Chuck operating device for hand drill

The drill includes the usual tool spindle driven by reversible motor, and conventional chucking jaws which rotate with the spindle. The jaws are surrounded by an actuator which is drivingly connected to the jaws, and normally rotates with the jaws when the drill is in use. A manually operable control member on the housing is movable between two operating positions in each of which it holds the actuator against rotation, and consequently causes the spindle to move the jaws to bit-locking or bit-releasing positions, depending upon the direction or rotation of the spindle. Whenever the control member is moved from one to the other of its positions it switches the direction of rotation of the motor. A projection on the control member is releasably engagable selectively in a matching recess in the actuator to impart static loading to the jaws during movement thereof to their bit-locking positions, or in a larger recess in the actuator to impart dynamic loading to the chucking jaws during movement thereof to bit-releasing positions. Safety means is provided for preventing accidental movement of the control member from one to the other of its positions during use of the drill.

This invention relates to electrically operated hand drills, and more 
particularly to a novel device for utilizing the motor of a hand drill for 
operating its chucking jaws. 
With current manufacturing techniques it has been possible to mass produce 
small electrical hand drills. Typically these drills include two-speed 
fractional horsepower electrical motors that are designed to be operated 
on 115 volt household circuits, and the like. Drills of this type are 
usually designed to have the associated drill bit secured in the unit by a 
manually-operated chuck. The jaws of such chuck are reciprocated by a 
small hand wrench which has a head shaped like a bevel gear, and which 
engages simultaneously in a radial hole in the drill spindle and in the 
teeth of a jaw-operating gear which is rotatable on the spindle. 
An obvious disadvantage of this type of construction is that the 
specially-shaped hand wrench is frequently mislaid or lost, thus rendering 
the drill, in essence, useless until the wrench has been replaced. Still 
another disadvantage of this type of mechanism is that whether or not the 
drill bit is securely locked in the chuck depends to a great extent upon 
the strength of the operator. 
In order to obviate the above-noted disadvantages efforts have been made to 
provide a mechanism which utilizes the power of the electric motor of the 
hand drill for operating its chucking jaws. One such mechanism is 
disclosed in the Rowe U.S. Pat. No. 2,716,555, wherein a chuck-operating 
sleeve, which normally rotates with the drill spindle, can be prevented 
from rotating with the spindle by pushing a manually-operated chucking 
button radially inwardly of the drill housing to engage a lug which 
projects from the chuck-operating sleeve. Engagement of the chucking 
button with the lug prevents the sleeve from rotating with the drill 
spindle. As a consequence the chucking sleeve is shifted axially of the 
spindle either forwardly or in a reverse direction, respectively to 
release or to secure a bit in the associated chucking jaws. 
The disadvantage of this construction, however, is that the operator can 
never be sure of the relative positions as between the chucking button, 
when it is pushed, and the lug on the operating sleeve, which is to be 
engaged by the button. In other words, it is possible that the lug will be 
in the way of the button and will prevent its operation, or alternatively, 
the lug may be out of alignment with the button at the time the latter is 
operated and will be rotated suddenly or with impact into engagement with 
the button as soon as the drill motor is started. Therefore, there can be 
no assurance as to whether or not there will or will not be any impact 
loading as between the chucking button and the lug on the chuck-operating 
sleeve. 
It is an object of this invention, therefore, to provide an improved chuck 
operating device of the type described which eliminates any guessing, and 
assures that whenever a chuck operating mechanism for drills of the type 
described is operated, the force with which the chucking jaws are opened 
and closed can be predicted with certainty. 
Another object of this invention is to provide an improved chucking device 
of the type described which is specifically designed to provide impact 
loading of the chucking jaws during the release thereof, and to provide 
static loading of the jaws during the movement thereof to their 
bit-engaging positions. 
Still another object of this invention is to provide an improved chuck 
operating device of the type described which incorporates safety devices 
which prevent any accidental operation of the chuck operating mechanism 
during normal operation of the drill. 
Other objects of this invention will be apparent hereinafter from the 
specification and from the recital of the appended claims, particularly 
when read in conjunction with the accompanying drawing.

Referring now to the drawing by numerals of reference, 10 denotes generally 
the housing of an electric hand drill having a chamber 11 containing an 
electric motor (not illustrated), the armature of which is drivingly 
connected to a shaft or spindle 13, which is journaled intermediate its 
ends in a bearing 14 that is secured in an opening in the front wall of 15 
of housing 10. Secured by a plurality of bolts 16 against a plane surface 
formed on the exterior of wall 15 are two annular members 18 and 19, which 
have identical internal and external diameters, respectfully. 
Shaft 13 extends axially through the bores in members 18 and 19, and is 
journaled in member 19 in a bearing which is similar to the bearing 14 in 
the housing wall 15. Threaded at its inner end onto an externally threaded 
shank 21 that is formed on the outer end of the shaft 13, and secured by a 
screw 22 against rotation relative to the shaft, is a tubular tool bit 
holder 23. Rotatably mounted in a conventional manner on the bit holder 23 
is a jaw actuating ring 25, which has an internally threaded bore 26 that 
is truncated-conical in configuration for a purpose noted hereinafter. The 
inner or left hand end of the ring 25, as shown in FIG. 1 is secured in 
the bore of an annular skirt or ring flange 28, which projects coaxially 
from one side of an annular operating disk 30, which surrounds the shaft 
13 in confronting coaxial relation to the outer end of the annular member 
19. The internally threaded bore 26 of the actuating ring 25 is drivingly 
engaged with the threaded outer edges 32 of each of a plurality of 
conventional chuck jaws 33, which are mounted in a conventional manner to 
reciprocate diagonally beneath flange 28, and into and out of bit engaging 
or bit gripping positions as noted in greater detail hereinafter. 
The direction of rotation of the motor which drives shaft 13 is controlled 
by a switch that is contained in a housing 41, which is secured against 
the outside of the housing wall 15 adjacent its lower edge, and which 
projects into a recess formed in the confronting side of member 18. The 
switch in housing 41 has an operating shaft 42, which projects into a 
central opening formed in one end of a cylindrical coupling member 43, 
which is mounted to rotate in a circular opening 44 that is formed in 
member 18 beneath and parallel to its axial bore. Shaft 42 has thereon a 
chordal flat 42' (FIG. 4) which engages a corresponding flat in the bore 
of member 43, so that any rotation of the latter will be imparted to the 
shaft 42. 
The counterbored end of member 43 remote from the housing 41 has therein 
opposed, diametral slots 45, which separate this annular section of member 
43 into two, opposed, arcuate lugs 46. Projecting slidably into spaces 45 
between the lugs 46 are two coupling projections 47, which extend from one 
end of a cylindrical control member 48, that is mounted for limited 
rotational and axial movement in a circular opening 49 formed in member 19 
beneath and parallel to its axial bore. 
Projecting radially from member 48 through an arcuate slot 51, which is 
formed in member 19 to communicate with the opening 49, is a rigid stem 
52, which carries a movable, spring-loaded operating knob 53. Stem 52 
extends into a bore 54 in the knob 53 and is surrounded by a spring 55, 
which is seated at one end against the bottom of the bore 54, and at its 
opposite end against the head of a screw 56 which is threaded in the upper 
end of the stem, whereby spring 55 urges the knob 53 resiliently and 
radially inwardly on the stem towards the axis of member 48. On its inner 
end knob 53 has at one side of the stem 52 an axial projection or lug 58, 
which is engagable selectively either with the outer surface of member 19 
(FIg. 1) or with the outer peripheral surface of control member 48, as 
described in greater detail hereinafter. 
Remote from its coupling section 47 the control member 48 has thereon an 
arcuate operating lug 61, which in the position as shown in the drawing, 
is releasably seated in a similarly shaped recess 62, which is formed in 
the confronting face of the actuating member 30. As shown more clearly in 
FIGS. 2 and 5, the arcuate recess 62 in member 30 has a centerline the 
axis of which does not coincide with the axis of member 30 and shaft 13. 
As a consequence there is only one angular position of member 30 relative 
to member 48, which will enable lug 61 to be inserted into recess 62; and 
this is the position of member 30 as illustrated in FIGS. 1, 2 and 6. When 
members 48 and 30 are in these engaged positions, stem 52 will be in the 
angular position denoted by line B in FIG. 3, in which case the stem 52 
will be positioned between one end of slot 51 (the upper end as shown in 
FIG. 6), and a stop lug or dog 59 which projects into the middle of slot 
51 from its forward edge (see FIG. 6). At this time the switch in housing 
41 will have been rotated by member 43 into a position in which it causes 
the associated motor to be driven in a forward direction, when the 
operating switch (not illustrated) is squeezed or closed in the usual 
manner during drill operation. As noted hereinafter, this is the 
chuck-closing position of the device; and this fact is indicated by the 
registry of a mark "C", which is inscribed on the periphery of member 30 
(FIG. 6), with an index arrow 75, which is inscribed on the periphery of 
member 19. 
At this time a bit may be inserted into the bore of holder 23, after which 
the operator momentarily squeezes or closes the motor operating switch. 
Assuming that this causes the motor momentarily to rotate shaft 13 in a 
clockwise direction as shown in FIG. 2 the holder 23 and its jaws 33 also 
will tend to rotate clockwise. However, since at this time lug 61 locks 
member 30 and the actuating ring 25 against rotation, the threaded 
connection between ring 25 and jaws 33 cause the latter to be shifted 
axially forwardly and radially inwardly into chucking or locking 
engagement with the peripheral surface of the tool bit. 
After the bit has been chucked in holder 23 by momentary energization of 
the drill motor, the control member 48 is manipulated by its knob or 
handle 53 rearwardly from its advanced or jaw-actuating position to a 
retracted or inoperative position (not illustrated) in which member 48 is 
shifted axially part way into the opening 44 in member 18, and far enough 
to cause its lug 61 completely to be withdrawn or disengaged from the 
actuating member 30. In this inoperative position the stem 52 of member 48 
will be engaged against the left end of the slot 51 as shown in FIG. 1, 
and the spring-loaded knob 53 will have been advanced radially inwardly 
far enough to cause its lug 58 to drop downwardly through slot 51 toward 
the outer periphery of member 48, and between the stop lug 59 and the 
upper end of slot 51 as this slot is illustrated in FIG. 6. At this time 
the control member 48 cannot be accidentally advanced axially to the right 
in FIG. 1 towards its operative position, nor can it be rotated 
accidentally from one to the other of its limit positions in slot 51 until 
such time as the knob 53 is once again drawn radially outwardly against 
the resistance of spring 55, and far enough to disengage the lug 58 from 
within the slot 51 as noted hereinafter. With the bit now secured in the 
chuck jaws 33, and the lug 61 disengaged from member 30, the drill may now 
be used in a conventional manner for drilling purposes. 
When it is desired to remove a bit from the drill, the motor is stopped, 
and handle 53 on the now-retracted member 48 is pulled upwardly against 
spring 55 to withdraw lug 58 from between stop lug 59 and the upper end of 
slot 51 as shown in FIG. 6. The handle and retracted member 48 are then 
rotated into motor-reversing and chuck-opening position as denoted by line 
A in FIG. 3, thus swinging stem 52 against the opposite or lower end of 
slot 51 as shown in FIG. 6. This causes the switch in housing 41 to change 
the motor rotation to reverse, or for counter-clockwise rotation of shaft 
13 as shown in FIGS. 2 and 5, and also rotates the lug 61 into its other 
limit position as shown in FIG. 5. 
Also at this time member 30 is rotated manually until a second indicator 
mark on its periphery (not illustrated) registers with the index arrow 75 
on member 19. When member 30 is in this latter position, a second recess 
63 in its inner face will have been rotated into the position shown in 
FIG. 5. This places one end of recess 63, which is disposed coaxially of 
shaft 13, in coaxial registry with the arcuate lug 61 on member 48, 
thereby permitting the control member 48 to be advanced axially forwardly, 
and thus causing its projection 61 to be inserted into the right end of 
recess 63 as shown in FIG. 5. This operatively couples the control member 
48 once again to the actuating member 30. Now, with the associated drill 
motor connected for rotation in a reverse direction, when the operator 
next closes the motor energizing switch the shaft 13 is caused suddenly to 
rotate in a counter-clockwise direction, thereby rotating with it the 
holder 23 and the locked jaws 33. During this initial movement the 
frictional engagement between the threads on the actuating ring 25 and the 
threads 32 on the jaws 33 causes the actuating member 30 also to be 
rotated counter-clockwise, and suddenly, from the position shown in FIG. 5 
until the left end of the recess 63 is swing into engagement with the 
stationary lug 61 on the control member 48. This sudden impact loading of 
the left end of the recess 63 against the stationary lug 61 causes the jaw 
actuating ring 25 suddenly to be rotated in a jaw unlocking direction 
relative to the jaws 33, so that the jaws are disengaged from the bit then 
in the bore of the holder 23. As soon as the bit is released the operator 
releases the motor energizing switch once again to deenergize the motor 
until such time that the control member 48 is thereafter disengaged from 
the actuating member 30. 
The reason that the elongate, arcuate recess 63 is employed in the member 
30 is because once the jaws 33 have become engaged with a tool bit, it has 
been discovered that it requires a sudden application of load to actuating 
ring 25 in order to cause it to disengage the jaws from the bit. The 
static loading which is imparted to the jaws during the closing thereof by 
operation of the lug 61 in the small recess 62 is not sufficient to unlock 
the jaws, although such loading is sufficient to effect satisfactory 
locking of the jaws against the bit. 
From the foregoing it will be apparent that the present invention provides 
a relatively simple and inexpensive means for utilizing the electric motor 
of a conventional hand drill for selectively locking a tool bit in the 
drill, or for releasing the bit after it has been used. By utilizing a 
specially shaped control lug 61 and cooperating recesses 62 and 63, it is 
possible to apply substantially static loading to the chucking jaws 33 
during the locking of a bit in the drill, while during the unlocking of 
the bit an impact load is applied through the ring 25 to the jaws to 
enable release thereof. Moreover, by utilizing the spring-loaded operating 
knob 53 together with a safety detent or lug 58 thereon accidental or 
undesirable movement of the control member 48 both angularly and axially 
in slot 51 is prevented during operation of the drill. 
Still another advantage of this invention is that the recesses 62 and 63 in 
the actuating member are so designated that it is impossible to insert the 
lug 61 into either recess 62 or 63 unless the actuating member is already 
in a predetermined angular position relative to lug 61. Moreover, when the 
operating knob 53 is in its jaw-locking or closing position B as shown in 
FIGS. 2, 3 and 6, it is virtually impossible to insert the operating lug 
61 into the recess 63, regardless of the angular position of actuating 
member 30 about its axis. Likewise, whenever the control member 48 is in 
its jaw-releasing position A, the center of the arcuate path defined by 
lug 61 will be registerable with the center of the arculate path as 
defined by the recess 63 in member 30, but it will be impossible at this 
time for the lug 61 to enter the recess 62, the centerline of which is not 
coincident with the centerline of recess 63. 
While this invention has been described in detail in connection with only 
one embodiment thereof, it will be apparent that it is capable of still 
further modification, and that this application is intended to cover any 
such modifications as may fall within the scope of one skilled in the art, 
or the appended claims.