U.S. patent number 3,702,553 [Application Number 05/141,875] was granted by the patent office on 1972-11-14 for cylinder lock plug.
This patent grant is currently assigned to Tool Research & Engineering Corporation. Invention is credited to Roger J. Nolin.
United States Patent |
3,702,553 |
Nolin |
November 14, 1972 |
CYLINDER LOCK PLUG
Abstract
A cylinder lock plug comprising two plug sections adapted to
mate on facing surfaces defining a keyway, with the periphery of
the sections adapted to slide into a cylindrical plug sleeve
containing pin tumbler holes to complete the plug. Each plug
section has an enlarged shoulder area adjacent one end and a
threaded section adjacent the other end. When the plug is assembled
with the cylindrical member into a cylinder, the enlarged shoulder
areas mate to form the front face of the plug, and the threaded
sections cooperate to define a threaded surface to receive a
threaded retaining member. Each plug section defines the shape of
one side of the keyway, so that plugs with a great variety of
keyways may be made by using different combinations of a few plug
sections.
Inventors: |
Nolin; Roger J. (Monterey Park,
CA) |
Assignee: |
Tool Research & Engineering
Corporation (Beverly Hills, CA)
|
Family
ID: |
22497637 |
Appl.
No.: |
05/141,875 |
Filed: |
May 10, 1971 |
Current U.S.
Class: |
70/375; 70/367;
70/385 |
Current CPC
Class: |
E05B
27/0007 (20130101); Y10T 70/7638 (20150401); Y10T
70/7684 (20150401); Y10T 70/7746 (20150401) |
Current International
Class: |
E05B
27/00 (20060101); E05b 009/04 (); E05b
015/08 () |
Field of
Search: |
;70/375,385,367,369,382,453,454 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe; Robert L.
Claims
I claim:
1. For use in the cylinder of a cylinder lock a plug comprised of
first and second plug sections, a plug sleeve and a retaining
means, said plug sleeve having an inner surface for receiving said
first and second plug sections and a substantially cylindrical
outer surface with a plurality of radially oriented pin holes
disposed therein, said first and second plug sections having an
enlarged first end section, a second end section and a center
section therebetween, said first and second plug sections being
retained in adjacent cooperative relationship with facingly
disposed surfaces by said plug sleeve, said facingly disposed
surfaces being contoured to define a keyway and a plurality of pin
cavities aligned with the respective pin holes in said plug sleeve,
said enlarged first end of said first and second plug sections
together defining a front face having a diameter greater than the
diameter of said outer surface of said plug sleeve, said retaining
means engaging said first and second plug sections on said second
end sections and defining a surface extending outward beyond the
diameter of said outer surface of said plug sleeve to retain said
first and second plug sections and said plug sleeve in functional
disposition with respect to each other and with respect to said
cylinder.
2. The plug of claim 1 wherein said plug sleeve is of substantially
uniform cross-section, except for said pin holes, having a
thickness in the region of said pin holes sufficient to dispose the
inner surface of said last named region adjacent the top of said
keyway.
3. The plug of claim 2 wherein said plug sleeve has a longitudinal
groove on the inner surface of said plug sleeve diametrically
opposite said pin holes for receiving and guiding the lower edge of
a key.
4. The plug of claim 3 wherein the inner surface of said plug
sleeve is a substantially cylindrical surface interrupted by an
inward projecting longitudinal region containing said pin holes and
by inwardly disposed, substantially parallel projections defining,
at least in part, said longitudinal groove, and said center
sections of said plug sections locate on said last named
cylindrical surface and being maintained in substantially fixed
separation by surface abutting the sides of said inward projecting
longitudinal region and said parallel projections.
5. The plug of claim 1 wherein said plug sleeve is a plastic
member.
6. The plug of claim 1 wherein said first and second plug sections
are sintered metal sections.
7. The plug of claim 1 wherein said retaining means is comprised of
a cap having internal threads adjacent one end thereof, said second
end section of said first and second plug sections having threads
forming a portion of a threaded cylindrical surface and said cap
engaging said threads on said first and second plug sections.
8. The plug of claim 7 wherein said cap is locked against rotation
at a position on said threads so as to limit the axial motion of
said plug sections and said plug sleeve with respect to the
cylinder by a cylindrical locking member and a coil spring, said
first plug section having a groove in its outer surface extending
from said second end section and terminating part way along said
plug, said cap having an inwardly directed shoulder, with an
inwardly directed serrated surface, projecting over the end of said
first and second plug sections, and partially covering said groove
to retain said locking member in said groove, said locking member
and said coil spring being located in said groove so that said coil
spring urges said locking member toward said inwardly projecting
shoulder, said locking member having an area of reduced diameter
adjacent the outer end thereof engaging said serrated surface to
prevent substantial rotation of said internally threaded cap.
9. The plug of claim 8 wherein said second plug section has a
groove in its outer surface extending from said second end section
and terminating adjacent said first end section.
10. In a cylinder lock, a cylinder assembly comprised of a cylinder
having a substantially cylindrical inner surface and a pin tumbler
chamber with a plurality of pin tumbler holes containing pin
tumblers and pin tumbler springs, and a cylinder plug having first
and second plug sections, a plug sleeve having a length
substantially equal to the length of said cylinder and a retaining
means, said plug sleeve having an inner surface for receiving said
first and second plug sections and a substantially cylindrical
outer surface slidably fitting within said cylinder, with a
plurality of radially oriented pin holes cooperatively disposed
therein with respect to said pin tumbler holes in said cylinder,
said first and second plug sections having an enlarged first end
section, a second end section and a center section therebetween,
said first and second plug sections being retained in adjacent
cooperative relationship with facingly disposed surfaces by said
plug sleeve, said facingly disposed surfaces being contoured to
define a keyway and a plurality of pin cavities aligned with the
respective pin holes in said plug sleeve, said enlarged first end
of said first and second plug sections together defining a front
face having a diameter greater than the diameter of said outer
surface of said plug sleeve, said retaining means engaging said
first and second plug sections on said second end sections and
defining a surface extending outward beyond the diameter of said
outer surface of said plug sleeve to retain said first and second
plug sections and said plug sleeve in functional disposition with
respect to each other and with respect to said cylinder.
11. The plug of claim 10 wherein said plug sleeve is of
substantially uniform cross-section, except for said pin holes,
having a thickness in the region of said pin holes sufficient to
dispose the inner surface of said last named region adjacent the
top of said keyway.
12. The plug of claim 11 wherein said plug sleeve has a
longitudinal groove on the inner surface of said plug sleeve
diametrically opposite said pin holes for receiving and guiding the
lower edge of a key.
13. The plug of claim 12 wherein the inner surface of said plug
sleeve is a substantially cylindrical surface interrupted by an
inward projecting longitudinal region containing said pin holes and
by inwardly disposed, substantially parallel projections defining,
at least in part, said longitudinal groove, and said center
sections of said plug sections located on said last named
cylindrical surface and being maintained in substantially fixed
separation by surfaces abutting the sides of said inward projecting
longitudinal region and said parallel projections.
14. The plug of claim 10 wherein said retaining means is comprised
of a cap having internal threads adjacent one end thereof, said
second end section of said first and second plug sections having
threads forming a portion of a threaded cylindrical surface and
said cap engaging said threads on said first and second plug
sections.
15. The plug of claim 14 wherein said cap is locked against
rotation at a position on said threads so as to limit the axial
motion of said plug sections and said plug sleeve with respect to
the cylinder by a cylindrical locking member and a coil spring,
said first plug section having a groove in its outer surface
extending from said second end section and terminating part way
along said plug, said cap having an inwardly directed shoulder,
with an inwardly directed serrated surface, projecting over the end
of said first and second plug sections, and partially covering said
groove to retain said locking member in said groove, said locking
member and said coil spring being located in said groove so that
said coil spring urges said locking member toward said inwardly
projecting shoulder, said locking member having an area of reduced
diameter adjacent the outer end thereof engaging said serrated
surface to prevent substantial rotation of said internally threaded
cap.
16. The plug of claim 15 wherein said second plug section has a
groove in its outer surface extending from said second end section
and terminating adjacent said first end section and said first end
section has a hole therethrough cooperatively disposed with said
groove for receiving and guiding an indicator pin therein.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of cylinder locks.
2. Prior Art
Prior art plugs for cylinder locks are generally fabricated by
either of two methods. These methods are to machine the plug from a
solid brass bar, or to use a zinc die casting for the plug.
Machining the plug from a solid brass bar yields an accurate and
durable plug for use in locks. However, such plugs are relatively
expensive because of the number of machining operations required to
complete the plug and the specialized machine tools required to
carry out these operations. By way of example, starting with a bar
of sufficient diameter to define the front shoulder or face of the
plug, the bar must be turned down on a screw machine to the inside
diameter of the cylinder. The pin holes must be drilled, the keyway
broached, and some provision made on the plug for locking the plug
in the cylinder. In one prior art plug this locking provision
required threading the end of the plug opposite the front face and
drilling a hole adjacent the periphery of the plug so that a
locking member could be screwed onto the plug to retain the plug in
the cylinder, with the locking member being retained by a spring
loaded pin inserted into the aforementioned hole. Further, for use
in hotels where a visual indicator pin is to be provided, the
visual indicator pin hole must be drilled the full length of the
plug. These various operations are all relatively slow and costly
operations requiring expensive and specialized equipment to assure
adequate accuracy and dimensional control. Also, it is clear that a
special broach must be used for each special keyway
configuration.
The number of operations and cost associated with producing a
finished plug from a zinc die casting is substantially less than
machining the plug from a solid brass bar. However, not all
machining operations are eliminated by the use of the zinc dye
casting since, in general, the pi tumbler holes must be drilled in
the dye casting to assure a sufficiently accurate location for such
holes. Also, zinc itself has certain disadvantages making it
undesirable or even unacceptable in certain applications. The major
disadvantage is the characteristically low melting point of zinc
and zinc alloys which make zinc lock parts unacceptable under
certain federal specifications and for commercial and industrial
applications. Also, it is difficult to maintain close tolerances in
a zinc die casting, particularly to maintain a close tolerance
keyway in the die cast plug.
One prior art lock plug having a split cylindrical section is
disclosed in U.S. Pat No. 3,429,154 entitled "Lock Plug." The plug
disclosed in that patent has a first section forming one-half of
the plug and having the front face or shoulder integral therewith.
A second member mates with the first member so as to define
therebetween a continuation of the keyway in the front face of the
plug integral with the first member, and to define a plurality of
pin holes. That plug is intended to be fabricated from plastic, and
though it contains certain advantages over other prior art plugs,
primarily in regard to fabrication, it also has certain
disadvantages in regard to utility which detract from its
usefulness. By way of example, the front face contains a portion of
the keyway and, therefore, defines the cross-section of the key.
Consequently, the other section mated with this first section must
match the same keyway and, therefore, different sections may not be
assembled in a different manner so as to create a large combination
of keyway shapes.
The prior art split plug is comprised of two half sections which
are held in functional disposition to each other at least in part
by the cylinder housing in which they operate. Thus, when a key is
inserted into the keyway in the plug and rotated, the two half
sections will be forced apart and pushed into firm rubber
engagement with the cylinder. This may cause increased wear of the
plug, particularly at the edges of the half sections, and may
result in an increasing looseness in the fitting of the various
parts of the assembly. In this regard, it should be noted that
because of the looseness of the two half sections defining the
keyway and the fact that the two half sections also define the pin
holes, looseness of the sections or a tendency of the sections to
move one with respect to the other will change the apparent
geometry of the pin holes, possibly binding the pins between the
two half sections and preventing the free operation of the
lock.
These problems are aggravated when a bent key is inserted into the
lock. In that case, the two sections are strongly forced apart by
the mere pressure of the key, thereby causing increased wear or
binding between the plug and the cylinder. Also, since the front
face is integral with only one section of the plug, the other
sections may tend to shift longitudinally when a bent key is
inserted, thereby shifting one-half of each pin hole with respect
to the other half and pinching the pins therein so as to prevent
the free operation of the lock.
BRIEF SUMMARY OF THE INVENTION
The present invention utilizes a cylinder lock plug comprising two
plug sections adapted to mate on facing surfaces defining a keyway,
with the periphery of the sections adapted to slide into a
cylindrical plug sleeve containing pin tumbler holes to complete
the plug. Each plug section has an enlarged shoulder area adjacent
one end and a threaded section adjacent the other end. When the
plug is assembled with the cylindrical member into a cylinder, the
enlarged shoulder areas mate to form the front face of the plug
having a keyway therein, and the threaded sections cooperate to
define a threaded surface to receive a threaded retaining member.
Each plug section defines the shape of one side of the keyway so
that plugs with a great variety of keyways can be made by using
different combinations of a few plug sections.
The threaded retaining member has an outer diameter which is
greater than the diameter of the plug sleeve. In assembly, it is
threaded onto the two plug sections to position so as to retain the
plug sections and plug sleeve in functional disposition with
respect to the cylinder with a minimum of axial freedom. One plug
section has a slot originating at the threaded end and terminating
adjacent the large shoulder area for receiving a coil spring and a
locking pin. The coil spring urges the locking pin against the
retaining member, and a protrusion on the end of the locking pin
engages the serration on an inward protruding lip on the back
portion of the retaining member so as to lock the retaining member
against any substantial rotation. The other plug section also has a
groove running from the threaded end up to the large shoulder area
which, in applications requiring an indicator pin through the front
face of the plug, may be extended by drilling a hole in the plug
face and used to receive the indicator pin.
Both plug sections are simple members which may be formed to their
finished dimensions by any of a number of processes. In the
preferred embodiment, sintered brass is used for the plug section.
The plug sleeve may also be formed to the finished dimensions
either by molding out of a suitable plastic such as nylon or by
forming the sleeve to the finished dimensions out of such material
as sintered brass.
Brief Description of the Drawings
FIG. 1 is a front view of a cylinder assembly using the cylinder
plug of the present invention.
FIG. 2 is a cross-section of the cylinder assembly of FIG. 1 taken
along lines 2--2 of that figure.
FIG. 3 is a partial cross-section of the cylinder plug of FIG.
2.
FIG. 4 is a back view of the cylinder assembly of FIG. 1.
FIG. 5 is a cross-section of the cylinder assembly of FIG. 1 taken
along lines 5--5 of FIG. 4.
FIG. 6 is a cross-sectional view of the cylinder assembly of FIG. 1
taken along lines 6--6 of FIG. 2.
FIG. 7 is a perspective view of the plug sleeve 40.
FIG. 8 is an exploded view of the cross-section of plug sleeve 40
with two plug sections 22a and 24a defining a specific key way
shape.
FIG. 9 is a cross-section of plug sleeve 40 with plug section 24a
of FIG. 8 and a new plug section 22b so as to define a different
keyway shape over the assembly of FIG. 8.
FIG. 10 is a perspective view of plug sections 22 and 24 showing
the details of the plug sections, and particularly the normally
facingly disposed surfaces of the plug sections.
DETAILED DESCRIPTION OF THE INVENTION
First referring to FIG. 1, a front view of the plug of the present
invention in a prior art cylinder may be seen. In this figure, the
front face and keyhole are formed by plug section 22 and plug
section 24 which abut each other at the front face on a vertical
plane 26. Also visible in this figure is the cylinder 28 and pin
tumbler chamber 30, well-known in the prior art, and a visual
indicator pin 32 which is used in locks for hotel and motel rooms
to indicate that the room is occupied. Such indicator pins are also
well-known in the prior art and are mentioned herein only to
indicate the ease with which an indicator pin may be used in
conjunction with the plug of the present invention.
Now referring to FIG. 2, a cross-section of the cylinder assembly
of FIG. 1 taken along lines 2--2 of that figure may be seen.
Cylinder 28 forms a cylindrical cavity surrounding the plug, with
pin tumbler chamber 30 integral therewith. The pin tumbler chamber
contains a plurality of holes having pin tumblers 34 and tumbler
springs 36 urging the pin tumblers toward the plug. Pins 38 are
located in cooperatively disposed holes in plug sleeve 40, which
forms a portion of the plug of the present invention. The bore of
cylinder 28 is smaller in diameter than the front face of sections
22 and 24 so that shoulder 42 defined by the front face of the two
sections locates the sections with respect to cylinder 28. The two
sections 22 and 24, as well as plug sleeve 40, are retained in the
cylinder by a internally threaded cap 44 which screws onto a
threaded area defined in part by an extension of each of sections
22 and 24. The cap 44 is retained against rotation by a pin in
section 22 (to be subsequently described in greater detail) at a
proper axial position to minimize the axial freedom between
sections 22 and 24 and cylinder 28, but allow the free rotation of
the plug with respect to the cylinder. Not shown in FIG. 2 is a
drive member for operating a bolt, well-known in the prior art,
which is captured between the surface 46 defined by the ends of
sections 22 and 24 and shoulder 48 on cup 44, and driven in
rotation by the same pin which retains cap 44 with respect to
sections 22 and 24.
When a proper key 50 is inserted into the plug, pins 38 take the
positions in plug sleeve 40 shown in FIG. 2, thereby allowing the
free rotation of the plug.
Further details of the plug sleeve 40 may be seen in FIG. 6, which
is a cross-section of the cylinder assembly taken along lines 6--6
of FIG. 2, and in FIG. 7 which is a perspective view of the plug
sleeve 40. Plug sleeve 40 is generally cylindrical sleeve of
substantially the same length as cylinder 28. The plug sleeve has a
uniform cross-section, except for pin holes 52, and has an outer
diameter adapted to provide a slip fit between the plug sleeve 40
and cylinder 28. As with prior art plugs, plug sleeve 40 has a
flattened surface 54 in the region of pin holes 52 so as to form a
flattened surface cooperative with the flat ends of the pins and
pin tumblers to allow the initial rotation of the plug upon
insertion of the proper key.
Plug sleeve 40 has an enlarged, substantially rectangular section
56 in the vicinity of pin holes 52. Though the plug sections 22 and
24 have cooperatively disposed surfaces 58 to define a continuation
of pin holes 52 (FIGS. 6 and 10), the major guidance for pins 38 is
provided by the holes 52 in regions 56 of the plug sleeve,
particularly as the pins approach their respective positions
allowing operation of the lock. This is to be compared with the
prior art split plug where the pin holes were totally defined by
the two plug halves, thereby allowing either looseness of the pins
on the separation of the two halves, or the binding of the pins by
the longitudinal shift of one part with respect to the other.
Diametrically opposite the pin holes 52 in the plug sleeve 40 is a
groove 60 defined by the inward protruding members 62 which are
integral with the plug sleeve. The groove 60 provides a guide for
the lower edge of key 50 so as to guide the key and maintain the
proper key position with respect to the pin tumbler chamber as the
key is being inserted into the plug.
Plug sections 22 and 24, and particularly the facingly disposed
surfaces thereof, may be best seen in FIG. 10. Each plug section
has an enlarged frontal area 64 adapted to mate with the frontal
area of the other plug section on the surfaces 66 to define the
front face or shoulder 42. The surfaces 66 and the two plug
sections are the only surfaces on the plug sections which mate or
substantially mate with each other in the preferred embodiment.
Surfaces 68 and 70 define the two sides of the keyway and are held
in separation in part by faces 66 on the enlarged frontal area 64,
and in part by location of each section between the rectangular
section 56 and the inward protruding members 62 in the plug sleeve
(FIG. 6). Surfaces 72 are flat surfaces adapted to slide along
rectangular section 56, and surfaces 74 are adapted to slide along
inward protruding members 62. Located at one end of the plug
sections is a threaded surface 76 which, when the sections are
assembled into the plug sleeve, are disposed so as to be engageable
by internally threaded cap 44. Also, visible in FIG. 10, are the
slots 78 and 80 originating at the threaded end of the plug
sections and running longitudinally along the sections. Groove 80
in plug section 22 is for receiving the locking pin and coil
spring, to be subsequently described, and projects from the
threaded end of the plug section up to the enlarged frontal area
64. Groove 78 in plug section 22 is for receiving the indicator pin
32 (FIG. 1) and also projects from the threaded end of the plug
section up to the enlarged frontal area 64. In those applications
using the indicator pin 32, the hole in the front face 64 of
section 24 for the pin is drilled in a subsequent operation. This
is to be compared with the prior art plugs, where the hole for the
indicator pin must be drilled the full length of the plug, a time
consuming and costly operation.
The mating of plug sections 22 and 24 may be best seen in FIG. 3,
which is a top view of the plug of the present invention in a
cylinder with the cylinder 28, retaining nut 44 and a portion of
the plug sleeve 40 shown in cross-section. The two plug sections
mate on surfaces 66 as hereinbefore described and are held in
separation by engagement with rectangular section 56 and inward
protruding members 62. The region between plug sections 22 and 24
within cylinder 28 define both sides of the keyway and since, as
may be seen in FIG. 2, the higher lobes on the key extend upward to
a position just below the inner surface of the rectangular section
56 and the lower edge of the key rides in the groove 60 in the plug
sleeve 40, the two plug sections must be held in separation in this
region to allow free passage of the key. Also, as may be seen in
FIG. 3, the two plug sections 22 and 24 do not mate in the region
within cap 44. This however, is not a requirement as the key 50
(FIG. 1) projects only into a portion of that area, and cylinder
plug sections 22 and 24 could have a configuration which included
inwardly disposed mating surfaces in the region under cap 44. Also,
while in the preferred embodiment of the present invention plug,
the key 50 substantially extends from rectangular section 56 to
groove 60 in cylinder plug 40 so as to prevent any facingly
disposed surfaces in the region of the keyway from mating, plugs
could be designed using the principles of the present invention in
which the plug sections had facingly disposed mating surfaces above
or below the key. By way of example, the plug sections 22 and 24
might be made to extend below the lower edge of key 50 so as to
mate in that region and define a groove or guide for the lower edge
of the key.
Now referring to FIGS. 4 and 5, details of the manner of locking
cap 44 in the desired position along the threads 76 on the plug
sections may be seen. FIG. 4 is a rear view of the cylinder
assembly of FIG. 1, and FIG. 5 is a cross-section taken along lines
5--5 of FIG. 4. The inner surface of shoulder 48 has a series of
serrations 90 which are generally in the shape of semicylindrical
reliefs on the inner diameter of the shoulder. Groove 80 in plug
section 22 houses a coil spring 92 and a locking pin 94. The
locking pin 94 has a first section 96 having a loose slip fit in
groove 80 between plug section 22 and the adjacent wall of plug
sleeve 40. A second section 98 of reduced diameter extends below
the minor diameter of the thread 76 on the end of plug section 22,
and in cooperation with the end 100 of further reduced diameter
defines shoulder 102 which abuts the interface of shoulder 48 so as
to retain locking member 94 and prevent its further expulsion by
coil spring 92. End section 100 engages one of the serrations 90 in
the inner surface of shoulder 48 so as to prevent the rotation of
the cup is desired, such as upon assembly or any subsequent
disassembly, the locking member 94 may be pushed in against coil
spring 92 so that end section 100 no longer engages the serrations
in retaining nut 44, thereby allowing the free rotation of the
retaining nut.
Now referring to FIGS. 8 and 9, one advantages of the present
invention cylinder plug may be seen. These figures are
cross-sections of typical plug sections and keys. In FIG. 8, plug
section 222 and 24a are shown which together define a keyway for
use with a key having the cross-section of key 50a. In FIG. 9, the
plug section 24a of FIG. 8 has been replaced with plug section 24b
so as to define a new keyway for use with a key 50b having a
different cross-section than key 50a. It is thus apparent that if
plug section 22a were replaced with a new plug section having a
different face defining one side of the keyway, plugs defining two
additional keyway shapes could be assembled therefrom. By having a
number of plug sections, each defining a different shape for one
side of the keyway, assemblies of the plug sections may be made to
define a great variety of keyway shapes. By way of example, if plug
section 22 and 24 were each made having five different shapes on
the surfaces defining the respective sides of the keyway, a total
of 25 plugs, each having a different keyway shape, could be
assembled from these plug sections. This is to be compared to the
prior art split plug in which the number of combinatiosn is limited
to the number of pairs of matched parts (five pairs of parts
produced only five combinations, rather than 25 combinations as in
the present invention).
The parts for the present invention plug may be fabricated in a
number of ways and out of a number of different materials depending
upon requirements for the specific application. In the preferred
embodiment, the plug sections 22 and 24 are sintered metal sections
and are sintered to their finished dimensions. It is to be noted
that because of the designs of the plug sections the plugs may be
molded with molds having simple cavities since there are no holes,
keyways, etc. which would require removable pieces in the mold.
This is also be compared with the prior art split plug wherein one
part of the plug had the entire plug face, with a keyway molded
into the face integral therewith, which necessarily requires a much
more complex mold to mold the part to the finished dimensions.
The plug sleeve 40 of the present invention plug in the preferred
embodiment is molded to its finished dimensions out of nylon. Of
course, any plastic material, preferably one having
self-lubricating characteristics, could be used for the sleeve. The
use of nylon or a similar plastic provides adequate strength for
holding the plug sections in proper disposition and results in a
smoothly operating plug within the cylinder. However, in certain
applications a plastic material for plug sleeve 40 will not be
acceptable because of the temperature limitations of the material.
In those applications a metal such as sintered brass, sintered to
the finished dimensions, would be used. In this regard, it should
be noted that except for the pin holes in the plug sleeve, the plug
sleeve has a uniform cross-section so that the plug sleeves could
be made from an extruded member such as a brass extrusion by simple
cutting the extrusion into the desired length and drilling the pin
holes. Of course, other materials such as stainless steel, zinc,
etc. may also be used for any or all of the parts of the present
invention plug.
The present invention plug results in a substantial cost reduction
and greater flexibility in the selection of key shapes by grossly
reducing the operations required to produce a finished plug and by
providing flexibility in the matter of assembly of various plug
sections to create a large variety of keyways. While the plug has
been shown in assembly with a conventional cylinder, it should be
noted that the plug may also be used with the cylinder of my
co-pending applications entitled "Cylinder Housing for Locks" filed
Oct. 7, 1970 wherein a cylinder is disclosed which may be assembled
from parts which also may be sintered to their finished dimension.
Consequently, these two inventions, when used in conjunction with
each other, result in a cylinder and cylinder plug combination
which may be assembled directly from molded and/or sintered parts
without any required machining, thereby resulting in a very
substantial cost reduction over the equivalent prior art parts,
while at the same time providing greater flexibility and lower
costs associated with the selection of new and different keyway
shapes. Also, the present invention lends itself readily to
improved "grand master keyway" applications which are standard in
the art, without the requirement of expensive tooling. Of course,
these results may also be obtained by making variations in the
design and configuration of the component parts making up the
assembly. Thus, while the invention has been particularly shown and
described with reference to a preferred embodiment, therefore, it
will be understood by those skilled in the art that various changes
in form and detail may be made therein without departing from the
spirit and scope of the invention.
* * * * *