U.S. patent number 3,876,236 [Application Number 05/390,847] was granted by the patent office on 1975-04-08 for dead-locking latch bolt mechanism.
This patent grant is currently assigned to Best Lock Corporation. Invention is credited to Walter E. Best, R. Gene McCullum.
United States Patent |
3,876,236 |
Best , et al. |
April 8, 1975 |
Dead-locking latch bolt mechanism
Abstract
A latch bolt mechanism for use with a cylindrical lock set has a
main latch bolt and an auxiliary bolt to control deadlocking of the
main bolt, all mounted in a tubular housing. The main bolt has a
tubular stem telescopically received over a tailpiece in the form
of a round rod with a retraction head at the rear. The tailpiece is
slidable in the stem through lost motion which is limited by
engagement between a stop ring on the stem and a timing groove in
the tailpiece, and the tailpiece is biased to forward position by a
spring acting between a cap at the front end of the tailpiece and a
reaction washer pressed into the bolt stem. A deadlocking dog is
pivoted on a rear support with its forward end positioned to block
rearward movement of the bolt stem. The tailpiece also has a cam
groove to receive the dogging end of the dog, and the cam of such
groove releases the deadlocking dog when the tailpiece is first
retracted through its limited lost motion in the stem and
thereafter retracts the latch bolt. The bolts are urged forward by
springs which seat on a foot lever fulcrumed against the end
closure of the tubular housing and engaged at its end with a lug on
the deadlocking dog to bias that dog toward its deadlocking
position. The auxiliary bolt carries a dog release finger which
normally holds the deadlocking dog in release position, but which,
when the auxiliary bolt is retracted relative to the bolt, lets the
locking dog move to bolt-blocking position. The tailpiece spring is
weaker than the bolt spring so that when the bolt is deadlocked
retraction of the tailpiece first moves it through its lost motion
to where its cam will release the locking dog, and then moves it to
retract the latch bolt.
Inventors: |
Best; Walter E. (Indianapolis,
IN), McCullum; R. Gene (Indianapolis, IN) |
Assignee: |
Best Lock Corporation
(Indianapolis, IN)
|
Family
ID: |
23544188 |
Appl.
No.: |
05/390,847 |
Filed: |
August 23, 1973 |
Current U.S.
Class: |
292/169.13;
292/DIG.57 |
Current CPC
Class: |
E05B
55/12 (20130101); E05B 55/005 (20130101); Y10T
292/098 (20150401); Y10S 292/57 (20130101) |
Current International
Class: |
E05B
55/12 (20060101); E05B 55/00 (20060101); E05c
001/16 () |
Field of
Search: |
;70/151R,151A,463
;292/169.13 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Craig, Jr.; Albert G.
Claims
We claim:
1. A deadlocking latch bolt mechanism comprising a bolt
housing,
a latch bolt slidably mounted in said housing and having a tubular
stem fixed thereto and extending rearward therefrom a distance not
less than the throw of the bolt, said stem having a
rearwardly-presented stop face,
a rod-shaped tailpiece telescopically mounted in said stem in
coaxially supporting relation therewith and having limited axial
lost motion therein, said tailpiece having a head at its rear end
for retraction engagement with the retractor of a lock
mechanism,
a locking dog mounted in said housing and having a
forwardly-presented dogging end, said dog having a dogging position
in which said dogging end lies in the path of said stop face of the
stem to block retraction of the bolt and a release position in
which said end lies out of said path so as to permit such
retraction,
said dog also having a cam portion which includes a sloping cam
surface rearward of said dogging end and which in dogging position
of the dog projects inward of the inner surface of the stem and
into interfering relation with the tailpiece,
said tailpiece having a groove therein which has an inactive
forward position aligned with said cam portion so as to receive the
same and allow the dog to assume its dogging position, and which
groove has an active rearward position to which it is moved by
rearward movement of the tailpiece relative to the stem and in
which its forward end is operative to engage said sloping cam
surface of the dog and move the dog outward sufficiently to
position its dogging end out of the path and its sloping cam
surface in the path of said stop face of the stem so as to cause
the dog to ride past such stop face and allow retraction of the
bolt upon further rearward movement of the tailpiece,
and an auxiliary bolt slidable in said housing and means movable
therewith for moving the locking dog to release position when the
auxiliary bolt is in projected position and permitting the dog to
assume its dogging position when the auxiliary bolt is retracted
relative to the latch bolt.
2. A deadlocking latch bolt mechanism as in claim 1, further
comprising
a timing groove in the tailpiece spaced forwardly from said
cam-receiving groove, and a stop member fixed to the stem and
engaged in the timing groove, the timing groove being axially
longer than the stop member by a predetermind amount so as to limit
the lost motion between the tailpiece and stem.
3. A deadlocking latch bolt mechanism as in claim 1, in which said
tailpiece has slidable telescopic engagement with said stem over a
long length thereof greater than the inside diameter of the stem so
as to form a coaxially self-sustaining assembly, and said bolt has
slidable bearing engagement with the forward end of said housing,
and bearing means at the rear of the housing and slidably
supporting the tailpiece to thereby support said assembly and the
bolt in coaxial slidable relation with the housing.
4. A deadlocking latch bolt mechanism as in claim 1, which includes
a bolt-advancing spring biasing said latch bolt toward projected
position, and biasing means acting between the tailpiece and latch
bolt to urge the tailpiece forward in its lost motion relative to
the stem, said biasing means being weaker than said advancing
spring so that rearward pull on the tailpiece by the retractor will
first move the tailpiece relative to the latch bolt to dispose said
tailpiece groove in its active position and thereafter retract the
latch bolt.
5. A deadlocking latch bolt mechanism as in claim 4, in which said
locking dog is pivotally mounted at the rear of the housing and has
a forward dogging end, and said tailpiece groove has a cam surface
formed at its forward end for engagement with said cam surface on
the dog.
6. A deadlocking latch bolt mechanism, comprising
a bolt housing,
a latch bolt slidably mounted in said housing and having a
rearward-extending tubular stem fixed thereto,
a rod-shaped tailpiece telescopically mounted in said stem and
having limited axial lost motion therein, said tailpiece having a
head at its rear end for retraction engagement with the retractor
of a lock mechanism,
a locking dog mounted in said housing and having a dogging position
in which it lies in the path of said stem to block retraction of
the bolt and a release position in which it permits such
retraction,
cam means on said tailpiece having an inactive forward position and
an active rearward position to which it is moved by rearward
movement of the tailpiece relative to the stem, said cam means
being operative in said active position to move the dog from its
dogging position to its release position,
an auxiliary bolt slidable in said housing and means movable
therewith for moving the locking dog to release position when the
auxiliary bolt is in projected position and permitting the dog to
assume its dogging position when the auxiliary bolt is retracted
relative to the latch bolt,
biasing means acting between the tailpiece and latch bolt to urge
the tailpiece forward in its lost motion relative to the stem to a
position in which it disposes the cam means in its inactive forward
position, and a bolt-advancing spring biasing said latch bolt
toward projected position, said biasing means between the tailpiece
and latch bolt being weaker than said advancing spring so that
rearward pull on the tailpiece by the retractor will first move the
tailpiece relative to the latch bolt to dispose said cam means in
its active position and thereafter retract the latch bolt,
said locking dog being pivotally mounted at the rear of the housing
and having a forward dogging end which in dogging position lies
adjacent the side of the tailpiece in the path of said stem,
said cam means comprising a cam element formed on said tailpiece
which in its forward inactive position during rearward movement of
the bolt allows the dog to engage the stem before it engages said
cam element, and in its active rearward position engages the dog to
move it out of the path of the stem before the dog engages the
stem,
said cam element being the forward portion of a circumferential
groove in the rod-shaped tailpiece, and said locking dog having a
cooperating cam element which lies in said groove when the dog is
in dogging position.
7. A deadlocking latch bolt mechanism, comprising
a bolt housing,
a latch bolt slidably mounted in said housing and having a
rearward-extending tubular stem fixed thereto,
a rod-shaped tailpiece telescopically mounted in said stem and
having limited axial lost motion therein, said tailpiece having a
head at its rear end for retraction engagement with the retractor
of a lock mechanism,
a deadlocking dog mounted in said housing and having a dogging
position in which it lies in the path of said stem to block
retraction of the bolt and a release position in which is permits
such retraction,
cam means on said tailpiece having an inactive forward position and
an active rearward position to which it is moved by rearward
movement of the tailpiece relative to the stem, said cam means
being operative in said active position to move the dog from its
dogging position to its release position,
an auxiliary bolt slidable in said housing and means movable
therewith for moving the locking dog to release position when the
auxiliary bolt is in projected position and permitting the dog to
assume its dogging position when the auxiliary bolt is retracted
relative to the latch bolt,
a spring extending longitudinally of said housing and urging one of
said bolts to projected position,
a support at the rear of the housing,
said deadlocking dog being pivoted at the rear of said housing,
extending forward therefrom, and having a pressure lug extending
inward of its pivot axis,
and a foot lever having a heel portion fulcrummed on said support
and having a toe portion engaging said pressure leg,
said spring being supported by and reacting against said foot lever
at a point between its heel and toe portions so as to urge the foot
lever about its fulcrum in a direction to press on the pressure lug
of the deadlocking dog and thereby bias the deadlocking dog inward
toward its deadlocking position.
8. A deadlocking latch bolt mechanism as in claim 7 which includes
two springs on opposite sides of said tailpiece, respectively for
urging the latch bolt and auxiliary bolt to projected positions,
said foot lever being arranged to support and sustain the reaction
of both of said springs.
9. A deadlocking latch bolt mechanism as in claim 8, in which said
rear support carries guide pins extending axially through said
springs and said foot lever is a C-shaped member having bifuricated
ends engaged about said pins.
10. A deadlocking latch bolt mechanism, comprising a generally
cylindrical bolt housing,
a latch bolt slidable in said housing and including a bolt member
and a rearward-extending tailpiece,
said bolt member having a latch side face extending chordally of
said housing,
an auxiliary bolt slidably mounted against said latch side face,
said auxiliary bolt being narrower than the chordal side face of
the latch bolt so as to form longitudinal angular grooves at
opposite sides of the auxiliary bolt,
and low-friction bearing blocks mounted in said grooves.
11. A deadlocking latch bolt mechanism as in claim 10, with the
addition of a stop plate fixed to the rear face of said latch bolt
member and having arms extending into said angular grooves, said
bearing blocks being engaged over said arms so as to move with the
latch bolt, and a plate closing said grooves at the outer end of
said housing, against which the bearing blocks engage to stop
outward movement of the latch bolt.
12. A deadlocking latch bolt mechanism as in claim 11 with the
addition of a stop segment fixed to the inner end of said auxiliary
bolt and overlying the rear faces of said bearing blocks so as to
engage the same to stop forward movement of the auxiliary bolt
relative to the latch bolt.
13. A deadlocking latch bolt mechanism, comprising
a tubular bolt housing,
a latch bolt slidably mounted in the forward end of said housing
and having a rearward-extending tubular stem fixed thereto,
a rod-shaped tailpiece telescopically mounted in said stem and
having limited axial lost motion therein, a tailpiece-biasing
spring or the like acting between the bolt and tailpiece and urging
the tailpiece forward with respect to the bolt, said tailpiece
having a head at its rear end for retraction engagement with the
retractor of a lock mechanism,
a locking dog pivotally mounted at the rear of the housing and
extending foward along side the tailpiece and having a forward
dogging end which normally lies in a dogging position in the path
of said stem to block retraction of the bolt, said dog being
pivotally movable outward from said dogging position to a release
position in which it lies out of the path of the stem so as to
permit retraction of the bolt, spring means biasing the dog to said
normal dogging position,
a cam element formed on the tailpiece opposite a portion of said
locking dog, said cam element having a normal position in which it
clears the locking dog to permit the same to assume its dogging
position when the tailpiece is forward with respect to the bolt,
said cam element being movable to a position to engage the locking
dog upon rearward lost-motion movement of the tailpiece and to move
the locking dog to its release position so as to permit rearward
movement of the tailpiece to retract the bolt,
a foot lever having a heel portion fulcrumed on a support at the
rear of said bolt housing and having a toe portion engaged with
said locking dog so as to tilt the same inward to its normal
locking position,
and a spring acting between one of said bolts and said foot lever
to urge the bolt forward and urge the lever in a direction to tilt
the locking dog to its dogging position.
14. A deadlocking latch bolt mechanism, comprising
a bolt housing,
a latch bolt slidably mounted in said housing and having a
rearward-extending stem fixed thereto,
a tailpiece connected with said stem and having limited axial lost
motion with respect to the stem, said tailpiece having means at its
rear end for retraction by the retractor of a lock mechanism,
a locking dog pivotally mounted at the rear of said housing,
extending forward therefrom and having a pressure lug extending
inward of its pivot axis, said dog having a dogging position in
which it lies in blocking relation with said stem to block
retraction of the bolt and a release position in which it permits
such retraction,
and a foot lever having a heel portion fulcrumed on a support at
the rear of the housing and having a toe portion engaging said
pressure lug,
a bolt-advancing spring supported by and reacting against said foot
lever at a point between its heel and toe portions so as to urge
the foot lever about its fulcrum in a direction to press on the
pressure lug of the deadlocking dog and thereby bias the
deadlocking dog inward toward its deadlocking position,
dog-controlling means on said tailpiece having an inactive forward
position and an active rearward position to which it is moved by
rearward movement of the tailpiece relative to the stem, said means
being operative in said active position to move the dog from its
dogging position to its release position,
and an auxiliary bolt slidable in said housing and means movable
therewith for moving the locking dog to release position when the
auxiliary bolt is in projected position and permitting the dog to
assume its dogging position when the auxiliary bolt is retracted
relative to the latch bolt.
15. A deadlocking latch bolt mechanism, comprising
a bolt housing,
a latch bolt slidably mounted in said housing and having an
elongated tubular stem fixed thereto and extending rearward
therefrom,
a rod-shaped tailpiece telescopically received in said stem and
having slidable engagement therewith over a substantial length
thereof greater than the diameter of the rod so as to form a stiff
coaxially self-sustaining assembly in which the tailpiece has
limited axial lost motion in the stem, said tailpiece having a head
at its rear end for retraction engagement with the retractor of a
lock mechanism,
said bolt being slidably supported in said housing at the front end
of said coaxially self-sustaining assembly and said tailpiece being
slidably supported at the rear end of said housing, so as to
provide widely spaced slidable bearing supports for said
self-sustaining assembly to thereby support the same and the bolt
in coaxial slidable relation with the housing,
a locking dog mounted in said housing and having a dogging position
in which it lies in blocking relation with said stem to block
retraction of the bolt and a release position in which it permits
such retraction,
cam means on said tailpiece having an inactive forward position and
an active rearward position to which it is moved by rearward
movement of the tailpiece relative to the stem, said means being
operative in said active position to move the dog from its dogging
position to its release position,
and an auxiliary bolt slidable in said housing and means movable
therewith for moving the locking dog to release position when the
auxiliary bolt is in projected position and permitting the dog to
assume its dogging position when the auxiliary bolt is retracted
relative to the latch bolt.
16. A deadlocking latch bolt mechanism as in claim 15 in which said
bolt member has a latch side face extending chordally of said bolt
housing, said auxiliary bolt is slidably mounted against said latch
side face and is narrower than said chordal side face so as to form
longitudinal angular grooves at opposite sides of the auxiliary
bolt, and low-friction bearing blocks mounted in said grooves to
slidably support the front end of said bolt and tailpiece
assembly.
17. A deadlocking latch bolt mechanism as in claim 15 in which said
housing is cylindrical, said auxiliary bolt is slidably mounted in
a guiding groove in the side face of said latch bolt, and has a
substantially cylindrical outer face in substantially mating
bearing engagement with he front end of the cylindrical housing so
as to support the latch bolt for coaxial sliding movement
therein.
18. A deadlocking latch blt mechanism, comprising a bolt
housing,
a latch bolt slidably mounted in said housing and having an
elongated rearward-extending tubular stem fixed thereto, the
internal bore of said stem having a shoulder formed therein
adjacent its forward end,
a rod-shaped tailpiece telescopically mounted in the bore of said
stem and having limited lost motion therein, said tailpiece having
a shoulder adjacent its forward end and a reduced diameter end
portion extending beyond said tailpiece shoulder and having a cap
at its forward end,
a reaction washer mounted about said tailpiece end portion and
shaped to engage said tailpiece shoulder in thrust relation,
a spring about said tailpiece end portion and compressed between
said cap and washer so as to urge the washer rearward and urge the
cap and tailpiece forward relative to the washer,
said washer being fixed in the bore of the stem against the
shoulder therein so as to support the adjacent end of the spring in
fixed position in the stem against rearward movement and thereby
cause the spring to bias the cap and tailpiece forward relative to
the stem,
a locking dog mounted in said housing and having a dogging position
to which it is biased and in which it lies in blocking relation
relative to said stem to block retraction of the bolt, and a
release position in which it permits such retraction,
means on said tailpiece responsive to rearward lost motion movement
of the tailpiece relative to the stem, against the bias of said
spring, for moving said dog from its dogging position to its
release position,
and an auxiliary bolt slidable in said housing and means movable
therewith for independently moving the locking dog to release
position.
Description
BACKGROUND OF THE INVENTION
This invention relates to a bolt mechanism for use with a
cylindrical lock set and includes a main bolt which is deadlocked
against retraction when an auxiliary bolt is held in retracted
position by the strike plate with which the bolt is engaged.
Deadlocking latch bolt mechanisms are known as from U.S. Pat. Nos.
1,876,081 and 2,930,646. Prior mechanisms, however, present a
number of installation and operating difficulties. For example, in
U.S. Pat. No. 1,876,081 the bolt mechanism is not self contained
but depends on an exact relationship with the cylinder lock, and
the tailpiece has a cross slot which must be accurately located to
receive the claw edges of the retractor. With another similar
device, installation faults occur which permanently deadlock the
latch bolt and make it and its door inoperative. In U.S. Pat. No.
2,930,646, the deadlocking action depends on spring-pressed
movement of a cross slide as the bolt is forced back, which is
unreliable.
It is the purpose of the present invention to provide an improved
deadlocking bolt mechanism which will avoid installation
difficulties and problems heretofore encountered, will provide a
lock mechanism in a tubular housing which is substantially enclosed
to exclude dirt and sawdust, will have smooth and reliable
operation even under adverse conditions, and will be subject to low
wear and have a long operating life.
In a preferred embodiment of the invention, a main latch bolt
having a tubular stem is mounted in a cylindrical housing having a
rear closure plate. The bolt has a rearward-extending tubular stem
in which a rod-shaped tailpiece is telescopically received. The
tailpiece has a head at the rear for one-way retraction engagement
by a retractor of the cylindrical lock mechanism and is guided at
the rear by a bearing in the rear closure plate. The tailpiece has
limited lost motion with respect to the bolt stem, and is
spring-pressed into the stem by a spring trapped between a forward
cap on the tailpiece and a shoulder fixed in the stem. Lost motion
is limited by a timing groove in the tailpiece engaged by a stop
clip inserted through the wall of the bolt stem.
A deadlocking dog is pivoted at the rear of the housing and has a
dogging position in which its forward end lies in the retraction
path of the bolt stem to block retraction of the latch bolt. The
tailpiece has a cam groove at the rear of the stem, which moves to
a dog-releasing position when the tailpiece is retracted through
its lost motion.
The main and auxiliary bolts are urged forward by springs
positioned at diametrically opposite points in the housing. The
springs seat against a foot lever fulcrumed at the rear of the
housing and engaged against a lug on the locking dog to pivot it
toward its dogging position. The auxiliary bolt carries a release
finger which, when the plunger is flush with the main bolt, holds
the locking dog in release position, and which, when retracted
relative to the main bolt, lets the locking dog move to dogging
position.
The latch bolt spring is stronger than the tailpiece spring, so
that when the tailpiece is pulled rearward by the retractor of the
cylindrical lock mechanism, the tailpiece first moves through its
lost motion with respect to the latch bolt and thereby carries its
cam groove into dog-releasing position so that continued rearward
pull on the tailpiece can retract the bolt.
The auxiliary bolt is seated in a longitudinal groove in the latch
bolt, to support it in accurate alignment and provide firm support
for the back face of the latch bolt, especially when it is cammed
to retracted position by engagement with a strike plate. To enhance
this action, the outer face of the auxiliary bolt desirably has a
limited area of bearing contact with the bolt housing. The main
bolt carries a stop plate at its rear face, which straddles the
auxiliary bolt and carries wear-resistant bearing blocks in the
corner areas at the sides of the deadlocking plunger. The tubular
housing is closed at the front by a face plate by which it may be
mounted in a door, and the guide blocks move against such front
plate as a stop. The auxiliary bolt carries a guide segment at the
rear which moves against the rear of the guide blocks as a
stop.
The housing is closed at the rear by a rear closure plate which has
rearward extending flanges which are bent outward to define
segments of arcuate grooves between themselves and the rear face of
the tubular housing. The arcuate grooves are easily engaged with
the edges of the cylindrical lock housing, and position the
tailpiece for easy installation engagement with the retractor of
the cylindrical lock. The one piece round tailpiece and head
facilitate proper engagement of the tailpiece with the retractor
and avoid difficulties encountered with prior mechanisms.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate the invention. In such
drawings:
FIG. 1 is a horizontal sectional view of a latch bolt mechanism
embodying the invention, with the bolts extended;
FIG. 2 is a similar view, omitting the cylindrical lock mechanism
and showing the bolts in locking relation with a strike plate;
FIG. 3 is a vertical section taken on the line 3--3 of FIG. 1,
omitting some background parts and showing the latch bolt in
fully-extended position as in FIG. 1 and showing the dog in release
position;
FIG. 4 is a vertical section taken on the line 4--4 of FIG. 2,
showing the dog in deadlocking position;
FIG. 5 is a fragmental view showing the dog-releasing position of
the tailpiece cam groove;
FIG. 6 is a view similar to FIG. 3 but showing the bolts retracted
by the retractor of the cylindrical lock mechanism;
FIG. 7 is a front elevation of the lock mechanism shown in FIG.
3;
FIG. 8 is a section taken on line 8--8 of FIG. 3;
FIG. 9 is a section taken on the line 9--9 of FIG. 3;
FIG. 10 is a section taken on the line 10--10 of FIG. 3;
FIG. 11 is a fragmental section showing a stop ring in the bolt
stem and about the tailpiece, taken on the line 11--11 of FIG. 1;
and
FIG. 12 is a partial section taken on the line 12--12 of FIGS. 1
and 8, showing the auxiliary plunger and its control finger.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The lock mechanism shown in the drawings comprises a cylindrical
lock 10 having an operating mechanism mounted in a transverse hole
through a door 12 operated by knobs 14, at least one of which will
contain a key-controlled locking device. The retractor mechanism
may be any of a number of conventional mechanisms, and comprises a
cylindrical shell 16 having an axially extending slot defined by
edges 18 of the shell, and a retractor 20 having a transversly
slotted end adapted to slide axially into one-way, retracting
engagement with a head 22 on the tailpiece 24 of the bolt assembly
26 described below. Rotation of either knob moves the retractor 20
to the left as shown to retract the tailpiece and the bolt to which
it is connected.
The bolt assembly 26 in accordance with the present invention
comprises an outer tubular housing 30 having an inward flange 32 at
its rear and, as shown in FIG. 3, an outward flange 34 at its
forward end. The forward flange 34 extends upward and downward
considerable distances and is provided with punched openings. A
mounting face plate 36 is mounted across the front of the housing
30 and has screw-receiving openings defined by rearward collars 38
which extend through the flange openings and are flared outward to
secure the two parts together. The face plate is formed with a bolt
opening 37 as shown in FIG. 7. The rear end of the housing 30 is
closed by a closure plate 40 having a forwardly offset edge portion
42 which seats against the inward flange 32 of the housing. At
opposite sides of the housing, the closure plate 40 has
rearward-bent tongues 44 which extend rearward from the rear end of
the housing. After assembly of the closure plate 44 in the housing,
these flanges 44 are flared outward as shown in FIG. 3, to define
arcuate grooves adapted to receive the slot-defining edges 18 of
the lock cylinder shell 16, and thus to interconnect that shell 16
with the bolt housing 30.
A main latch bolt 46 is slidably mounted through the face plate 36
of the bolt housing, and has a latching face 48 and a sloping cam
face 50. The bolt 46 is fixed to the forward end of a tubular stem
52 which is telescopically received over the forward end of the
tailpiece 24. The tailpiece 24 has a tapered forward end 53 of
reduced diameter surrounded by a light spring 54. A cap 56 is
riveted to the end of the tapered portion 53 and is engaged from
the rear by the spring 54. The rear end of the spring bears against
a dished washer 58 which is fixed by a press fit against a shoulder
in the tubular stem 52. The spring acts between such washer 58 and
the cap 56 on the tailpiece to urge the tailpiece forward into
fully telescoped position in the bolt 46.
A timing groove 60 is cut in the tailpiece at a point intermediate
the length of the tubular stem 52 and a spring clip or stop ring 62
is inserted through a slot in the wall of the stem 52 into the
timing groove 60 to limit the lost motion of the tailpiece with
respect to the stem 52 and bolt 46. At the rear end of the stem 64,
the tailpiece is provided with a cam groove 52 for purposes to be
described. Except for the two grooves 60 and 64, the tailpiece is a
straight cylindrical rod which is freely rotatable and slidable in
the stem 52 within the limits of its lost motion.
The rear end of the tailpiece 24 extends through a central opening
in the rear closure member 42 and is supported therein by the edges
of the opening. If desired, a bearing washer 65 may be mounted
against the inner face of the closure plate 40. The bolt 46 is
urged forward by a spring 66, guided by a pin 68 which is fixed at
the rear and slidably extends into a tubular guide 70 fixed in the
latch bolt 46.
An auxiliary bolt 72 is mounted against the locking face 48 of the
main bolt 46. As shown in FIG. 7, the deadlocking plunger 72 has
beveled edges at its inner face and is slidably received in a
shallow groove 74 formed in the locking face 48 of the latch bolt
46. As shown in FIG. 8, the opposite or outer face 76 of the
deadlocking plunger 72 has an arcuate configuration on a somewhat
shorter radius than the inside radius of the tubular housing 30 so
as to slidably engage that housing over a limited line-contact
area. The deadlocking plunger 72 is urged forward by a spring 78
guided by a pin 80 which slidably extends into bore 82 in the
plunger 72.
A deadlocking dog 88 is mounted as follows. The two spring-guided
pins 68 and 80 are mounted at the rear in a mounting ring 84 which
seats against the peripheral edge of the rear closure plate 40 and
traps the bearing washer 65 against that plate. At one position on
the periphery of the mounting ring 84, at the bottom as shown in
FIGS. 3-5, a pivot tongue 86 is bent forward to form a pivot
bearing for the rear end of the locking dog 88. A central tongue 89
at the rear of the locking dog 88 is bent out of the plane of the
dog and the end of such tongue is bent at right angles to form a
pressure lug 90. The side portions 91 left by that central tongue
are formed with opposed notches and bent to engage the pivot tongue
86, as shown in FIG. 10.
As shown in FIG. 3, the pressure lug 90 of the deadlocking dog 88
lies behind the toe 92 of a C-shaped foot lever 94, the heels 96 of
which are fulcrumed against the mounting ring 84, and the arched
portions 98 of which underlie the rear ends of the springs 66 and
78 to take the spring reaction. The spring reaction tends to tilt
the foot member 94 about its heel portions 96 and press the toe 92
against the pressure lug 90 of the deadlocking dog 88, and thus to
bias that deadlocking dog for tilting movement about its supporting
pivot 86.
As shown in FIGS. 3-6, the forward or dogging end of the dog 88 is
formed with an inward extending cam nose 100 adapted to enter the
cam slot 64, and with an angular end 102 adapted to lie in abutting
relation with the rear end of the bolt stem 52 as shown in FIG. 4.
The cam groove 64 is so shaped that when the tailpiece is pulled
rearward relative to the sleeve 52, its cam surface 61 will engage
the angular end 102, as shown in FIG. 5; so that further rearward
movement of the tailpiece will cam that end outward out of abutting
relation with the stem 52 and permit that stem to engage the
angular face of the dog and slide past the dog, as shown in dotted
lines in FIG. 5. The stem 52 can then retract freely, as to the
fully retracted position shown in FIG. 6.
The deadlocking dog 102 is also controlled by the auxiliary bolt
72. The rear of such bolt carries a rearward extending arm 104 as
shown in FIGS. 1, 9 and 12. This is mounted by means of a radial
segment 103 engaged in a groove at the rear of the bolt 72, and at
its rear end carries a transverse finger 106 which extends
tangentially across the side of the tailpiece 104 and beneath the
dog 88. When the plunger 72 in normal advanced position as shown in
FIGS. 1 and 3, the finger 106 engages the locking dog 88 to cam it
outward away from dogging position, and to a release position as
shown in FIG. 3. The bolts 46 and 72 will then retract freely under
end pressure on the latch bolt 46. However, when the auxiliary bolt
72 is retracted relative to the latch bolt 46, as shown in FIG. 2,
the finger 106 moves rearward to an idle position as shown in FIGS.
2 and 4, where it is completely out of engagement with the locking
dog 88, and this permits that locking dog to pivot inward to its
dogging position as shown in FIG. 4. With the dog in that position,
attempt to push the latch bolt 46 inward carries the end of the
bolt stem 52 into abutment with the end of the dog 88. This
deadlocks the bolt against forced retraction.
The mounting of the auxiliary bolt 72 in the groove 74 of the main
bolt 46 provides mutual support between them, and allows the
auxiliary bolt to form a supporting filler between the flat
latching face 48 of the main bolt and the opposite bearing surface
of the face plate 36 and tubular housing 30.
Additional guiding support and stop means for the bolts is provided
as follows. The rear face of the bolt 46 is counter-bored to leave
a peripheral collar 110 and provide a flat rear seat for a stop
plate 112. This is held in place by bending the peripheral collar
110 inward as shown in FIG. 3. The stop plate 112 is C-shaped as
shown in FIG. 8, with a central opening to clear the stem 52 and
with cordially extending tongues 114 extending along the sides of
the auxiliary bolt 72. These fingers 114 support triangular bearing
blocks 116 which bear at their outer faces against the inside
surface of the tubular housing 30, and at their inner side faces
against side faces of the auxiliary bolt 72. The bearing blocks
move with the main bolt 46. Their front faces engage the rear of
the face plate 36 to stop forward movement of the main bolt 46.
Their rear faces are engaged by the projecting ends of the segment
103 at the rear of the auxiliary bolt 72 and form a stop for that
bolt which holds it flush with the main bolt.
Operation is as follows: The normal position of the bolt mechanism
is as shown in FIGS. 1 and 3. The main bolt 46 and the auxiliary
bolt 72 are both fully extended. The cam finger 106 at the rear of
the control arm 104 carried by the auxiliary bolt 72 lies against
the locking dog 88 to cam it to its release position, as shown in
FIG. 3. The bolts will freely retract in response to thrust on the
main bolt 46, so that if a door containing the bolt mechanism is
closed to carry the bolts against a strike plate 120, the bolts
will be thrust rearward by the camming action of the strike plate
120 against the cam face 50 of the latch bolt 46. The auxiliary
bolt will be carried with the main bolt. When the latch bolt comes
into alignment with the keeper opening 122 in the strike plate 110,
the main bolt 46 is projected into that opening 122 by its biasing
spring 66. The auxiliary bolt 72, however, is caught by the strike
plate 120 and is held in retracted position as shown in FIGS. 2 and
4. This holds the dog-release finger 106 in its rearward position
and releases the locking dog 88 to its dogging position, as shown
in FIG. 4. The cam nose 100 enters the cam groove 60 of the
tailpiece 24 and the dogging end 102 of the dog moves into
alignment with the rear face of the bolt sleeve 52. The main bolt
46 is then prevented by the locking dog from moving rearward and is
deadlocked in projected position.
When the bolts 46 and 72 are thrust rearward by the strike plate
120, the rear end of the tailpiece 24 moves freely through the jaws
of the retractor 20 of the cylindrical lock mechanism, since the
engagement is a one-way retraction connection which allows the
tailpiece to move freely rearward in this way. This relationship,
and the bolt structure which permits it, greatly reduces the need
for exact alignment and spacing between the lock and bolt
mechanism.
The latch bolt 46 may be retracted by the retractor 20 of the
cylindrical lock 10 at any time, and the operation will be similar
whether the bolt 46 is in normal position (FIG. 1) or in deadlocked
position (FIG. 2). In either case, the retractor 20 pulls rearward
on the tailpiece 24, the forward biasing spring 66 of the bolt 46
will tend to maintain the bolt 46 in projected position and the
weaker tailpiece-biasing spring 54 will yield, so that the
tailpiece 24 will move rearward through its lost motion with
respect to the sleeve 52. This will carry the cam surface 61 of the
cam groove 60 into position for engagement with the out-turned end
102 of the locking dog 88 as shown in FIG. 5. Further retraction of
the tailpiece will then cause that cam surface 61 to move that end
102 outward away from its dogging position, toward the dotted line
position inn FIG. 5, and this will allow the sleeve 52 to slide
past the end of the dog and move freely to the position shown in
FIG. 6.
The main bolt 46 is well supported for sliding movement in the
housing 30 by the bearing blocks 116 and the plunger 72, and is
supported against tilting by the fixed stem 52 and the tailpiece 24
which in turn is supported at the rear in the rear closure wall 40
and by the bearing washer 65, if present. The auxiliary bolt 72 on
the other hand is well supported by its wide area of engagement
with the groove 74 in the main bolt and by the guide pin 80. The
mechanism is substantially wholly enclosed by the cylindrical
housing 30 and its end closure plates 36 and 40. Installation of
the bolt assembly in proper relation with the cylindrical lock
mechanism 10 is facilitated by the arcuate shape of the grooves
defined by the tongues 44 for receiving the edges 18 of the shell
16 of the housing 30, and is facilitated by the shape of the
tailpiece and the nature of its engagement with the retractor 20.
Operation does not depend upon an exact relationship between the
retractor 20 and the head 22 of the tailpiece, and the lost-motion
connection permits some leeway in this relationship. The
construction simplifies manufacture and assembly and provides good
operating characteristics over a long life.
* * * * *