GB2054799A - Clamping hub - Google Patents

Abstract

A loose-fitting hub 2 is made to clamp firmly onto a shaft 6 by providing an axially extending slot-like cavity 8 spaced from and parallel to the bore 4 of the hub, whereby the portion of the hub between the bore and the cavity may be displaced relative to the portion of the hub radially outward of the cavity by elastic deformation in the direction of the axis of the bore. <IMAGE>

Description

SPECIFICATION Clamping hub The invention relates to a hub or the like coupled or for coupling to a shaft, and particularly but not exclusively where the shaft and hub have no keyways.

The locking of a plane cylindrical shaft to a hub or other body having a cylindrical bore for receiving the shaft therein, hereinafter in this specification likewise referred to for simplicity as a hub, so as to prevent relative angular or axial movement, such as is required for example in a rotary pump given by rotation of a shaft, presents serious problems, if the bore of the hub is of diameter sufficiently greater than that of the shaft to facilitate assembly and subsequent disassembly, and it is the object of the invention to provide means whereby those problems may be solved in a simple and inexpensive manner.

According to the invention there is provided a hub having a cylindrical bore for receiving a cylindrical shaft therein, said hub comprising a first portion defining part of the inner surface of the bore and capable of displacement relative to another portion radially inwardly of the bore by elastic deformation, and means for effecting said relative displacement.

Preferably the dispalceable first portion is provided by forming a slot in the hub spaced from and parallel to a tangent to the inner surface of the bore. The displacement effecting means is preferably reversible and may comprise at least one screw means threadedly engaged in said other portion. Where the bore extends from one to the other of both faces of the hub, the slot preferably also extends from one to the other of said faces.

The invention will be further described by way of example and with reference to the accompanying drawings of which Fig. 1 is a side view of a hub according to the invention mounted on a shaft; Fig. 2 is a section along lines li-Il of Fig. 1; and Fig. 3 is a detail of a portion of an alternative embodiment.

In the figures hub 2 is provided with a central bore 4 for receiving a shaft 6. Whilst the diameter of the bore 4 must be greater than the external diameter of the shaft 6 for ease of assembly, the tolerance shown in the figure is exaggerated for purposes of illustration.

A slot 8 is cut through the thickness of the hub 2 parallel to and spaced from the tangent to the bore at point A. Thus, between the slot and the bore there is left a bridge-like portion 10 against which a set screw 12, thread engaged in bore 14, may be urged.

In use of the hub, the screw 1 2 is screwed within the threaded bore 14 so as to engage the bridge portion 10 and displace it as shown by dotted lines in Fig. 1. Provided that the displacement is kept within the elastic limit of the material of the hub 2, the original position of the bridge portion 10 will be recovered on subsequent removal of the screw 12.The displacement of the bridge portion 10 effectively reduces the width of the bore at point 8, and although in the Figure the distortion is not sufficient to engage with shaft 6, in practice the diameter tolerance of the shaft and bore is such that the inward displacement of the bridge portion 10 is sufficient to take up the slackness between shaft and bore and bind the shaft against the internal surfaces of the bore at point A and, by reactionary forces, at the diametrically opposed point.

Whilst in Fig. 1 the slot 8 is shown as being parallel sided with rounded ends, a preferred section is shown in Fig. 3 and takes the form of a central portion with parallel sides spaced by a distance d, the portion terminating at each side in bores of diameter D where D is greater than d. With this arrangement there are formed articulating points B about which the bridge portion 10 is able to be displaced by elastic deformation.

Whilst the invention is applicable to shafts without splines, it is nevertheless possible, if required, to incorporate a spline between the hub and the shaft in a keyway located, for example, diametrical opposite point A.

1. A hub or the like having a cylindrical bore for receiving a cylindrical shaft therein, said hub comprising a first portion defining part of the inner surface of the bore and capable of displacement relative to another portion radially inwardly of the bore by elastic deformation, and means for effecting said relative displacement.

2. A hub or the like according to Claim 1 wherein the first portion is caused to be displaceable relative to the other portion by forming an axially extending cavity in the hub spaced from the bore.

3. A hub or the like according to Claim 2 wherein the cavity is generally in the form of a slot parallel to the tangent to the part of the inner surface, of the bore defined by said first portion of the hub.

4. A hub or the like according to any preceding claim wherein the displacement effecting means comprise at least one screw means threadedly engaged in said other portion of the hub.

5. A hub or the like substantially as described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Clamping hub The invention relates to a hub or the like coupled or for coupling to a shaft, and particularly but not exclusively where the shaft and hub have no keyways. The locking of a plane cylindrical shaft to a hub or other body having a cylindrical bore for receiving the shaft therein, hereinafter in this specification likewise referred to for simplicity as a hub, so as to prevent relative angular or axial movement, such as is required for example in a rotary pump given by rotation of a shaft, presents serious problems, if the bore of the hub is of diameter sufficiently greater than that of the shaft to facilitate assembly and subsequent disassembly, and it is the object of the invention to provide means whereby those problems may be solved in a simple and inexpensive manner. According to the invention there is provided a hub having a cylindrical bore for receiving a cylindrical shaft therein, said hub comprising a first portion defining part of the inner surface of the bore and capable of displacement relative to another portion radially inwardly of the bore by elastic deformation, and means for effecting said relative displacement. Preferably the dispalceable first portion is provided by forming a slot in the hub spaced from and parallel to a tangent to the inner surface of the bore. The displacement effecting means is preferably reversible and may comprise at least one screw means threadedly engaged in said other portion. Where the bore extends from one to the other of both faces of the hub, the slot preferably also extends from one to the other of said faces. The invention will be further described by way of example and with reference to the accompanying drawings of which Fig. 1 is a side view of a hub according to the invention mounted on a shaft; Fig. 2 is a section along lines li-Il of Fig. 1; and Fig. 3 is a detail of a portion of an alternative embodiment. In the figures hub 2 is provided with a central bore 4 for receiving a shaft 6. Whilst the diameter of the bore 4 must be greater than the external diameter of the shaft 6 for ease of assembly, the tolerance shown in the figure is exaggerated for purposes of illustration. A slot 8 is cut through the thickness of the hub 2 parallel to and spaced from the tangent to the bore at point A. Thus, between the slot and the bore there is left a bridge-like portion 10 against which a set screw 12, thread engaged in bore 14, may be urged. In use of the hub, the screw 1 2 is screwed within the threaded bore 14 so as to engage the bridge portion 10 and displace it as shown by dotted lines in Fig. 1. Provided that the displacement is kept within the elastic limit of the material of the hub 2, the original position of the bridge portion 10 will be recovered on subsequent removal of the screw 12.The displacement of the bridge portion 10 effectively reduces the width of the bore at point 8, and although in the Figure the distortion is not sufficient to engage with shaft 6, in practice the diameter tolerance of the shaft and bore is such that the inward displacement of the bridge portion 10 is sufficient to take up the slackness between shaft and bore and bind the shaft against the internal surfaces of the bore at point A and, by reactionary forces, at the diametrically opposed point. Whilst in Fig. 1 the slot 8 is shown as being parallel sided with rounded ends, a preferred section is shown in Fig. 3 and takes the form of a central portion with parallel sides spaced by a distance d, the portion terminating at each side in bores of diameter D where D is greater than d. With this arrangement there are formed articulating points B about which the bridge portion 10 is able to be displaced by elastic deformation. Whilst the invention is applicable to shafts without splines, it is nevertheless possible, if required, to incorporate a spline between the hub and the shaft in a keyway located, for example, diametrical opposite point A. CLAIMS

1. A hub or the like having a cylindrical bore for receiving a cylindrical shaft therein, said hub comprising a first portion defining part of the inner surface of the bore and capable of displacement relative to another portion radially inwardly of the bore by elastic deformation, and means for effecting said relative displacement.

2. A hub or the like according to Claim 1 wherein the first portion is caused to be displaceable relative to the other portion by forming an axially extending cavity in the hub spaced from the bore.

3. A hub or the like according to Claim 2 wherein the cavity is generally in the form of a slot parallel to the tangent to the part of the inner surface, of the bore defined by said first portion of the hub.

4. A hub or the like according to any preceding claim wherein the displacement effecting means comprise at least one screw means threadedly engaged in said other portion of the hub.

5. A hub or the like substantially as described with reference to the drawings.