Chuck key

A portable electric drill is disclosed which includes a loss-proof chuck key. The drill includes a cord set and the chuck key includes a simple, rod-like handle which is shaped to form a closed loop. The loop is slightly larger than the diameter of the cord set but sufficiently smaller than the cross sectional dimensions of the plug so that the key cannot be slipped off over the plug. In a preferred embodiment, the key comprises a triangular handle to provide a good gripping surface for the user. Other accessory hand tools for use with electric or pneumatic power tools attached to the power tool in a similar manner are also disclosed.

BACKGROUND OF THE INVENTION 
In the manufacture of portable electric drills, the chuck key is a 
seemingly minor element of the system which has been a continuing source 
of irritation to both the manufacturer and the user. The chuck key is 
necessary for adequate tightening of the chuck jaws on the shafts of 
various working implements. However, if the key design is selected so as 
to permit low cost manufacture, the design is inconvenient for the user. 
On the other hand, if the design chosen is reasonably convenient for the 
user, then the manufactured cost is unreasonably high. 
A further problem with chuck keys lies in the fact that they must be a 
separate and freely movable element of the system and cannot be affixed to 
the drill. Consequently, they are easily lost which can cause substantial 
inconvenience. 
A variety of chuck key constructions have been designed in the past which 
have solved one or another of these problems. For example, British Pat. 
No. 560,546, dated Apr. 7, 1944, discloses two versions of a chuck key in 
which generally wingshaped extensions of the key body are formed 
integrally therewith to provide a large flat gripping surface which is 
well suited for use by the operator. However, a chuck key of this design 
is relatively expensive to manufacture. 
Another version of a chuck key is shown in British Pat. No. 1,396,859, 
dated June 11, 1975. In this design, a generally straight shaft is formed 
by bending operations to provide an approximation of a T-shape which is 
relatively inexpensive to manufacture. However, this design is less 
convenient and less comfortable for the operator to use, particularly if 
significant force is to be applied to ensure adequate tightening. 
Another chuck key design which is still less expensive to manufacture is 
the widely known and used L-shaped key. This design is basically similar 
to that of the British Pat. No. 1,396,859 except that the handle portion 
is bent only once to form an L. 
An improved chuck key of simple construction is shown in the recent U. K. 
Registered Design No. 974,037, issued Oct. 27, 1976. This design is 
basically similar to the handle illustrated in U.S. Pat. No. 3,213,720, 
dated Oct. 26, 1965 and also to a variety of similar handles used on such 
items as Allen wrenches and can opener keys. 
Despite the variety of chuck key constructions available in the prior art, 
a continuing difficulty has been that of ensuring against the loss of the 
chuck key. The most satisfactory solution to this difficulty for the 
ultimate user is to tape the key to the cord set of the drill. However, 
this is not a good solution for the manufacturer and therefore it is not 
of assistance in preventing loss and theft of keys from the cartons during 
shipping and distribution. 
A further difficulty sometimes encountered is that caused by a careless 
operator who turns the drill on while the key is in place in the chuck. 
The key can be thrown out with sufficient force to cause injury or damage. 
OBJECTS OF THE INVENTION 
It is accordingly a principle object of this invention to provide a simple 
and secure method of attaching a chuck key to a drill so as to prevent 
loss or theft thereof. 
Another object of this invention is the provision of a chuck key and drill 
combination which reduces the likelihood that a user will turn the drill 
on while the key is inserted in the chuck and which limits the distance 
which the chuck key can be thrown if the drill is turned on. 
It is also an object of this invention to provide a structure which reduces 
the likelihood of loss of tools such as Allen wrenches which are used in 
association with other corded tools such as jig saws and circular saws. 
Further objects of this invention will become apparent as the description 
and illustration thereof proceed.

DESCRIPTION 
In FIG. 1, a portable electric drill 10 is illustrated which, in accordance 
with conventional practice, comprises a housing 11 having a hand grip 12, 
a trigger switch 13, a cord 14 and an output chuck 15. An electric motor 
enclosed within the housing is arranged to be energized by power supplied 
through the cord when the trigger switch is closed. Activation of the 
motor causes rotation of the chuck and of a working implement which may be 
engaged by the chuck. 
Also in accordance with conventional design, the chuck 15 is provided with 
a plurality of jaws 16 for gripping the shaft of a working implement. The 
jaws may be hand tightened to an initial position in engagement with the 
shaft of the work implement but in general, a tighter engagement is 
preferred to prevent slippage. This is accomplished by providing a 
plurality of gear teeth 17 on the forward edge of the chuck cover 18 and a 
plurality of pilot holes 19 in the chuck body 20. A chuck key 21 is 
mounted in the pilot hole and a gear on the chuck key is engaged with the 
gear teeth 17. Rotation of the chuck key firmly tightens the jaws on the 
working implement. 
The chuck key 21 shown in FIG. 1 and again in more detail in FIG. 3, is 
provided with a pilot 22 and gear 23 which engage in the conventional 
manner with the pilot hole 19 and teeth 17 to permit tightening or 
loosening up of the jaws. In accordance with the present invention, the 
chuck key 21 is provided with a triangular handle 24 including portions 
25, 26 and 27 which form a substantially closed loop. In further accord 
with this invention, the handle 24 is disposed over the cord 14. This is 
preferably accomplished by manufacturing the chuck key to an open 
configuration, for example, as shown in FIG. 2, wherein the portion 27 is 
bent upwardly leaving an opening. The cord 14 is moved through the opening 
into the center of the chuck key handle, and then the handle is closed by 
bending a portion 27 down to complete the key handle. In accordance with 
this invention, the chuck key handle is sized so that it cannot easily 
slip over the cord set plug 28 and the handle is closed sufficiently so 
that the cord set cannot slip out through the small space 29 between the 
portions 25 and 27. 
Several significant advantages are inherent in the chuck key arrangement of 
this invention. First, it is simple and inexpensive to manufacture since 
the entire key can be manufactured from a simple rod by cold heading and 
bending. Heavier duty chuck keys may require somewhat more expense to 
accommodate harder usage, but manufacture of the handle portion thereof is 
still of the utmost simplicity. 
Secondly, the key configuration provides the advantage of a wide gripping 
surface which was previously only provided by keys which were relatively 
expensive to manufacture. The wide rear portion 27 can be fitted into the 
operator's palm and the side portions 28 and 29 provide a grip surface to 
be engaged by the operator's fingers. 
Thirdly, due to the mounting arrangement of the present invention, the 
accidental loss of the key is prevented, it is always immediately at hand 
along the length of the cord set. Directly related to this, the operator 
is unlikely to activate the tool with the key mounted in the chuck since 
the cord set will necessarily be folded in front of the handle toward the 
chuck and will thus provide a clear warning to the operator that the key 
must be removed. Even if the tool is accidentally actuated the key will be 
stopped by the cord set within a relatively short distance, thus reducing 
the likelihood of damage or injury. 
FIGS. 4 and 5 illustrate alternative embodiments of this invention. In FIG. 
4, an alternative chuck key 30 is illustrated which comprises a rod shaped 
to define a substantially closed circular loop handle 31 which receives 
the cord 14. In FIG. 5, an Allen wrench 32 of the type frequently provided 
for securing jig saw blades or adjusting circular saws is shown which 
includes a third alternative loop handle 33. In each case, the advantages 
derived are similar to those previously identified. The respective handles 
may be initially straight rods formed by bending into the configuration 
illustrated or they may be cast or otherwise manufactured to their final 
configuration. In this instance, the cord set is threaded through the loop 
prior to the installation of the plug, or prior to its connection to the 
power tool. 
While the description and illustration of this invention have been limited 
to several selected embodiments, it will be clear that other adaptations 
of this concept to further alternative embodiments may easily be 
accomplished. For example, with a suitable loop size, a chuck key may be 
similarly attached to a pneumatic tool. Accordingly, it is intended that 
the appended claims cover all such changes and modifications as may fall 
within the true spirit and scope of this invention.