Combination lock

A combination lock has a locking bolt movable in bolt-opening and bolt-closing directions by a bolt-operating knob; a plurality of displaceable locking bars each having a predetermined position dependent upon a set combination; an arrangement for preventing the locking bolt from movement from a fully-closed position unless each locking bar is in its predetermined position; a plurality of displaceable code bars connected to the locking bars; a plurality of displaceable digit slides each having an externally accessible, manually engageable portion, a plurality of digit markings and a lug operatively engaging into the associated code bar; a movable carrier plate traversed by the lugs of the digit slides, whereby the locking bars, the code bars and the digit slides are displaced by the carrier plate during a motion thereof in a direction opposite the direction of movement of the locking bolt during opening. The bolt-operating knob is coupled with the carrier plate for moving the latter in a direction opposite the bolt-opening direction during displacement of the locking bolt in the bolt-opening direction.

BACKGROUND OF THE INVENTION 
This invention relates to a combination lock for vaults, safes or the like 
and is of the type in which the combination is arbitrarily changeable; the 
opening movement of a locking bolt is effected by manually turning a 
bolt-operating knob after the set combination is properly dialed; for each 
digit of the combination a locking bar is provided which, in case the set 
combination was improperly dialed, prevents the opening motion of the 
locking bolt; and the visible display of the dialed combination disappears 
during the opening motion of the locking bolt. It is noted that the term 
"dialing" is intended to include a shifting (linear) displacement of the 
digit-bearing lock component or components into the position corresponding 
to the set combination. 
A combination lock for vaults, safes or the like has to meet essentially 
the following requirements: 
(a) The possibility of setting or changing the combination without a 
disassembly of the lock; 
(b) Protection against monitoring the combination by scanning or listening; 
(c) Preventing the locking bolt of the combination lock from opening in 
case of improper dialing of the combination and/or by force; 
(d) Cancelling the visual display of the combination as early as the 
opening motion of the locking bolt. 
In a known combination lock disclosed, for example, in German Pat. No. 
2,552,789, for the opening of the locking bolt a manipulator is provided 
which also serves for dialing the combination. A number of gear wheels 
rotatable by the shiftable manipulator are mounted in series on the shaft 
of the manipulator. Each gear wheel meshes with a toothed rack having 
notches into which locking projections of a tumbler mechanism may extend. 
The tumbler mechanism has a plurality of immobilizable tumbler plates on 
which the locking projections are provided and which are assigned 
individually to the toothed racks and combined into a raising and lowering 
unit held in a disengaging position by return springs. The unit carries a 
locking pawl which immobilizes the locking bolt in the disengaging 
position. For shifting the locking plates for the purpose of resetting the 
combination, an eccentric pin coupled in the shifting direction with the 
raising and lowering unit is provided with an actuating head which, after 
opening of the door served by the combination lock, is accessible through 
an opening in the lock housing. The manipulator may be coupled with a 
bolt-actuating disc having actuating components such as entraining 
projections, ribs and a slot in such an arrangement that upon rotating the 
manipulator subsequent to dialing the combination, the raising and 
lowering unit is moved, in an initial rotational phase, into the engaging 
position against the force of the return springs. In the engaging 
position, the locking projections extend into the notches of the toothed 
racks and, as a result, the locking pawl releases the locking bolt. Upon 
rotation of the manipulator (after clearing the locking arrangement) 
beyond a predetermined position, the display of the combination visible 
from the outside is cancelled. Upon further rotation the locking bolt is 
retracted, whereby the raising and lowering unit is released and is moved 
rearwardly by the return springs into the disengaging position. 
The known combination lock of the above-discussed type is disadvantageous 
in that it has a cluttered construction; it is circumstantial to set and 
to dial the combination; the device which cancels the display of the 
combination is complex; and the lock mechanism operates with a great 
number of movable components without improving operational safety and 
security. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide an improved combination lock of 
the above-outlined type which is of simple construction, and in which, 
while preserving the greatest possible safety and security, the setting 
and the dialing of the combination as well as the cancellation of the 
visible display of the combination during the opening motion of the 
locking bolt are effected in a simple manner. 
These objects and others to become apparent as the specification 
progresses, are accomplished by the invention, according to which, briefly 
stated, each locking bar of the combination lock is coupled with a 
separate code bar into which engages a lug of a digit slide which may be 
shifted from the outside. The lug of each digit slide passes through the 
door and through a carrier plate situated between the door and the code 
bars. The carrier plate is moved, by means of a bolt-operating knob, in a 
direction opposite to the opening motion of the locking bolt after 
clearing the locking bars. 
In a combination lock according to the invention, the locking bars may be 
placed into the proper opening position in a simple manner by the digit 
slides with the intermediary of the respective code bars. In a similarly 
simple manner, the visible display of the combination is cancelled by 
virtue of the fact that the lugs pass through a carrier plate which is 
situated between the door and the code bars. The carrier plate is moved by 
the bolt-operating knob during the second half of the opening motion in a 
direction opposite to the opening motion of the locking bolt, in the sense 
of cancelling the display of the combination. The entrainment of the lugs 
is effected in a simple manner by virtue of the fact that they first pass 
through windows provided in the carrier plate. A transverse member 
bounding the windows at their rear edge entrains all the lugs. Between a 
half-open and a fully-open position, the combination lock may be opened 
without dialing the combination anew. Only when the combination lock again 
assumes its fully closed position, dialing of the combination has to be 
effected again for opening the combination lock. 
According to additional features of the invention, each locking bar is 
guided in a grooved plate supported in a lock housing and is connected 
with a code bar by means of a setting screw which, in the dialed position, 
is accessible through an aperture provided in a lock plate covering the 
lock housing from the inside. The code bars are guided in engagement with 
the grooved plate between detent bars arranged in the plane of the code 
bars. Each code bar is provided with an aperture for receiving the lug of 
the externally operable digit slide. 
In a combination lock incorporating the above-outlined additional features, 
the mechanism of the combination, on the one hand, and the mechanism for 
bolting and unbolting, on the other hand, are actuated by separate 
actuating devices. The combination mechanism includes linearly 
displaceable digit slides guided parallel to one another in a 
slide-supporting plate. Each digit slide engages into a code bar which, in 
turn, is connectable with a locking bar in an arbitrarily selectable 
position relative thereto. For setting the combination, that is, to 
arbitrarily set the relative position between the code bar and the locking 
bar, first the then operative combination has to be dialed. As a result, 
behind the hole in the lock assembly plate the setting screw becomes 
accessible which may thus be unscrewed and then screwed back in a new 
position of the code bar relative to the locking bar. The dialed 
combination appears for each bar behind an observation window provided in 
the slide-supporting plate. If for all the digit slides the set digit 
appears behind the observation window, that is, the combination has been 
properly dialed, the leading end of all the locking bars lie in the same 
plane. This means that the locking bars may be traversed by a toothed 
plate which is moved upon actuation of the bolting mechanism. 
The combination lock according to the invention has an uncluttered 
construction which is easily overseeable. The combination may be set in a 
simple manner and all requirements for a secure combination lock are met. 
According to a further feature of the invention, a drive plate which is 
moved by the bolt-operating knob during its rotation, is displaceable by 
means of a pivot-and-carrier pin with the locking bolt and a rocker plate 
in the direction of motion of the locking bolt. The drive plate is 
pivotally held and is spring-biased. A tip of the rocker plate engages a 
locking plate which is pivotal in a toothed plate. The toothed plate abuts 
against the improperly positioned locking bars, but if all the locking 
bars are in the proper position corresponding to the set combination, the 
toothed plate is movable transversely to the locking bolt past the end 
faces of the locking bars. 
The coupling of the drive plate, the locking bolt and the rocker plate by 
means of a pivot-and-carrier pin provides for a superposition of a 
longitudinal motion executed by the drive plate and the rocker plate 
together with the locking bolt and a relative pivotal motion between the 
drive plate and the rocker plate. An outward pivoting of the rocker plate, 
however, is possible only if all the locking bars are situated between the 
boundary legs of the toothed plate. In such a case, the rocker plate lifts 
the toothed plate by means of the locking plate and thus clears the way 
for the motion of the locking bolt. Even if a single locking bar is not in 
its position according to the set combination, the toothed plate abuts 
against such a locking bar and thus prevents a pivotal motion of the 
rocker plate with respect to the locking plate. Once the rocker plate has 
cleared the way for the motion of the locking bolt--because all the 
locking bars are in the proper position corresponding to the set 
combination--the toothed plate can drop back into its initial (starting) 
position. Between such a half-closed position and the fully-open position 
the combination lock may be closed or opened regardless of whether the 
locking bars are in their position corresponding to the set combination. 
It is thus feasible to scramble the combination during such a closing 
step.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Turning first to FIGS. 11, 13, 13a and 13b, on a door 11 of, for example, a 
safe, there is externally mounted a slide supporting and guiding plate 12 
provided with slots (one shown at 12.1 in FIG. 11) in which digit slides 
13 are guided, each having a bar or strip-like configuration. On its 
frontal face each digit slide 13 is provided with a handle 13.1, whereas 
on its reverse face, in alignment with the handle 13.1, each digit slide 
13 has a lug 13.2. Each digit slide 13 is displaceable from the outside by 
manual engagement of the handle 13.1. The lug 13.2 transmits any shifting 
motion of a respective digit slide 13 to other components of the 
combination lock as will be described below. On the frontal face of each 
digit slide 13 there is further provided a digit zone 13.3 on which there 
are provided, for each digit slide 13, a plurality of digits or letters; 
in the present example there are provided digits from 0 to 9. Behind 
windows (one shown at 12.2 in FIG. 11) provided in the slide-supporting 
plate 12 one digit appears according to the shifted position of the digit 
slide 13. According to the set combination--which is effected in a manner 
to be described below--to each slide 13 there is assigned a certain 
position and thus a predetermined digit. The door 11 can be opened only if 
all the digit slides 13 have reached their position corresponding to the 
set combination and in the windows the associated digits are being 
displayed, that is, the combination has been dialed. The described 
embodiment has six digit slides 13 which provide for millions of 
combinations. 
Also referring to FIGS. 12, 12a, 12b and 12c, on the inside of the door 11, 
in alignment with the slide-supporting plate 12, there is mounted a lock 
housing 14 which accommodates the combination lock and which is designed 
to guide the lugs 13.2 of the digit slides 13. The housing 14 is formed 
essentially of two elongated, parallel-arranged mounting angles 14.1 
between which there is secured a grooved plate 14.2 which has, on its side 
oriented towards the door 11, longitudinally extending grooves 14.3. In 
the zone of the locking mechanism the grooved plate 14.2 is free from 
grooves. In the grooveless zone, on the grooved plate 14.2 there is 
arranged a solid plate 14.4 having an opening for guiding the drive of the 
locking mechanism. Transversely to the grooves 14.3 between the mounting 
angles 14.1 of the housing 14 two parallel-extending transverse slots 14.5 
are provided. As shown in FIG. 11, with the aid of stationary pins 14.6 
passing through holes 14.7 provided in the mounting angles 14.1 the 
housing 14 is secured to the door 11 in such a manner that the angle legs 
of the mounting angles 14.1 extend parallel to the door 11. 
Also referring to FIGS. 14, 14a and 14b, adjacent the bolting part of the 
door 11 there are held or guided in the housing 14 code bars 15 which are 
coupled with the digit slides 13. On the code bars 15, in the same plane 
therewith, there are arranged detent bars 16, while on the code bars 15, 
on their face oriented away from the door 11, there are mounted locking 
bars 17. In the housing 14 there is further supported a toothed plate 18 
and a locking bolt 19. 
Each code bar 15 has along its lower edge a rectangular opening 15.1 and, 
parallel thereto, a bore 15.2 extending from the same edge. Transversely 
to the bore 15.2, in a side wall there extend in a single row ten 
parallel-arranged and uniformly spaced threaded bores 15.3. As shown in 
FIG. 11, into the opening 15.1 extends the lug 13.2 of the respective 
digit slide 13. By virtue of this arrangement, the digit slide 13, upon 
its displacement to a preset digit, carries with it the code bar 15. The 
bore 15.2 receives a ball detent 15.4 whose ball engages the respective 
detent bar 16. For this purpose, the detent bar 16 has a series of bores 
16.1 oriented towards the code bar 15. The distance between the bores 16.1 
is identical to that between the threaded bores 15.3 of the code bar 15. 
In this manner, definite positions ("click stops") for the code bar 15 are 
provided. While in FIG. 14, as noted above, the bore 15.2 extends from the 
same edge of the code bar 15 where the opening 15.1 is provided, it is 
feasible to place the bore 15.2 in the opposite edge. Such an arrangement 
is shown in FIG. 11, where the ball detent 15.4 received in the bore 15.2 
of the code bar 15 is oriented upwardly to cooperate with a detent bar 16 
situated above the code bar 15. The threaded bores 15.3, as will be 
described below, provide for setting and resetting the combination. 
Turning now to FIGS. 15, 15a and 15b, each locking bar 17 has on one side 
face a series of groove-like depressions 17.1 having a rectangular outline 
to form together a toothed rack. Transversely to the lateral side of each 
locking bar 17, in the vicinity of one end thereof, there is provided a 
throughgoing threaded bore 17.2. The depressions 17.1 protect the 
combination lock against monitoring in a manner described below. As shown 
in FIG. 11, the threaded bore 17.2 receives a setscrew 17.3, by means of 
which the locking bar 17 is connected with the code bar 15. If--for 
changing the combination--the locking bar 17 is to be connected with the 
code bar 15 in a different position, the setscrew 17.3 is unscrewed from 
the code bar 15, but remains threadedly engaged in the locking bar 17 for 
preventing the screw from dropping out, as shown at 17.3' in FIG. 11. The 
setscrew 17.3 is accessible through holes (one shown at 14.10) provided in 
a series in a base plate 14.8. After unscrewing the setscrew 17.3 into the 
position 17.3', the respective code bar 15 is, by means of the digit slide 
13, moved into its position corresponding to the new combination. The 
position is defined by the ball detent 15.4, in cooperation with the 
detent bar 16. Thereafter, the setscrew 17.3 is, in the selected position, 
screwed into another threaded bore 15.3 of the code bar 15. The detent bar 
16 is supported by the adjoining face of the grooved plate 14.2 which 
guides the locking bars 17 in the grooves 14.3 (FIG. 12). The code bars 15 
are guided, on the one hand, between adjoining detent bars 16 and, on the 
other hand, on the adjoining surfaces of the grooved plate 14.2. 
Turning now to FIGS. 16, 16a and 16b, the toothed plate 18 has a clip-like 
configuration as best seen in FIG. 16a. The toothed plate 18 has a central 
raised strip portion 18.1 which, close to an end of the toothed plate 18, 
has a hole 18.2 and at the opposite end has a shallow, rectangular cutout 
18.3. On both sides of the raised central strip 18.1 there are provided 
planar lateral faces 18.4. One of the lateral faces 18.4 is extended 
beyond one of the plate ends to continue as a tab 18.5 and is provided 
with a series of holes 18.6. The other lateral face 18.4 of the toothed 
plate 18 is, on the same side as the tab 18.5, provided with a cutout 18.7 
which has a rectangular inner area that opens trapezoidally towards the 
plate end. The toothed plate 18 has legs 18.8 along opposite longitudinal 
edges. The legs 18.8 extend perpendicularly to the lateral faces 18.4 and 
are oriented away from the raised central strip 18.1 and are provided with 
teeth 18.9 at their free edges. 
As seen, for example, in FIG. 4, the toothed plate 18 straddles 
transversely the housing 14 in the zone of the locking bars 17. The inner 
width of the toothed plate 18, that is, the distance between the legs 18.8 
equals the length of each of the locking bars 17. The division of the 
teeth 18.9, that is, the distance between two adjoining teeth 18.9 equals 
the division of the grooved plate 14.2, that is, the distance between two 
adjoining grooves 14.3. Thus, each locking bar 17 may be displaced by 
means of its associated digit slide 13 with the intermediary of the 
respective code bar 15 connected with the respective slide 13 to which the 
locking bar 17 is attached by connecting screw 17.3; such displacement may 
take place through spaces defined between adjoining teeth 18.9. As the 
code bar 15 reaches its position corresponding to the set combination, the 
associated locking bar 17 is situated precisely between the legs 18.8 of 
the toothed plate 18. In order to be able to open the combination lock, a 
displacement of the toothed plate 18 transversely to the housing 14 is 
required. If all the locking bars 17 assume their proper position between 
the legs 18.8 of the toothed plate 18, such an opening motion may be 
performed. If, however, even a single locking bar 17, because of an 
improper positioning of the associated code bar 15, is not situated 
between the legs 18.8 of the toothed plate 18, the toothed plate 18, with 
the teeth 18.9, abuts against the improperly positioned lock bar 17 and 
thus an opening of the combination lock is prevented. 
Turning now to FIG. 10, six digit slides 13 are placed--as viewed 
downwardly from the top--to positions 1-2-3-4-5-6, respectively. In this 
position, the toothed plate 18 may clear all six locking bars 17 and thus 
the combination lock may be opened. 
As shown, for example, in FIG. 1, on the outside of the door 11, adjacent 
the digit slides 13 in the longitudinal direction thereof, there is 
mounted a rotatable bolt-operating knob 21 (shown laterally removed for 
clarity). The bolt-operating knob 21 rotates a drive shaft 22 which, as 
shown in FIG. 4, engages into a drive plate 23. 
The bolt-operating knob 21 which is of circular disc-shaped configuration 
has, on its front side, a raised cross bar 21.1 which extends diametrally 
across the knob 21. An observation window 21.2 cut out along the 
circumference of the knob 21 is in alignment with a halving center line 
extending perpendicularly to the cross bar 21.1. To the side of the 
bolt-operating knob 21 remote from the window 21.2 there is secured, to 
the rear face thereof, a carrier pin 21.3 which is also in alignment with 
the halving center line extending perpendicularly to the cross bar 21.1. 
Also turning now to FIGS. 18, 18a and 18b, the drive shaft 22 is coupled 
with the bolt-operating knob 21 in a torque-transmitting (form-fitting) 
manner. For this purpose, the drive shaft 22 is provided adjacent one of 
its end faces with a transverse bore 22.1. After axially inserting the 
drive shaft 22 in a socket on the rear side of the bolt-operating knob 21, 
a setscrew is received in the transverse bore 22.1. At the opposite end 
the drive shaft 22 has a flange 22.2 on whose face oriented away from the 
drive shaft 22, there are secured diametrally arranged drive pins 22.3. 
Turning now to FIGS. 17 and 17a, the drive plate 23 has, at a distance from 
the drive pins 22.3 of the drive shaft 22, a plurality of uniformly spaced 
teeth 23.1 formed in an edge of an opening 23.2 in the drive plate 23. 
Between the teeth 23.1 there are defined, as viewed from the left in FIG. 
17, first, second, third and fourth notches 23.10 which are spaced from 
one another identically to the spacing between the two drive pins 22.3. 
The latter extend into the opening 23.2 of the drive plate 23 and 
cooperate with the notches 23.10 upon rotation of the drive shaft 22. In 
the zone of the opening 23.2 the drive plate 23 has a generally 
rectangular configuration which, at its upper outer corner (as viewed in 
FIG. 17) has a step-like cutout portion 23.3 as well as an angled tab 
23.4. In the zone remote from the opening 23.2, the drive plate 23 is of 
reduced rectangular configuration, at the outer corners of which two 
protuberances (buttons) 23.5 are embossed. In the zone of the transition 
from the smaller to the larger rectangle of the drive plate 23, there is 
provided, at the lower edge thereof, a rectangular cutout 23.6 and, on the 
opposite side, at the upper edge, there is provided a projection 23.7 
provided with a bore 23.8. Further, a bore hole 23.9 is provided in the 
drive plate 23 at the intersection of that edge of the cutout 23.6 which 
is closer to the buttons 23.5 and the connecting line of the teeth 23.1. 
As seen in FIG. 4, the drive plate 23 is connected with an elongated 
locking bolt 19 and a rocker plate 24 by means of a pivot-and-carrier pin 
25. Since the drive shaft 22 is supported stationarily for rotation in the 
housing 14, upon rotation of the drive shaft 22, the drive plate 23 is 
longitudinally displaced as a result of the cooperation between the drive 
pins 22.3 and the notches 23.10. The rocker plate 24 moves together with 
the drive plate 23. In the locking position, the rocker plate 24 is 
form-lockingly coupled with the toothed plate 18. When the toothed plate 
18 is movable (which is permitted by virtue of the fact that all the 
locking bars 17 are in their proper position), the rocker plate 24 may 
pivot and release the locking bolt which, as will be described in more 
detail below, may be moved into the open position by the bolt-operating 
knob 21. 
Turning now to FIG. 20, the rocker plate 24 has a rectangular window 24.1 
having a lower edge engaged by the drive pins 22.3 rotated between the 
teeth 23.1 of the drive plate 23. The longitudinal directions of the 
window 24.1 and the rocker plate 24 define an acute angle; the rocker 
plate 24 is generally boot-shaped. In the zone of the upper end of the 
boot shaft, on the upper outer edge, there is formed a tab 24.2 whose 
outer edge 24.3 is angled as shown in FIG. 20a. At the opposite 
longitudinal end the rocker plate 24 has an embossed tip 24.4 (foot of the 
boot). Approximately in the center of the rocker plate 24 there is 
provided a hole 24.5 through which passes the pivot-and-carrier pin 25 
which also traverses the hole 23.9 of the drive plate 23. Reverting to 
FIG. 4, the pin 25 also passes through a hole 19.1 of the locking bolt 19 
which is arranged on that side of the rocker plate 24 which is oriented 
away from the drive plate 23. At its upper edge the locking bolt 19 is 
provided with an elongated rectangular notch (cutout) 19.2. In the closed 
position of the combination lock the notch 19.2 receives a spacer member 
26. 
Also referring to FIGS. 19 and 19a, the tip 24.4 of the rocker plate 24 
abuts against a locking plate 27 which has generally the shape of an 
irregular pentagon having a partially rounded corner 27.1 engaged by the 
tip 24.4 of the rocker plate 24 and a fully rounded corner 27.6. The 
locking plate 27 is provided with a hole 27.2 which is located in the zone 
of the fully rounded corner 27.6 and through which a pin extends which 
also passes through the hole 18.2 of the toothed plate 18. If the tip 24.4 
of the rocker plate 24 presses, transversely to the direction of motion of 
the locking bolt 19, against the partially rounded corner 27.1 of the 
locking plate 27, the latter, provided all the locking bars 17 are in the 
proper position of the combination, lifts the toothed plate 18 from the 
position shown in FIG. 4 to the position shown in FIG. 5. The locking 
plate 27 has a window 27.3 in its tapering zone opposite from the rounded 
corner 27.6, as shown in FIG. 19. The window 27.3 receives the spacer 26 
arranged in the cutout 19.2 of the locking bolt 19. The spacer 26 provides 
for an additional safety measure against an opening movement of the 
locking bolt 19 as long as the locking plate 27 has not been swung into 
its releasing position. Approximately in the zone of connection between 
the bore 27.2 and the window 27.3, the locking plate 27 has a punched-out 
tab 27.4 extending perpendicularly to the plane of the locking plate 27. 
As shown in FIG. 4, in the bore 23.8 provided in the projection 23.7 of the 
drive plate 23 there is fitted a post 28 for supporting a hairpin-shaped 
spring 29. One end of the spring 29 engages the angled outer edge 24.3 of 
the rocker plate 24, whereas the other end of the spring 29 engages the 
angled tab 23.4 of the drive plate 23. The hairpin-shaped spring 29 seeks 
to move away the outer edge 24.3 and the tab 23.4 from one another by 
relative motion of the rocker plate 24 and the drive plate 23 about the 
pivot-and-carrier pin 25. 
Still referring to FIG. 4, a securing post 31 mounted in the housing 14 
supports a hairpin-shaped spring 32 whose one leg engages an adjacent leg 
of the housing angle 14.1 of the housing 14, whereas its other leg engages 
a pin 27.5 which is secured to the locking plate 27 in a slot formed by 
bending out a tab 27.4 and which extends into the cutout 18.7 of the 
toothed plate 18. 
In the starting position, as shown in FIG. 4, the two drive pins 22.3 are 
in engagement with the lower edge of the window 24.1 of the rocker plate 
24 and further, the drive pins 22.3 are situated within the third and 
fourth notch 23.10 (as viewed from the left in FIG. 4) of the drive plate 
23. In the starting position, the spacer member 26 is situated in the 
cutout 19.2 of the locking bolt 19. The tip 24.4 of the rocker plate 24 
engages the partially rounded corner 27.1 of the locking plate 27. 
Upon turning the drive shaft 22 supported in the bore 14.9 of the housing 
14 (FIG. 12) about 90.degree. (clockwise, as viewed in FIG. 4) the drive 
pin 22.3 situated in the fourth notch 23.10 moves downwardly, whereas the 
adjacent drive pin 22.3 (situated in the third notch 23.10) moves 
upwardly. The drive plate 23 and the rocker plate 24 are pivoted in 
opposite directions against the force of the spring 29 about the 
pivot-and-carrier pin 25. At the same time, the locking bolt 19 is shifted 
longitudinally one-quarter turn in the opening direction, whereby the 
pivotal axis of the pivot-and-carrier pin 25 also shifts. These motions 
can take place only if all the locking bars 17 are situated between the 
legs 18.8 of the toothed plate 18. A pivotal motion of the rocker plate 24 
in a counterclockwise direction (as viewed in FIGS. 4 and 5) causes its 
tip 24.4 to be pressed against the locking plate 27 which, in response, 
moves the toothed plate 18 against the force of the spring 32 transversely 
to the motion of the locking bolt 19. During this occurrence, the tab 18.5 
of the toothed plate 18 extends into a slot provided in the securing angle 
14.1 of the housing 14. As a result of the motion of the locking plate 27 
transversely to the locking bolt 19, the spacer member 26 is moved out of 
the cutout 19.2 of the locking bolt 19 which, as a result, may be opened 
further. 
Upon rotation of the drive shaft 22 through an additional 90.degree. from 
the position shown in FIG. 5 to the position shown in FIG. 6, the rocker 
plate 24 and the drive plate 23 essentially assume their starting position 
with respect to one another. By virtue of the fact that the initially 
externally positioned drive pin 22.3 now fills the second notch 23.10 (as 
viewed from the left in FIG. 6), the pivot-and-carrier pin 25 shifts a 
further distance with the locking bolt 19 from its original position. In 
the position shown in FIG. 6, the tip 24.4 of the rocker plate 24 releases 
the locking plate 27 which, under the effect of the spring 32, moves back 
into its initial position together with the toothed plate 18 in a 
direction transversely to the motion of the locking bolt 19. Such a return 
motion, however, does not take place relative to its angular motion since 
the spacer member 26 engages the upper edge of the locking bolt 19. Thus, 
the locking bolt 19 is now opened one half-turn and the toothed plate 18 
has dropped. 
A further rotation of the drive shaft 22 by 180.degree. from the position 
shown in FIG. 6 to the position shown in FIG. 8 (through the intermediary 
position illustrated in FIG. 7) results in a full opening of the locking 
bolt 19. During this operation the toothed plate 18 is not pivoted and the 
locking plate 27 is only slightly pivoted, since the rocker plate 24 
remains disconnected from the locking plate 27. The locking bolt 19 is 
first opened to a three-quarter turn and eventually assumes its fully-open 
position. 
Since between a half-open and a fully-open position of the locking bolt 19 
the toothed plate 18 is not moved because the rocker plate 24 and the 
locking plate 27 are disconnected from one another, the combination lock 
may be half closed and again opened without the need to place the locking 
bars 17 into the combination position. The combination position thus may 
be cancelled in advance, whereby no visible display will appear for the 
unauthorized. 
The rocker plate 24 and the locking plate 27 enter into mutual engagement 
with one another only after the combination lock is returned to its 
starting position. To open the combination lock anew, it is then 
necessary--because of the motion of the locking plate 18--that all the 
locking bars 17 assume their position corresponding to the set 
combination. FIG. 9 shows the combination lock immediately prior to the 
return into the closed position. The tip 24.4 of the rocker plate 24 
slides along the partially rounded corner 27.1 of the locking plate 27 and 
pivots the latter against the force of the spring 32 in a clockwise 
direction about the pin 27.5. At the same time, the pin 27.5 swings out of 
the opening 18.7 of the toothed plate 18 without moving the latter. The 
tip 24.4 of the rocker plate 24 thus may pass by the locking plate 27 and 
the combination lock may assume its closed position. 
In the combination lock according to the invention the externally visible 
display of the combination is cancelled as soon as the bolt-operating knob 
21 has executed one full revolution. 
Turning now to FIG. 1, on the drive shaft 22 there is mounted a carrier 
disc 33 of circular configuration, arranged exterior of the plate 12. At a 
distance from and concentrically with a central bore 33.1 through which 
the drive shaft 22 passes, the disc 33 has an opening 33.2 shaped as an 
annular segment into which extends the carrier pin 21.3 of the 
bolt-operating knob 21. The disc 33 has a carrier lug 33.3 which is 
symmetrically spaced from the ends of the opening 33.2. On its outer 
periphery the carrier disc 33 is serially colored red, yellow and green. 
These colors appear behind the observation window 21.2 of the 
bolt-operating knob 21. Red indicates the closed position of the 
combination lock locking bolt 19; this position may be changed only after 
the combination has been properly dialed. Yellow indicates an intermediate 
position in which the locking bolt 19 is between open and half-closed 
positions. In the intermediate position the lock may be opened without 
dialing the combination. Green indicates the fully open position. 
Referring to FIGS. 1, 10 and 21, the carrier lug 33.3 of the carrier disc 
33 extends into a carrier plate 34 which is guided in the housing 14 
between the door 11 and the code bars 15. The carrier plate 34 has a 
cutout 34.1 which is open towards the plate end. In the cutout 34.1 there 
is formed a transverse slot 34.2 which is defined by two projections 34.3 
and which extends parallel to the adjoining frontal edge of the carrier 
plate 34. The transverse slot 34.2 receives the carrier lug 33.3 of the 
carrier disc 33. A button 34.5 is embossed in the legs 34.4 bounding 
longitudinally the cutout 34.1 of the carrier plate 34. The substantially 
rectangular cutout 34.1 which has bevelled inside corners, is so 
dimensioned that it permits the carrier pin 21.3 to be turned fully within 
its outline. The carrier plate 34 has three windows 34.6 at its end remote 
from the cutout 34.1. The two flanking (outer) windows are open in the 
direction of the longitudinal side of the carrier plate 34. Through each 
window 34.6 there pass, in a pairwise arrangement, the lugs 13.2 of 
adjoining digit slides 13. Upon motion of the carrier plate 34 in the 
direction of the opening of the cutout 34.1, the digit slides 13 are 
carried by a transverse member 34.7 which forms an end of the carrier 
plate 34 and which bounds the windows 34.6. As a result of such a motion 
of the carrier plate 34, the digit slides 13 are shifted into the zero 
position. The length of each window 34.6 equals that of the digit width 
13.3. Thus, in the starting position of the combination lock, each digit 
slide 13 may be shifted, within the windows 34.6, to a position 
corresponding to a digit from 0 to 9. 
A rotation of the bolt-operating knob 21 about 180.degree. in a clockwise 
direction will cause no return motion of the slides 13. As a result of 
such a rotation, however, behind the display window 21.2 of the 
bolt-operating knob the red color is replaced by the yellow color, 
corresponding to a transition from the position shown in FIG. 1 to the 
position shown in FIG. 2. During this rotation there occurs a verification 
whether the combination lock is dialed to the proper combination as it was 
described above in conjunction with FIGS. 4, 5 and 6. Of two abutment pins 
35 secured to the housing 14, the inner abutment pin, as before, engages 
into the annular segment 33.2 at a corner thereof formed by the end and 
the inner side. The carrier pin 21.3 of the knob 21 is rotated within the 
annular segment 33.2 from its lower position into its upper position, 
while the observation window 21.2 is moved from its upper position into 
its lower position. 
Upon further rotation of the bolt-operating knob 21 by 180.degree. from the 
position shown in FIG. 2 to the position shown in FIG. 3, the carrier pin 
21.3 abuts the frontal boundary of the circular segment 33.2. From the 
time such an abutting relationship is established, the carrier pin 21.3 
entrains the carrier disc 33, whose carrier lug 33.3 projects into the 
slot 34.2 of the carrier plate 34. The entrainment of the carrier disc 33 
causes, by virtue of simultaneous rotation of the carrier lug 33.3, a 
shift of the carrier plate 34 in the direction of the opening provided in 
the cutout 34.1. Upon this motion, the carrier lug 33.3 first slides in 
the slot 34.2 downwardly and subsequently moves therein in an upward 
direction. The rotary motion of the carrier disc 33 and thus the 
longitudinal motion of the carrier plate 34 is terminated when the 
circular annular segment 33.2 abuts the outer abutment pin 35 with its 
opposite end. At this time, the last-named abutment pin 35 engages the 
corner between the inner boundary and the end face of the annular segment 
33.2. Upon displacement of the carrier plate 34 in the direction of the 
opening of the cutout 34.1, the transverse member 34.7 of the carrier 
plate 34 contacts in sequence all the lugs 13.2 of the digit slides 13 and 
brings the latter into the zero position. Behind the observation window 
(not shown in the drawing) for the digit slides 13 at this time the digit 
0 appears throughout. Behind the observation window 21.2 of the 
bolt-operating knob 21 the green color appears. Between the half-open and 
fully-open positions (FIGS. 2 and 3 as well as FIGS. 6, 7 and 8) the 
combination lock may be actuated without the need to dial the combination 
anew. If, however, the combination lock is fully closed (as shown in FIG. 
1 and as described in connection with FIG. 4) the lock may be opened only 
if the combination is again dialed. 
It will be understood that the above description of the present invention 
is susceptible to various modifications, changes and adaptations, and the 
same are intended to be comprehended within the meaning and range of 
equivalents of the appended claims.