WO 2011/150468 PCT/AU2011/000698 Retaining Mechanism for a Handgun Holster Field of the invention This invention relates generally to the retention of holstered service items such as weapons and communication devices. The invention will be described herein in relation 5 to the retention of holstered handguns, but it will be understood that the invention has wider application. Background of the invention Handgun holsters are generally fitted with devices, often called holster locks, for guarding against inadvertent or unauthorised release of the handgun from the holster, 10 for example through unintended dislodgement or through removal by a person with whom the bearer, typically a law enforcement officer, is engaged in a confrontation. It is of course desirable that these devices do not mitigate against rapid release and deployment of the weapon when it is needed to protect the bearer or others from imminent attack. 15 A typical holster in widespread use has a pair of straps, viz a top strap that wraps over the rear of the gun and a lateral strap that wraps transversely around the holster in the vicinity of the otherwise exposed trigger. Each of the straps is secured into position by a stud button. To remove the gun, a bearer must first flick open each stud: this requires two separate actions, one for each stud, that make it difficult to maintain a firm grip on 20 the gun handle. This in turn limits the speed with which the gun can be removed and the lack of a secure grip on the gun provides an opportunity for an adverse party to wrestle control of the gun. In another holster system, there is a single upper strap pivotally connected at both ends to the holster body. When a release button at the side of the holster body is pushed, the 25 action rotates the strap forward to allow the gun to be removed. A problem with this arrangement is that an adverse party -standing in front of the gun bearer can actively rotate the strap forward, either directly or by engaging the release button, to enable free access to remove the gun. To counter this disadvantage, a releasable lock element may WO 2011/150468 PCT/AU2011/000698 2 be included behind the release button: the lock element is pulled toward the rear of the holster to unlock the strap. In this case, an adverse party may still reach into the holster, push the lock release and proceed to remove the gun as previously described, while the lock release incurs an additional action that the gun bearer must remember to do when 5 putting the gun away. This limits the speed at which the gun may be returned to the holster, and can result in a dangerously insecure gun if the bearer forgets to re-engage the lock release. Furthermore, even with this system, it is difficult to maintain a secure grip on the gun handle while operating the release mechanism. US patent 7,461,765 discloses a security hood assembly for a holster. A lever is 10 operably coupled to the hood for driving the hood toward an open position to allow the service item to be removed from the holster. In some embodiments, the lever is latched to the hood when in the closed position to prevent the hood from being opened through direct manipulation of the hood. Reference to any prior art in the specification is not, and should not be taken as, an 15 acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art. It is an object of the invention to provide a retaining mechanism for a holster that 20 addresses the twin objectives of being readily releasable by the bearer of the holster, but not conducive to unauthorised release of the service item from the holster. Summary of the invention The invention provides a retaining mechanism for a holster that includes: a hood unit mountable to a holster for rotation about a first axis between a 25 retaining condition in which it overlies a service item in the holster to prevent its withdrawal and a retracted condition in which the service item can be withdrawn; WO 2011/150468 PCT/AU2011/000698 3 a hand operable lever assembly mountable for rotation about a second axis offset from the first axis and engageable with the hood unit whereby rearward rotation of the lever assembly effects said rotation of the hood unit to its retracted condition and vice versa, wherein the lever assembly includes an element outstanding at a location 5 that in situ is behind and clear of the hood unit, and that is depressible against a restoring bias force' to be disengaged from a lock formation that locks the lever assembly and thereby the hood unit against rotation; and a housing securable to the holster and configured to provide said lock formation. Advantageously, the first and second axes are arranged so that, when the holster is 10 being worn, the second axis is rearwardly of and below the first axis. Preferably, the hand operable lever assembly is engageable with the hood unit by means of respective intermeshing teeth formations, for example on respective gear elements formed on or carried by the lever assembly and hood unit. Advantageously, the hand operable lever assembly and the depressible element thereof 15 are such that depression of the element and rearward rotation of the lever assembly to forwardly rotate the hood unit to its retracted condition may be effected by a single digit, preferably the thumb, in a substantially continuous movement. Preferably, the lever assembly is of elongate form projecting upwardly and rearwardly from the second axis when the holster is being worn in its usual position. 20 The depressible element may include a digit rest pad with a rear protrusion against which a digit on the rest pad is pushed to rotate the lever assembly. Preferably, the lever assembly, the housing providing said lock formation and said teeth formations are provided on the inside of the holster in its normal worn position, i.e. between the holster and the bearer's body. 25 The depressible element is advantageously fitted at the outer end of, and is slideably mounted on, the elongate body of the lever assembly. The aforementioned restoring WO 2011/150468 PCT/AU2011/000698 4 bias force is advantageously provided by an internal compressible spring. The arrangement is preferably such that when the lever assembly is rotated forwardly, either by direct hand engagement or by rearward movement of the hood unit, the biasing force snaps the depressible element back into engagement with said lock formation when it 5 reaches a home position corresponding to the retaining condition of the hood unit. Preferably, a maximum rearward position of the lever assembly is defined by a further, latch, formation, for example on said housing, in which the lever assembly and therefore the hood are latched so as to require a light hand force for disengagement. The invention further extends to a holster fitted with the aforesaid retaining mechanism. 10 As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps. Brief description of the drawings The invention will be further described, by way of example only, with reference to the 15. accompanying drawings, in which: Figure 1 is a lateral rear perspective view of a retaining mechanism, or holster lock, for a handgun holster, which mechanism is an embodiment of the invent-ion; Figure 2 is a front perspective view of the retaining mechanism of Figure 1 shown mounted to a handgun holster, with a retained handgun shown in shadow lines; 20 Figure 3 is an exploded view of the retaining mechanism and holster of Figure 2; Figure 4 is a perspective view from the other side of the mechanism of Figure 1, but with the back plate removed; Figure 5 is a view of the rear of the housing of the retaining mechanism; WO 2011/150468 PCT/AU2011/000698 5 Figures 6 and 7 are respective front and rear views of the body of the lever assembly; Figure 8 depicts a driving gear that is keyed with the lever assembly; Figure 9 is a side view of the thumb depressible element of the lever assembly; 5 Figures 10A to 10D show successive operational conditions of the retaining mechanism; and Figures 11 and 12 are views respectively similar to Figures 1 (from a different angle) and 3 of a modified embodiment of the invention. Description of preferred embodiment 10 The illustrated retaining mechanism, or holster lock, 10 includes a hood unit 20, a housing 60, and a hand operable lever assembly 30 having a slideably interengaged body 32 and thumb depressible element 34. The housing 60 has a pair of inwardly projecting slotted bosses 62, 63 (Figs 4,5) that engage matching pins 72, 73 (Figure 3) projecting laterally from the outer surface of the inside wall 71 of the- holster 70. These 15 bosses 62, 63 provide respective mounting axles for one side of hood unit 20 and for lever assembly 30. Hood unit 20 and lever assembly 30 have journals 20a, 30a for the axles and are retained between housing 60 and a backplate 80 that has apertures 82, 83 for pins 72, 73 and is located between bosses 62, 63 and the outer surface of the holster side wall 71. Spacer pillars 61. integrally formed on housing 60 define its 20 separation from backplate 80. Hood unit 20, best seen in Figures 3 and 4, is an integral one piece moulding of general inverted-U profile having respective arms 21, 22. Arm 21 has an integral collar 23 on its outer face with a sector of projecting teeth 24 and a bore 25 by which it is rotatably mounted on boss 62. Arm 22 has an aperture 26 aligned with bore 25 by which it is 25 rotatably mounted on and clipped to an integral projecting pin.72a on the outside face of the other side wall 71a of holster 70. Pins 72, 72a are aligned to thereby define with boss 62 a first axis 12 about which hood unit 20 is rotatable between a retaining WO 2011/150468 PCT/AU2011/000698 6 condition (Figures 1 to 4 and Figure 10A), in which the hood unit overlies the rear of the handgun 100 in the holster 70 to prevent its withdrawal, and a retracted condition (Figure 1OD) in which the handgun can be withdrawn. Lever assembly 30 includes, as already foreshadowed, an elongate body 32 and a 5 thumb depressible element 34. Lever body 32 (Figures 6 and 7) is of broadly rectangular outline and includes side rims 35 and tabs 36 that define opposed slideways for corresponding formations 37 of a broadly rectangular body 38 of element 34. Thumb depressible element 34 is an integral moulding that comprises body 38 and a thumb shaped rest pad 40 at its top that extends parallel to the holster wall 71 and overhangs 10 body 38 on all sides. The under surface 41 of pad 40 thereby defines one abutment for a zigzag compression spring 50 retained within a top edge cutaway 52 of lever body 32. The other spring abutment is the inner end wall 53 of recess 52, which is also formed with a cantilevered finger 54 for holding spring 50 in place. Spring 50 provides a restoring bias force to maintain thumb depressible element 34 in its slideably outer 15 position unless it is depressed with sufficient force against the spring. It will be seen that thumb depressible element 34 is outstanding at a location that is behind and clear of hood unit 20, that lever assembly 30 is rotatable about a second axis 13 defined by boss 63, and that this second axis 13 is parallel to but offset from axis 12, rearwardly of and below axis 12 when holster.70 is being worn. 20 The lower end of lever body 32 has, on the side facing housing 60, an integral peripherally toothed collar 39 by which it is keyed to a gear element 45 (Figure 8) that has a cylindrical bearing surface 46 for rotatable support on boss 63, a surrounding inner rebate 47 with teeth 47a that drivingly engage the teeth of collar 39, and a radially projecting tab 48 with a rake of teeth 49 across its outer edge that drivingly mesh with 25 teeth 24 of collar 23. Thus, if lever assembly 30 is rotated rearwardly (when this is enabled in the manner to be shortly described), hood unit 20 is contra-rotated forwardly, and vice versa.
WO 2011/150468 PCT/AU2011/000698 7 On the side of thumb depressible element 34 that faces housing 60 and adjacent the lower end of its body 38 are a pair of frustoconical teeth 55 (Figures 3 and 9) that, in the outer position of element 34, firmly engage a lock formation in the form of a pair of closely matching socket recesses 65 (Figure 5) under a rim 66 of housing 60. This locks 5 lever assembly 30 very firmly against rotation and, by virtue of the positive toothed interengagement between gear element 45 and collar 23 of hood unit 20, also locks the hood unit against any attempt at forced rotation. When the bearer of the holstered weapon 100, with his fingers firmly on the handle 102 of the weapon, uses his thumb to engage thumb rest pad 40 and to depress the element 34, teeth 55 disengage from 10 socket recesses 65 and free lever assembly 30 to rotate (Figure 10B). This allows the thumb to now be employed, by pressing against an upstanding convex rear land 42 of thumb rest pad 40, -to rotate the lever assembly rearwardly through the position depicted in Figure 10C to the condition shown in Figure 10D. Hood unit 20 is driven by the engaged gears to correspondingly rotate to its fully retracted condition. 15 A maximum rearward rotation of lever assembly 30 is defined by an end wall of housing 60 being struck by the rear edge of lever body 32, and is then latched or indexed when one of the teeth 55 engages a detent recess 68 (Figure 5) on the housing. This detent recess has a gently curved front face 69 so that either some forward thumb force on lever 30 or rearward hand force on hood unit 20 will disengage the latch and allow the 20 lever and hood unit to be contra-rotated back to the home position of the lever assembly and the retaining condition of the hood unit. There, spring 50 snaps thumb depressible element 34 back into engagement with socket recesses 65. The assembly 10 is completed by a figure-of-eight dust cover 90 that is retained on collars 23, 39 to minimise dust and grime entry to the meshed gear trains, and 25 teeth/recess pairs 55,65. It will be appreciated that the illustrated mechanism can be released by a single smooth thumb motion - down then back - while the bearer's hand maintains a very firm controlling grip on the handgun handle in the holster. When the gun is reinstated to its holster, a quick flick of either the hood unit or the lever assembly or both will return the 30 retaining mechanism to its home retaining condition. At no time does the bearer have to WO 2011/150468 PCT/AU2011/000698 8 remove his or her grip on the weapon while opening or closing the holster lock mechanism. The very positive locking engagement between teeth 55 and socket recesses 65, and the positive counter-rotational engagement between teeth trains 24 and 49, help guard against any attempt to pull hood unit 20 forwardly, or to force back 5 lever assembly 30. If an adverse person in front of the bearer reaches over the holster and gun and does succeed in depressing element 34, his hand will be in such a position that the subsequent attempted rotation of the hood unit will be physically opposed by the position of his own hand. This situation will at least delay and confuse the attempt to extract the handgun, giving crucial. advantage to the officer bearing the holstered 10 handgun. Figures 11 and 12 illustrate a modified embodiment in which a more positive latching of the hood unit is provided. Thumb depressible element 34 has a forwardly projecting elongate extension 33 with an inturned hook formation 33a at its tip. When element 34 is in its outermost position, urged there by spring 50, hook formation 33a engages firmly 15 behind a forward flat edge 29 of an integral V-shaped protrusion 28 on the outside of hood arm 21. This engagement positively locks hood unit 20 against any unauthorised or adverse attempt to pull the hood unit forwardly from its retaining condition. Protrusion 28 is dimensioned and positioned so that when element 34 is depressed sufficiently to release lever assembly 30 for rotation, hook formation 33a is lowered out of 20 engagement behind bulge edge 29. The modified embodiment illustrated in Figures 11 and 12 further differs in that housing 60 and backplate 80 are complementarily enlarged at the rear 60a, 8a to further strengthen the endwall stop for lever assembly 30 on the housing and to allow for an additional fastening 61 between the housing and the backplate.