GB2373745A

GB2373745A - Chuck With Locking Sleeve

Info

Publication number: GB2373745A
Application number: GB0214393A
Authority: GB
Inventors: J Larry Wilson
Original assignee: Power Tool Holders Inc
Current assignee: Power Tool Holders Inc
Priority date: 1998-08-14
Filing date: 1999-07-08
Publication date: 2002-10-02
Anticipated expiration: 2019-07-08
Also published as: GB2373745B; GB0214393D0

Abstract

A chuck includes a generally cylindrical body 16 member having a forward section 20 and a rearward section 22. The rearward section is configured to mate with a manual or powered driver. A plurality of angularly disposed passageways 30 is formed in the forward section of the body and intersect an axial bore 24 formed therein. The body defines a ledge portion 62 about its outer circumference and a front face 21 transverse to the longitudinal body axis. One of a plurality of jaws 18 is slidably positioned in each passageway. A nut 48 is rotatably mounted to the body rearward of the ledge portion so as to engage the jaws. A generally cylindrical sleeve 12 engages the nut and includes a flexible protrusion 58 extending axially rearward from an inner circumferential surface of the sleeve proximate the sleeve forward end. The protrusion has a tab portion 60 disposed rearward of the ledge portion 62 and projecting radially inward of the outer circumference of the ledge portion to prevent forward axial movement of the sleeve with respect to the body.

Description

CHUCK WITH LOCKING SLEEVE Background of the Invention The present invention relates generally to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present

invention relates to a chuck of the keyless type which p e wl,-i c may be tightened or loosened by hand or by accusation of the driver motor.

Both hand and electric or pneumatic tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools.

Since the tool shanks may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore.

A variety of chucks have been developed in the art. In an oblique jawed chuck, a body member includes three passageways disposed approximately 1200 apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis forward of the chuck. The passageways constrain three jaws which are movable in the passageways to grip a cylindrical tool shank displaced approximately along the chuck center axis. The chuck includes a nut which rotates about the chuck center and which engages threads on the jaws so that rotation of the nut moves the jaws in either direction within the passageways. The body is attached ono the drive shaft of a driver and is configured so that rotation

of the body in one direction with respect to the nut forces the jaws inca gripplng relatlonship with the tool shank, while rotation in the opposite direction releases the gripping relationship. Such a chuck may be keyless if it is rotated by hand. One example of such a chuck is disclosed in U. S. Patent No. 5, 125, 673 entitled"Non-impact Keyless Chuck,"commonly assigned to the present assignee and the entire disclosure of which is incorporated by reference herein. Various configurations of key-ess chucks are known in the arc : and are desirable for a variety of applications.

Summary of the Invention The present invention recognizes and addresses

ConS 4 the foregoing considerations, and others, of prior art constructions and methods.

Accordingly, it is an object of the present invention to provide an improved chuck.

It is another object of the present invention to provide an improved mechanism for attaching the sleeve to the chuck.

These and other objects are achieved by providing a chuck for use with a manual or powered driver having a rotatable drive shaft. The chuck has a generally cylindrical body member with a forward section and a rearward section. The rearward section is configured to mate with the driver. The forward section has an axial bore formed therein and a plurality of angularly disposed passageways formed therethrough and intersecting the axial bore. The forward section also defines a ledge portion about its outer circumference and a front face transverse to the longitudinal axis of the body. A plurality of jaws are slidably positioned in each of the angularly disposed

passageways. Each jaw has a jaw face formed on one side and threads formed on the other. A nut is rotaably mounted to the body rearward of the ledge so as to engage the aw threads. A generally cylindrical sleevehasanannularopenforwardendandisreceived over the forward section of the body. The sleeve engages the nut so that when the sleeve is rotated, the nut will be rotated therewith to operate the jaws.

The sleeve's forward end includes an annular lip portion extending radially inward therefrom and at

leas partially covering the body's froni transverse face. The sleeve includes a flexible protrusion extending axially rearward from the inner circumference of the sleeve proximate the sleeve forward end. The protrusion includes a tab portion disposed rearward of the ledge portion and projecting radially inward of the outer circumference of the ledge portion to prevent forward axial movement of the sleeve with respect to the chuck body.

In one preferred embodiment, the forward end of the ccdy is tapered so that the body's outer diameter gradally increases rearwardly from the front face.

When the sleeve is mounted onto the body, the tab bears against the tapered surface so that the protrusion deflects radially outward. The tab eventually snaps into the groove.

The sleeve may further include drive ribs that engage drive rib receiving slots on the nut. When the sleeve is rotated with respect to the body, the nut is rotated therewith. Therefore, rotation of the sleeve member actuates movement of the chuck jaws in either

the forward or rearward direction depending on the direction of sleeve rotation.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invent-on.

Brief Description of the Drawings A full and enabling disclosure of the present invention, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the accompanying figures, in which: Figure 1 is a longitudinal view, partly in section, of a chuck in accordance with an embodiment of the present invention ; Figure 2 is an exploded view, partly in section, of a chuck in accordance with the embodiment as in Figure 1; and Figure 3 is an exploded view, partly in section, of a chuck in accordance with an embodiment of the present invention.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

Detailed Description of Preferred Embodiments Reference will now be made in detail to presently preferred embodiments to the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not limitation of the

invention.Infact, it : will be apparent to those facz, i 4 skilled in the ar- that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, . Z-Fcr i----szance, features illustrated or described as par- : of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modification and variations as come within the scope of the appended

claims and their equivalents.

A chuck 10 in accordance with the pressent invention is illustrated in Figures 1 and 2. Chuck 10 includes a sleeve 12, a body 16 and jaws 13. Body 16 is generally cylindrical in shape and comprises a nose

or forward section 20 and a tail or rearward section r L 22. Nose section 20 has a front face 21 transverse to the longitudinal axis 25 of body 16 and a tapered surface 23 at its forward end. An axial bore 24 is formed in the nose section. Axial bore 24 is dimensioned somewhat larger than the largest tool shank that the chuck is designed to accommodate. A threaded. bore 26 is formed in tail section 22 and is of a standard size to mate with the drive shaft of a powered or hand driver (not shown). The bores 24,26 may communicate at a central region 28 of body member 16. While a threaded bore 26 is illustrated, such bore could be replaced with a tapered bore of a standard size to mate with a tapered drive shaft.

Passageways 30 are formed in body member 16 to accommodate each jaw 18. Three jaws 18 are employed, and each jaw is separated from the adjacent jaw by an

arc of. ipproximaely. l20 . The axes of the passageways 33 and the jaws 18 are angled with respect to the chuck axis and intersect the chuck axis a* : a common point ahead of the chuck body 16. Each jaw 1 has a tool engaging face 32, which is generally parallel ro r : he axis of the chuck body 16, and threads 34 on its opposite or outer surface. Threads 34 may be constructed in any suitable type and pitch.

As illustrated in Figures 1 and 2, body member 16 includes a thrush ring member 36 which, in a preferred embodiment, may be integral with the bod, i. In an alternate embodiment, thrust ring 36 and body 16 may y be separate components. Thrust ring 36 includes a plurality of jaw guideways 42 formed around its circum erence to permn renraccicn of he jaws 18 therehrough and may also include a ledge portion 38 to receive a bearing assembly 39.

In the exemplary embodiment illustrated in Figures 1 and 2, body member 16 includes a rear cylindrical portion 22 with a knurled surface 46 for receipt of an optional rear sleeve 14 to be pressed thereon if so desired. It should be appreciated that rear sleeve 14 could also be retained in place by press fi- : without knurling, or by use of a key. It could also be retained in place by crimping, staking, riveting, threading, or any other suitable securing mechanism. Further, the chuck may be constructed with a single sleeve having no rear sleeve.

Chuck 10 includes a nui 48 hat, in a preferred embodiment, is a one piece nui and tha includes threads 50 for mating wi h zhreacs 34 on jaws 18. Nut

48 is positioned about the body in engagement with the jaw threads so when the is rotated with respect to body 16, the jaws will be advanced or retracted depending on the nut's rotational direction.

Nut 48 may include slots 52 to receive drive ribs 54 so that nut 48 rotates with sleeve 12 no move the jaws.

In the illustrated embodiment, axial movement of nut 48 in the forward direction is prevented by a -iular retaining ring 56. Retaining ring 56 is an annular cone having a cylindrical front section pressed onto front section 20 of body 16 and a frustoconical sec ion expending rearward from the cylindrical section to engage nut 48 at 5'. It should be understood, however, that other methods of axially securing the nut on the body may be used. For example, the nut may be a two-piece nui held on the body within a circumferential groove.

The outer circumferential surface of sleeve 12 may be knurled or may be provided with longitudinal ribs or other protrusions to enable the operator to grip it securely. In like manner, the circumferential surface of a rear sleeve 14, if employed, may be knurled or ribbed if desired.

As shown in Figures 1 and 2, an annular lip 64 extends from the forward end of sleeve 12 radially inward from an outer diameter 33 to an inner diameter 35. Lip 64 covers front transverse face 21 of body 16. A metal nose portion 68 is co-molded with front sleeve 12 and covers the forward section of sleeve 12 and annular lip 64.

T''i. e front and rear sleeves may be molded or r 4 otherwise fabricated from a structural plastic such as polycarbonate, a filled polypropylene, for example glass filled polypropylene, or a blend of structural plastic materials. Other composite materials such as, for example, graphite filled polymerics would also be suitable in certain environments. As should be appreciated by one skilled in the art, the materials for which the chuck of the present invention is fabricated will depend on the end use of the chuck, and the above materials are provided by way of example only.

As indicated above, rear sleeve 14 is secured to body 16 by the press fit at 46. Front sleeve 12, however, is secured from movement in the forward axial direction by a snap-on engagement between the sleeve and the body provided by protrusions 58. protrusions 58 expend axially rearward from an inner circumferential surface of sleeve 12 proximate its forward end. Tabs 60 are disposed at the axially rearward ends of protrusions 58 and project inward of the outer circumference of a groove 62 in the body.

At the chuck's assembly, tabs 60 bear against tapered surface 23 so that further rearward movement of sleeve 12 with respect to body 16 causes the protrusions to outwardly deflect. Upon moving the sleeve far enough back, however, the tabs snap down into groove 62. Groove 62 forms a ledge 63 which opposes tabs 60, thereby preventing significant forward axial movement of sleeve 12. Though front sleeve 12 may move slightly in the forward direction

with respect to bodylc, engagement of tabs 60 with ledge 63 prevents sleeve 12 from disengaging nut 48. The protrusions should be made of appropriate materials and in such dimensions that they will

deflecr. oucwardly during assembly ye resist forward axial pressures on the sleeve. For example, in one embodiment, the sleeve and the protrusions are made from glass-filled (40%) nylon. Each protrusion is 0.129 inches long (including the tab) and 0.036 inches thick approximately midway along the length of the tab. The inner diameter of the protrusions is constant between the main sleeve and the tab at 0.732 inches. The outer circumference of each protrusion rises (with respect to the chuck axis) at about So from the tab end to the main sleeve. It should be understood, however, khat thus is only one example and that the construction of a particular chuck may suitably vary.- Ledge 63 may be constructed in any suitable configuration. For example, the ledge may be formed in a series of spaced-apart sections so that it does not extend continuously around the body. In addition, it is not necessary that the ledge and body be unitarily constructed. The ledge may comprise a snap ring received in a suitable circumferential groove.

Other constructions of protrusions 58 are also possible. For example, the protrusions may be relatively narrow finger-like projections as shown in Figure 2 but may also comprise angularly wider projections, as in Figure 3, that form an annular ring about the chuck axis. The ring in Figure 3 is

interrupted by four equiangularly spaced gaps 59.

It should be appreciated that rear sleeve member 14 is fixed to body 16, while front sleeve member 12 is operatively associated wi-h nut 48 and axially secured with respect to the body to permit rotation with respect. to the body. Due to the interaction between threads 34 on jaws 18 and threads 50 on nut 48, relative movement of the front and rear sleeve members 12 and 14 causes Jaws 18 to be advanced or

retracted, depending upon the direction of relative movement.

While one or more preferred embodiments of the present invention has been described above, it should be understood that any and all equivalent realizations of the present invention are included within the scope and spirit thereof. The depicted embodiments are presented by way of example only and are not intended as limitations on the present invention. It should be understood that aspects of the various one or more embodiments may be interchanged both in whole or in pari. Therefore, it is contemplated that any and all such embodiments are included in the present invention as may fall within the literal or equivalent scope of the appended claims.

Claims

Claims

1. A chuck for use with a manual or powered driver having a rotatable drive shaft, said chuck comprising: a generally cylindrical body, said body having a forward section and a rearward section, said rearward section being configured to rotate with the drive shaft and said forward section having an axial bore formed therein, a plurality of angularly disposed passageways formed therethrough and intersecting said axial bore, a ledge portion defining an outer circumference of said body forward section; a thrust bearing ring fixed on said body axially rearward of said ledge portion; a plurality of jaws, one of said jaws slidably positioned in each of said angularly disposed passageways, wherein each said jaw has a jaw face formed on one side and threads formed on the opposite side thereof ; a nut rotatably mounted to said body rearward of said ledge portion so as to engage said jaw threads, wherein said nut operatively engages said thrust bearing ring and said thrust bearing ring transfers rearward axial force from said nut to said body; a generally cylindrical sleeve having an annular open forward end, said sleeve being received over said body rearward

section and engaging said nut so that when said sleeve is rotated with respect to said body said nut rotates therewith, said sleeve including a plurality of flexible protrusions extending axially rearward from an inner circumferential surface of said sleeve proximate said sleeve forward end, each said protrusion defining a tab portion disposed rearward of said ledge portion and projecting radially inward of said ledge portion to hold said sleeve against movement in the axially forward direction with respect to said body; and a rear sleeve disposed about said body rearward section, said rear sleeve extending at least partially axially forward of an axially rearward end of said sleeve.

2. The chuck as in claim 1, wherein said ledge portion forms a continuous annular ledge.

3. The chuck as in claim 2, wherein said annular ledge and said body are of a unitary construction.

4. The chuck as in claim 1, wherein said thrust bearing ring and said body are of a unitary construction.

5. The chuck as in claim 1, wherein said rear sleeve includes an inner circumferential surface that extends at least partially axially forward of an axially rearward end of said sleeve.

6. The chuck as in claim 1, wherein said rear sleeve surface forms a continuous circular surface.

7. The chuck as in claim 1, wherein said rear sleeve is press fit to said body rearward section so that said rear sleeve is axially and rotationally fixed to said body.

8. The chuck as in claim 1, wherein said nut is a one piece nut.

9. The chuck as in claim 1, including at least one antifriction bearing disposed between said nut and said thrust ring.

10. The chuck as in claim 7, wherein said rear sleeve including an outer circumferential surface defining a longitudinally ribbed gripping surface thereon.

11. The chuck as in claim 1, including a nut retaining mechanism pressed onto said body forward section and in communication with said nut to operatively prevent axial movement of said nut in the forward axial direction.

12. The chuck as in claim 11, wherein said nut retaining mechanism is pressed on to a second outer circumferential surface of said body defined on said body forward section axially rearward of said ledge portion, wherein said second outer circumferential surface defines a diameter greater than a diameter of said ledge portion outer circumference.

13. A chuck for use with a manual or powered driver having a rotatable drive shaft, said chuck comprising : a generally cylindrical body having a forward section and a rearward section, said rearward section being configured to rotate with the drive shaft of the driver and said forward section having an axial bore formed therein; a plurality of angularly disposed passageways formed within said body and intersecting said axial bore; and a ledge portion defined about the outer circumference of said forward section, said ledge portion forming a continuous annular ledge; a plurality of jaws, one of said jaws slidably positioned within each of said passageways, each of said jaws having a jaw face formed on one side thereof and threads formed on the opposite side thereof ; a nut rotatably mounted to said body rearward of said ledge portion so as to engage said jaw threads, said nut having a plurality of slots located in an axially forward edge of said nut; a nut retaining mechanism on said body and in communication with said nut to operatively prevent axial movement of said nut in the forward direction; and a generally cylindrical first sleeve, said first sleeve having an annular open forward end; a plurality of ribs disposed on the inner circumferential surface of said first sleeve reward of said annular open forward end, each of said ribs engaging a corresponding slot in said nut so as rotationally lock said nut to said first sleeve; and a plurality of flexible protrusions extending axially rearward from said inner circumferential surface of said first sleeve proximate said first sleeve forward end, each said protrusion defining a tab portion disposed rearward of said ledge portion and projecting radially inward of said ledge portion to hold said first sleeve against movement in the axially forward direction with respect to said body,

wherein said first sleeve is received over the forward section of said body so that rotation of said first sleeve causes said jaws to move towards or away from said axial bore depending on the direction of rotation of said first sleeve.

14. The chuck as in claims, wherein said annular ledge and said body are of a unitary construction.

Is The chuck as in claim3, wherein said annular lip has an inner and an outer diameter, said inner diameter being equal to said axial bore diameter formed in said forward section of said body. lb. The chuck as in claim 13, including a plurality of said protrusions forming an annular ring about said axis of said body.

1 9. The chuck as in claim \6, including four said protrusions separated by equiangularly spaced gaps. g. The chuck as in claim3, wherein said nut is a one-piece nut. iel The chuck as in claims, including a thrust ring located on said body in communication with said nut to transfer rearward axial force from said nut to said body.

20 The chuck as in claim 19, including at least one anti-friction bearing disposed between said nut and said thrust ring.

'3J. The chuck as in claim t), including a second sleeve received on the rearward section of said body, said second sleeve extending partially axially forward of an axially rearward end of said first sleeve.

'2. 1.. The chuck as is claim 11, including a decorative metal nose portion co-molded with a forward section of said first sleeve.

23 The chuck as in claim lez wherein the forward end of said body is tapered.

aLt. A chuck for use with a manual or powered driver having a rotatable drive shaft, said chuck comprising : a generally cylindrical body member, said body member having a forward section and a rearward section, said rearward section being configured to mate with said driver and said forward section having an axial bore formed therein, a plurality of angularly disposed passageways formed therethrough and intersecting said axial bore, a ledge portion defined about the outer circumference thereof, and a front face transverse to the longitudinal axis of said body; one of a plurality of aws slidably positioned in each of said angularly disposed passageways, each of said jaws having a jaw face formed on one side thereof and threads formed on the opposite side thereof; a nut rotatably mounted to said body rearward of said ledge portion so as to engage said jaw threads; and a generally cylindrical sleeve having an annular open forward end, said sleeve being received over the forward section of said body and engaging said nut so. that when said sleeve is rotated, said nut-will be rotated therewith to operate said jaws, said forward end of said sleeve including an annular lip portion extending radially inward therefrom and at least partially covering said front transverse face of said body, wherein said sleeve includes a flexible protrusion extending axially rearward from an inner

circumferential surface of said sleeve proximate said sleeve forward end, said protrusion having a tab portion disposed rearward of said ledge portion and projecting radially inward of the outer circumference of said ledge, poriion to prevent forward axial movement of said sleeve with respect to said body.

The chuck as in claim24, wherein said ledge portion forms a continuous annular ledge.

24 ; The chuck as in claimT- ! *, wherein said annular ledge and said body are of a unirary construction.

;. The chuck as in claim24, wherein said annular lip has an inner and an outer diameter, said inner diameter being equal to said axial core diameter formed in said forward section of said body.

28 . The chuck as in claim 24, including a plurality of said protrusions forming an annular ring

aboli, said axis of said body.

29. The chuck as in claimT. , including four said protrusions separated by equiangularly spaced gaps. zu The chuck as in claim4 wherein said nut is a one piece nut.

31 . The chuck as in claim 24, including a thrust ring located on said body in communication with said nut to transfer rearward axial force from said nut to said body.

32 . The chuck as in claim31, including at least one anti-friction bearing disposed between said nur and said thrust ring. dz The chuck as in claim including a rear sleeve received on the rearward section of said body.

34 . The chuck as is claim 24, including a

decorative metal nose portion co-molded with a forward section of said sleeve.

The chuck as in caim24, including a nut retaining mechanism on said body and in communication with said nut to operatively prevent axial movement of said nut in the forward direction. zu The chuck as in claim24, wherein the forward end of said body is tapered.

37 . A chuck for use with a manual or powered driver having a rotatable drive shaft, said chuck comprising: a generally cylindrical body member, said body member having a forward section and a rearward section, said rearward section being configured to mate with said driver and said forward section having an axial bore formed therein, a plurality of angularly disposed passageways formed therethrough and intersecting said axial bore, an annular-ledge portion defined about the outer circumference thereof, and a front face transverse to the longitudinal axis of said body; one of a plurality of jaws slidably positioned in each of said angularly disposed passageways, each of

said jaws having a jaw face formed on one side thereof and threads formed on the opposite side thereof; a nut rotatably mounted to said body rearward of said ledge portion so as to engage said jaw threads; a generally cylindrical sleeve having an annular open forward end, said sleeve being received over the forward section of said body and engaging said nut so that when said sleeve is rotated, said nut will be

rotated therewith to. operate said jaws, said forward end of said sleeve including an annular lip portion extending radially inward therefrom and at least partially covering said fron transverse face of said body, wherein said sleeve includes a plurality of flexible protrusions extending axially rearward from an inner circumferential surface of said sleeve proximate said sleeve forward end, each said protrusion having a tab portion disposed rearward of said ledge portion and projecting radially inward of the outer circumference of said ledge portion to prevent forward axial movement of said sleeve with respect to said body; and a thrust ring located on said body in

W4 communication with said nut to transfer rearward axial force from said nut c : said body.

3. The chuck as in claim 3, including a decorative metal nose portion co-molded with a forward section of said sleeve.

The chuck as in claim 3S, including at leas, including at least one anti-friction bearing disposed between said nut and said thrust ring.

40. The chuck as in claim 37, wherein-said nut is a one piece nut.

41. The chuck as in claim 37, including a nut retaining mechanism on said body and in communication with said nut to operatively prevent axial movement of said nut in the forward direction.

42 . A chuck for use wiih a manual or powered driver having a rotatable drive shaft, said chuck

comprising : a generally cylindrical body member, said body a gener :- member having a forward section and a rearward section, said rearward section being configured to

mate with said driver and said forward section having an axial bore formed therein, a plurality of angularly disposed passageways formed therethrough and intersecting said axial bore, an annular groove defined abou the outer circumference of said forward section of said body, and a front face transverse to the longitudinal axis of said body ; one of a plurality of jaws slidably positioned in

4 eacn of said angularly disposed passageways, each of said jaws having a jaw face formed on one side thereof and threads formed on the opposite side thereof ; a one-piece nut rotatably mounted to said body rearward of said annular groove so as to engage said jaw threads ; a generally cylindrical sleeve having an annular open forward end, said sleeve being received over the forward section of said body and engaging said nut so thai when said sleeve is rotated, said nut will be rotated therewith to operate said jaws, said forward end of said sleeve including an annular lip. portion extending radially inward therefrom and at least partially covering said front transverse face of said body, wherein said sleeve includes a plurality of flexible protrusions extending axially rearward from

an inner circumferential surface of said sleeve L proximate said sleeve forward end, each said

protrusion having a tab portion projecting radially inward of the outrer circumference of said groove to prevent forward axial movement of said sleeve with respect to said body; a thrush ring in communication with said nut to transfer rearward axial force from said nur : to said body; a bearing disposed between said nut and said thrust ring; a rear sleeve received on the rearward section of said body; a decorative metal nose portion co-molded with a forward section of said sleeve; and a nut retaining mechanism on said body, said nui retaining mechanism including a first substantially cylindrical portion press fitted onto said body member and a second frustoconical portion in communication with said nut to transfer rearward axial force from said nut to said body.

L,, 3 The chuck as in claim 1, wherein said sleeve includes drive ribs and said nut includes drive rib receiving portions receiving said drive ribs so that said sleeve rotationally drives said nut through said drive ribs.

t. r-. The chuck as in claim 14, wherein said frustoconical portion of said nut retaining mechanism bears on said nut.