely lowered, and then it is
released to allow the piston 167 and locking plate pusher 169 to
lower back downward to their retracted position. This occurs as a
result of air bleeding off from cylinder 165 via line 197 and the
space around rod 193.
IN view of the above, it will be seen that the several objects of
the invention are achieved and other advantageous results
attained.
As various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all
matter contained in the above description or shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
* * * * *