U.S. patent number 3,914,830 [Application Number 05/440,869] was granted by the patent office on 1975-10-28 for tools having locking adjustments.
Invention is credited to Robert Benjamin Bolton.
United States Patent |
3,914,830 |
Bolton |
October 28, 1975 |
Tools having locking adjustments
Abstract
A tool, in particular a G-clamp, having a fixed clamping face on
one end of an elongate body member and a further abutment face
mounted on a slide member movable along the body member, the
abutment face being movable relative to the slide member, and the
slide member being capable of being slid along the body member to
give quick-setting of the initial spacing between the clamping and
abutment faces, subsequent pressure on said latter face effecting
locking of the slide member on the support member.
Inventors: |
Bolton; Robert Benjamin
(Ponteland, EN) |
Family
ID: |
23750510 |
Appl.
No.: |
05/440,869 |
Filed: |
February 8, 1974 |
Current U.S.
Class: |
24/490; 81/158;
269/189; D8/73; 269/171.5 |
Current CPC
Class: |
B25B
1/125 (20130101); B25B 5/102 (20130101); Y10T
24/44299 (20150115) |
Current International
Class: |
B25B
5/00 (20060101); B25B 1/12 (20060101); B25B
1/00 (20060101); B25B 5/10 (20060101); A44B
021/00 (); B25B 001/02 (); B25B 005/02 () |
Field of
Search: |
;24/263PJ,263LL,263LS,263A,263P,134L,249FP ;81/175,176,157,158
;269/189,203-205,171.5,166 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
75,695 |
|
Jun 1961 |
|
FR |
|
83,349 |
|
May 1920 |
|
CH |
|
334,157 |
|
Aug 1930 |
|
GB |
|
Primary Examiner: Griffin; Donald A.
Attorney, Agent or Firm: Larson, Taylor & Hinds
Claims
What I claim and desire to protect by Letters Patent is:
1. A tool comprising a support member with rectangular cross
section, opposed first and second surfaces on said support member,
a slide member mounted on the support member, a body portion which
forms part of said slide member and which embraces said support
member to allow free sliding movement between them, a trapping
surface on said slide member lying adjacent said first surface of
the support member, a jamming member pivotally mounted on the slide
member, resilient means urging the jamming member in one rotational
direction against the second surface of the support member, a stop
on the slide member to limit the movement of the jamming member in
the other rotational direction, and an abutment face for contacting
a workpiece or item to which force is to be applied, this abutment
face being mounted on the jamming member and being movable
relatively to the slide member, the arrangement being such that
pressure on the abutment face further urges the jamming member in
the one rotational direction to cause increased pressure of said
member against the second surface of the support member, said
support member thus being gripped between the jamming member and
said trapping surface to lock the slide member to the support
member, the jamming member being releasable from the support member
by pivoting movement of said jamming member and abutment face in
the said other rotational direction whereby the slide member is
slidable in either direction relative to the support member.
2. A tool as claimed in claim 1 in which the jamming member
includes an arcuate cam surface adapted to press against the second
surface of the support member, the abutment face being to the side
of the pivot remote from said cam surface, whereby pressure on said
abutment face rotates the jamming member in the one direction to
bring an increased-diameter portion of said cam surface into
contact with the second surface of the support member to effect
said locking.
3. A tool as claimed in claim 2 and including toothed serrations on
the arcuate cam surface of the jamming member.
4. A tool as claimed in claim 3 in which each tooth of the
serrations is substantially V-shaped in transverse section to give
substantially point contact of each tooth with the second surface
of the support member.
5. A tool as claimed in claim 2 in which the resilient means
comprises a coil spring reacting between the slide member and a
region on the jamming member to the same side of the pivot as the
abutment face.
6. A tool as claimed in claim 5 and including an externally
threaded shaft at one end of which is formed said abutment face,
the jamming member defining therein a correspondingly threaded bore
in which said shaft is mounted.
7. A tool as claimed in claim 6 in which a clamping face is carried
at one end of the support member, said abutment face being adapted
to co-operate with said clamping face to enable an item to be
clamped therebetween.
8. A tool as claimed in claim 1 in which the slide member, jamming
member, resilient means and abutment face comprise a unit which can
be removed from the support member and replaced on said support
member in the reverse direction, the slide member then being locked
to the support member on application of pressure on the abutment
face in the reverse direction.
9. A tool as claimed in claim 1 wherein said body portion embraces
enough of each surface of said rectangular support member as to
support said slide member thereon independently of any support
contributed by said jamming member.
10. A tool as claimed in claim 9 wherein the interior of said body
portion is of closed rectangular cross-section corresponding to
said support member and completely encompasses said rectangular
support member, and is axially spaced on said slide member from
said jamming member so as to encompass said support member at
locations axially removed from the locations at which said jamming
member contacts the support member.
Description
The present invention relates to tools having locking adjustment
and, in particular to G-clamps although it may be applied to any
tool where a force-applying slide member is to have an adjustable
position on a substantially rigid support member before force is
applied, it being necessary to lock the force-applying member in
position relative to the support member when force is being
applied.
Most known G-clamps include a rigid support member provided with a
fixed position clamping face and an adjustable member carrying an
abutment face movable towards and away from the fixed clamping
face. The adjustable abutment face is formed on one end of a
threaded stem extending through a correspondingly threaded bore in
the support member, the stem being provided at its other end with
means for rotation thereof.
These known clamps have the disadvantage that adjustment of the
clamp opening is provided for wholly by rotation of the threaded
stem and such adjustment is a slow operation.
According to the present invention I provide a tool comprising a
support member with rectangular cross-section having opposed first
and second surfaces, a slide member mounted on the support member,
the slide member having a body portion which embraces the support
member and a trapping surface adjacent the first surface of the
support member, a jamming member pivotally mounted on the slide
member, resilient means urging the jamming member in one rotational
direction against the second surface of the support member a stop
on the slide member to limit the movement of the jamming member in
the other rotational direction, and an abutment face for contacting
a workpiece or item to which force is to be applied, this abutment
face being mounted on the jamming member and being movable
relatively to the slide member, the arrangement being such that
pressure on the abutment face further urges the jamming member in
the one rotational direction to cause increased pressure of said
member against the second surface of the support member, said
member thus being gripped between the jamming member and said
trapping surface to lock the slide member to the support member,
the jamming member being releasable from the support member by
pivoting movement of said jamming member and abutment face in the
other rotational direction whereby the slide member is slidable in
either direction relative to the support member.
Preferably the jamming member includes an arcuate cam surface
adapted to press against the second surface of the support member,
the abutment face being to the side of the pivot remote from said
cam surface, whereby pressure on said abutment face rotates the
jamming member in the one direction to bring an increased-diameter
portion of said cam surface into contact with the second surface of
the support member to effect said locking.
Conveniently the abutment face is formed at one end of an
externally threaded shaft mounted in a threaded bore in the jamming
member.
The resilient means may comprise a coil spring reacting between the
slide member and a region of the jamming member to the same side of
the pivot as the abutment surface. Said spring may be sufficiently
light to allow the slide member to be pushed by hand along the
support member in a direction opposed to that of the force to be
applied to the abutment face. The threaded shaft however
constitutes a convenient lever for pivoting the jamming member in
the other rotational direction about its pivot against the bias of
the spring thereby to permit ready sliding movement of the slide
member in either direction relative to the support member.
Thus the invention provides a tool, for example a clamping tool,
permitting quick-setting of the clamping opening during initial
engagement of a workpiece or item to be gripped, and which is such
that the greater the clamping pressure on the item the greater is
the locking effect of the mechanism.
An embodiment of the present invention will now be described, by
way of example only, with reference to the accompanying drawings,
wherein:
FIG. 1 is a side view of part of a G-clamp having a slidable
force-applying member adjustably mounted on a support member in
accordance with this invention;
FIG. 2 is a vertical section along the line II--II of FIG. 1,
and
FIG. 3 is a vertical section along the line III--III of FIG. 2.
Referring to the drawings a G-clamp 1 has a substantially rigid
support member in the form of a metal rod 2 of rectangular
cross-section having an abutment surface 2a. A head member 3 is
fixed to one end of the rod 2, conveniently by means of bolts or
spring dowels. A slide member 4 is mounted on the rod 2 and is
slidable along the rod so that a clamping head 5 can be brought
towards the head member 3 to grip an item between them.
The slide member 4 has a generally cylindrical portion 6 of
rectangular cross-section that engages the rod 2. In one embodiment
of the invention a pair of pins or bolts (not shown) are fixed at
the end of the rod 2 opposite the head member 3 and project from
the sides of the rod to prevent the member 4 being slid off the
rod, the pins or bolts engaging recesses 20 in the member 4.
A pair of lugs 7, integrally formed with the portion 6, provide
bearing support for a pivot 8 carrying a jamming member 9 having an
internally threaded bore 10. An externally threaded shaft 11 screws
into the bore 10 and carries the clamping head 5 at one of its
ends. The clamping head is mounted on the shaft 11 by means of a
ball-joint 12 so that, over a large range of angular positions of
the bore 10 about the pivot 8, the clamping head 5 can grip an item
by contact over its abutment face 13. A transverse handle 14 is
provided in a bore 15 in the end of the shaft 11 remote from the
clamping head 5.
A coil spring 16 is provided in a blind recess 17 in the member 9
and bears on a face 18 of the member 4 to exert a pivoting moment
biassing the jamming member 9 onto the rod 2.
The jamming member 9 contacts the abutment surface 2a of the rod 2
with a hardened, curved portion 21 whose radius relative to the
pivot 8 increases anticlockwise in the plane of its pivoting
movement so that an increasing clockwise moment exerted on the
jamming member 9 provides an increasing pressure between the
jamming member and the rod 2. The curved portion 21 is serrated,
the transverse section through each tooth being slightly V-shaped
(for example of the order of 3.degree. from the horizontal) as seen
in FIG. 2 thus ensuring that the jamming member 9 engages with the
central region of the associated surface 2a of the rod 2 thereby
decreasing the possibility of deformation of said surface 2a of the
rod 2 that full face contact of the teeth with the rod might cause.
A trapping surface 22 of the portion 6 lies adjacent the lower
surface of the rod 2 and co-acts with the jamming member to grip
the rod.
The strength of the spring 16 may be such as to permit, when the
G-clamp is to grip an item between the head member 3 and the
clamping head 5, a "quick-set" movement of the slide member 4
merely by pushing it to slide the rod 2 towards the head member 3,
the jamming member pivoting slightly against the relatively weak
bias of the spring as the sliding occurs. The spring 16 may be such
as to exert a relatively large clockwise moment on the jamming
member to make simple pushing of the member 4 along the rod towards
the head member 3 difficult. The jamming member 9 can then be
disengaged from the rod 2 by applying an anticlockwise moment to
the jamming member about its pivot 8 using the shaft 11 as a lever,
the top end of the face 18 of the slide member acting as a stop to
limit the counterclockwise movement of the jamming member; this
position of the jamming member 19 permits ready sliding movement of
the member 4 along the rod 2. Similarly, whatever strength spring
16 is used, said disengagement using the shaft 11 as a lever
permits sliding movement of the clamping head 5 away from the fixed
head member 3. It is preferred that the spring 16 is at least
strong enough to hold the member 4 in position on the rod against
the weight of the member 4.
Subsequent to the "quick-set" movement of the member 4, the item
can be gripped by rotating the shaft 11 using the handle 14 so that
the clamping head is translated towards the head member 3. The
reaction to the gripping force of the clamping head 5 produces a
clockwise moment on the jamming member 9, locking the member 4 in
position on the rod. The greater the gripping force exerted by the
clamping head the greater is the normal reaction of the jamming
member on the rod giving a greater frictional force opposing
movement of the member 4 relative to the rod 2.
In an alternative embodiment of the invention, the slide member 4
and its associated components can be slid off the end of the rod 2.
In order to prevent possible loss of the spring 16 from this unit
when off the tool, a stop member is formed on the jamming member
adjacent the lower right hand region thereof, as viewed in FIGS. 1
and 3, and adapted to abut the adjacent sidewall of the member 4
thereby to prevent clockwise rotation of the jamming member 9 into
the slide member 4. The spring 16 cannot then completely disengage
with the surface 18 of the member 4 and cannot therefore fall out
of its recess 17. Clearly the location of the stop member is such
as not to come into effect during normal operation of the tool.
Such removability enables the member 4 to be turned through
180.degree. on the rod 2 and the tool to be used to provide a
spacing or stretching action.
It is to be understood that while the rod 2 has been described as
being of rectangular cross-section it could be of round or any
other cross-section which provides the rod with sufficient
rigidity.
It has been found that the G-clamp described above, which can be
modified in various ways, is a versatile and reliable tool which
can be used to give quick-set movement and high gripping
pressures.
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