Improvements in Clamping Devices, Chiefly Designed for the Seat-posts of Cycles and the like.
Year: 1899

page_text: Date of Application, 28th Mar., 1899-Accepted, 13th May, 1899
Improvements in Clamping Devices, Chiefly Designed for the
Seat-posts of Cycles and the like.
I, AXEL LEVEDAHL, of Aurora, County of Kane, State of Illinois, United States
of America, Manufacturer, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
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This invention relates to an improvement in telescopic clamps or devices for
detachably securing an inner cylindric part within au exterior tube or cylindric
socket. The invention is more particularly designed for use in securing bicycle
seat posts to bicycle frames, but it is equally applicable for other purposes, as for
instance, for attaching the handle bar post to the fork spindle of a bievele, or
other similar uses. The invention consists in the matters hereinafter described
and pointed out in the appended claims.
In the accompanying drawings illustrating my invention
Figure 1 is a side elevation of a telescopic clamp embodying my invention
together with a bicycle seat post and a socket therefor, which latter is shown
in vertical section.
Figure 2 is a longitudinal cross section of the clamp taken on line 2-2
Figure 1.
of
Figure 3 is a transverse section of the same taken on line 3-3 of Figure 1.
Figure 4 is a separate detail view of the split sleeve of the clamp.
Figure 5 is a detail elevation of the inner split tube of the clamp.
Figure 6 is a plan or end view of the outer sleeve shown in Figure 4.
Figure is a view in side elevation of the rotative coupling member or nut.
Figure 8 is a view in side elevation of a telescopic clamp. differing somewhat
from the form thereof shown in the other figures of the drawings.
Figure 9 is a sectional view of the same.
As shown in said drawings, (Figures 1 to 7). A indicates an exterior cylindric
socket and B the lower end of a bicycle seat post inserted therein, it being under-
stood that said part A may represent any socket and B any cylindric part which
is to be secured therein. The telescopic clamp constituting the subject of my
invention consists of an outer split sleeve C, an inner tube which is split at its
Jower end or portion and an annular coupling member or nut E, which joins the
two parts C and D and serves to move the same endwise relatively to each other.
The split sleeve C is provided with a longitudinal slot or opening extending
throughout the entire length of the same and which is provided at its lower part
with downwardly diverging side edges c¹¹ forming a wedge shaped opening at
one side of said sleeve. At its upper margin said sleeve is provided with a
Hange C in the inner surface of which is formed a groove having parallel

page_text: bottom and top walls located in planes perpendicular to the longitudinal axis
of the clamp. Said sleeve has a cylindric or substantially cylindric inner surface.
The inner tube D is solid or continuous in its upper part and at its lower part is
provided with a longitudinal slot or opening d. The upper or solid part of said
tube is provided with external screw threads d' which are engaged by internal
screw threads on the annular coupling or nut E. On the lower part of said inner
tube at either side of the slot d are formed elevated parts or ribs D', 1', having
outwardly divergent inclined side edges, surfaces or shoulders d, d³, which are
adapted for engagement with the inclined or oblique edges cl c¹ of the outer
sleeve C which said inner tube is inserted within said sleeve. Said projections
or flanges D D with their tapered side edges together constitute in effect an
upwardly tapering wedge. Aside from the projections or flanges D', D¹ the lower
part of said tube is substantially cylindric upon its outer surface. The nut E is
provided at its lower part with an external radial flange e having parallel bottom
and top surface, said flange being adapted for engagement with the groove c³ of
the outer split sleeve C when the parts are assembled.
From the above description of the construction of this form of the device it will
be seen that when the parts are assembled, if the inner tube is drawn upwardly
within the outer sleeve by the action of the nut on the screw threads of the inner
sleeve, the action of the inclined edges of the outer sleeve on the wedge shaped ribs
or projections of the inner tube will have the effect of expanding the outer sleeve
and at the same time contracting the inner tube. It follows that when the tele-
scopic clamp is inserted in the tubular socket and the seat post or other cylindric
part to be secured in said socket is inserted through the inner sleeve of said clamp,
the rotation of the nut in the proper direction will have the effect of expanding
the outer sleeve into contact with the socket and at the same time contracting
the lower or expansible part of the inner tube into contact with the said seat post
or cylindric part within the same, the expansion and contraction of said parts
being produced by a wedge action operating circumferentially on the split sleeve
and tube to spread apart the edges of the split sleeve and thereby increase the
diameter of the same and to draw together the edges of the split tube and thereby
reduce the diameter of the latter. A reverse movement of the nut will, of course,
move the outer sleeve and inner tube in a direction to release the clamp from
engagement with the socket and cylindric part.
An important advantage obtained from the construction herein described is
that the expansion and contraction of the outer and inner parts by a wedge action
operating circumferentially or edgewise on the split tabular parts, aflords a clamp-
ing or binding action which is much stronger, with the same amount of power
applied to turn the nut or coupling piece by which relative endwise movement is
given to the parts, than if produced by radially acting wedges.
Moreover, the expanding wedge arranged as described, not only operates to give
a clamping action of great force and effectiveness, but is adapted to be easily
released; the relatively small area of surfaces of the tube and sleeve in frictional
contact enabling the part to be moved in a direction for the release of the clamp
by the application of a relatively small amount of power to the nut. The inven-
tion is illustrated in the accompanying drawing the figures of which are herein-
after referred to.
The telescopic clamp shown in Figures 8 and 9 consists of three main parts,
namely, an inner tube F which is split at its lower end or portion, an outer split
sleeve G, and an annular coupling member or nut H which has interior screw-
threads engaging exterior screw-threads f on the inner tube F and which has
swivelled engagement with the split sleeve G by means similar to that described
in connection with Figures 1 to 7 the same consisting of a flange h on the nut
engaging a groove in the split sleeve. In this instance the exterior surface of
the inner split tube F is made conical or tapered, while the inner surface of the
split sleeve G in contact therewith is correspondingly conical or tapered, so that

page_text: when the inner tube and split sleeve are moved endwise relatively to each other
by turning the nut H on the screw-threaded part of the inner tube in a direction
to draw the tube into the sleeve the sleeve will be expanded and the tube will be
contracted. A stud f projecting from the inner tube and engaging the slot
between the separated ends of the outer split sleeve prevents the inner tube from
turning in the sleeve. The result produced by this construction is, generally the
same as that obtained by the construction illustrated by Figures 1 to 7, it being
obvious that when the clamp is inserted in a socket, such as indicated by 1,
Figure 9, and a seat post or like cylindric part J is inserted through the inner
tubular part F, by turning the nut so as to draw the said part Finwardly into
the split sleeve G, the inner part will be contracted into contact with the post J, and
the outer part will be expanded into contact with the surrounding wall of the
socket I and the post will be thereby rigidly and firmly clamped within said
socket.
An important advantage gained by the employment of the connection described
between the nut and the outer split sleeve, and embodied in with form of clamp
above described, namely, a radial flange on one part and a groove to engage the
other part, is that such groove and flange being of considerable radial width,
the sleeve may expand and contract to a considerable extent without liability of
disengagement from the nut and without changing the longitudinal position of the
said sleeve with respect to the nut.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
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1. A telescopic clamp, comprising inner and outer longitudinal clamping mem-
bers, both of which are slotted to make them expansible and contractible, and the
inner one of which has a non-slotted, screw-threaded part which projects beyond
the outer member and a coupling piece or nut having screw-threaded engage-.
men't with the non-slotted part of the inner member which projects beyond
the outer member, and having swivelled connection with the outer member, said
inner and outer members being provided with co-acting wedge surfaces which
operate to expand the outer and contract the inner part when the same are given
longitudinal movement by the action of said coupling piece or nut.
2. A telescopic clamp, comprising inner and outer members which are slotted
to make them expansible and contractible, a nut having serew-threaded engage-
ment with the non-slotted end of the inner member which projects beyond the
outer member and engaging the outer member by means of a radial flange and
groove, said inner and outer parts being provided with co-acting wedge surfaces
which operate to expand the outer and contract the inner member.
3. A telescopic clamp, comprising inner and outer longitudinally movable clamp-
ing members, both of which are expansible and contractible and a coupling piece
adapted to give endwise relative movement to said parts, said outer members being
provided with co-acting wedged surfaces which operate circumferentially on said
parts to expand the outer and contract the inner part.
4. A. telescopic clamp comprising an inner part or tube which is screw threaded
at one end and is provided with a horizontal slot at its opposite end, and exterior
member or sleeve also provided with a slot, said inner and outer parts having
co-acting wedge surfaces at the sides of the slots therein, and a rotative coupling
member engaging a screw-thread on one of the members and acting on the other
member to give relative endwise movement to said parts.
5. telescopic clamp comprising an inner tube screw-threaded at one end
and having a longitudinal slot at its opposite end, and provided at either side of
said slot with wedge shaped projections or flanges, an exterior part or sleeve which
is split through its entire length and provided with oblique edges adapted for
engagement with the oblique edges on said wedge shaped projections, and a

page_text: coupling member or nut engaging the screw threads on the inner sleeve and
having connection with the outer sleeve by means of a flange and groove.
Dated this 28th day of March 1899.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.