Bicycle freewheel core holder

Two generally semicylindrical halves are held by an O ring encircling them with generally diametral matching surfaces in engagement. Lugs projecting from the matching surfaces are engageable in sockets in the other matching surfaces to deter sliding of the halves parallel to the matching surfaces. The matching surfaces have transverse ridges and clearance so that pressing tail portions of the halves at one side of the ridges will spread head portions at the opposite side of the ridges into clamping engagement with the aperture of a freewheel core into which such head portions are fitted.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a holder for clamping a bicycle freewheel core so 
that it can be worked on. 
2. Prior Art 
No comparable prior art is known. 
SUMMARY OF THE INVENTION 
A principal object of the present invention is to provide a holder for a 
bicycle freewheel core that can be operated to hold such core firmly so 
that it can be worked on conveniently. 
Another object is to provide a holder that can be applied to and released 
from the core quickly. 
A further object is to provide a holder that is compact while being 
effective to clamp a bicycle freewheel core securely. 
Another object is to provide a bicycle freewheel core holder which is 
economical to construct. 
The foregoing objects can be accomplished by a clamp having two halves of 
generally semicylindrical shape with substantially diametral matching 
surfaces that can be placed in contact and which have generally central 
transverse crowns or ridges that can contact each other for effecting 
spreading of freewheel core-engaging head portions by squeezing of tail 
portions in a vise.

DETAILED DESCRIPTION 
A conventional bicycle freewheel FW is shown in FIGS. 1 and 2. Such a 
freewheel includes a core FWC having in it an aperture with which the 
holder is engageable for holding the freewheel steadily in a fixed 
position so that it can be worked on. 
The freewheel core holder is composed of two identical halves 1 of 
substantially semicylindrical shape. Each half includes a semicylindrical 
head portion 2 having a diametral matching face 3, and a tail portion 4 
having a substantially semicylindrical outer surface and a flat matching 
face 5 which is substantially diametral but somewhat beveled from a 
transverse ridge or crown 6 disposed generally centrally lengthwise of 
each half toward the end of the tail portion so as to leave a small acute 
clearance angle 7 between the tail portions when the matching faces 3 of 
the head portions are in contiguous engagement. 
In each half 1 the radius of the head 2 is somewhat shorter than the radius 
of curvature of the cylindrical surface 4 of the tail portion so as to 
provide a shoulder 8 between the head portion and the tail portion facing 
toward the head portion. At the root of such shoulder is a rounded 
circumferential groove 9 of a size to receive an elastic O ring 10 
encircling the two halves when they are in assembled relationship with 
their matching faces 3 and 5 mutually facing and their crowns or ridges 6 
in contact. 
In order to maintain the halves 1 in proper registration when they are in 
assembled relationship with their ridges 6 in engagement, semicylindrical 
lugs 11 are provided projecting from the matching faces 3 of the head 
portions of the halves in positions offset radially from diametral planes 
of the halves disposed perpendicular to the matching faces 3. Offset to 
the opposite side of such perpendicular plane is a semicylindrical socket 
12 complemental to the lug 11 of the other half. When the halves are in 
assembled relationship, the lug 11 of one half will fit into the socket 12 
of the other half to maintain the halves in registration both 
longitudinally and transversely as they are held together by the O ring 10 
in the manner shown in FIGS. 1, 2, 3, 6 and 7. 
Spaced from the ends 13 of the tail portions 4 of the halves are shoulders 
14 facing such ends and located at the sides of such tail portions 
opposite the matching faces 5. Between such shoulders and the ends 13 of 
the halves are flats 15 engageable with the jaws J of a vise. 
The head portions 2 of the halves are of a radius such that the head 
portions of the halves will fit cooperatively into the aperture of the 
freewheel core FWC with a snug fit. Such head portions can be inserted 
into such aperture until the O ring 10 substantially abuts the freewheel 
core, as shown in FIG. 2. Longitudinal movement of the O ring along the 
halves toward the ends 13 will be limited by engagement of the O ring in 
the grooves 9 and the bearing of such ring against the shoulders 8. 
Movement of the tail portions downward between the jaws J of the vise will 
be limited by engagement of the shoulders 14 with the jaws, as shown in 
FIG. 2. 
In order to secure the freewheel core, therefore, it is merely necessary to 
insert the head portions 2 of the holder into the aperture of the 
freewheel and then to insert the flats 15 between the jaws J of a vise. By 
moving the jaws toward each other, the ridges 6 will be pressed against 
each other and the head portions 2 of the halves will be spread to clamp 
firmly within the aperture of the freewheel core.