AU775134B2 - Gate latch - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): D D GROUP PTY LIMITED A.C.N. 003 210 179 Invention Title: GATE LATCH The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 The present invention relates to gate latches which can be used for securing in a closed position a gate, door or like structure. More particularly, the invention is concerned with a latch having a latching tongue which is urged to a latching position in which it engages and restrains a latch pin, the tongue being displaceable against the urging force to release the latch pin so that a gate or door may be opened. Usually such a latch is of an automatic closing type whereby when the gate or door is closed, the associated pin strikes the tongue and displaces it against the urging force to permit the pin to be received and then engaged.

Generally, the urging force is provided solely by gravity since such an arrangement is reliable and effective and in the case of automatic closing latches, minimises the force needed to strike and displace the tongue whereby the pin is received and retained by the tongue. However, in the context of the present invention, it is not only pure gravity latches to which the invention may be applied but also similar latches which may include an element of biasing e.g. through a spring.

The form of the most common long-standing gravity latch is one often known as a D-latch, whereby a D-shaped tongue is pivotally mounted in an edge region so as normally to fall down with a straight face approximately vertical and behind which a striker pin of the latch assembly engages in a latching position. Automatic latching is provided for by the curved leading face of the latch being adapted to be engaged so as to displace the latch tongue. However, such devices are relatively crude and do not provide any integrated locking function and are Speci\400-499\40730.doc 3 not adapted to be actuated from either side of a door or gate.

An important development in the art is that disclosed in the present applicant's prior patent application 78822/98 (now 725095) filed in Australia and the subject of equivalent USA patent 6,058,747. That application disclosed a gravity latch having a housing incorporating a lock accessible to the front of a slim housing for the lock and optionally provided for a remote actuator to permit opening of the latch, providing it is unlocked, from the other side of the gate or door.

However, hitherto there has been available no more sophisticated gravity latch to the best of the applicant's knowledge and with a view to devising improved functionality and more advantageous designs, the present applicant now provides a development which offers advances in the art.

According to the present invention there is, broadly, provided a latch for gates and doors and having front and 20 rear units adapted to be mounted on opposite sides of a o* structure associated with a gate or door, ooo the front unit having a housing adapted to be mounted on the structure, a manually displaceable latching tongue displaceably mounted in the housing and adapted to interengage with a .co.o: striker pin mounted on a gate or door and for holding the striker pin in a closed position to prevent opening of the gate or door, a locking S. element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, and a key-activated front lock adapted to displace the locking element, Speci\400-499\40730.doc 4 (ii) the rear unit having a housing accommodating a key-actuated rear lock and a displaceable element for displacing the latching tongue and, (iii) the latch having connection means operable on actuation of either the front lock or the rear lock to displace the locking element between its locking and retracted positions and operable when either of the locks is in an unlocked position to permit a displaceable element of the rear unit to act through part of the connection means to displace the tongue to release the striker pin.

Preferably a rotary action is provided for displacement of the locking element through a lost motion system which permits the displacement of the latching system by either of the locks.

In a preferred embodiment, each lock can be of a quality cylinder-type with a rotatable lost-motion collar attached to the rear of the lock cylinder, the collar •having an interior cavity with a cut-out typically of 2700, o leaving a 90' wedge such that there is engagement with a first flat bar forming part of the connection means, a portion of the relative rotation between the bar and the collar being free motion which can be taken up and further relative motion causes the collar and bar to move 25 together. A suitable configuration at the respective oooo front and rear locks is provided so that 90' of rotation at either lock provides for lost motion effect whereby the locks can be independently locked and unlocked and thereby independently lock and unlock the locking element which is associated with and displaced by the first flat bar.

Preferably, rotational motion through interconnected gears is provided for rotating the locking element into position to engage the tongue.

Speci\400-499\40730.doc In a preferred embodiment, the connection means includes an elongate strip-like connector which interconnects with the rear lock and is displaceable manually towards the front unit whereby a front portion of the connector engages the tongue and displaces it to release the striker pin, this action being possible when either of the locks are unlocked and the arrangement being such that locking of one of the locks displaces the locking element to lock the tongue and prevent the displacement of the tongue and the connector.

An advantageous design is one in which the rear and front locks are not axially aligned but offset and a gear box is used to transmit a rotary motion from the connector to the flat-bar which is axially offset and which extends forwardly to engage in a lost motion device associated with the front lock. Thus, in this embodiment, the flat bar directly displaces the locking element when rotation occurs. Rotation is applied directly from the front lock to the flat bar when lost motion has been taken up and further rotation occurs, and rotation is applied indirectly upon rotation of the connector when the rear lock is rotated and lost motion is taken up.

A significant aspect of the present invention is that it can be incorporated in a durable, secure and highly functional slimline housing adapted to be mounted on a S• gate post with access to the lock being through the surface of each housing remote from the gate post.

Furthermore, at least in preferred embodiments, the S. connecting means can pass neatly through the gate post or other structure and preferably all that is needed is to bore a circular hole of the appropriate diameter in the appropriate location. This facilitates accurate and easy Speci\400-499\40730.doc 6 fitting without high trade skills or special equipment.

No morticing is required for the structure.

Preferably, the rear unit housing incorporates a push button in which the rear lock is mounted, the push button being spring-biased to an outer position. The push button connects to the connecting means. Depression of the button is not possible when the locking element is engaged with the tongue by virtue of either lock being moved into the locked position.

Preferably, the front unit is formed with the tongue as a pure gravity latch which is mainly encased within a housing of the front unit.

The invention also extends to a front unit separately supplied and adapted to cooperate with a rear unit as described above and in any one of the forms described herein.

For illustration only, an embodiment of the invention will now be described with reference to the accompanying drawing of which: Figure 1 is a cut-away drawing from the right partly in perspective view from the rear and showing front and rear units mounted on a gate post; Figure 2 is a perspective view from the left on an enlarged scale from in front and below of the front unit of the device shown in Figure 1; Figure 3 is an exploded schematic sketch of the apparatus to illustrate the principles of construction and operation; and Figure 4 is an enlarged sketch showing an apertured collar mounted to the rear of each lock cylinder and forming part of a lost-motion connection and rotated by rotation of a key in the lock.

Speci\400-499\40730.doc 7 The embodiment shown will usually be described as a gravity latch which in this case comprises a front unit a rear unit 11 and a horizontal striker pin (not shown) which usually is mounted on and projects from a gate or door. The striker pin moves in horizontal plane through an arc in order to engage with a latching tongue 12 within the front unit, the latching tongue having a pivot axle 13, and a centre of gravity laterally offset to the front so the tongue falls under its own weight to adopt the position shown in Figure 2. The tongue 12 has a leading striker surface 14 which when impacted by a striker pin deflects the tongue upwardly to admit the pin into a recess 15, the tongue then falling to capture the pin whereby the gate or door cannot be open.

The principles of operation will first be described with reference to Figure 3 where like reference numerals have been used for the components in Figures 1 and 2.

'The schematic drawing of Figure 3 shows the tongue in the upper position corresponding with Figure 1, a position adopted by manual displacement of the tongue to the position in which the striker pin is released.

oe e Figure 3 shows schematically how locking and unlocking from either side of the structure is achieved. A wedgeshaped locking finger 16 is provided on a first rotationally mounted gear 17 which permanently engages with a second gear 19 which is adapted to be driven upon rotation of a flat bar 20. Thus, clockwise rotation of the bar 20 rotates the second gear clockwise and that rotates the first gear 17 anticlockwise to raise the locking finger 16 from the 3 o'clock to the 12 o'clock position when viewed as in Figure 3. In this position, and since the tongue has been manually raised, the finger can engage behind a rear face 21 of the tongue to lock the Speci\400-499\40730.doc 8 tongue in the open position so that the gate does not latch in a closed position. Alternatively, when the tongue is in the lower position shown in Figure 2, the finger 16 engages in front of the recess surface 22 of the tongue and thereby locks the tongue in the closed position. Usually this step is carried out after the gate has been closed.

Rotation of the drive bar 20 can be achieved by rotation of a key-actuated cylinder front lock 23 which has a barrel 24 fixedly mounted in a housing 10A and a rotatable apertured collar 25 which rotates when the key is turned. As shown in the scrap view of Figure 4, viewing the lock from the rear, the collar 25 has a 2700 cut-out or aperture 26 and a solid 90' segment 27. The end of the drive bar 20 extends diametrically across the cutout 26 and axially along the cut-out with the bar vertical so that 90' of rotation of the key clockwise rotates the collar, and no motion to the drive bar occurs. A further eeoeo 900 rotation of the key rotates the collar (which when 20 viewed from the rear of the lock as in Figure 4 rotates anti-clockwise) and this rotates the drive bar through to a horizontal position whereby the locking finger 16 is eooee "moved to the 12 o'clock locking position.

Rotation of the drive bar 20 causes rotation of a 25 third gear 30 on which the drive bar is mounted and supported. This rotation causes a fourth gear 31 to be rotated and thereby connecting bar 32 is rotated. The connecting bar 32 is similarly engaged in a collar 33 of S"the same form as collar-25 and associated with a rear cylinder lock 34. Rotation of the connecting bar 32 through 900 in an anticlockwise direction (as seen in Speci\400-499\40730.doc 9 Figure 3) is a free motion by virtue of a cut-out in the collar 33 (similar to that shown in Figure 4).

If desired, with the configuration shown in Figure 3, the rear cylinder lock may be rotated clockwise when viewed from the rear in the direction of arrow A and motion is transmitted through the system to again raise the locking finger 16 to the 12 o'clock locking position.

Figure 3 schematically illustrates in exploded view how the first gear 17 can be rotationally mounted. The cylinder lock 23 has a rectangular pin-containing casing 28 around which fits a mounting bracket 29 and from which a mounting pin 29A extends in order to rotationally mount the gear 17.

The system is such that when the locking finger 16 is in the 12 o'clock position, unlocking can occur by virtue either of the front or rear locking cylinders being actuated in the unlocking direction.

Although not shown in Figure 3, the connecting bar 32 has a second function which will be explained with reference to Figure i. As shown in Figure 1, the rear cylinder lock 34 is mounted in a corresponding moulded oooo• S"cavity in a push button 40, the button being spring-biased by a helical compression spring 41 to its outermost position as shown. The button 40 is retained by a circlip arrangement (not shown) within a moulded housing 42 which •is secured to a gate post 43 by screws (not shown) inserted though preformed apertures 44. A clearance hole 45 is bored in front and rear walls of the post 43 to accommodate the connecting bar 32.

The leading tip 46 of the connecting bar 32 is disposed to engage the rear face 21 of the tongue 12 so as to push it to the displaced position shown in Figure 1 whereby the striker pin is released. For this purpose, Speci\400-499\40730.doc 10 the connecting bar 32 is a sliding axial fit through the centre of the fourth gear 31. The third and fourth gears each have circular cross section bosses extending axially from the cut gear portion so that the gears are rotationally mounted through the bosses in a housing.

As shown in Figure 1, when released, the push button is retracted by the spring 41 and thus the tongue 12 is free to fall. Figure 1 schematically shows the tongue held in the released position by a finger Details of the front unit are best seen in Figure 2 which shows the locking position with the tongue 12 located behind the locking finger 16. As shown in Figure 2, the locking cylinder 24 is secured in a corresponding shape moulded cavity in a front housing 51. An inner rear wall 52 and an outer rear wall 53 and between which is a cavity for accommodating rotatably the meshed third and fourth gears 30 and 31. A rearwardly projecting central boss 54 is provided for engaging within the bored hole in the gate post and accommodating the connecting bar 32 (omitted from Figure 2) which extends through a corresponding rectangular aperture 55 in the centre of the o Sfourth gear 31 so that the leading tip 46 of the connecting bar can engage on the rear surface 21 of the tongue for raising the tongue when it is unlocked.

A mount 56 is provided for connection to the inner rear wall 52 and for rotationally supporting the first and second gears 17 and 19 through a forward wall portion 57 spaced forwardly by a pair of diametrically spaced spacer arms 58. Between the forward wall 57 and the inner rear wall 52 is provided a rotary stop element 59 which, in the position shown in Figure 2, engages with a detent (not shown) and which is fixedly mounted in the cut-away portion of the housing. This function positively fixes Speci\400-499\40730.doc 11 the position of the locking finger 16 in the 12 o'clock position, as well as giving the key operation a positive feel for locked and unlocked positions.

Speci\400-499\40730.doc

Claims (29)

1. A latch for gates and doors and having front and rear units adapted to be mounted on opposite sides of a structure associated with a gate or door, the front unit having a housing adapted to be mounted on the structure, a manually displaceable latching tongue displaceably mounted in the housing and adapted to interengage with a striker pin mounted on a gate or door and for holding the striker pin in a closed position to prevent opening of the gate or door, a locking element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, and a key- activated front lock adapted to displace the locking element, (ii) the rear unit having a housing i.. ~accommodating a key-actuated rear lock and (b) ooeoQ a displaceable element for displacing the latching tongue and, (iii) the latch having connection means operable on actuation of either the front lock or the •ff rear lock to displace the locking element between its locking and retracted positions and operable when either of the locks is :in an unlocked position to permit a displaceable element of the rear unit to act through part of the connection means to displace the tongue to release the striker pin. Speci\400-499\40730 .doc 13

2. A latch as claimed in claim 1 wherein the connection means includes a rotatably displaceable mechanism for displacing the locking element and includes a lost- motion system which permits the displacement of the locking element to be achieved by operation of either the front lock or the rear lock.

3. A latch as claimed in claim 2 wherein each of the front and rear locks is a cylinder lock and the lost- motion system comprises a rotatable collar associated with each lock, each collar having a cavity with a part-circular cross-sectional aperture extending approximately 2700 around the axis of the collar and a wedge portion extending approximately 90' around the axis with flat faces at each end, the latch further comprising as part of the connection means a flat bar 0eeS for engaging in the cavity of each collar to provide ooooo lost-motion between the collar and the associated 20 flat bar for approximately 90' of rotation whereby either of the locks can be operated independently to displace the locking element between unlocked and locked positions. 25

4. A latch as claimed in claim 3 and wherein the front oo oo unit has meshing gear wheels, one of which carries OSOO the locking element and the other of which is adapted to be rotated upon rotation of either of the flat .o bars when a key operates one of the locks.

A latch as claimed in any one of claims 2-4 and wherein the connection means includes an elongate connector extending from the rear unit to the front Speci\400-499\40730.doc 14 unit along an axis offset laterally from the axis of the lock on the front unit, and the latch having first and second connecting gears to provide rotary motion to be transmitted between the elongate connector and the rotatably displaceable mechanism.

6. A latch as claimed in any one of the preceding claims wherein the connection means includes an elongate strip-like connector which interconnects with the rear lock and is displaceable manually towards the front unit a front portion of the connector being displaceably mounted engaging and displaying the tongue to release the striker pin when either of the locks are unlocked.

7. A latch as claimed in any one of the preceding claims wherein the respective housings for each of the front and rear units have means for mounting the units on either side of a gate post or similar structure and 20 for mounting the associated lock with a key entry *L face disposed on a face opposite to the side of the rear and front units which contacts the gate post when installed.

8. A latch as claimed in any one of the preceding claims wherein the connection means includes an elongate connecting element adapted to be inserted and be movable within bores drilled through a gate post to which the unit is to be mounted.

9. A latch as claimed in any one of the preceding claims wherein the rear unit has a push button mounted for reciprocating motion in the rear housing and spring- Speci\400-499\40730.doc 15 biased to an outer position, the push button being connected to the connecting means for displacement to cause the tongue to move for releasing the striker pin, providing the tongue is not locked in the locked position.

A latch as claimed in any one of the preceding claims wherein the front unit mounts the tongue as a gravity latch, the tongue being substantially enshrouded in the housing of the front unit.

11. A latch for gates and doors having a front unit adapted to be mounted on one side of a structure such as a gate post and to interact with a latch striker pin mounted on a gate and adapted to cooperate if desired with a complimentary rear unit to be mounted on the opposite side of the gate post, the unit having a housing adapted to be mounted on the structure, a manually displaceable latching tongue displaceably mounted in the housing and ~adapted to interengage with a striker pin mounted on eoeee a gate or door and for holding the striker pin in a closed position to prevent opening of the gate or door, a locking element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, a key-activated front lock adapted to displace the locking element, S. the front unit being adapted to be connected to the rear unit which has a housing accommodating a key-actuated rear lock and a displaceable element for displacing the latching tongue, the latch having connection means adapted to be connected to the rear Speci\400-499\40730.doc 16 lock and connected to the front lock such that actuation of either the front lock or the rear lock displaces the locking element between its locking and retracted positions when either of the locks is in an unlocked position the connection means permits the displaceable element of the rear unit to displace the tongue to release the striker pin.

12. A latch for a gate substantially as herein described with the reference to the accompanying drawings.

13. A latch device for use with a gate, the latch device having front and rear units adapted to be mounted on opposite sides of a structure associated with the gate and against which the gate closes, the front unit having a first housing adapted to be mounted on the structure, a manually displaceable latching tongue displaceably mounted in the housing and adapted to inter-engage with a striker pin mounted on the gate and for holding the striker pin in a closed position to prevent opening of the gate, a locking element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, and a key-actuated front lock, S(ii) the rear unit having a second housing accommodating a key-actuated rear lock and (b) a displaceable actuator, the latch device having connection means comprising a rotatable actuator connected to :the front lock, the displaceable actuator connected to the rear lock, the locking element of the front unit and interconnecting means interconnecting the rotatable actuator, the Speci\400-499\40730 17 displaceable actuator and the locking element, the connection means being operable on actuation of either the front lock or the rear lock to displace the locking element between its locking and retracted positions and (b) being operable when the front lock or the rear lock has been actuated to position the locking element in a retracted position to permit the displaceable actuator of the rear unit to displace the tongue to release the striker pin, the interconnecting means including a rotatably displaceable mechanism for displacing the locking element and including a lost-motion system which permits the displacement of the locking element to be achieved by operation of either the front lock or the rear lock; (iv) the front unit mounts the tongue as a gravity latch, the tongue being enshrouded in a tongue housing, the displaceable actuator includes a rotatably mounted elongate connector extending from the rear unit to the front unit along an axis offset laterally from the axis of the rotatable actuator of the front lock, and the 25 interconnecting means having first and second connecting elements to provide rotary motion to be transmitted between the elongate connector and the rotatable actuator; (vi) the displaceable actuator further having 30 axially displaceable means for engaging and displacing the tongue to release the striker pin when either of the locks has been actuated to position the locking element in a retracted position and the displaceable actuator is 35 axially displaced in the second housing.

-14. A latch device as claimed in claim 13 wherein the S *peci\400-499\40730 Speci\400-499\40730 18 lost motion system includes a rotatably mounted element associated with the rear cylinder lock and rotatable responsive to a key turning in that lock, the lock of the rear unit being connected through a lost motion connection to the displaceable actuator and an element of the front lock being connected through a lost motion connector of complementary character to the rotatable actuator whereby either of the locks can be rotated to displace the locking element between locking and retracted positions independently of the other lock.

A latch device as claimed in claim 13 or claim 14 wherein the rotatably mounted elongate connector is axially displaceable against spring biasing provided in the rear housing for displacing the tongue of the gravity latch.

16. A latch device as claimed in claim 15 wherein the elongate connector is strip-like and the first connecting element is a gear wheel mounted on the elongate connector but in a relatively axially displaceable manner and the second connecting element is a complementary gear wheel to transmit a rotary 25 motion to a mounting shaft of the rotatable actuator.

17. A latch device as claimed in any one of the preceding claims 13 to 15 wherein each of the first and second housings have means for mounting on respective sides 30 of a gate post with respective front and rear locks having a key entry face disposed on a face opposite to the face of the first and second housing which contacts the gate post when installed.

18. A latch device as claimed in any one of the preceding S"claims 13 to 16 and wherein the front unit has meshing gear wheels, one of which carries the locking Speci\400-499\40730 ii 19 element and the other of which is adapted to be rotated upon key rotation of at least one of the front lock and the rear lock.

19. A latch device for use with a gate, the latch device having front and rear units adapted to be mounted on opposite sides of a structure associated with the gate and against which the gate closes, the front unit having a first housing adapted to be mounted on the structure, a manually displaceable latching tongue displaceably mounted in the housing and adapted to interengage with a striker pin mounted on the gate and for holding the striker pin in a closed position to prevent opening of the gate, a locking element displaceably mounted in the housing for locking the tongue when in a locking position and displaceable to a retracted position in which the tongue is released, and a key-activated front lock adapted to displace the locking element between its locking and retracted positions, (ii) the rear unit having a second housing accommodating a key-actuated rear lock and (b) a displaceable actuator spring biased to an ~outer position, (iii) the latch device having connection means comprising a rotatable actuator connected to the front lock, the displaceable actuator 30 connected to the rear lock, the locking element of the front unit and interconnecting means interconnecting the rotatable actuator, the S"displaceable actuator and the locking element, the connection means being operable on 35 actuation of either the front lock or the rear S"lock to displace the locking element between its locking and retracted positions and being Speci\400-499\40730 20 operable when the front lock or the rear lock has been actuated to position the locking element in a retracted position to permits the displaceable actuator to displace the tongue to release the striker pin, the interconnecting means including a rotatably displaceable mechanism for displacing the locking element and including a lost-motion system which permit the displacement of the locking element to be achieved by operation of either the front lock or the rear lock; (iv) the front unit mounts the tongue as a gravity latch, the tongue being enshrouded in a tongue housing; the displaceable actuator includes a rotatably mounted and axially displaceable elongate connector extending from the rear unit to the front unit along an axis offset laterally from the axis of the rotatable actuator of the front lock, a leading tip of the connector being mounted to engage and displace the tongue to an open position when the displaceable actuator is urged from its outer position, (vi) the interconnecting means of the latch device 25 having connecting gears to provide rotary motion to be transmitted between the elongate connector and therotatable actuator; (vii) each of the locks is a cylinder lock having a cylinder axis at right angels to the face of 30 the housings adapted to abut the structure, the respective cylinder axes of the locks being parallel and laterally offset relative to one another, (viii) the locking element is mounted on a rotatable gear element engaged with a driven S"gear element forming part of the interconnecting means, and SSpeci\400-499\40730 Speci\400-499\40730 21 (ix) the lost motion system includes a rotatable element connected to the rear cylinder lock and interconnecting with the elongate connector though a linkage providing at least about freedom of rotation in one direction, and a rotatable element connected to the front cylinder lock and interconnecting with the rotatable actuator through a linkage providing at least about 900 of freedom of rotation in a direction complementary to the freedom of rotation provided at the rear lock, the rotatable actuator associated with the front lock mounting and driving the driven gear element.

A latch device for use with a gate, the latch device having front and rear units adapted to be mounted on opposite sides of a structure associated with the gate and against which the gate closes, the front unit having a first housing adapted to be mounted on the structure, a manually displaceable latching element displaceably mounted in the housing and adapted to inter-engage with a striker pin mounted on 25 the gate and for holding the striker pin in a ~closed position to prevent opening of the gate, a locking element displaceably mounted in the housing for locking the latching element when in a locking position and displaceable to a retracted position in which the latching element is released, and a key-actuated front cylinder lock unit, S(ii) the rear unit having a second housing accommodating a key-actuated rear cylinder lock 35 units and a displaceable actuator operatively connected to the rear lock unit, S.(iii) the latch device having connection means Speci\400-499\40730 -22 comprising a rotatable actuator connected to the front lock unit, the displaceable actuator of the rear unit, the locking element of the front unit and interconnecting means interconnecting the rotatable actuator, the displaceable actuator and the locking element, the connection means being operable on key- actuation of either the front lock unit or the rear lock unit to displace the locking element between its locking and retracted positions and being operable when the front lock unit or the rear lock unit has been actuated to position the locking element in a retracted position to permit the displaceable actuator of the rear unit to displace the latching element to release the striker pin, (iv) the interconnecting means including a rotatably displaceable mechanism for displacing the locking element and including a lost-motion system which permits the displacement of the locking element to be achieved by operation of either the front cylinder lock unit or the rear cylinder lock unit with each cylinder lock unit having limited rotational freedom of motion 25 about the axis of the cylinder and its ~connection to an associated respective front and rear interconnection element of the iinterconnection means; the displaceable actuator of the rear unit o..eei 30 comprising a rotatably mounted elongate connector; extending from the rear unit generally towards the front unit along an axis offset laterally from the axis of the 35 cylinder of the front lock unit, to S"transmit rotary motion upon key actuation of the rear cylinder lock unit, and Speci\400-499\40730 16/01 '04 FRI 13:29 FAX 81299255911 GRIFFITH HACK PATENT/SECURE 1Z002 23 being axially displaceable for engaging and displacing the latching element to release the striker pin when either of the lock units has been actuated to position the locking element in a retracted position.

21. A latch device as claimed in claim 20, wherein the front unit mounts the latching element as a gravity latch substantially enshrouded in a housing.

22. A latch device as claimed in claim 20 or claim 21 wherein the interconnection means includes meshing gear wheels a first of which carries the locking element and the gear wheels area arranged to be rotated upon key actuation of either the front lock unit or the rear lock unit.

23. A latch device as claimed in claim 22 wherein elongate connector is a flat strip and has a free end tip for engaging and displacing the latching element when the locking element is in an unlocked position, a forward end portion of the flat strip being arranged as a sliding fit through one of the gear wheels and a rear end portion having a lost motion connection of at least about 90° with a rotatable element associated with the rear lock unit.

24. A latch device as claimed in claim 22 or claim 23, 30 wherein the meshing gear wheels comprise four, two of which are engaged by respective rotatable drive elements of the interconnection means and have respective parallel spaced axes. 35

25. A latch device as claimed in any one of claims 22 to 24, wherein the rear lock unit is mounted in a depressible button spring-biased to an outer 0 Speci\d00-499\40730 COMS ID No: SMBI-00574467 Received by IP Australia: Time 13:31 Date 2004-01-16 24 position, and axially displaceable in the second housing.

26. A latch device as claimed in any one of claims 22 to 25 wherein each of the first and second housings has means for mounting on respective sides of a gate post with respective front and rear lock units having a key entry face disposed on a face opposite to the face of the first and second housing which contacts the gate post when installed.

27. A latch device as claimed in any one of claims 22 to 26 wherein the front unit has meshing gear wheels, one of which carries the locking element and the other of which is adapted to be rotated upon key rotation of at least one of the front lock and the rear lock. 0 9%

28. A latch device as claimed in any one of claims 22 to 20 27 wherein the latching element is in the form of a notched plate which pivots under gravity to effect latching, the notch of the plate accommodating in latching engagement the striker pin and the plate being substantially enshrouded in the first housing. o

29. A latch device having a front unit and being adapted to be mounted on a gate post or similar structure and to co-operate with a rear unit as defined in any one of the preceding claims, the front unit being as defined in any one of the preceding claims. 25 A gate in combination with a latch device as claimed in any one of the preceding claims. DATED this 17 th Day of May 2004 D D GROUP PTY LIMITED By their Patent Attorneys GRIFFITH HACK *o o* or o