Locking device

A locking device which may be used in locking two objects together, includes a stud having a threaded axial hole extending rearwardly from the forward end thereof and a keyed portion having at least one key, and a knob which locks over a forward portion of the stud and includes a casing with an inner surface including at least one keyway each of which receives the corresponding key on the stud to prevent rotation of the casing with respect to the stud. The knob also includes a tumbler housing which is mounted in an axially fixed position within the casing to rotate freely when a key is inserted into the tumbler housing, and to remain locked in a fixed position when the key is withdrawn. Connected to a rear end of the tumbler housing is a threaded stud which engages the threaded axial hole of the stud when the tumbler housing is turned by a key to thereby pull a forward portion of the stud into the casing hole.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to locking and security devices. More 
specifically, the present invention relates to locking devices, which may 
be used to lock sway-control, weight distribution and other utility 
hitches for connecting vehicles, or to lock one object to another object 
such as a spare tire to a motor vehicle. 
2. Description of the Prior Art 
Various types of locking devices have been designed for a multitude of 
purposes. U.S. Pat. No. 3,605,457 to Foster and No. 3,139,291 to Geresy 
disclose trailer hitch locking devices which are used to lock a trailer 
hitch tongue to the ball of a conventional type of trailer hitch. Another 
type of device called a coupler lock has been used for locking together 
the central member and outer member of telescoping type utility hitches. 
In this type of utility hitch, the smaller central member fits 
telescopically into an outer member. Apertures through both members may be 
aligned so that a pin may be inserted therethrough to hold the central 
member within the outer member. If the pin is not locked onto these 
members in some manner it may be removed, and the vehicle which was 
connected to the hitch member, such as a trailer could be stolen. 
Other types of locking devices have been designed for securing attachments 
and accessories to vehicles. The U.S. Pat. No. 1,828,658 to Henke, Jr. 
discloses an antitheft tire lock which utilizes band sections which wrap 
around a portion of the tire. U.S. Pat. No. 1,491,691 to Godshalk and No. 
1,444,214 to Shultz disclose automobile spare tire locks utilizing a 
holding mechanism which presses against the tire rim to prevent removal of 
the spare tire from the vehicle. Spare tires for vehicles generally are 
mounted to racks affixed to the vehicle. Since tires almost uniformly have 
stud holes for operably connecting the tires with studs to the vehicle, it 
would be desirable to use the stud holes in a tire in combination with the 
tire rack to lock the spare tire to the vehicle. 
SUMMARY OF THE INVENTION 
The locking device of the present invention includes a stud having a first 
threaded surface and a keyed portion having at least one key and a knob 
which locks over a forward portion of the stud, the knob including a 
casing having an inner surface which defines a hole which extends axially 
through the casing and at least one keyway which, when the knob is placed 
over a forward portion of the stud, receives the corresponding key to 
prevent rotation of the casing with respect to the stud. The knob also 
includes a tumbler housing which is mounted in an axially fixed position 
within a forward section of the casing hole so as to rotate freely when a 
key is inserted into a keyhole in the tumbler housing and be locked in a 
fixed position when the key is withdrawn. The knob also includes a second 
threaded surface which is connected to a rearward end of the tumbler 
housing, such that, when the knob is placed over a forward portion of the 
stud so that the stud extends partly into a rearward section of the casing 
hole, rotation of the tumbler housing in one direction with the key causes 
a second threaded surface to engage the first threaded surface so that the 
forward portion of the stud is drawn into the rearward section of the 
casing hole. The stud of the locking device also includes a non-keyed 
portion which preferably may be in the form of a rod and is integrally 
connected to and located rearwardly of the keyed portion of the stud. 
Furthermore, the stud of the locking device preferably includes an 
expanded head which is integrally connected to and located rearwardly to 
the non-keyed rod portion, the expanded head being of larger diameter than 
the non-keyed rod portion and being similar in external form to the knob. 
In the preferred locking device, which is called a locking hitch pin, the 
stud has a threaded axial hole extending rearwardly from the forward end 
of the stud which forms the first threaded surface, and the knob has an 
axially oriented threaded stud which is connected to the rearward end of 
the tumbler housing to form the second threaded surface. The keyed portion 
of the stud has four axially oriented keys 90.degree. apart, and the inner 
surface of the casing hole has four axially oriented keyways 90.degree. 
apart which are able to slidably receive the keys on the stud. When the 
forward portion of the stud is inserted partially into the rear section of 
the casing hole, the key may be used to turn the tumbler housing and 
connected threaded stud to thereby pull the forward portion of the stud 
into the rear section of the casing hole by engaging the threaded axial 
hole in the stud. As the forward portion of the stud is pulled into the 
casing hole, the keys on the keyed portion of the stud slide forwardly 
into the keyways on the inner surface of the knob casing. These keys and 
keyways have opposed mating surfaces which prevent rotation of the stud 
and knob with respect to each other as the forward portion of the stud 
moves into the casing hole and rests therewithin. Withdrawing the key from 
the tumbler housing allows slide tumblers to extend partially out from the 
tumbler housing into one of the keyways on the casing inner surface with 
which the slide tumblers are aligned, thereby locking the knob over the 
stud. When the stud includes an expanded head on the end of the non-keyed 
rod portion opposite the knob, the locking device may be used as a locking 
hitch pin for utility hitches which have telescoping central and outer 
members. The non-keyed rod portion may be inserted to extend through the 
aligned apertures in the telescoping hitching members, to thereby lock the 
central member within the larger outer member. This preferred embodiment 
of the locking device may be used to lock such hitching members together 
even when the central member is solid instead of hollow. The expanded head 
at one end of the stud and the knob at the other end of the locking hitch 
pin maintain the locking hitch pin within the aligned apertures of the 
hitching members, so that the locking hitch pin cannot be removed without 
a key. The locking hitch pin may also be used to lock a spare tire to the 
rack on which it is mounted to a vehicle. The rod portion of the stud can 
be inserted through a hole bored in the rack, then through one of the stud 
holes in the tire. The knob can then be locked over the forward portion of 
the stud to lock the tire in place. 
Other objects, features, and advantages of the invention will be apparent 
with the following detailed description taken in conjunction with the 
accompanying drawings showing a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring more particularly to the drawings, wherein like numbers refer to 
like parts, FIGS. 1 and 2 show a preferred locking device 10 which is 
embodied as a locking hitch pin shown generally at 10, including a stud 11 
having a rod portion 12 and an expanded head 13, and a knob 14 with a 
locking key 16 inserted in the forward end 17 thereof. FIG. 1 shows the 
knob 14 locked over a forward portion 18 of the stud 11, and FIG. 2 shows 
the knob 14 separated from the forward portion 18 of the stud 11. The 
forward portion 18 of the stud 11 includes a keyed boss portion 19 of the 
stud 11, and the forward end 20 of the rod portion 12. When the knob 14 is 
locked over the forward portion 18 of the stud 11, the boss 19 and forward 
end 20 of the rod portion 12 are entirely contained within the knob 14. 
The boss 19 preferably has four axially oriented keys 21 located 
90.degree. apart. As shown in FIGS. 2 and 5, the stud 11 has a threaded 
axial hole 24 which forms a first threaded surface of the locking hitch 
pin 10. 
The knob 14 includes a cylindrical casing 25 and an internal mechanism 26 
enclosed within a hole 27 extending axially through the casing 25, the 
hole 27 being defined by the inner surface 28 of the casing 25. The inner 
surface 28 also has four axially oriented keyways 30 located 90.degree. 
apart which are adapted to receive the keys 21 on the keyed boss portion 
19 of the stud 11 when the forward portion 18 of the stud 11 is inserted 
into the casing hole 27. These keyways 30 are shown in FIGS. 2-4. The keys 
21 have mating surfaces 31 which are adapted to mate with opposed mating 
surfaces 29 which are on the keyways 30 of the knob 14. When each pair of 
opposed mating surfaces 29 and 31 abut against one another, the knob 14 
and stud 11 are prevented from rotating relative to one another. For these 
mating surfaces 29 and 31 to prevent rotation of the knob 14 and stud 11 
with respect to each other while allowing the knob and stud to slide 
axially with respect to each other, the surfaces should be parallel to a 
central axis through the knob and the stud. 
As shown in FIGS. 4 and 6, the internal mechanism 26 of the knob 14 
includes a tumbler housing 32 and a second threaded surface formed by an 
axially oriented threaded stud 33 which is connected to the rearward end 
34 of the tumbler housing 32. In the preferred knob 14, the rearward end 
34 of the tumbler housing 32 has a short threaded bore (not shown) into 
which the threaded stud 33 is turned. A small pin 36 is inserted through 
the tumbler housing 32 and threaded stud 33 to maintain the threaded stud 
in its position extending axially from the rearward end 34 of the tumbler 
housing 32. At the forward end 37 of the tumbler housing 32 is a keyhole 
38 into which the key 16 may be inserted, as shown in FIG. 6. The tumbler 
housing 32 includes slide tumblers 39, operable by the locking key 16 
which are substantially entirely contained in the tumbler housing 32 when 
the key 16 is fully inserted into the keyhole 38. When the key 16 is 
withdrawn, the slide tumblers 39 are biased to extend partially outside of 
the tumbler housing 32 into one of the four axially oriented keyways 30 
when aligned therewith to prevent the tumbler housing 32 from rotating. 
Since there are four keyways 30 on the inner surface 28 of the casing 25, 
the tumbler housing 32 can lock into a fixed rotational position every 
one-quarter turn of the key 16. 
In the preferred locking hitch pin 10, the inner surface 28 of the casing 
25 also has an annular groove 41 as best shown in FIG. 4. The tumbler 
housing 32 includes a catch ring 42 which is biased to extend radially 
outwardly from the tumbler housing 32 as shown in FIGS. 4 and 6. This 
biasing of the catch ring 42 causes the ring 42 to extend from the tumbler 
housing 32 into the larger annular groove 41 to maintain the tumbler 
housing 32 in its axially fixed position. As the tumbler housing 32 is 
turned by the key 16, the catch ring 42 maintains its position within the 
larger annular groove 41 so that the tumbler housing 32 can neither move 
forwardly nor rearwardly from its position. Additionally, the inner 
surface 28 of the casing 25 has a shallow annular groove 43 which is 
located adjacently rearward of the tumbler housing 32 rearward end 34 as 
shown in FIG. 4. The knob 14 further includes an expansion ring 44 which 
is seated in the shallow annular groove 43 to thereby restrain the tumbler 
housing 32 against any rearward movement thereof as shown in both FIGS. 3 
and 4. In the preferred locking hitch pin 10, this expansion ring 44 
within the casing hole 27 divides that hole 27 into a forward section 46 
where the tumbler housing 32 fits, and a rearward section 47 into which 
the threaded stud 33 extends and which is adapted to receive the forward 
portion 18 of the stud 11. 
The forward end 48 of the casing hole 27 is preferably widened to form a 
forward sheath 49 and a radial retention surface 50 which faces in a 
forward direction. A forward end 37 of the tumbler housing 32 is also 
widened to form a flange 52 which has an outside diameter which is 
slightly smaller than the inside diameter of the forward sheath 49 so that 
the flange 52 fits snuggly within the forward sheath 49 when the tumbler 
housing 32 is properly positioned within the forward section 46 of the 
casing hole 27. The fit must not be so tight that the tumbler housing 32 
cannot rotate within the casing 25. When the flange 52 is seated within 
the forward sheath 49, the flange 52 should obscure the keyways 30 and the 
casing hole 27 so that they cannot be pried. In order for the keyways 30 
to be obscured, they cannot extend into the forward sheath 49. Therefore, 
the forward end 48 of the casing hole 27 which forms the forward sheath 49 
must be widened to an extent which is at least as far outward radially as 
the radially outermost extent of the keyways 30, i.e. that point within 
the keyways 30 which is radially furthest from the central axis of the 
casing 25 and casing hole 27. The forward sheath 49 should extend 
rearwardly within the casing hole 27 to a point where the radial retention 
surface 50 abuts against the flange 52 to provide further restraint 
against the tumbler housing 32 moving rearwardly, but such that the 
forward end 37 of the tumbler housing 32 is flush with the forward end 17 
of the knob 14. 
The rearward end 53 of the casing hole 27 is also preferably widened to 
form a rearward sheath 54 which is adapted to receive the forward end 20 
of the non-keyed rod portion 12 when the forward portion 18 of the stud 11 
is fully inserted within the rearward section 47 of the casing hole 27. 
The non-keyed rod portion 12 therefore preferably has an outer diameter 
which is slightly smaller than the inside diameter of the rearward sheath 
54 so that the non-keyed portion 12 seats snuggly within the rearward 
sheath 54 when the forward portion 18 of the stud 11 is drawn into the 
rearward section 47 of the casing hole 27. The forward end 20 of the 
non-keyed rod portion 12 should seat within the rearward sheath 54 so as 
to obscure the casing hole 27 and keyways 30. For the non-keyed portion 12 
of the stud 11 to obscure the keyways 30, the keyways 30 in the inner 
surface 28 of the casing 25 cannot extend into the rearward sheath 54. 
Therefore to form the rearward sheath 54, the rearward end 53 of the 
casing hole 27 must be widened to an extent at least as far outward 
radially as the radially outermost extent of the keyways 30. Since the 
non-keyed portion 12 of the stud 11 seats snuggly within the rearward 
sheath 54, neither the casing hole 27 nor the keyways 30 may be pried from 
the outside. The rearward end 55 of the casing 25 is tapered rearwardly 
and radially inwardly to the rearward end 53 of the casing hole 27, so 
that when the forward end 20 of the non-keyed rod portion 12 of the stud 
11 is drawn into the rearward sheath 54, the tapered rearward end 55 of 
the casing 25 inhibits use of that end to pry the knob 14 away from the 
stud 11. 
FIGS. 1-6 are an exemplification of the invention, and are not intended to 
limit the embodiments of the invention to that shown. The non-keyed 
portion 12 of the stud 11 may vary both in length and diameter, and the 
stud 11 need not include an expanded head 13. Although the non-keyed 
portion 12 shown in FIG. 1 is a rod portion which is integrally connected 
to and located rearwardly of the keyed portion 19, alternatively the 
non-keyed portion even could be so short as to not resemble a rod. For 
example, in one embodiment the locking device could be used for locking 
and holding a panel cover to an electrical control box. In such a case, 
the stud 11 would have no expanded head 13, and the non-keyed portion 12 
might be very short and connected by its rearward end 57 to the control 
box by a weld. Such an electrical control box could have a plurality of 
these locking devices for locking and holding a cover panel thereon. The 
cover panel would have holes that would receive the non-keyed portions 12 
of the studs 11 when the cover panel is placed over the electrical control 
box opening. After the cover panel is properly placed, the knobs 14 could 
then be locked over the studs 11 to hold and lock the cover panel to the 
control box. In another embodiment, a shorter version of the locking hitch 
pin 10 shown in FIG. 1, could be used for locking spare tires to the rack 
in which they are placed on a motor vehicle. The locking device also could 
be used for locking scaffolding together and for locking various other 
types of equipment and apparatus together. 
The keyed portion 19 of the stud 11 also need not be a boss 19. Instead the 
keys 21 on the keyed portion 19 could extend radially outward from the 
axis of the stud 11 as far as the surface of the non-keyed rod portion 12. 
In such a case, the keyed portion 19 would not have the appearance of a 
boss, because at least where the keys 21 were, the keyed portion would 
have the same outside radius as the non-keyed rod portion 12. Furthermore, 
an alternative embodiment of the locking device 10 may have mating 
surfaces on the stud 11 and knob 14 which take a form other than keys 21 
and keyways 30. 
In its use, the locking device 10 is intended to be used for locking two or 
more pieces of equipment, apparatus, or objects together, such as a 
trailer to a towing vehicle. When used with a weight distribution hitch, 
sway control trailer hitch or a Hi-Lo Utility hitch, before attempting to 
insert the stud 11 the user should make sure that the central member 58 of 
the hitch is properly inserted into the outer member 59 so that the 
apertures 60 and 61 are properly aligned with one another as shown in FIG. 
1. The stud 11 may then be inserted into the apertures 60 and 61 so that 
the keyed portion 19 extends out from the apertures 60 and 61 to the side 
63 opposite to that side 62 in which the stud 11 was inserted. While 
holding the stud 11 by its expanded head 13 so the stud 11 does not come 
out of the apertures 60 and 61, the user may place the knob 14 over the 
keyed portion 19 or boss, so that the forward portion 18 of the stud 11 
extends partly into the rearward section 47 of the casing hole 27. Turning 
the key 16 clockwise will cause the threaded stud 33 to engage the 
threaded axial hole 24, thereby drawing the forward portion 18 of the stud 
11 fully into the rearward section 47 of the casing hole 27. As the key 16 
is turned, only the tumbler housing 32 and threaded stud 33 which comprise 
the internal mechanism 26 rotate within the casing 25. Neither the casing 
25 nor the stud 11 rotate as the key 16 is turned. Every one-quarter turn 
of the key 16 causes the slide tumblers 39 to be aligned with one of the 
four keyways 30 within the casing hole 27. When so aligned, the key 16 may 
be withdrawn and the tumbler housing 32 locked into position. Without the 
key 16, the knob 14 cannot be removed from the stud 11. Re-inserting the 
key 16 and turning the key 16 counterclockwise until the threaded stud 33 
and threaded axial hole 24 disengage removes the knob 14 from the stud 11. 
In other applications of the present invention, the knob 14 is locked to 
the stud 11 in much the same manner as described above. 
The locking hitch pin 10 shown in FIG. 1 may be also used with trailer 
hitching systems where the central member 58 is solid instead of hollow. 
Once in place, the locking hitch pin 10 according to the present invention 
is very difficult to pry open or to otherwise improperly remove. All 
surfaces on the locking device which might be vulnerable to prying are 
obscured or tapered to remove prying or pivoting points. 
It is to be understood that the present invention is not limited to the 
particular arrangement and embodiments of the parts disclosed and 
illustrated herein, but embraces all such modified forms thereof as come 
within the scope of the following claims.