Note: Descriptions are shown in the official language in which they were submitted.
~x~
CI,AMPI NG D~V ICE
Tile tool which is the subject of this application is known
as a llalld clamp. The name probably derives from the fact that
it is applied by hand rather than by any power-enhancirlg means
SUCtl as air or hydraulic pressure, but it is also true that in
mo~t cases a clamp serves as a surrogate human hand, to apply
and maintain pressure where and as required. Hand clamps take
many forms, some highly specialized; vi2~ clamps for holding
picture frames square for nailing, or for holding two pipe
ends in alignment for welding, and as such having little or
no other use~ul purpose. The variety of such special clamps
is probably in the several hundreds, many of which have been
the subject of patents.
The Eundamental di~ferences between the device of U. S.
Patent No. ~,736,G29 and that of this disclosure, aside from
component design changes dictated by a need to reduce produc-
tion costs at some minor loss of utility, are two: In place
of th~ ~asher~ e component of the original clamping device
which, in conjunction with a small pin projecting from the
~0 side of the cam, limited the cam's rotation (a system which
was expensive to produce and presented the possibility of
pin-shearing in use), the improved design provides a sturdy
cross-pin in the cam member, rotation of which is limited by
the adjacent spacer-rivets joining the jawplates. The second
area of improvement is in the direction in which camming force
is applied: In the original design, the cam~.ing action spread
the opposing iaws on a ~ine parallel to the adjusting sc~ew.
~n the improved d~sign, the ja~ opposite the scre~ head is
merely a br~ce, ~orce being applied to the ja~ und~r the screw
33 head perpendicularly to an imaginary line drawn between the
~2~
pivot center of the trunnion block under the screw head and the
pivot center oE th~e cam member. This change in dire~tion of
force provides a leveraye improvement of over 39%.
Thus, this invention may be summarized, at least in part,
with reEerence to its objects. It is an object of this inven-
tion to provide, and it does provide, an improved clamping
device in which a pair of C-shaped arm members is pivotally
retained at one end in an overlaid arrangement and with their
other ends with pivotally-retained pressure pads. Intermediate
the ends of these arm members there is disposed an adjusting
screw tha~ is adjusted to not only provide -the desired distance,
but also to provide the primary force-applying means and the
force-retaining means. The plVOt pin at the one end of the
arms has cam surfaces to provide a selective pressure adjustment
of -the gripping pads at the other end of the arm.
A further object of this inven-tion is to provide, and it does
provide, a clamping mechanism in which two pivo-ted C-shaped arms
are pivotaily retained in an overlaid condition and position at
one end, with thls pivot having cam means. The other ends of
20; the arms are provided with pivotally-re-tained, inwarùly--directed
clamping pads adapted to re-tain the workpiece. Near the mid-
length oE each arm is positioned a rotatable screw with pivot-
able retaining means, said screw haviny a threaded portion that
is carried in a threaded, pivoted-retaining means on one arm so
as to ~ove the arms toward or away from each other to bring the
pads into retaining condition and apply primary pressure. The
pivot cam at the overlaid ends is turned to provide maximum
; clamp force. This clamp thus provides a rugged device that is
easily manipulated to exer-t the desired holding action. This
clamp is easily assembled from stamped steel arms, rivets and
-- 3 --
~7~
hardened screw machine members.
A preferred co~struc-tion oE this invention is described in
detail below wi-th reference to the drawings which illustrate
only olle specific embodiment in which:
FIG. 1 represents an exploded isometric view, partly diagram-
matic, and showing relative placement or positioning of the com-
ponents as used in the clamping device of this invention;
FIG. 2 represents a top or plan view oE the clamping device
of FIG. 1 with the several components i~ an~assembled condition
lQ and with the jaws in a substan-tially opened condition;
FIG. 3 represen-ts the clamping device of FIG. 2 with the jaw
ends brought together;
FIG. 4 represents a diagrammatic pl~an view in a greatly
enlarged scale and showing the eccentric cam:portions as formed
on this pivot pin member, this view absent the arm portions and
taRen on the line 4 - 4 o:f FIG. 5 and looking in the direction
of the arrows;
FIG. 5 represents a diagratnmatic and sectional side view in
; the enLarged scale of FIG. 4 and showing the eccen-tric portions
formed on the pivot pin, this view taken on the line 5 - 5 of
FIG. 2 and looking in the direction of the arrows;
-FIG. 6 represents a fragmentary side and sectional view,
partly diagrammatic, and showing the preEerred arrangement of
mèmbers, with this view taken on the line 6 - 6 of FIG. 2 and
looking in the direction of the arrows;
FIG. 7 represents a side sectional view, partly diagramma-tic,
;: and showiny the midlength adjusting screw, this view taken on
-the line 7 - 7 of FIG. 2 and looking in the direction of the
arrows;
.
6~;
FIG. 8 A represents a diagrammatic view oE the limit or stop
pin as moved to a "cam free" condition, with the pressure pads
adjusted to the outer limit and with the screw head to the left;
FIG. 8 B represen-ts the view of FIG. 8 A, but with -the pres-
sure pads adjustably rnoved -to inner limi-ts;
FIG. 8 C represents the view of FIG. 8 A, bu-t with the stop
pln moved to bring the cam into a "tight" condi-tion, and
FIG. 8 D represen-ts the view of FIG. 8 B, but with the pres-
sure pads adjustably moved into an inner condilion and the pin
moved to bring the cam into a l'tight" condi-tion.
Referring now to the drawings as brieEly described above,
the several components a~e shown in FIG. 1. In this ~iew, ik
is to be noted that a socket-headed cap screw, generally identi-
fied as 10, is shown as extendlng from the right, whereas in
FIGS. 2 and 3 the knurled head of this screw is depicted on -the
left. This showing position is intended to particularly empha-
size -tha~ the clamping device oE this invention may be used with
the head of -the screw of the clampin~ device in ei-ther attitude.
The head end Oe this screw conven-tionally has therein ~. hex
¦ 20 socket 11, although other conEigurations may be provided. To
the left of this head and in and on -the shank portion thereof
is formed a ~hallow groove 12 spaced a given dis-tance from the
head. A thread 13 is cgnventlonally -formed on this cap screw.
A trunnion bloclc~ generaLly identified as 1~, has a hole 15
therethrQugh. This hole is ~ sliding fit on the shank of the
screw 10. The -thickne~s or width (right ~o Left) of the trun-
; nion bloc]c 1~ is jus~ a fçw th~usand~h$ of an inch less than
the distance fro~ the shoulder Oe -the head of screw 10 to the
shallow yroove 12. A retaining ring or washer 16 is adpated -to
be moun-ted in -this groove 12 to retain this trunnion block 14
1~67~66
on the shanlc oE the screw 10. 'I'runnion block 1~ as shown has
two pivot pins 17~which provide pivoted movemen-t and also reten-
tion of -this block.
As depicted in FIG. 1, the right C-shape arm movement in-
cludes stamped and formed sheet-metal members, generally identi-
fied as 20 and 21, each of which is provided with inwardly-
direc-ted ofEset portions 20 a and 21 a. Extending downwardly
from these offset portions are the major portions of -these arms.
These portions are identiEied as 20 b and 21 b. It is to be
noted -that in each arm component there are formed rivet holes 23,
24 and 25. These holes may or may not be of a like size, but
are sized to be a snug fit for the reduced ends of the rive-ts
used to provide the assembly. Spacer-rivets 27, 28 and 29 are
depic-ted. Each arm portion 20 b and 21 b also has holes 30
which are sized to rotatably retain the pivot pins 17 formed on
the trunnion bloclc 14. Also shown and pivotally carried by
rivet 29 is clamp pad 32 which has a hole 33 -through which this
rivet passes. It is -to be noted that the lower ends oE the
arms 20 and 21 are contoured so that the movement of clamp pad
32 may be li.mlted, thereby assurinq proper orientation oE the
pacl Eace with the wor~piece.
A threaded trunnion block 35 has threads 36 that are compa-t-
ible with threads 13 on cap screw 10. Pivot pin portions 37 are
also provided as in block 14. Another retaining ring or washer
38 is adapted to be secured in a groove 39 formed in and at the
terminal end of the sc~ew 10.
The left arm also, as an assembly, employs two C-shaped
sheet-s-teel members. These members are generally identified as
41 and 42. The upper ends have outwardly-directed oEfset por-
tions 41 a and 42 a. Ex-tending downwardly from -these oEfset
-- 6 --
~26~
portions are the major portions 41 b and 42 b o~ the C-shaped
arms. As in the ~igh-t arm assembly, -there are Eormed in each
member three rivet holes, respectively identifed as ~5, 46 and
47. Rivets 48, 49 and 50 are used -to secure these plates in
spaced array. The spacing is provided by the larger cen-tral por-
tion of all rivets. Trunnion block 35 is movable between these
secured plates ~1 and 42 and rotates about pivot pin portions 37
which are rotatably mounted in like holes 52 formed in pla-tes 41
and 42. On the lower end of this arm assembly is clamp pad 54
having a through hole 55 providing a pivoting ac-tion ahout
rivet 50. The lower ends of members 41 and 42 are contoured as
in 20 and 21 to provide a limited movement of khe clamp pad 5~.
A pivot cam, generally identified as 60, is better described
in conjunction with the showing in FIGS. 4 and 5. This is con-
templated to be a screw machine part with a hex aper-ture 62
-therethrough which is best seen in FIG. 4. As depicted in
FIGS. 4 and 5, this pivot cam has a central larger body portion
63 and reduced end portions 64 and 65. In these reduced por-
tions are Eormed like eccentric cam areas 66 a and 66 b. These
cam areas are particularly formed and have a wid-th to actuate
the arm portions 20 and 21. A stop pin 68 is mounted and
secured in a transverse hole in the pivot cam 60 to provide
means, in conjunction with the body portions of rivets 27 and
48, to limit the movement oE pivot cam 60. The forming of this
pivot cam and the eccentric cam portions 66 and the transverse
hole ~or stop pin 68 is calculated precisely, and in FIGS. 8 A,
B, C and D the relationship of the several Eormed por-tions of
this pivot cam is shown and discussed.
The arm members are provided wi-th apertures for mounting and
actuation oE the pivot cam 60. In 20 a there is depicted
i6
aperture 70 and in 21 a there is depicted aperture 71. In arm
~1 a there is for~ed a through aperture 73 and in arm 42 a -there
is ~ormed aperture 74. These aper-tures are oE like size. The
several other holes in the arm members are of other like diame-
ters. It is conte~plated -tha-t the C-shaped arm members will be
made with a single die, and with another die offsets are formed
so that the arms 20 and 21 will be offset -to form an inner
spacing and -the ar~s ~1 and ~2 ~rill be offset to form an ou-ter
spacing in which the arm ends overlay one another as seen in
FIG. 5.
It is to be noted that rivet 27 is shorter than rivets 28
and 29 as this rivet is used to retain the inwardly-directed
offset portions 20 a and 21 a of the C-shaped arm members. In
like manner, rivet 48 is diPferent from the other rivets in that
it has the body portion lengthened to accommodate the outward
oEfsets ~1 a and 42 a oE the other C-shaped arm members. The
several rivet holes may be of like or diEferent diameters and
are merely a matter o~ sele~ction. As viewed in FIG. 1, holes
25 and 47, which retain the ends of rivets 24 and 50, are
slightl~ smaller than the diame-ter of holes 23, 24, 45 and ~6,
but this is merely a mat-ter of selection. All -trunnion block
holes for the pin portions provided thereon are like size. The
stop pin 68 for limiting -the cam rotation is a dowel or commer-
cial pin member such as a roll pin. Rive-ts 28, 29, ~9 and 50
are contemplated to be alike in length as arm portions 20 b,
21 b, ~1 b and 42 b in the assembled condition are in parallel
array and move in like and the same planes.
In FIG. 2, the screw head is shown to the left and the clamp
is de~picted in a partially open condition, about two-t~irds oE
capaci-ty. As can be seen, the threaded portion 13 of screw 10
~l2~
still has some wa~ to go. As depicted, the stop pin 68 is mid-
way of stop limits as pr'ovided by secured rive-ts 27 and 48.
A discussion oE -the pivot cam 60 will be made here'inafter.
In FIG. 3, the clamping device of FIG. 2 is repeated, but
with the clamp pads 32 and 5~ in substantially a closed condi-
tion and with the stop pin 68 still in the condition oE FIG. 2.
In the showing of FIG. ~, which is very fraymen-tary and in
an enlarged scale, the pivot cam 60 is shown in a plan view
clearly depicting a hex passageway 62. Other configura-tions
0 may be used as this through passageway is merely a matter oE
selection and convenience as most machine shops have hex
wrenches (Allen-type). A hex wrench is also used with the
screw 10. An aperture is formed in this pivot cam in which is
tigh-tly moun-ted stop pin 68. The eccentric cam portion 66 is
- particularly formed in relation to this stop pin 68. This
relationship is more fully discussed later in conjunction wi-th
FIGS. 8 A, B, C and D. It is to bs noted tha-t s-top pin 68 pro-
vides a seat Eor insertion oE a hex wrench into the pivot cam 60
Eor final ti~htening from either side.
The cLampiny device as shown in FIG. 5, when assembled, u-til-
izes the pivot pin 60 and the cam portions 66 a and 66 b to pro-
vide the desired application oE clamping force. The upper off-
set portions ~1 a and 42 a are shown disposed as outer arm por-
tions. These arm portions and the apertures 73 and 79 therein
rotata~ly engage the reduced diameter 64 as formed on the pivot
cam. Immediately inside of~sets 41 a and '12 a and parallel to
and slideable thereby are inner offset portions 20 a and 21 a.
These ends also have apertures'70 and 71 which are the same size
as the apertures 73 and 7~ in the other two outer members.
These apertures 70 and 71 are slideable past diameter 6~ and
1~'7~
rest on the enlar~ed diame-ter 63 of the pivot pin. These aper-
tures 70 and 71 e~gage and move in -the eccen-tric yrooves 66 a
and 66 b formed in this pivot pin 60. The stop pin 68 is shown
substantially mid~ay of the hex passageway 62 formed in said
pivot pin.
In FIG. 6, a fragmen-tary sectional vie~ is provided to illus-
trate the relationship of the threaded trunnion 35 with the
pivot pin portions 37 in holes 52 in pla-tes 41 and 42. Rivet 50
is depicted pivotally retaining clamp pad 54. Rivet 49 is also
shown securing and providing the spacing of and for arm plates
~1 and ~2.
In FIG. 7, a sectional ~iew taken on the line 7 - 7 of FIG. 2
is depicted -to illustrate that the clamping device in an assem-
bled condition is adapted to lie flat and be used with -the
adjusting screw head ei-ther to the leEt or to the right. Shown
in this view are retaining rings 16 and 38 mounted on screw 10.
The a~m members 20 and 21 are shown as substantially in the
same plane as arm members 41 and ~2. The -trunnion block 1~ and
the threaded -trunnion blocl~ 35 are also shown. The rivets 27
and ~8 are also seen and provide limit stops for the manipula-
tion of the stop or limit pin 68 seen in FIGS. 4 and 5 above.
Referring finally to FIGS. 8 A, 8 B, 8 C and 8 D, these FIGS.
are merely a diayrammatic showing of the pivot cam of a clamp
of about -three-inch maximum opening. In these drawings-diagrams,
the dimensions are for a three-inch maximum clamp, which diagrams
are illustrati-ve of said clamp. In these FIGS., the precise
relationship of the pivot cam to the stop pin 68, the C-shaped
arms and the rivet stops is noted. It is to be noted that
rivets 27 and 48 establish the limits of rotative movement of
stop pin 68.
-- 10 --
6~
In FIG. 8 A is shown the relationship of the cam portion 66
to the stop pin 6~ and assuming -the head of screw 10 is on the
lef-t. In this FIG., the C-shaped arms have been moved -to sub-
stantially the maximum opening, with the trunnion pivots 17 and
37 about four inches apart. As seen, stop pin 68 is swung to
the left to -the limit establishe~ by rivet 27.~ For comparison
of sizes, the body oE the rivet is three-eighths of an inch in
di~meter and is sevèn-eigh-ths oE an inch on cen-ters from -the
center of pivot eln 60. The diameter oE -the stop pin 68 is con-
templated -to be three-eighths of an inch in diameter and, in the
angles and dimensions as noted, the size or diame-ter of this
stop pin is very important as to -the actuating relationship.
Assuming a theoretical line 80 parallel to line 31, which is
the theoretical line between trunnion pins 17 and 37, stop pin
68 is about ten and ane-~uarter degrees, identified as included
angle 82. The lowes-t point oE cam 66 is at an angle 83 oE about
Eorty-Eour degrees, which is about the same as angle 85 from a
theoretical center line to a trunnion pivot. These assumed
dimensions contemplate that the screw center line at this show-
ing is slightly more than two and one-sixteenth inches from the
screw center line 81 to the center of the pivot cam 60.
In FIG. 8 B, the adjus-tin~ screw lO has brough-t the clamp
jaw ends 32 and 54 into a together condition as depicted in
FIG. 3, but with the stop pin 68 moved into the leftward limit-
.
ing position a~ainst rivet 27. The stop ~in 68, ra-ther than
above the theoretical horizontal line 80, is now below (-toward
the screw) and with about the same amoun-t oE swing, identiEied
as 87. It is to be noted that trunnion pins 17 and 37 have
moved toward each other -to about two and three-tenths inches
therebetween. The rivets 27 and 48 have been cor~espondingly
-- 11 --
moved so that, whereas the angle in FIG. 8 A was about EiE-teen
and one-half degrees, this angle is about thir-ty~six degrees.
This angle is identiEied as 88. The lowest poin-t of the cam,
rather than -the angle 83 of FIG. 8 A, is now about twenty-three
and one-half degrees and is identiEied as 89. The cam's low
poin-t is always perpendicu].ar to a line drawn Erom the center of
the cam 60 to the center of the trunnion 17. Wi-th the movirly oE
the trunnions closer together, the distance from the center line
of the screw to the center of the pivot pin is increased and is
about two and five-eigh-ths inches.
In FIG. 8 C, the arrangement of the trunnion spacing of FIG.
8 A is repea-ted, but with -the stop pin 68 swung so that it now
is against rivet ~8. The cam portion 66 has been moved so -tha-t
the high point of the cam bearing is about forty-Eou~ degrees
~identified as 90) above the horizontal line and left of -the
verti~al center line. The direction of force swinging the jaw
32 in-to the workpiece is supplied by this high po.r-tion of the
cam.
In FIG. 8 D, the arranyement of -the trunnion spacing of FLG.
8 B is repeated, but the stop pin is shown as swung to the right
against rivet 48. The cam portion 66 now brings the high point
oE the cam in position to move the jaw 32 into the worlspiece
gripping condition. The direction oE force, identiEied as 92,
is about twenty-three and one-halE degrees.
It is to be noted tha-t the cam 66 formed in pivot pin 60 has
abou-t a sixty-degree Eull-diameter dwell area. The purpose of
-this Eeature is to compensate for the di-Efering angles of FIG.
8 C, 90, and FIG. 8 D, 92, and infini-tely -therebe-tween. Thus,
when the clamping device is ful1y open and cam 66 is in the
full, "tight" position, FIG. 3 C, the full diameter of cam 66 is
- 12 -
~à7~
entered upon about nine and one-half degrees. When the clampin~
device is fully c~osed and cam 66 is in -the Eull, "tight" posi-
tion, FIG. 8 D, -the sixty degree Eull-diameter dwell area is
~ithin about nine and one-half degrees of being overridden. The
purpose of this dwell area is to prevent such override bu-t, in
practice, it is only necessary to rotate the cam sufficiently to
enter upon the dwell area to achieve Eull force.
It is also to be noted -that the pivot pin 60 has the hex pas-
sageway 62 comple-gely therethrough. This permits tightening of
-the clamping device from either side, as necessary or convenient
It is also perceived -to be desirable in the manufacturing proc-
ess, aEEorcling a means of orienting the pivot pin 60 Eor forming
the transverse hole for stop pin 68 and forming the cam surfaces
66 in proper rela-tionship to one another.
All measuremen-ts and degrees are noted for a clamping device
of about three-inch maximurn opening, bu-t variations may be made
to suit the designer and producer, and such sugges-ted dimensions
are not lirnitiny.~
It is realized that although illustrated as forming the arm
assemblies of like blanking and starnping dies, one arm assembly
may be made withou-t offset end portions. Such an arrangement
would resultin altering the positioning of the apertures for the
pivot pin. The illus~rated offse-t allows the C-shaped arm mem-
bers to be blanked and punche~ f~om the same die and ~hen to be
offset the same amount, which is one~hal~ the thickness oE the
metal sheet used for the$e arm members. The rive-ts are usually
of plated steel a~d the reduced ends are made of suEFicient
ex-tended length for rivet forming oE the re-tained ends. The
- pressure pads are pivotally retained by rivets. In an assembled
condi-tion, the l~wer portions of eacn arm member lie in parallel
- 13 -
. . .
~lX~7~
or the same planes.
As shown in FI~S. 8 A, 8 B, 8 C and 8 D, the eccentric cam
portlons 66 are forrned -to provide dwell portion 91 which, as
noted, is about sixty degrees. ~his dwell, identiEie~ as 91,
is Eormed as a result of not forming the eccentric cam areas as
circular, but only about three hundred degrees of arc. This
dwell as described above provides the abili-ty of u-tilizing this
clamp for workpieces oE various thicknesses from -the very -thin
-to substan~ially maximum opening, with the adjustment allowing
movement of the stop arm 68 Erom open to a closed condition.
,
This clamping device as made and assembled is believed to
provide a novel method of construction and assembly, which
includes -the steps of;
- Eorming and assembling a pair of C-shaped arms;
- pivotally retaining a pair oE C-shaped arm assemblies at
one end and at the other end of each arm assembly re-taining a
pressure clamp pad, with each arm assembly oE two substan-tially
alilce plate-lilce members of metal, and arranying and maintaining
said members in spaced array by spacer and securing means, and
at the pivotally-retained end disposing these arms in overlaid
condition, and in each plate forming a pivot aperture, with -the
formed apertures disposed for axial alignment;
positioning and retaining a pivot cam at one end oE the
overlapped arm members and forming on this pivot cam two eccen-
-tric cam surfaces sized ~to be engaged with each of the apertured
surfaces of the two plate-like members of only one of the pair
of arms and forming -the intermediate portion of the pivot cam
with an enlarged portion si~ed to be slideably retained between
-the smallest distance between pla-te-like arm members when in
overlaid condition;
- 14 -
~2~71~i
- forming a pair of trunnion blocks with pivot portions and
mountin~ one trunr~ion block so as to be pivotally car.ried between
said plate-like members in each arm, and posi-tioning each trun-
nion block intermediate the extent o:E the C-shaped arm assemblies
with each block disposed to be a precisely equal distance from
the axis of the mounted pivot cam, one trunnion block having
threads formed therein and the other trunnion block having a
smooth bore therethrough;
- mounting in the trunnion blocks a threaded cap screw
having a head member adapted for rotative manipulation and
having a shank portion wi-th a threaded end portion, with these
threads compatible with -those threads in the threaded trunnion
block, and providing limitiny means for longitudinal retention
ofthe cap screw in that -trunnion block having a smoo-th bore and
inserting -the threads on the cap screw in the threads Eormed in
the threaded trunnion block, said cap screw providiny an adjust-
ing means and a force member that ~rings the pressure clamp pads
toward and away from each other;
- mounting a first rivet near the pivot cam, said rivet
having an enlarged midportion of a determined size and length so
as -to establish and maintain the plate-like members of a first
arm in spaced a.rray, and securing this first rivet at a precise
location and distance from the axis of the pivot cam;
- mounting a se~ond rivet near the pivot cam, this second
rivet also having an enlarged midportion of a size like that pro-
vided by the Eirst rivet, this second rivet having a lenyth so as
to establish and maintain the plate-like members of -this other
clamp arm in spaced array, and securing this second rivet at a
precise location and distance from the axis oE the pivot cam,
the f:irst and second rivets so positioned that their axes
- 15 -
establish a t~leoretical ~ine therebetween so as to be always
parallel to a the~oretical line through the pivot axes of the
trunnion blocks, said first and second rivets and their precise
:location at a like distance from the axis of the pivot cam;
- mounting ano-ther pair of rivets, each having enlarged
midportions, one rivet positioned in said first arm a.ssembly
adjacent a trunnion block, and another similar rivet positioned
in the other a~m assembly and also adjacent the trunnion block
in said other arm assembly, and
- forming a hole and fixedly inserting in said hole a stop
pin in the enlarged portion of the pivot cam, this stop pin of
sufficien-t length so that said stop pin as i-t is swung in an arc
is limited by said first or second rivet, this stop pin being
secured so -that -when the stop pin engages one of the first or
second rivets, the cam surfaces formed on the pivot cam engage
the apertures in that arm assembly disposed to be actuated by
the eccentric cam, -the maxlmum throw of the arm assembly moviny
the pressure clarnp pads closer toyether and, when the stop pin
is moved to the other limit, the clamp pads are moved away from
each other.
- 16 -
