Field of the invention

This invention relates to a locking mechanism intended specifically, but not exclusively, for securing a door of a shipping container against unauthorized opening.

Background to the invention Shipping containers have, at one end, a pair of doors which are hingedly mounted on the door frame of the container, the hinges being along the outer vertical edges of the doors. When the doors are closed the edges thereof which are remote from the hinges are in close proximity. Each door carries at least one vertically extending locking bar. The locking bars protrude, in the upward direction, beyond the top edge of the door and, in the downward direction, beyond the bottom edge of the door. The bars are carried by mounting brackets and are rotatable in these brackets. The upper end of each bar carries one part of a latching mechanism. The other part of the latching mechanism is carried by the transverse lintel of the doorframe of the container. Likewise, the lower end of the bar carries part of another latching mechanism.

Once the door is closed, the locking bar is rotated in its brackets to bring the two parts of each latching mechanism into co-operating relationship which prevents the door being opened until such time as the locking bar has been rotated in the opposite direction to disengage the parts of the latching mechanism.

It will be understood that unauthorised entry to the container is possible unless the locking bars are secured against rotation. Various mechanisms have been proposed for this purpose The inventor believes that a need exists for an improved structure for preventing unauthorised rotation of the said locking bars and hence unauthorised access to the interior of the container.

Summary of the invention

According to an aspect of the invention there is provided a locking mechanism comprising an inner ring, a shaft inserted into said inner ring, the shaft and ring having transverse bores which are aligned, a first pin in said aligned bores and a first pin lock for preventing withdrawal of said pin from said bores, slots in said ring and said shaft through which access can be had to said pin, groove in the outer surface of said ring, an outer ring, the two rings being co- axial, a transverse bore defined by the outer ring, a second pin in said transverse bore of the outer ring, part of said pin lying in said groove of the inner ring, a slot in said outer ring which is transverse by said second pin and through which access can be had to said pin, and a second pin lock for preventing withdrawal of said second pin from the bore of the second ring.

The inner ring may define two slots. The inner ring may define two diametrically opposed slots which extend inwardly from one end of the inner ring.

The inner ring may define aligned bores through a wall thereof, such bores being displaced by 90° around the circumference of the inner ring from the slots defined by the inner ring.

The radially outer ends of the bores as defined by the inner ring may be countersunk. The inner ring may include at least one groove, said groove may be machined into an outer surface of the inner ring. The groove on the outer surface of the inner ring may be generally tangential and may be found between one end of the ring and one of the bores as defined by the inner ring.

The inner diameter of the inner ring may match the outer diameter of a shank, and may be defined to receive at least a part of said shank.

The shaft may comprise a shank, said shank may include a flange at one end.

The shank may define at least one bore, the outer end of the bore being countersunk.

The shank may define at least one slot.

The slot may be located on the end of the shank which is remote from the flange, said slots extending beyond the bores as defined by the shank.

The slot may be displaced by between 60° and 120° around the circumference of the shank from the bores as defined by the shank.

Typically, the slot may be displaced by 90° around the circumference of the shank from the bores as defined by the shank.

The outer ring may be in the form of a split ring.

The split ring may include a gap in the circumference thereof.

The split ring may define an inner diameter that can receive at least a part of the inner ring.

The split ring may be attachable to at least one block, the block typically attachable to the split ring by welding. The split ring may be attachable to a plurality of blocks, typically two blocks.

The blocks may be welded to the outer surface of the split ring, specifically on each side of the gap defined by the split ring.

The blocks may define a bore, said bore being axially aligned and dimensioned and positioned to cut through the wall of the outer ring. The bore as defined by the blocks may be countersunk at their outer ends.

The bores may be shaped and dimensioned to receive a pin.

Typically, the pin may be inserted into the bore, thereby assisting in allowing a part of the shank to lie in the groove of the split ring.

The pin may include a shank and a head.

The pin may be attachable to a pin lock, said pin lock assisting in securing the pin in place when the locking mechanism is in use, the pin may be positioned in the countersunk end of the bore.

Typically, once the shank of the pin is pushed into the pin lock the pin may not be withdrawn.

Typically, the locking mechanism may be assembled by sliding the shaft into the inner ring and inserting the pin into the aligned bore.

Typically, when the bores are aligned, the slots may be aligned, and the pin may be pushed onto the shank of the pin. The inner ring may then slid into the outer ring, the groove may be positioned so that it is in alignment with the bores. The pin may then be pushed through the aligned bores part of the shank of the pin may enter the groove in the inner ring. This may lock the outer ring against rotational movement with respect to the inner ring, and may also lock the rings against axial movement of the rings with respect to one another. The pin lock may be pushed onto the end of the pin.

It may not be possible to disassemble the locking mechanism except by cutting through the shank of the pin by means of an angle grinder inserted into the slot. Once the two pieces of the cut pin may be removed, the outer ring can be slid off the inner ring, thereby providing access, via the aligned slots to the shank of the pin which may also be cut through. Once the pieces of the cut pin have been removed the shank can be withdrawn from the inner ring.

The locking mechanism may include a channel, said channel which may be open on the side facing towards a handle of a shipping container. For purpose of this specification it is to be understood that to latch and unlatch the closed door of a ship, a bar of the handle of the door of the ship being rotatale about its vertical axis by moving the handle in the direction which is out of the plane of the paper.

The handle may be within a channel which is open on the side facing towards the handle. Movement of the handle in the direction which rotates the bar to unlatch the door may be prevented by a flange of the channel.

The channel may be welded to a vertical plate which lies adjacent the bar. Part of the plate may be bent to form a U-bracket. The bracket may extend around the bar with the web of the bracket between the door and the bar, the flange of the channel on one side of the bar and the remainder of the plate on the other side.

An angle may be welded to the flange of the channel, the limb of the angle being against the door of the container. The shank of the shaft may pass through the other limb of the angle , the head assisting in preventing the shaft moving to the right. Detailed description of drawings

The invention will now be described with reference to the following non- limiting drawings, wherein; Figure 1 illustrates the components of a locking mechanism including a shaft; an inner ring; an outer ring; two pins and two pin locks;

Figure 2 is a view of the shaft of Figure 1 , Figure 2 being at right angles to the view of the shaft n Figure 1 ;

Figure 3 is a side elevation of the inner ring of Figure 1 , Figure 3 being at right angles to the view of figure 1 ;

Figure 4 is an end view of the ring of Figure 3;

Figure 5 is a side elevation of the outer ring of Figure 1 , Figure 5 being at right angles to the view of Figure 1 ;

Figure 6 is an end view of the outer ring;

Figure 7 illustrates the locking mechanism in a partly assembled condition;

Figure 8 illustrates the locking mechanism in its assembled condition; and Figure 9 illustrates the locking mechanism fitted to a door of a shipping container.

Referring firstly to Figure 1 , the locking mechanism illustrated includes a shaft 10; and inner ring 12; an outer ring 14; two locking pins 16 and 18 and two pin locks 20 and 22.

The shaft 10 comprises a shank 24 which has a flange 26 at one end. A bore 28 is drilled in the shank 24 and a slot 30 (see figure 2) is cut into the shank 24 from the end of the shank remote from the flange 26. The slot extends beyond the bores 28. The slot 30 is displaced by 90° around the circumference of the shank 24 from the bores 28. The outer ends of the bores 28 are countersunk.

The inner ring 12 (see also Figures 3 and 4) has two diametrically opposed slots 32 which extend inwardly from one end of the ring. The ring also has aligned bores 34 drilled through the wall thereof, the bores 34 being displaced by 90° around the circumference of the ring from the slots 32. The radially outer ends of the bores 34 are countersunk. A groove 36 is machined in the outer surface of the ring 12, the groove 36 being generally tangential and between one end of the ring 12 and one of the bores 34.

The inner diameter of the ring 12 matches the outer diameter of the shank 24 and, as will be described, during assembly the shank 24 is slid into the ring 12.

The outer ring 14 is not continuous but is in the form of a split ring with a gap 38 in the circumference thereof. Its inner diameter is such that the ring 12 can be slid into the ring 14. Two blocks 40 are welded to the outer surface of the ring 14, the blocks 40 being one on each side of the gap 38. Each block 40 has a bore 42 through it, the bores 42 being axially aligned and being dimensioned and positioned so that they cut through the wall of the outer ring 14 (see Figure 6). The bores 42 are, at their outer ends, countersunk. When the pin 18 is inserted into the bores 42, part of the shank 44 lies in the groove of the ring 14.

The pin 16 has a shank 44 and a head 46 and the pin has a shank 48 and a head 50. The pin locks 20 and 22 and the pin shanks 44 and 48 are configured so that once the shanks 44 and 48 are pushed into the pin locks 20 and 22, they cannot be withdrawn. The locking mechanism is assembled by sliding the shaft 10 into the ring 12 and inserting the pin 18 into the aligned bores 28 and 34. The head 46 of the pin 16 seats in the countersunk end of the bore 34. It will be understood that when the bores 28 and 34 are aligned in this way, the slots 32 and 38 are alos aligned. The pin lock 20 is pushed onto the shank 44 of the pin 16.

The inner ring 12 is then slid into the outer ring 14, the groove 36 being positioned so that it is in alignment with the bores 42. The pin 18 is then pushed through the aligned bores 42, part of the shank 48 of the pin 18 entering the groove 36 in the inner ring 12. This locks the outer ring 14 against rotational movement with respect to the ring 12, and also locks the rings against axial movement of the rings with respect to one another. The pin lock 22 is pushed onto the end of the pin 18.

It is not possible to disassemble the locking mechanism except by cutting through the shank 48 of the pin 18 by means of an angle grinder inserted into the slot 38. Once the two pieces of the cut pin 18 have been removed, the ring 14 can be slid off the ring 12. This provides access, via the aligned slots 30 and 32 to the shank 44 of the pin 16 which can also be cut through. Once the pieces of the cut pin 16 have been removed the shank 24 can be withdrawn from the ring 12.

Turning finally to Figure 9, this shows the locking mechanism of Figures 1 to 8 secured to one of the vertically extending locking bars 52 of a container door. The handle of the door is designated 54. To latch and unlatch the closed door, the bar 52 is rotated about its vertical axis by moving the handle 54 in the direction which is out of the plane of the paper.

The handle 54 is within a channel 56 which is open on the side facing towards the handle. Movement of the handle 54 in the direction which rotates the bar 52 to unlatch the door is prevented by the flange 58 of the channel 56. The channel 56 is welded to a vertical plate 60 which lies adjacent the bar 52. Part of the plate 60 is bent to form a U-bracket 62. The bracket extends around the bar 52 with the web 64 of the bracket 62 between the door and the bar 52, the flange 66 on one side of the bar 52 and the remainder of the plate 60 on the other side.

An angle 68 is welded to the flange 66, the limb 70 of the angle being against the door of the container. The shank 24 passes through the other limb 72 of the angle 68, the head 26 preventing the shaft 10 moving to the right.