Chuck with locking unit

A chuck for use with a manual or powered driver having a rotatable drive shaft is provided. The chuck includes a plurality of jaws slidably positioned in angularly disposed passageways in a body member. Each of the jaws has a jaw face formed on one side and threads formed on the other. A nut includes axially aligned threaded sections. Each of the sections is rotatably mounted on the body in engagement with the jaw threads. A generally cylindrical front sleeve member is in driving engagement with the nut whereby the jaws will be moved by the nut when the front sleeve member is rotated with respect to the body. The first section and the second section are rotated with respect to each other when the jaws are in a gripping engagement with a tool shaft.

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 may be tightened or 
loosened by hand or by actuation of the driver motor. 
Both hand tool drivers and electric or pneumatic tool drivers are well 
known. Although twist drills are the most common tools used with such 
drivers, screw drivers, nut drivers, burrs, mounted grinding stones and 
other cutting or abrading tools may also be used. Since the tools may have 
shanks of varying diameter or of polygonal cross section, the device is 
usually provided with a chuck that is adjustable over a relatively wide 
range. The chuck may be attached to the driver by a graded or tapered 
bore. 
A wide variety of chucks have been developed in the art. In the simplest 
form, three jaws spaced circumferentially approximately 120.degree. apart 
from each other are constrained by angularly disposed passageways in a 
body attached onto the drive shaft and configured so that rotation of the 
body in one direction relative to a constrained nut engaging the jaws 
forces the jaws into gripping relationship with respect to the cylindrical 
shank of the tool, 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. Pat. No. 5,125,673 
entitled "Non-impact Keyless Chuck" and commonly assigned to the present 
assignee, the entire disclosure of which is incorporated by reference 
herein. 
When such a chuck is tightened, the jaws eventually stop in a gripping 
relationship with a tool shaft, and the nut is then urged rearward by the 
jaw threads. Typically, the nut bears against the body, for example via a 
thrust ring or a bearing inserted between the nut and a thrust ring, when 
forced rearward. Further rotation of the nut wedges the nut between the 
jaw threads and the body, resisting further tightening rotation and 
bringing the chuck into a tightened condition. 
The wedged nut, which is generally maintained in its rotational position by 
friction, maintains the jaws in their gripping relation to the tool shaft. 
The tightened condition of the chuck, however, depends upon the 
maintenance of the axial forces between the tool shaft and the body 
through the jaws, the nut, and the bearing (if present). Use of the chuck, 
particularly in hammer drills, may cause vibrations which temporarily 
alter these forces and which may cause the nut to move in either 
rotational direction so that the chuck is undesirably tightened or 
loosened. 
SUMMARY OF THE INVENTION 
The present invention recognizes and addresses 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 a chuck that 
remains tightened while in use. 
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 
comprises a generally cylindrical body member having a nose section and a 
tail section. The tail section has an axial bore formed therein to mate 
with the drive shaft of the driver. The nose section has an axial bore 
formed therein and a plurality of angularly disposed passageways formed 
therethrough and intersecting the axial bore. A plurality of jaws are 
slidably positioned in each of the angularly disposed passageways. Each of 
the jaws has a jaw face formed on one side thereof and threads formed on 
the opposite side thereof. 
A nut includes axially aligned threaded sections. A first section is 
rotatably mounted on the body in engagement with the threads on the jaws. 
A second section is also rotatably mounted on the body in engagement with 
the threads on the jaws. A generally cylindrical front sleeve member is in 
driving engagement with the nut whereby the jaws will be moved by the nut 
when the front sleeve member is rotated with respect to the body member, 
and whereby the first section and the second section are rotated with 
respect to each other when the jaws are in a tightened gripping engagement 
with a tool shaft. 
These and other objects are also accomplished by providing a chuck for use 
with a manual or powered driver having a rotatable drive shaft. The chuck 
comprises a generally cylindrical body member having a nose section and a 
tail section. The tail section has an axial bore formed therein to mate 
with the drive shaft of the driver, and the nose section has an axial bore 
formed therein and a plurality of angularly disposed passageways formed 
therethrough and intersecting the axial bore. A plurality of jaws are 
slidably positioned in each of the angularly disposed passageways, each of 
the jaws having a jaw face formed on one side thereof and threads formed 
on the opposite side thereof. 
A nut includes axially aligned threaded annular sections. A first section 
is rotatably mounted on the body in engagement with the threads on the 
jaws. A second section is rotatably mounted on the body rearward of the 
first section with respect to the body in engagement with the threads on 
the jaws and in frictional engagement with the first section. A generally 
cylindrical front sleeve member is in driving engagement with the first 
section whereby the jaws will be moved by the nut when the front sleeve 
member is rotated with respect to the body member. A thrust ring is fixed 
on the body member axially rearward of the second section so that the 
second section bears upon the thrust ring when the jaws are in a tightened 
gripping engagement with a tool shaft. 
The relative rotation of the second section with respect to the first 
section causes the threads on the sections to mismatch and causes the two 
sections to push in opposite directions against the jaw threads, locking 
the sections to the jaws. The lock is substantially independent of the 
force applied to the nut by the tool shaft through the jaws or the force 
applied to the nut from the body, although these forces are used to put 
the sections into the locked conditions. Once in this position the lock 
will ordinarily be maintained until released by reverse rotation of the 
sleeve. 
Accordingly, the nut substantially maintains its position with respect to 
the jaws during typical vibrations experienced during use of the chuck. 
Thus, the chuck ordinarily does not undesirably loosen or tighten, and the 
gripping position of the jaws on the tool shaft is maintained. 
The accompanying drawings, which are incorporated in and constitute a part 
of this specification, illustrate two preferred embodiments of the 
invention and, together with the description, serve to explain the 
principles of the 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 the presently preferred embodiments 
of 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. In fact, it will be 
apparent to those skilled in the art that modifications and variations can 
be made in the present invention without departing from the scope or 
spirit thereof. For instance, features illustrated or described as part 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 
modifications and variations as come within the scope of the appended 
claims and their equivalents. 
Referring to FIGS. 1 and 2, a chuck 10 in accordance with the present 
invention is illustrated. Chuck 10 includes a front sleeve member 12, an 
optional rear sleeve member 14, a body member 16 and jaws 18. Body member 
16 is generally cylindrical in shape and comprises a nose or forward 
section 20 and a tail or rearward section 22. An axial bore 24 is formed 
in the nose section 20 of the body member 16. Axial bore 24 is somewhat 
larger than the largest tool shank that the chuck is designed to 
accommodate. A threaded bore 26 is formed in tail section 22 of body 16 
and is of a standard size to mate with the drive shaft of a powered or 
hand driver (not shown). The bores 24 and 26 may communicate at the 
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. 
Preferably, three jaws 18 are employed, and each jaw 18 is separated from 
the adjacent jaw by an arc of approximately 120.degree.. The axes of the 
passageways 30 and the jaws 18 are angled with respect to the chuck axis 
but intersect the chuck axis at a common point ahead of the chuck body 16. 
Each jaw 18 has a tool engaging face 32 which is generally parallel to the 
axis of chuck body 16 and threads 34 on its opposite or outer surface. 
Body member 16 includes a thrust ring 36 which is preferably integral with 
body 16. Thrust ring 36 incudes a thrust face 38 which may include an 
arcuate seating surface 40 for engagement with the inner race of a 
self-contained anti-friction bearing assembly 42. Thrust ring 36 includes 
a plurality of jaw guideways 50 formed around its circumference to permit 
retraction of the jaws 18. Of course, any thrust ring and/or bearing 
configuration could be utilized. 
Body member 16 includes a rear cylindrical portion 44 with a knurled 
surface 46 thereon for receipt of optional rear sleeve 14 to be pressed 
thereon if so desired. Body 16 further includes a first tapered portion 48 
extended from rear cylindrical portion 44 to thrust ring 36. A second 
tapered portion 51 extends from the area of the thrust face 38 to a front 
cylindrical portion 52. Front cylindrical portion 52 is of greater 
diameter than the smaller end of second tapered portion 51 and forms a 
first circumferential groove 54 intermediate the nose and tail sections 20 
and 22 of body 16. Body 16 further includes a reduced diameter nose 
portion 56 that is adapted to receive a nosepiece 58. 
A nut 60 includes threads 62 for mating with threads 34 on jaws 18 whereby 
when the nut is rotated with respect to the body, the jaws will be 
advanced or retracted. Nut 60 includes a front section 64 and a rear 
section 66 disposed axially behind front section 64 with respect to the 
body. Both front section 64 and rear section 66 are axially split into 
halves and are therefore adapted to receive a retaining band 68 to assist 
in maintaining nut 60 together after assembly. It should be appreciated 
that sleeve 12 could be utilized to maintain nut 60 together without a 
band. In another preferred embodiment as shown in FIG. 3, each section 64 
and 66 is unitarily constructed, and no retaining band is utilized. 
Various suitable chuck constructions may be employed to accommodate the 
unitary sections. 
Referring again to FIGS. 1 and 2, front section 64 includes drive slots 70 
for mating with drive ribs 73 on front sleeve 12 so that when front sleeve 
12 is rotated, front section 64 rotates with the sleeve and moves jaws 18. 
In another preferred embodiment, the front sleeve may be press fit to the 
front section. 
The threads of, and the interface between, front section 64 and rear 
section 66 may be lubricated with a suitable lubricant, for example 
molybdenum disulfide grease. Despite the lubricant, a frictional interface 
exists between front section 64 and rear section 66 so that rear section 
66 turns with front section 64 as front sleeve 12 is rotated in the 
tightening direction. 
When jaws 18 reach a closed position, for example against a tool shaft, 
their movement in a forward direction is resisted. Continued rotation of 
nut 60 creates a rearward force from the jaws through the threads of front 
section 64 and rear section 66 to thrust ring 36 via bearing assembly 42. 
At this point, friction between the threads of rear section 66 and the jaw 
threads overcomes the friction between rear section 66 and front section 
64 and stops rotation of rear section 66 with respect to body 16. 
Thereafter, when front section 64 is further rotated to its fully tightened 
position, front section 64 applies a rearward force to rear section 66, 
causing the threads of rear section 66 to bear against front faces 72 of 
jaw threads 34. The threads of front section 64, which are now mismatched 
with respect to the threads of rear section 66, bear against rear faces 74 
of jaw threads 34. Front section 64 and rear section 66 bear against each 
other at their interface in opposition to these forces. The mismatched 
threads thus tend to lock front section 64 and rear section 66 to the 
jaws, thereby substantially preventing movement of nut 60 with respect to 
the jaws that could cause undesirable tightening or loosening of the chuck 
during use. 
To release the locked nut, sleeve 12 is rotated in the loosening direction. 
This brings the threads of front section 64 and rear section 66 back into 
alignment and releases the lock. Although front section 64 is urged away 
from rear section 66 as it rotates in the loosening direction, sufficient 
friction typically exists to rotate rear section 66 with front section 64. 
In this way, the chuck may be opened. 
Contaminants may, however, inhibit the rotation of the rear section when 
the chuck is turned in the releasing direction. Accordingly, mechanisms 
may be provided to apply torque directly from the sleeve to both the front 
section and the rear section. This aids in both tightening and loosening. 
Additionally, the front section may cooperate with the rear section so 
that the front section catches the rear section as the front section 
rotates back in a releasing direction when the front section threads and 
the rear section threads become aligned. 
In a preferred embodiment, a self-contained bearing assembly 42 is adapted 
to be placed between thrust ring 36 and end face 76 of rear section 66. 
Self-contained bearing assembly 42 includes an inner race 78, an outer 
race 80 and bearing elements 82 maintained therebetween. In a preferred 
embodiment, bearing elements 82 are ball bearings. Self-contained bearing 
assembly 42 may further include a shroud 84 surrounding the inner and 
outer races 78 and 80 for maintaining the bearing assembly as a 
self-contained component. Inner race 78 may include an arcuate surface 
that is dimensioned and configured to mate with arcuate seating surface 40 
on thrust face 38 of thrust ring 36. Such mating relationship assists in 
alignment and minimization of stresses when the chuck is operated. In one 
preferred embodiment, self-contained bearing assembly 42 may be a radial 
thrust bearing. 
Use of a self-contained bearing assembly simplifies assembly in that 
individual ball bearings and cages do not have to be handled. In addition, 
the body and nut are not required to be as hard or dense as is necessary 
with conventional bearing systems where the body or nut may also serve as 
a thrust race, thus allowing more flexibility in materials and reducing 
secondary manufacturing operations and, ultimately, cost. 
Front sleeve 12 is adapted to be loosely fitted over nose section 20 of 
chuck 10. Drive ribs 73 of front sleeve 12 engage drive slots 70 of front 
section 64 so that front sleeve 12 and front section 64 will be 
operatively connected. That is, when front sleeve 12 is rotated, front 
section 64 will rotate therewith. Front sleeve 12 includes an annular 
ledge portion 86 adapted to rest at the interface of front cylindrical 
portion 52 and nose portion 56. Nosepiece 58 is dimensioned and adapted to 
be pressed onto nose portion 56 to maintain front sleeve 12 on chuck 10. 
It should be appreciated that nosepiece 58 could also be secured by snap 
fit, threading or the like. Nosepiece 58 is exposed when the chuck is 
assembled and is preferably coated with a non-ferrous metallic coating to 
prevent rust and to enhance its appearance. While such coating may be, for 
example, zinc or nickel, it should be appreciated that any suitable 
coating could be utilized. 
The operation of a nosepiece such as nosepiece 58 is disclosed in U.S. Pat. 
No. 5,348,317, the disclosure of which is fully incorporated herein by 
reference. 
While the above description is set forth with respect to a keyless chuck, 
it should be appreciated that the principles of the present invention are 
equally applicable to a keyed chuck. Furthermore, it should be understood 
that various suitable chuck constructions could be employed. For example, 
the bearing may be omitted so that the rear section 66 bears directly on 
the body in some fashion. Furthermore, the chuck may be constructed so 
that the front sleeve drives the rear nut section and so that the rear nut 
section drives the front nut section by the frictional interface between 
the sections. 
Accordingly, while preferred embodiments of the invention have been 
described above, it is to be understood that any and all equivalent 
realizations of the present invention are included within the scope and 
spirit thereof. Thus, the embodiments depicted are presented by way of 
example only and are not intended as limitations upon the present 
invention, and those of ordinary skill is this art should understand that 
many modifications may be made. 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.