Indicator for loose lug nuts

A device for indicating when a lug nut has come loose on an automobile wheel. In one embodiment, the device operates by detecting relative movement between the lug nut and the axle stud on which it is mounted. In a second embodiment, the detected relative movement is between the lug nut and the wheel itself. In the preferred embodiment, the device has a first member with an open-ended channel and second and third members slideably received in it. The second member operates in cooperation with the sides of the channel and one of the springs to hold the third member in a retracted or cocked position when the lug nut is in its preferred, tight position against the wheel. Thereafter, should the lug nut come loose and move relative to the stud, the second member will follow or move under the force of its spring outwardly to maintain contact with the free end of the stud. In doing so, the third or indicator member is released to move in the opposite direction under the force of its spring to protrude beyond the outer surface of the lug nut where it can be easily and quickly seen or felt by hand. In the second embodiment, the second or follower member abuts the wheel itself rather than the free end of the stud but otherwise operates in the same manner.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the field of devices for indicating relative 
movement between two objects and more specifically to the field of devices 
for indicating when a lug nut has come loose on an automobile wheel. 
2. Background Discussion 
Lug nuts are almost universally used to secure wheels to the axles of cars. 
In the most common case, each of the car axles has a plurality of threaded 
studs on it wherein the car tires are first mounted on wheels and each 
wheel then secured to the axle studs by lug nuts. Like the studs, the lug 
nuts are threaded and in operation, they are tightened to a flush position 
against each wheel. 
In use, the problem can subsequently arise that one or more of the lug nuts 
may become loose and a wheel begin to wobble. If the loose nut is not 
discovered and re-tightened, the wobbling can become worse. This can then 
distend or distort the stud hole in the wheel to the point that the wheel 
is ruined. Additionally, it can cause the other lug nuts to come loose and 
in extreme cases, the wheel may even fall off. 
Presently, it is virtually impossible to tell just by looking at the lug 
nuts whether one or more of them are beginning to come loose. Further, it 
is equally difficult to manually inspect them for looseness without a 
torque wrench or other tool because although the nuts may be coming loose 
and have moved away from their tight position, they may still feel tight 
at least to the touch. That is, the nuts only need to move a very small 
amount (e.g., 1/16 of a turn or about 0.005 inches away from the wheel) to 
be loose enough that it may become dangerous. With such a small amount, 
most if not all people cannot detect any difference either visually or by 
simply touching the nuts. In the extreme situation, it is usually easy to 
tell when a nut has come completely off but by then the damage may have 
already been done. For example, in cars with wheel covers, a lug nut that 
has come completely off can usually be heard clanking around inside the 
cover as the car moves. Similarly, in cars with exposed wheels such as mag 
wheels, it is fairly easy to tell by visual inspection when a lug nut has 
come completely off. However, in both cases, once the nut has come 
completely off, it is usually too late since severe damage has often 
already occurred. Consequently, to prevent such damage and the 
accompanying unsafe conditions, it is necessary to be able to easily and 
quickly detect the initial movement of even the slightest amount by the 
lug nut away from its tight position particularly since once the nut 
begins to come loose, it is only a very short time before it becomes so 
loose as to be dangerous. 
With this in mind, the present invention was developed. With the present 
invention, lug nuts can be quickly and easily inspected to determine if 
they have become loose and moved even the smallest amount away from their 
tight positions. Further, in the preferred embodiment of the invention, 
this inspection can be done visually by simply looking at the lug nuts or 
manually by simply running ones fingers over the outer surfaces of the lug 
nuts. Additionally, once a loose condition has been detected, the lug nut 
can be easily and quickly re-tightened with the indicator device of the 
present invention also being easily and quickly re-set at the same time. 
SUMMARY OF THE INVENTION 
This invention involves a device for indicating when a lug nut has come 
loose on an automobile wheel. In one embodiment, the device operates by 
detecting relative movement between the lug nut and the axle stud on which 
it is mounted. This, in turn, indicates that the nut has moved away from 
its tight position and become loose. In a second embodiment, the detected 
relative movement is between the lug nut and the wheel itself. In the 
preferred embodiment, the device has a first member that has a channel in 
it. The channel is open-ended and has second and third members slideably 
received in it. The second and third members are each spring biased away 
from each other and respectively toward one of the open ends of the 
channel. The second member operates in cooperation with the sides of the 
channel and one of the springs to hold the third member in a retracted or 
cocked position when the lug nut is in its preferred, tight position 
against the wheel. In this position, the second or follower member abuts 
the stud and is also held in a retracted or cocked position. Thereafter, 
should the lug nut come loose and move relative to the stud, the second 
member will follow or move under the force of its spring outwardly to 
maintain its contact with the free end of the stud. In doing so, the third 
or indicator member is released to move in the opposite direction under 
the force of its spring. A portion of the third member then protrudes 
beyond the outer surface of the lug nut and can be easily and quickly seen 
or felt by hand. Upon seeing or feeling the protruding third member, the 
operator then knows that the lug nut has come loose and moved away from 
its tight position. In the second embodiment, the second or follower 
member abuts the wheel itself rather than the free end of the stud but 
otherwise operates in the same manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As illustrated in FIG. 1, automobile wheels such 1 are almost universally 
secured to cars such as 3 by lug nuts 5. The lug nuts are commonly either 
of the mag-type variety (member 5 in FIGS. 1-5) or the open-ended type 5' 
in FIG. 7. The primary difference being that the mag-type nuts 5 (see FIG. 
2) cover the free end 9 of the axle stud 7 while the more conventional, 
open-ended nuts 5' in FIG. 7 leave the free end 9 of the stud 7 exposed. 
Referring to FIG. 2, the lug nut 5 serves to securely hold the wheel 1 on 
the car axle 11. In doing so, the lug nut 5 is screwed onto the threaded 
stud 7 until the chamfered surfaces 13 and 15 on the wheel 1 and lug nut 5 
are flush and tight against one another usually under a force of, for 
example, 15 pounds. This is commonly accomplished by using a torque 
wrench, air drill, tire iron, or similar tool. Once set in the preferred, 
tight position of FIG. 2, the wheel 1 and axle 11 will then operate in a 
safe and efficient manner. However, the problem can subsequently arise 
that the lug nut 5 will work itself loose during extended operation of the 
car 3 and the wheel 1 will begin to wobble. Unless this loose condition is 
discovered and the lug nut 5 re-tightened, the condition will worsen to 
the extent that the stud hole 17 (see FIG. 2) in the wheel 1 will be 
distended or distorted to the point that the wheel 1 is ruined. 
Additionally, it can cause other lug nuts 5 to come loose and in the 
extreme case, the wheel 1 may even fall off. 
A lug nut such as 5 in FIG. 2 does not have to move very far at all from 
its tight position of FIG. 2 in order to be loose enough to begin to cause 
damage and present an unsafe condition. Also, although it may take a long 
time for a lug nut 5 to initially become loose and move away from its 
tight position, it may take very little time thereafter for the condition 
to worsen to the point that the lug nut 5 has come completely off the stud 
7 and the wheel 1 has been severelly damaged. In this light, it is highly 
desirable to be able to easily and quickly detect when a lug nut 5 has 
initially come loose and moved away from its tight position (e.g., moved 
1/16 of a turn or about 0.005 inches away from the wheel 1) and it is with 
this in mind that the present invention was developed. 
With the present invention, even the slightest amount of movement between 
the lug nut 5 and wheel 1 (see FIGS. 3 and 4) can be detected. In doing 
so, the indicator 20 of the present invention employs a first or channel 
member 22 (see FIG. 3), a second or follower member 24, and a third or 
indicator member 26. The channel member 22 has a channel in it extending 
along the axis A--A in FIG. 3. The channel is open-ended and has first and 
second chambers 30 and 32 in it separated by a smaller, interconnecting 
passageway 34. The second or follower member 24 is dimensioned to be 
slideably received in chamber 30 for movement along the axis A--A between 
a retracted or cocked position (FIG. 3) and an extended or uncocked 
position (FIG. 4). The second or follower member 24 is substantially 
T-shaped and is biased under the force of coil spring 36 to the left in 
FIG. 3 or away from its cocked position. As illustrated in FIG. 3 and 4, 
the follower member 24 abuts against the free end 9 of the stud 7 and when 
the lug nut 5 comes loose and moves away from the wheel 1 (see FIG. 4), 
the second member 24 will follow or move under the force of the spring 36 
outwardly of the channel member 22 (compare FIGS. 3 and 4) to maintain its 
contact with the free end 9 of the stud 7. 
The third or indicator member 26 of the present device is actually made up 
of two parts 38 and 40 that are press-fit together. The first part 38 (see 
FIG. 3) is substantially T-shaped and the second part 40 is an elongated 
member whose one end at 42 is press-fit into the end 44 of the first part 
38. The other end 46 of the second part 40 is cut and hollowed out (see 
FIG. 6) to form two flexible, free-standing sections 48 and 50. The 
indicator member 26 (which is composed of parts 38 and 40) is dimensioned 
to be slideably received in the chambers 30 and 32 as well as the 
interconnecting passageway 34 of the channel member 22. In this manner, 
the indicator member 26 can be moved along the axis A--A between a 
retracted or cocked position (FIG. 3) and an extended or uncocked position 
(FIG. 4). Like the follower member 24, the indicator member 26 is biased 
under the force of a coil spring 52 away from its cocked position or to 
the right in FIG. 3. In this manner and in the retracted or cocked 
positions of FIG. 3, the follower member 24 and indicator member 26 are 
biased in opposite directions away from each other and toward their 
respective extended or uncocked positions of FIG. 4. 
In the cocked position of FIG. 3, the pointed, male end 54 of the follower 
member 24 is received in the hollowed out, female end 46 of the indicator 
member 26. In doing so as best seen in FIG. 3, the two flexible, 
free-standing sections 48 and 50 of the indicator member 26 are wedged 
apart and against the wall of the channel member 22 substantially at the 
location 56 where the chamber 30 and interconnecting passageway 34 meet. 
This, in turn, holds the indicator member 26 in its retracted or cocked 
position of FIG. 3 against the force of the coil spring 52. Alternately or 
in addition, this holding can be accomplished by wedging the sections 48 
and 50 outwardly so that the lip portion 58 of the indicator means 26 (see 
FIG. 3) is wedged against the wall of the channel member 22 or a section 
of the lip portion 58 abuts and is held in place by a coil of the spring 
36 as shown in FIG. 3. 
In operation and in order to cock the device 20 of the present invention, 
the indicator member 26 (see FIG. 4) is first moved to the left against 
the force of its biasing spring 52 by, for example, a tire iron such as 60 
in FIG. 5. In the position of FIG. 5, the lug nut 5 is then tightened with 
the indicator member 26 depressed in its cocked position until the 
follower member 24 abuts against the free end 9 of the stud 7 (see FIG. 
5). Thereafter, continued tightening of the lug nut 5 with the free end 9 
of the stud 7 abutting the follower member 24 will cause the follower 
member 24 to move to the right against the biasing force of its spring 36 
(compare FIGS. 3 and 5). In doing so, the male end 54 of the depressed or 
retracted follower member 24 will be received in the female end 46 of the 
indicator member 26 and the flexible sections 48 and 50 of the indicator 
member 26 will be wedged apart. In this position (FIG. 3), the holding 
mechanism of the male end 54 of the follower member 24, the female end 46 
of the indicator member 26, and the wedging at 56 of the sections 48 and 
50 against the wall of the channel member 22 serves to hold or maintain 
the indicator member 26 in its retracted or cocked position of FIG. 3 even 
when the tire iron 60 is removed. Additionally or in the alternative, the 
holding mechanism can also include the wedging of the lip portion 58 of 
the indicator member 26 against the wall of the channel member 22 or the 
catching of the lip portion 58 on a coil of the spring 36 (see FIG. 3). 
As long as the lug nut 5 remains in its tight position against the wheel 1 
(FIG. 3), the indicator member 26 remains in its retracted or cocked 
position. However, should the lug nut come loose and move even the 
slightest amount (e.g., 1/16 of a turn or about 0.005 inches away from the 
wheel one--greatly exaggerated in FIG. 4), the member 24 will follow or 
move to the left in FIGS. 3 and 4 under the force of the biasing spring 36 
to maintain its contact with the free end 9 of the stud 7. This movement 
and the structure that accomplishes it serves to release the indicator 
member 26 to move under the force of its biasing spring 52 to its extended 
or uncocked position of FIG. 4. An observer can then easily detect by 
merely visually inspecting the lug nut 5 or running his fingers over it 
that the indicator member 26 has popped out to its extended or uncocked 
position and, consequently, that the lug nut 5 has come loose. The extent 
to which the indicator member 26 pops out of the lug nut 5 can be varied 
and is determined by how far the end 46 of the indicator member 26 extends 
into the chamber 30. That is, the indicator member 26 will pop out the 
throw distance between FIG. 3 and when the lip portion 58 (see FIG. 4) on 
the indicator member 26 abuts against the end of the passageway 34 at 56. 
To assemble the device 20 of the present invention, the part 40 of the 
indicator member 26 can be moved into the channel member 22 from left to 
right in FIG. 4. At the same time and with the biasing spring 52 in place 
about the shaft of the T-shaped part 38, the part 38 of the indicator 
member 26 is moved into the channel member 22 from right to left in FIG. 
4. The two parts 38 and 40 are then snapped or press-fit together at 42 
and 44 to form a unitary piece. The spring 36 and follower member 24 can 
then be inserted into the channel member 22 from left to right in FIG. 4 
and the open end of the channel member 22 crimped or coined at 62 to 
maintain the follower member 24 in the channel member 22. The channel 
member 22 is then secured in the lug nut 5 and the device 20 is ready for 
operation. Alternatively and if desired, the channel with chambers 30 and 
32 and interconnecting passageway 34 could be formed directly in the lug 
nut 5. However, in the embodiments of FIGS. 1-7, the channel member 22 is 
preferably separate from the lug nuts 5 and 5'. 
In the second embodiment of FIG. 7, the device 20 of the present invention 
has been adapted for use with a conventional, open-ended lug nut 5'. In 
doing so, the channel member 22 is positioned off-set from the axis A--A 
and the follower member 24 abuts against the wheel 1 rather than against 
the free end 9 of the stud 7 as in the preferred embodiment of FIGS. 1-6. 
As in the preferred embodiment, the movement of the indicator member 26 to 
its extended position then serves to indicate that the lug nut 5' has come 
loose. This can be preferably done either by visual or manual inspection 
but it is also contemplated that the movement of the indicator member 26 
in either embodiment could be sensed and used, for example, to set off an 
alarm or to activate a remote monitor. 
While several embodiments of the present invention have been shown and 
described in detail, it is to be understood that various modifications 
could be made to these embodiments without departing from the scope of the 
invention.