AU2015261541A1 - A safety device for use with lock-out procedures - Google Patents

Abstract

An interlock mechanism is disclosed for use with a plurality of padlocks and a trap key. The interlock mechanism includes a plurality of padlock receptacles each adapted to receive a padlock shackle therein, and a trap lock adapted to receive a trap key. The trap lock and each padlock receptacle are associated with a respective cam member rotatable between an engaged position and a disengaged position. The cam members are mechanically coupled such that the trap lock cam member can only be rotated from its engaged position to its disengaged position when each and every padlock receptacle cam member is in its disengaged position. This mechanism and procedure ensures that all of the padlocks are returned to the lock-out station before the trap key can be removed. in C> N 0) 0 i0 Ln LO) CV3V Iw. LO C) co 1 Is) NI)

Description

A SAFETY DEVICE FOR USE WITH LOCK-OUT PROCEDURES FIELD OF INVENTION

[0001] The present invention relates to the field of safety devices, particularly devices suitable for use with lock-out, tag-out procedures.

BACKGROUND ART

[0002] The discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor and, moreover, any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.

[0003] In an industry or research setting, it is important that machines which may be hazardous to personnel not be used when they are faulty and/or undergoing maintenance. In these circumstances, a lock-out, tag-out procedure may be employed as a safety measure. Under this procedure, each relevant power source is turned off and prevented from being reactivated by a padlock locking the device or power source, often in conjunction with a tag describing the fault and other details. The procedure ensures that dangerous machines are properly shut off and not started up again prior to completion of maintenance or servicing work. Each padlock generally has a separate, individual key, of which there is only one, and separate, individual personnel may be designated to carry each respective key.

[0004] Problems can arise when a machine is fixed but the padlock not removed, particularly if the person with that padlock key leaves the site. In an industrial plant, for example, having one machine locked may prevent the entire plant from operating. In this situation, it is necessary to either contact the person with the key to return and remove the padlock, or to cut the padlock off. Cutting the padlock off has its implications as it may require a gathering of engineers or electricians to decide if it is in fact safe to cut the padlock off and restart the machine. There is also the question of liability if something was to go wrong once the padlock was cut off. If the person with the key cannot be contacted or cannot return to the site immediately, this can lead to machines being rendered unusable for extended periods of time, especially for machines that would normally be in operation 24 hours a day. This can result in both time and money lost.

[0005] One way to reduce the likelihood of inadvertent non-removal of locks from operable machines is the use of a “padlock station” or “lockout station” where each padlock and key may be provided with a separate hook or other means of attachment to the station when they are not in use. In this way, a person can look at the station and visually identify if any of the padlocks are missing before leaving the site. However, this system relies on the operator diligently checking the station. There is nothing to prevent a person not checking the station properly and then leaving the site without ensuring all padlocks are removed from machines.

[0006] It is an object of the present invention to overcome or alleviate at least one of the above noted drawbacks of related art systems or to at least provide a useful alternative to related art systems.

SUMMARY OF INVENTION

[0007] In accordance with a first aspect of the present invention there is provided a device for use with lock-out padlocks, comprising: one of more padlock receiving means; and a trap lock for use with a trap lock key; wherein the or each padlock receiving means are capable of movement from an engaged position to a disengaged position upon receipt of a padlock therein; and whereby the trap lock key is prevented from being removed from the trap lock unless all the one or more padlock receiving means are in the disengaged position.

[0008] Preferably, the device further comprises locking means to lock the padlock onto the device.

[0009] Preferably, the locking means also prevent removal of the padlock from the device without unlocking the padlock. Advantageously, this means that the padlock can only be removed by a person who has the key to the lock.

[0010] Preferably, the locking means is a shackle bar across the face of each padlock receiving means.

[0011 ] In one embodiment, the cam is a scallop cam.

[0012] In an alternative embodiment, the cam is a tear drop cam.

[0013] Preferably, the trap lock key is adapted for connection with other keys.

[0014] In accordance with another aspect of the present invention there is provided an interlock mechanism for use with a plurality of padlocks and a trap key, the interlock mechanism including a plurality of padlock receptacles each adapted to receive a padlock shackle therein, and a trap lock adapted to receive a trap key, wherein the trap lock and each padlock receptacle is associated with a respective cam member rotatable between an engaged and a disengaged position, the cam members being mechanically coupled such that the trap lock cam member can only be rotated from its engaged position to its disengaged position when each and every padlock receptacle cam member is in its disengaged position.

[0015] Preferably, each padlock receptacle cam member is moveable from its engaged position to its disengaged position by inserted a padlock shackle into the corresponding padlock receptacle and turning the padlock to effect rotation of that cam member..

[0016] Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention.

[0017] In essence, the present invention stem from the realization that if there was a padlock device with a trap key and that trap key was prevented from removal from the device unless all lock-out padlocks were removed from the machines and placed on the device, and that trap key was furthermore associated with a person’s car or house keys, the device would provide an effective fail safe mechanism to prevent a person leaving the premises with lock-out padlocks still on the machines.

[0018] Advantages provided by embodiments of the present invention include the following: • Prevents lock-out padlocks being left on a machine at the end of personnel’s shift • Minimise unnecessary down time due to lock outs being left on machine [0019] Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:

Figure 1 is a front view of an interlock device in accordance with an embodiment of the present invention, shown in an unengaged configuration;

Figure 2 is a top view of the interlock device of Figure 1;

Figures 3A, B and C are isolated views of padlock receptacle apertures of the interlock device of Figure 1;

Figure 4 is an internal rear view of the interlock device in accordance with an embodiment of the invention; and

Figure 5 is an internal rear view of an interlock device in accordance with another embodiment of the invention.

DETAILED DESCRIPTION

[0021] Embodiments of the invention are described hereinbelow in the form of an interlock device that finds particular use in lock-out, tag-out safety procedures and the like. The interlock device may take the place of a conventional padlock station. The purpose of the interlock device is to ensure, by means of an interlock mechanism, that all of the relevant padlocks are present and accounted for when required, such as at the end of a shift for example. In the preferred embodiment the device includes a trap lock and trap key and a plurality of padlock receptacles. In order to remove any or all of the padlocks from the device the trap key must be in place in the trap lock. Conversely, in order to remove the trap key from the trap lock, each and every padlock must be in place. Examples of mechanical arrangements by which these functions may be accomplished are provided by description of the embodiments below.

[0022] An interlock device 10, constructed in accordance with an embodiment of the invention, is shown in front view in Figure 1 and top view in Figure 2. The device 10 has a box-like chassis 20 with a flange 25 at each end for attaching it to a structure. As seen in Figure 1, the device has a front plate 30 which is formed with a plurality of padlock receptacle apertures 50 spaced across its width, and at one end a trap lock aperture 40. Each padlock receptacle aperture is adapted to receive the shackle portion 65 of a padlock 60, as described further below. The trap lock aperture is provided to allow a trap key 70 to be inserted in a key-slot 45 of a trap lock, the operation of which is also described in greater detail below. Attached to the front of the device is a shackle bar 35, seen in Figure 2, which extends across the centre of the apertures 50 spaced from the front plate except at its connection points 36 (Figure 1). The shackle bar itself is not shown in Figure 1.

[0023] Padlock receptacle apertures are shown in greater detail in Figures 3A, 3B and 3C. Each aperture 50 is generally S-shaped with a straight central portion dimensioned to receive a padlock shackle. Each end of the aperture 50 has an arcuate portion extending circumferentially through about 65-degrees in the clockwise direction (Figure 3A). The location of the shackle bar 35 is illustrated in dashed lines extending across the centre of the apertures 50. In Figure 3B a padlock shackle portion 65 is illustrated positioned in the central portion of the aperture 50. When the padlock is in this orientation in the aperture it can be inserted and removed. Figure 3C illustrates the padlock shackle portion 65 inserted in the aperture 50 and then rotated clockwise to the end extent of the aperture. The extent of rotation of the padlock shackle allowed by the aperture 50 is roughly the same as permitted by the shackle bar 35 which passes through the centre of the padlock shackle. When the padlock is oriented as seen in Figure 3C it is prevented from being removed from the aperture 50 by the portions of the front plate indicated at 55.

[0024] The interlock device 10, in a first embodiment of the mechanism, is shown from the rear in Figure 4. The device has a plurality of rotatable cam members 100 each aligned with a corresponding aperture 50 on the front of the device. The cam members 100 are supported by the chassis 20 for rotation each about its own axis normal to the plane of the Figure 4 drawing. The front of each of the cam members 100 has a padlock receptacle (not shown) that aligned with a respective aperture 50 and adapted to receive a padlock shackle portion when inserted in that aperture. Each of the cam members 100 is thus capable of being rotated by means of rotation of a padlock in the corresponding aperture 50, although rotation of each member is restricted by their interlocking design as described hereinbelow.

[0025] Another rotatable member 110 is provided aligned and corresponding to the trap lock aperture 40. Rather than a padlock receptacle the member 110 includes a trap lock with key-slot 45, whereby the member 110 can only be rotated by means of the corresponding trap key 70.

[0026] The rotatable members 100 and 110 interfit with one another by scallop formations 105 on the otherwise cylindrical periphery thereof. The scallop formations are arranged so that each rotatable cam member 100 can permit or restrict rotation of an adjacent cam member 100 depending on its own rotational orientation. For example, the rotatable cam members 100 as shown in Figure 4 are all in an engaged configuration. The trap lock member 110 is prevented from rotation by the member 100F, which is prevented from rotation by the member 100E, and so on. In this configuration the trap key cannot be removed from the trap lock because the trap lock cannot be rotated.

[0027] In the configuration of Figure 4, the only cam member that can be rotated is 100A. In order to permit rotation of the trap lock member to remove the trap key the members 100A to 100F would have to be rotated in sequence from their engaged position to a disengaged position. For each cam member 100 this can only be done by locking a padlock around the shackle bar and inserting the padlock shackle portion in the corresponding aperture and receptacle and rotating within the extent of the aperture. (Note that since Figure 4 is a rear view, clockwise rotation from the front of the device results in anti-clockwise rotation of the members 100 as seen here). Only when all of the cam members 100 have been rotated using respective padlocks will the scallop formation on the member 100F be positioned to permit rotation of the trap lock member 110.

[0028] In this embodiment, padlocks are inserted into the device 10 in sequence starting from the position farthest away from the trap lock and continuing towards the trap lock. The movement of each cam member 100 enables the member adjacent on the side closer to the trap lock to be moved to a disengaged position on insertion and rotation of a padlock. Once the cam member 100F adjacent to the trap lock member 110 is rotated to a disengaged position, the member 110 and trap lock can also be rotated to release the trap key. A spring loaded detent pin or the like may be used to prevent the rotation of each padlock receptacle without having a padlock first inserted, thus preventing removal of the trap lock key from the trap lock until the last cam member is disengaged.

[0029] An alternative embodiment using a different mechanical arrangement is shown in Figure 5 illustrating the interlock device 10 from the rear. In this case, a runner bar 230 is supported by the chassis 220 for longitudinal sliding movement on rail support pins 225. Tear-drop shaped cams are used instead of scallop formations on each of the cam members 200 and the trap lock member 210, and drive pins 235 project from the runner bar 230 next to each cam member 200 on the side away from the trap lock member. A lock pin 240 is next to the trap lock member 210, on the opposite side.

[0030] The interlock device 10 is shown in Figure 5 in the disengaged configuration, wherein rotation of the trap lock member 210 is not restricted by the lock pin 240. In this configuration the trap lock member may rotate to insert or remove the trap key. In the same manner as described hereinabove, the cam members 200 can only be rotated by inserting a padlock shackle in the corresponding aperture. If any one of the cam members is rotated (in an anticlockwise sense in the rear view of Figure 5) the cam member bears against its adjacent drive pin 235 which results in sliding movement of the runner bar 230 (toward the right hand side in Figure 5). Each cam member 200 can rotate independently to its engaged position, and if any one of the cam members is in the engaged position (e.g. because the corresponding padlock is not present) the runner bar 230 is prevented from sliding back (toward the left) by the drive pin engaging with the curved surface of the cam member. Thus, when any of the cam members is in its engaged position, the runner bar 230 is placed in an engaged position and prevented from returning to a disengaged position by each engaged cam member.

[0031] When the runner bar 230 is in its engaged position the lock pin is positioned against the flat surface of the trap lock member 210 preventing its anticlockwise rotational movement. This means the trap key is fixed in the trap lock. To disengage the device, each and every one of the cam members 200 must be placed in their disengaged position, allowing the runner bar 230 to slide (to the left in Figure 5) by action of the trap lock member 210 cam surface bearing against the lock pin upon rotation of the trap key.

[0032] In this embodiment, having any one of the cam members in an engaged position will prevent rotation of the trap lock cam. This method has the advantage that any padlock in any order can be removed or replaced, whilst still ensuring that all padlocks must be in place to disengage the device and enable release of the trap lock key.

[0033] As described above in relation to Figures 1 and 2, a shackle bar 35 extends across the centre of the padlock apertures 50. In use, the padlocks are locked onto the shackle bar prior to inserting the padlock shackle into the aperture and padlock receptacle. The shackle bar prevents removal of padlocks from the device without unlocking the padlock. This ensures a padlock cannot be inserted or removed without use of its key, which prevents the padlock being removed by anyone other than the owner of the padlock, for example. The shackle bar also prevents padlocks from being lost when not in use.

[0034] The trap key 70 may be adapted for connection with other keys by way of a tamper-proof key ring or the like. For example, it is envisaged that the trap key may be affixed to as the shift supervisor’s house keys or car keys. The trapping of these keys to the device means that the person responsible for returning all padlocks to the device at the end of their shift is less likely to leave the site with padlocks still in place on one or more machines.

[0035] As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive.

[0036] Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures.

[0037] The terms “comprising”, “including”, and variations thereof, when used in this specification are taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, ‘includes’, ‘including’ and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

Claims (10)

1. A device for use with lock-out padlocks, comprising: one or more padlock receiving means; and a trap lock for use with a trap lock key; wherein the or each padlock receiving means are capable of movement from an engaged position to a disengaged position upon receipt of a padlock therein; and whereby the trap lock key is prevented from being removed from the trap lock unless all the one or more padlock receiving means are in the disengaged position.

2. The device of claim 1, further comprising locking means to lock the padlock onto the device.

3. The device of claim 2 wherein the locking means also prevent removal of the padlock from the device without unlocking the padlock.

4. The device of any one of claims 2 and 3, whereby the locking means is a shackle bar across the face of each padlock receiving means.

5. The device of any preceding claim wherein the movement of the padlock receiving means from the engaged position to the disengaged position is by use of a cam attached to each padlock receiving means and the trap lock.

6. The device of claim 5 wherein the cam is a scallop cam.

7. The device of claim 5 wherein the cam is a tear drop cam.

8. The device of any preceding claim wherein the trap lock key is adapted for connection with other keys.

9. An interlock mechanism for use with a plurality of padlocks and a trap key, the interlock mechanism including a plurality of padlock receptacles each adapted to receive a padlock shackle therein, and a trap lock adapted to receive a trap key, wherein the trap lock and each padlock receptacle is associated with a respective cam member rotatable 10 between an engaged position and a disengaged position, the cam members being mechanically coupled such that the trap lock cam member can only be rotated from its engaged position to its disengaged position when each and every padlock receptacle cam member is in its disengaged position.

10. An interlock mechanism according to claim 9, wherein each padlock receptacle cam member is moveable from its engaged position to its disengaged position by inserting a padlock shackle into the corresponding padlock receptacle and turning the padlock to effect rotation of that cam member.