NZ587436A

NZ587436A - A safety block for lifting objects by rope which clamps the rope if the tension on the rope lowers quickly

Info

Publication number: NZ587436A
Application number: NZ58743610A
Authority: NZ
Inventors: Marc Taal
Original assignee: Marc Taal
Priority date: 2010-08-18
Filing date: 2010-08-18
Publication date: 2011-01-28
Also published as: WO2012021989A1

Abstract

A safety wheel block (100) is disclosed. The block (100) will prevent a load it is being used hoist from falling if the rope end being hauled upon (510) is released. The block (100) has first wheel (320) and second wheel (340) on a carriage (310) that is connected by a pivot (410) to a base (212) suspended using a ring (230). The rope is threaded over the wheels but under the base (212). The pivot axis (A) is positioned such that when a pulling force (TT) and the tension force (TL) created by the weight of the object being hoisted are substantially equal, the pivoting arrangement remains in a first position but will move to a second position when the pulling force (TT) at the tension end of the rope (510) is rapidly reduced. In the first position the rope may travel freely over the wheels. In the second position the carriage (310) pivots up, lifting the second wheel (340) and causing the rope to contact with the base (212) and be pressed onto a breaking pad (330) within the carriage (310). As long the forces on the rope are unbalanced the weight of the object being hoisted will bring about this breaking action. The actuation of the breaking action will actuate a further process such an alarm.

Description

NEW ZEALAND PATENTS ACT, 1953 No: Date: COMPLETE SPECIFICATION SAFETY WHEEL BLOCK I, MARC TAAL, a New Zealand citizen of 16 Cedarwood Bay SW, Calgary Alberta T2W3H7, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: TECHNICAL FIELD The present invention relates to a safety wheel block. More particularly but not exclusively it relates to a safety wheel block having an automatic safety system.

BACKGROUND OF THE INVENTION Pulley systems are known for use in a wide variety of industries — from window-cleaning and mountain climbing to logistics or furniture removals. Where a pulley is generally required, this typically means that there is a situation where, for example an object is being lifted to a height not easily reachable by a person (for example lifting furniture to a second story door or a can of paint to a painter), or the direction of pull by a rope is merely required to be changed or reversed {for example when using a pulley to retrieve a stuck vehicle from mud). In any of these situations, the effect of failure of the cable or rope can be catastrophic.

On typical pulley systems, one end of a cable (hereinafter the "tension end") extends from the pulley to be pulled on by manual or mechanical means (such as a winch) while the lifting end is attached to the object to be lifted or pulled on. For obvious reasons, when the tension end is suddenly released, the tension or lifting force on the item being pulled or lifted is released, and may result in undesirable, dangerous and even catastrophic circumstances.

For this reason, a safety system is desirable to prevent unsafe circumstances caused by the sudden loss of tension on the tension end of the cable in a pulley system.

In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

For the purposes of this specification, the term "rope" shall be construed to mean a general term for a wide range of flexible elongate arrangements of any configuration (for example, woven, wound, forged, twisted or otherwise) and composed of any material, (including but not limited to metallic material, canvas, fibres, and shall include, but not be limited to rope, cable, chain, string, line, cord or any other similar arrangement.

For the purposes of this specification, the term "wheel' is to be construed as any member or arrangement which is provides for the relatively frictionless movement of a rope over-it, and can include but is not limited to a pulley wheel, gear wheel, sprocket, or the like, and can but need not rotate on bearings, bushings, or the like.

OBJECT OF THE INVENTION It is ail object of the present invention to provide a safety wheel block which overcomes or at least ameliorates some of the abovementioned disadvantages or which at least provides the public with a useful choice.

SUMMARY OF THE INVENTION In a first aspect the present invention may be said to broadly consist in a safety wheel block suitable for facilitating the exertion of a pulling force on an object (such as to effect a holding or moving of said object) by a rope that is operationally engaged towardsa lifting end of the rope with said safety wheel block, by virtue of a tension force exerted at or toward an opposed tension end of said rope, said safety wheel block comprising: a base assembly mountable to a support structure; a support assembly including a pivoting arrangement pivotally coupled to the base assembly about a pivot axis to be able to move between a first position and a second position relative said base assembly, a first wheel mounted to the pivoting arrangement at a distance from the pivot axis and over which said rope is extendable, and a second wheel mounted to the pivoting arrangement and over which said rope is extendable, said second wheel being disposed from the pivot axis of the pivoting arrangement, and configured and adapted for engaging the rope at a distance from the first wheel; wherein said first wheel and second wheel and said pivot axis are positioned such that when said pulling force and said tension force are substantially equal, said pivoting arrangement remains in said first position but will move to the second position when the tension force at the tension end of the rope is rapidly reduced, and wherein, when the tension in the lifting end of the rope and the tension end of the rope is operationally imbalanced, the imbalanced tension in the rope acting on the first wheel and second wheel will cause pivoting of the pivoting arrangement about the base assembly between its first position and second position, to actuate a further process.

Preferably, said safety wheel block further comprises a restraining arrangement able to restrain movement of the rope relative to the safety wheel block; and moveable between a restraining position in which it restrains movement of the rope relative the safety wheel block, and an unrestrained position in which movement of the rope relative the safety wheel block is relatively less constrained.

Preferably, said process is one or more selected from the actuation of the restraining arrangement for restraining movement of the rope relative the safety wheel block; the actuation of an alarm; and the generation of a signal.

Preferably, said signal is for use in a control system.

Preferably, said safety wheel block further comprises a control system.

Preferably, a tension force is exerted at or towards a tension end of said rope, and the rope is coupled operationally via said safety wheel block to exert a pulling force on an object at or towards air opposed lifting end of said rope; and wherein, when the tension in the lifting end of the rope and the tension end of the rope is operationally substantially similar, the restraining arrangement will be configured to its unrestrained position to allow relatively unrestrained movement of the rope relative to the safety wheel block.

Preferably, the second wheel is disposed at a distance from the first wheel.

Preferably, the base assembly includes a support arrangement for allowing pivotal coupling of the pivoting arrangement to the base assembly.

Preferably, the wheel is one selected from j ' a pulley wheel, a sprocket, a gear wheel, and a cog.

Preferably one or more selected from the first wheel and the second wheel includes a friction reduction device for reducing rotational friction.

Preferably, the friction reduction device is one or more selected from a bearing, and a bushing.

Preferably, the restraining arrangement comprises support assembly restraining formations associated with the support assembly.

Preferably, the restraining arrangement comprises the support assembly and/or restraining formations on the base assembly and that cooperate to restrain movement of the rope.

Alternately, the restraining arrangement is coupled to one or more selected from the base assembly and the support assembly.

Preferably, the restraining arrangement operates to restrain movement of the rope by means of one of more selected from a clamping action; a positive engaging action; a braking action; a clutch braking action.

Preferably, the pivot axis acts as a fulcrum for the leverage member.

Preferably, when the restraining arrangement is in its restraining position, it prevents the rope from being withdrawn from the support assembly in a direction towards its lifting end.

Preferably, when the restraining arrangement is in its restraining position, it prevents the rope from being withdrawn from the support assembly by clamping the rope.

Alternately, the restraining arrangement is one or more selected from a mechanical device, an electromechanical device, a hydraulic device, a pneumatic device, an electronic device, and an electromagnetic device.

Preferably, the first wheel and leverage member are configured and adapted to operationally receive said rope over the first wheel and over the leverage member in tension, so that when tension is released at the tension end of the rope, the tension in the lifting end of the rope acts on the pivoting arrangement to cause the rope to be restrained by the restraining arrangement, thereby to prevent the rope from being withdrawn from the safety wheel block towards its lifting end and/or to at least facilitate continued at least partial support of the object to be supported by the rope.

Preferably, both of the first wheel and the second wheel arc offset by a distance to either side of a line extending downwardly from the pivot axis of the pivoting arrangement.

Preferably, the one or more selected from the base assembly and the support assembly include clamping formations.

Preferably, the rope is caused to be clamped between clamping formations on each of the base assembly and the support assembly.

Preferably, the leverage member includes a clamping formation.

Preferably, the rope is caused to be clamped between a clamping formation on the base assembly and the leverage member.

Preferably, the leverage member is integrally formed with the pivoting arrangement.

Preferably, the pivoting arrangement comprises a pair of plates spaced apart by at least one transverse strut.

Preferably, the leverage member comprises a pair of plates spaced apart by at least one transverse strut.

Preferably, the leverage member is configured and adapted to support the rope at a distance from the first wheel at the second wheel.

Preferably, the leverage member comprises a pair of spaced apart plates, between which is supported one or more selected form the first wheel and the second wheel.

Preferably, the pivoting arrangement is pivotally coupleable to the base assembly by means of an axle arrangement.

Preferably, the pivoting arrangement comprises an axle that is received or receivable into a complementary aperture in the base assembly.

Alternately, the base assembly comprises an axle that is received or receivable into a complementary aperture in the pivoting arrangement.

Preferably, the clamping formation extends from the base assembly.

Preferably, the clamping formation on the base assembly is adapted and configured to clamp the rope against the second wheel on angular movement of the support assembly caused by the operational loss of tension at the tension end of the rope.

Alternately, the clamping formation 011 the base assembly is adapted and configured to clamp the rope against the first wheel.

Alternately, the clamping formation on the base assembly is adapted and configured to clamp the rope against a clamping formation on the pivoting arrangement.

Preferably, the base assembly includes securing formations for securing the base assembly to a securing point.

Preferably, the securing point is raised relative to the object to be lifted.

Preferably, the safety wheel block includes at least one selected from a sensor or switch for detecting pivotal movement of the pivoting arrangement.

Preferably, the safety wheel block includes at least one actuation device for actuating the restraining arrangement to at least partially restrain movement of the rope.

Preferably, the safety wheel block includes a power input arrangement for powering one or more selected from the sensors, actuation device and restraining arrangement.

Preferably, the power input arrangement is one or more selected from an electrical plug, or a receiving conduit for pressurised fluid.

Preferably, the safety wheel block includes a power supply for powering one or more selected from the sensors, actuation device and restraining arrangement.

Preferably, the power supply is one or more selected from a compressor a hydraulic power pack a generator.

Preferably, the axes of any two or more of the first wheel, second wheel and pivot axis of the pivoting arrangement are parallel to each other.

Preferably, the rope applies forces to the first wheel and/or second wheels in a direction normal to their axes of rotation.

Preferably, the rope applies forces to the pivoting arrangement in a direction normal to its pivoting axis.

In another aspect the present invention may be said to broadly consist in a safety pulley wheel block for facilitating the exertion of a pulling force on an object by way of a rope, wherein a tension force is exerted towards a tension end of said rope, and said elongate arrangement is coupled to said safety wheel block to exert a pulling force on an object towards a lifting end of said rope, said safety pulley wheel block comprising: • a base assembly mountable to a support structure; • a restraining arrangement for restraining movement of the rope relative to the safety wheel block; and moveable between • a restraining position in which it at least partly restrains movement of the rope relative to the safety wheel block, and • an unrestrained position in which movement of the rope relative to the safety wheel block is relatively less constrained; • a pulley assembly including ■ a pivoting arrangement pivotally coupleable to the base assembly in a pivoting fashion; ■ a first pulley wheel rotationally mounted to the pivoting arrangement offset from the pivot axis of the pivoting arrangement; and ■ wherein the pivoting arrangement comprises an associated leverage member configured and adapted for engaging the rope at. a distance from the first pulley wheel and a distance from the pivot axis of the pivoting arrangement; • wherein the first pulley wheel and associated leverage member are configured and adapted to operationally receive said rope over the first pulley wheel and over the leverage member in tension, so that when tension is suddenly released at the tension end of the rope, the tension in the lifting end of the rope causes pivoting of the pivoting arrangement about the base assembly, to move the restraining arrangement to its restrained position to thereby prevent the rope from being withdrawn from the pulley towards its lifting end and to at least facilitate the continued exertion of a pulling force on said object.

The base assembly may includc a support arrangement for allowing pivotal coupling of the pivoting arrangement to the base assembly.

In another aspect the present invention may be said to broadly consist in a safety wheel block for facilitating the exertion of a pulling force 011 an object by way of a rope, wherein a tension force is exerted towards a tension end of said rope, and the rope is coupled to the safety wheel block to exert a pulling force on an object at or towards a lifting end of said rope, said safety wheel block comprising: • a base assembly mountable to a support structure; • a support assembly including ■ a pivoting arrangement pivotally coupleable to the base assembly in a pivoting fashion; ■ a first wheel rotationally mounted to the pivoting arrangement offset from the pivot axis of the pivoting arrangement; and ■ wherein the pivoting arrangement comprises an associated leverage member configured and adapted for engaging the rope at a distance from the first wheel and a distance from the pivot axis of the pivoting arrangement; • wherein the first wheel and leverage member are configured and adapted to operationally receive said rope over the first wheel and over the leverage member in tension, so that when tension is released at the tension end of the rope, the tension in the lifting end of the rope acts on the pivoting arrangement to cause the rope to be clamped between the support assembly and the base assembly, thereby to prevent the rope from being decoupled from the safety wheel block and/or to at least facilitate continued at least partial exertion of a pulling force on the objcct.

Preferably, the safety wheel block includes a clamping arrangement associated with the base assembly and the support assembly for clamping the rope to at least partially restrain movement of the rope relative to the safety wheel block; said clamping arrangement being moveable between ■ a clamping position in which it at least partially restrains movement of the rope relative to the safety wheel block, and ■ an undamped position in which movement of the rope relative to the safety wheel block is relatively less restrained; " wherein the clamping arrangement is actuated between its clamped and undamped positions by pivoting movement of the pivoting arrangement relative to the base assembly.

In a further aspect the present invention may be said to broadly consist in a safety wheel block suitable for facilitating the exertion of a force on an object (such as to effect a holding or moving of said object) by a rope that is operationally engaged with said safety pulley block, by virtue of a tension force exerted at or toward and opposed tension end of said rope, said safety wheel block comprising: • a base assembly mountable to a support structure; • a support assembly including ■ a pivoting arrangement pivotally coupled to the base assembly about a pivot axis to be able to move between a first position and a second position relative said base assembly, ■ a first wheel mounted to the pivoting arrangement at a distance from the pivot axis and over which said rope can extend; and ■ a second wheel mounted to the pivoting arrangement at a distance from said first wheel and from the pivot axis and over which said rope can extend, • a restraining arrangement that can be caused, by virtue of pivotal movement of the pivoting arrangement, to assume; ■ a first condition (herein after "unrestrained condition") when said pivoting arrangement is in said first position in which the rope can run unimpeded by said restraining arrangement; and ■ a second condition (herein after "restraining condition") when said pivoting arrangement is in said second position, in which the restraining arrangement restrains movement of the rope, and said first wheel and second wheel and said pivot axis are positioned such that when said pulling force and said tension force are substantially equal, said pivoting arrangement remains in said first position but will move to the second position when the tension force is rapidly reduced, thereby causing the restraining arrangement to assume the second condition.

Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

As used herein the term "and/or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

Th e term "comprising" as used in this specification and claims means "consisting at least in part of'. When interpreting statements in this specification and claims which include that teim, the features, prefaced bv that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted m the same manner.

To those skilled in the art to which the invention relates, many changes in construction and widelv differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example only and with reference to the drawings in which: Figure 1: shows a cutaway side view of one embodiment of a safety wheel block showing hidden detail of those sections that were cut away; Figure 2: shows a cutaway side view of the embodiment of figure 1 showing hidden detail of those sections that were cut away, in a position in which movement of the rope is restricted, showing hidden detail of those sections that were cut away; Figure 3: shows a perspective top view of a second embodiment of a safety wheel block showing hidden detail; Figure 4: shows a side view of a third embodiment of a safety wheel block j showing a restraining arrangement actuatable by the pivoting of the pivoting arrangement to restrain the rope; Figure 5: shows a cutaway side view of a fourth embodiment of a safety wheel block showing hidden detail of those sections that were cut away, in a position in which movement of the rope is restricted; Figure 6: shows a bottom perspective view of a fifth embodiment of a safety7 wheel block, in a position in which movement of the rope is not restricted; Figure 7: shows a bottom perspective cutaway view of a sixth embodiment of a safety wheel block , in a position in which movement of the rope is restricted; Figure 8: shows a bottom perspective view of the fifth embodiment of a safety wheel block of figure 6 showing hidden detail of, in a position in which movement of the rope is restricted; Figure 9: shows a side view of a seventh embodiment of a safety wheel block utilising sprockets as first and second wheels, in a position in which movement of the chain is restricted; Figure 10: shows a side view of a eighth embodiment of a safety wheel block showing hidden detail, in a position in which movement of the rope is restricted; Figure 11: shows a side view of an ninth embodiment of a safety wheel block showing hidden detail, in a position in which movement of the rope is restricted; and Figure 12: shows a perspective top view of a tenth embodiment of a safety' wheel block showing hidden detail, in a position in which movement of the rope is restricted.

Figure 13: shows a side view of a eleventh embodiment of a safety wheel block utilising gear sprockets as first and second wheels, in a position in which movement of the chain is restricted; Figure 14: shows a side view of the seventh embodiment of a safety wheel block utilising gear sprockets as first and second wheels, in a position in which movement of the chain is not restricted; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) With reference to the above drawings, in which similar features are generally indicated by similar numerals, and which are not in scale but are merely for illustrating the operation of the invention, a safety wheel block according to a first aspect of the invention is generally indicated by the numeral 100. The safety wheel block 100 is for lifting or otherwise exerting a pulling force on an object (not shown) by means of a rope, cable, chain or the like 500, wherein a tension force Tt is exerted towards a tension end 510 of the rope 500, and the rope 500 is coupled to and extends through the safety wheel block 100 to pull on the object to be supported at a lifting end 520 of the rope 500 with tension force Tj .(as shown in figures 2 and 3).

It is envisaged that the safety wheel block 100 could also be used for exerting a pulling force on an object in a sideways or downwards direction (for example for pulling vehicle out of mud), and does not necessarily always have to exert a lifting or supporting force on the objcct. Where the term "lifting' is used in this specification, it should also be appreciated that a non-upwards pulhng force could also be exerted.

The safety wheel block 100 comprises a base assembly 200, and a support assembly, which in one preferred embodiment (as shown in figures 1-14) includes a first wheel 320 in the form of first pulley wheel 321 or first sprocket 322 and a second wheel 340 in the form of a second pulley wheel 342 or second sprocket 344 (and is therefore referred to as a pulley assembly 300 hereinafter).

The base assembly 200 comprises a support arrangement 210 on which the pulley assembly 300 is pivotally suspendable. In the embodiments shown, the support arrangement 210 is a simple hole for the insertion of an axle, but it will be appreciated that a wide variety of formations may be possible in other embodiments.

The safety wheel block 100 further comprises a restraining arrangement 110 for restraining relative movement of the rope 500 relative to the safety wheel block 100.

It should be noted that the base assembly restraining formation 220 is envisaged as being able to clamp or otherwise restrain the rope in a variety of ways, for example by clamping it against the first pulley wheel, the second pulley wheel or against dedicated clamping formations associated with the support assembly.

In one preferred embodiment the restraining arrangement comprises associated components on each of the base assembly 200 (for example a base assembly restraining formation 220 in the form of a clamping formation 221 shown in Figures 1-3 and 5-12) and the support assembly (for example a support assembly restraining formation in the form of a clamping block 354 shown in Figures 1-12).

In another embodiment shown 111 figures 9 and 13-14, die restraining arrangement 110 includes a base assembly restraining formation 220 in the form of an engaging formation 225 on the base assembly 200, that is engageable with a plurality of support assembly restraining formations 350, in the form of ratchet teeth 352.

The restraining arrangement 110 further includes the sprocket teeth 324 for restraining movement of the chain 500 in figures 9 and 13-14. This will be discussed in more detail below.

The restraining arrangement 110 is operated and/or actuated by the pivotal movement of the pivoting arrangement 310 relative to the base assembly 200. The restraining arrangement 110 is moveable between a restraining position (shown in figures 2, 3, 5, 7, 8, 9, 10, 11, 12, and 13) in which it restrains movement of the rope 500 through the safety wheel block, and an unrestrained position in which movement of the rope 500 through the safety wheel block 100 is relatively less restrained (as shown in figures 1, 6, and 14).

The pulley assembly 300 includes a pivoting arrangement 310 pivotally coupleable to the support arrangement 210 in a pivoting fashion about axis A.

In a preferred embodiment the support arrangement 210 is a pivoting mechanism 400 comprising an axle stub 410 extending through an aperture 420, however it will be appreciated by a person skilled in the art that any other suitable pivoting arrangement could be used.

In figures 1-9 and 11, the support arrangement 210 includes an aperture 420 through which an axle stub 410 is received.

In figure 10, however, the pivoting arrangement 310 is associated with an aperture 420, through which an axle stub 410 is received.

The support arrangement 210 shown in figures 1-8 and 12 comprises a single base member 212 defining an aperture 420 therethrough for hanging the pulley assembly 300 on. A further embodiment of a support arrangement 210 is shown in figures 10 and 11, wherein the support arrangement 210 comprises a pair of base members 212, each defining an aperture 420 for hanging the pulleys assembly 300 on.

The base assembly 200 can preferably also include securing formations 230 for releasably securing the base assembly 200 to a securing point, such as a ledge (as shown on figure 10 and 11) or a hook (not shown), preferably at a raised level relative to the object to be lifted. In an alternative embodiment, the base assembly 200 can be permanendy secured or integrally formed with the securing point. Securing formations 230 are shown in figure 3 as a swivel 232, and in figures 10 and 11 as a flange 234 (together with securing bolts not shown).

The base assembly further includes base assembly restraining formation 220 secured to the support, arrangement. The clamping formation 221 is preferably integrally formed with the base member 212 of the support arrangement 210, but could also be secured to it by means of a securing arrangement 222 such as a nut and bolt mechanism 224 shown in figure 11, or a square pin arrangement 226 shown in figure 10.

The pivoting arrangement 310 of the pulley assembly 300 is pivotally coupled to the support arrangement 210 about a pivot axis A between at least a first position and a second position.

The first position of the pivoting arrangement corresponds to the unrestrained position of the restraining arrangement, in which the restraining arrangement is in an unrestrained condition in which movement of the rope relative to the safety" wheel block is free to move.

The second position of the pivoting arrangement corresponds to the restrained position of the restraining arrangement, in which the restraining arrangement is in a restrained condition in which it restrains movement of the rope relative to the safety wheel block.

The pulley assembly 300 further comprises a first pulley wheel 321 rotationally mounted to the pivoting arrangement 310; and a leverage member 330 extending from the pivoting arrangement 310.

The pivoting arrangement 310 comprises a pair of spaced pivoting arrangement members 312a & b, preferably in the form of planar plates. The first pulley wheel 321 is rotationally mounted between the spaced pivoting arrangement members 312a & b on an axis B.

In another embodiment shown in figures 6 and 8, the pivoting arrangement only includes a single plate with the first pulley wheel 321 and second pulley wheel 342 rotatably secured to it in a cantilevercd fashion.

The leverage member 330 is configured and adapted for supporting the rope 500 at a distance from the first wheel 320 on second wheel 340.

In one preferred embodiment, the leverage member 330 comprises a pair of spaced leverage member members 332a & b, preferably in the form of planar plates that are integrally formed with the planar plates of the spaced pivoting arrangement members 312a & b. The leverage member 330 is adapted and configured to support the rope 500 by means of a second wheel 340 extending between the spaced plates as shown in figure 3.

In one embodiment, the second wheel 340 is a second pulley wheel 342 that is rotationally mounted between the spaced leverage member members 332a & b on an axis C.

In the embodiments described in this specification, and as shown in the figures, the support assembly is described as a pulley assembly 300 where it includes at least a first pulley wheel 321 or a second pulley wheel 342, however, it is envisaged that the support assembly could include no pulley wheels, and instead use alternative supporting formations that offer little restriction to movement of the rope 500 over them. Kxamples could include struts or lugs made of or covered in low friction material, that offer low friction to a rope moving over them, or having friction lowering arrangements such as bearings or bushings that they rotate on. The struts or lugs could have a diameter that is large relative to the rope, to reduce the possibility of the rope snagging on the strut or lug. These could be in the form of transverse struts (not shown) between the plates of the spaced pivoting arrangement members 312a&b and/or spaced leverage member members 332a & b or arranged in a cantilevered configuration from a single pivoting arrangement member.

The operation of the safety wheel block 100 is now described with reference to the lifting of an object, however, it should be noted that similar principles of operation will apply when an object is being pulled sideways or downwards.

In operation, both the first pulley wheel 321 and second pulley wheel 342 receive a rope 500 over them. An object is attached to the lifting end 520 of the rope 500 and the tension end 510 of the rope is tensioned up by exerting a downward force on the tension end 510.

This tension is spread evenly throughout the rope as tension is slowly put on the rope, so tension in the rope (shown as arrow T , in figure 2 and 3) to the side of the tension end becomes substantially equal to the tension in the rope (shown as arrow T, in figures 2 and 3) to the side of the lifting end 520, so that the same tension force acts inwardly on the top of both the pulley wheel 321 and second pulley wheel 342.

This equality of tension forces Tr and T, causes the pivoting arrangement 310 to remain relatively stationary and balanced at either end, so that it is aligned with a small distance between the rope 500 and the clamping formation 220 of the base assembly 200 (as shown in figure 1) . If the force downwardly on the tension end 510 increases slowly to increase Tr, the tension Tt is spread substantially evenly through the rope 500 so that T, equals Tt until eventually T; will overcome the downward force (weight) of the object to be lifted and cause the object to rise.

In this way, the object can be lifted upwardly. Further, if it is desired to lower the object, then the downward force on the tension end 510 is decreased slowly, so that the tension forces Tj- and T; in the rope 500 at either side of the safety wheel block 100 remain substantially equal, and the pivoting arrangement 310 remains m equilibrium.

While the tension forces T-r and T, are closely balanced, the pivoting arrangement 310 is balanced about its pivot axis A, and remains in equilibrium. Tension force Tt acts on the second puller wheel 342 to exert a substantially downward force on it. This downward force is transferred to the pivoting arrangement at its axis C.

Similarly, Tension force T, acts on the first pulley wheel 321 to exert a substantially downward force on it. This downward force is transferred to the pivoting arrangement at its axis B.

The tension forces Tr and T, each act on the pulley assembly 300 to create a moment on it about the pivot axis A. For the pivoting arrangement 310 to be in equilibrium about axis A, these moments must equal each other.

A line drawn from axis A perpendicularly to the tension forces in the rope 500 at each end (shown as Lr and L,) will need to equal each other when the tension forces are equal, and the pivoting arrangement 310 will pivot until this equilibrium is reached.

However, if the tensions are unbalanced, such as may happen if the tension end is released, or the rope 500 snaps along its length towards the tension end 510, then the following sequence of events are envisaged (as will now be described with reference to figure 3).

When the tension is suddenly released, the force from the rope 500 acting downward on the leverage member 330 (at the second pulley wheel 342) is reduced relative to the force acting downwardly on the first pulley wheel 321. This means that the moments about axis A caused by tension Tt and tension Tj will be unbalanced. The downward force of the rope 500 acting on the first pulley wheel 321 is no longer balanced by the downward force of the tensioned rope 500 acting downwardly on the second pulley wheel 342. This causes the pivoting arrangement 310 to pivot about its axis A. The pivoting arrangement 310 then pivots about axis A in an anticlockwise direction shown in figure 2, to clamp the rope 500 against the clamping formation 221 of the base assembly 200.

As shown in figure 2, the rope 500 is clamped between the clamping formation 221 and the second pulley wheel 342. Further, and as shown in figure 2, it is envisaged that a pivoting arrangement restraining formation 350 shown in the form of clamping block 354, could be provided to ensure a strong clamping or gripping action is provided to at least slow, but preferably stop movement of the rope 500 through the safety wheel block 100.

This will thereby at least partially assist in preventing the object that is being lifted from falling in an uncontrolled and/or unsupported and/or unslowed manner, and/or provided for the continued at least partial support of its weight. A person skilled in the art will appreciate that the effect of the clamping of the rope 500 will depend on the configuration of the restraining arrangement 110 , as well as that of the pulley assembly 300. In this regard, the safety wheel block 100 could be configured to clamp the rope 500 tightly to prevent it moving at all, or it could be configured to at least slow movement of the rope 500 through the safety wheel block 100.

Various embodiments of both the clamping formation 221 as well as the pulley assembly 300 are shown in the figures.

Figure 9 and 13-14 show two more embodiments of the invention, where the rope 500 is replaced by a chain 500, and the first and second wheels are in the form of first and second sprockets 322 and 344 respectively. The sprockets 322 and 344 are for positively engaging with the chain 500. In these embodiments, the restraining arrangement comprises an engaging formation 220 on the base assembly 200 that engages with a plurality of pivoting arrangement restraining formation 350, in the form of ratchet teeth 352 arranged about axis B of the sprocket 322 on the support assembly to prevent movement of sprocket 322, which in turn restrains movement of the chain 500 through the safety wheel block 100 by virtue of the positive engagement of the sprocket 322 with the chain.

As shown in figures 13 and 9, when the pivoting arrangement 310 is pivoted, the restraining arrangement is operated and /or actuated to move between an unrestrained position and a restraining position in which movement of the chain 500 is restrained by virtue of its engagement with the teeth of the sprocket 322.

It is envisaged that the restraining formation 220 could be configured and dimensioned to engage with either or both of the sprockets 322 or 344 or pulley wheels to indirectly restrain movement of the chain or rope 500. It is further envisaged that a large variety of mechanical, electromechanical, hydraulic, pneumatic, electronic, electromagnetic or devices could be employed to assist in restraining movement of the rope 500 when actuated by the pivoting movement of the pivoting arrangement 310 relative to the base assembly 200. Such an arrangement is shown in figure 4. These may necessitate the requirement for providing of one or more sensors (not shown) or switches 112 for sensing or detecting the pivotal movement of the pivoting arrangement about axis A, an actuation devicc (not shown) such as a valve or lever for actuating the restraining of movement of the rope, and a restraining arrangement 114 such as a hydraulic ram, pneumatic ram, or electromagnet for at least partially restraining movement of the rope. It will be appreciated by a person skilled in the art that a large variety of ways exist by which movement of the rope may be restrained. This will also depend upon the nature of the rope 500.

As an alternative to restraining of the rope 500, it is envisaged that in alternative embodiments, the pivoting movement of the pivoting arrangement between its first and second positions could also actuate one or more of a wide variety of other processes. Such processes include the generation of a signal, which preferably may be used in a control system, or the generation of an alarm, such as a visual or audible alarm.

The safety wheel block 100 could further include a power input arrangement (not shown), such as a plug, or a receiving conduit for pressurised fluid, for receiving power for powering one or more selected from the sensor or switch, actuation device and restraining arrangement.

The safety wheel block 100 could further include a power supply means (not shown), such as a compressor, hydraulic power pack, a compressed fluid tank or generator, for powering one or more selected from the sensors, actuation device and restraining arrangement 114.

However the embodiments shown in the figures provide a simple, relatively cost effective way to achieve this objective.

It is envisaged that the current invention could be utilised for safe handling of goods, including heavy goods, where rigging of the goods are required. It is further envisaged that a safety wheel block 100 could be used for, but not limited to applications in various forms for winching of a vehicle, or for use in mountain climbing applications.

Where in the foregoing description reference has been made to elements or integers having known equivalents, then such equivalents are included as if they were individually set forth.

Although the invention has been described by way of example and with reference to particular embodiments, it is to be understood that modifications and/or improvements may be made without departing from the scope or spirit of the invention.

In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognise that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Received at IPONZ 29 November 2010

Claims

1. A safety wheel block suitable for facilitating the exertion of a pulling force on an object by a rope that is operationally engaged towards a lifting end of the rope with said safety wheel block, by virtue of a tension force exerted at or toward an opposed tension end of said rope, said safety wheel block comprising: a. a base assembly mountable to a support structure; b. a support assembly including i. a pivoting arrangement pivotally coupled to the base assembly about a pivot axis to be able to move between a first position and a second position relative said base assembly, ii.a first wheel mounted to the pivoting arrangement at a distance from the pivot axis and over which said rope is extendable, and iii. a second wheel mounted to the pivoting arrangement and over which said rope is extendable, said second wheel being disposed from the pivot axis of the pivoting arrangement, and configured and adapted for engaging the rope at a distance from the first wheel; c. wherein said first wheel and second wheel and said pivot axis are positioned such that when said pulling force and said tension force are substantially equal, said pivoting arrangement remains in said first position but will move to the second position when the tension force at the tension end of the rope is rapidly reduced, and d. wherein, when the tension in the lifting end of the rope and the tension end of the rope is operationally imbalanced, the imbalanced tension in the rope acting on the first wheel and second wheel will cause pivoting of the pivoting arrangement about the base assembly between its first position and second position, to actuate a further process.

2. A safety wheel block as claimed in claim 1, further comprising a restraining arrangement able to restrain movement of the rope relative to the safety wheel block; and moveable between a restraining position in which it restrains movement of the rope relative the safety wheel block, and an unrestrained position in which movement of the rope relative the safety wheel block is relatively less constrained.

3. A safety wheel block as claimed in claim 2, wherein said process is one or more selected from Received at IPONZ 29 November 2010 -20- a. the actuation of the restraining arrangement for restraining movement of the rope relative the safety wheel block; b. the actuation of an alarm; and c. the generation of a signal.

4. A safety wheel block as claimed in claim 3, wherein the signal is for use in a control system.

5. A safety wheel block as claimed in any one of claims 1-4, further comprising a control system.

6. A safety wheel block as claimed in claim 5, wherein a tension force is exerted at or towards a tension end of said rope, and the rope is coupled operationally via said safety wheel block to exert a pulling force on an object at or towards an opposed lifting end of said rope; and wherein, when the tension in the lifting end of the rope and the tension end of the rope is operationally substantially similar, the restraining arrangement will be configured to its unrestrained position to allow relatively unrestrained movement of the rope relative to the safety wheel block.

7. A safety wheel block as claimed in any one of claims 1-6, wherein the second wheel is disposed along a leverage member at a distance from the first wheel.

8. A safety wheel block as claimed in any one of claims 1-7, wherein the base assembly includes a support arrangement for allowing pivotal coupling of the pivoting arrangement to the base assembly.

9. A safety wheel block as claimed in any one of claims 1-8, wherein one or more selected from the first wheel and the second wheel is one selected from a. a pulley wheel, b. a sprocket, c. a cog; and d. a gear wheel.

10. A safety wheel block as claimed in any of claims 1 -9, wherein one or more selected from the first wheel and the second wheel includes a friction reduction device for reducing rotational friction.

11. A safety wheel block as claimed in claim 10, wherein the friction reduction device is one or more selected from a bearing, and a bushing.

12. A safety wheel block as claimed in any one of claims 2-11, wherein the restraining arrangement comprises support assembly restraining formations associated with the support assembly. Received at IPONZ 29 November 2010 -21 -

13. A safety wheel block as claimed in any one of claims 2-12, wherein the restraining arrangement comprises support assembly restraining formations on the support assembly and/or base assembly restraining formations on the base assembly that cooperate to restrain movement of the rope.

14. A safety wheel block as claimed in any one of claims 2-12, wherein the restraining arrangement is coupled to one or more selected from the base assembly and the support assembly.

15. A safety wheel block as claimed in any one of claims 2-14, wherein the restraining arrangement operates to restrain movement of the rope relative to the wheel block by means of one or more selected from a. a clamping action; b. a positive engaging action; c. a braking action; d. a clutch braking action.

16. A safety wheel block as claimed in any one of claims 7-15, wherein the pivot axis acts as a fulcrum for the leverage member.

17. A safety wheel block as claimed in any one of claims 1-16, wherein, when the restraining arrangement is in its restraining position, it prevents the rope from being withdrawn from the support assembly in a direction towards its lifting end.

18. A safety wheel block as claimed in any one of claims 2-17, wherein the restraining arrangement is one or more selected from a mechanical device, an electromechanical device, a hydraulic device, a pneumatic device, an electronic device, and an electromagnetic device.

19. A safety wheel block as claimed in any one of claims 1-18, wherein both of the first wheel and the second wheel are offset by a distance to either side of a line extending downwardly from the pivot axis of the pivoting arrangement.

20. A safety' wheel block as claimed in any one of claims 1-19, wherein the one or more selected from the base assembly and the support assembly include clamping formations.

21. A safety wheel block as claimed in any one of claims 1-20, wherein the rope is caused to be clamped between clamping formations on each of the base assembly and the support assembly. Received at IPONZ 29 November 2010 -22-

22. A safety wheel block as claimed in any one of claims 20-21, wherein the leverage member includes a clamping formation.

23. A safety wheel block as claimed in any one of claims 20-22, wherein the rope is caused to be clamped between a clamping formation on the base assembly and the leverage member.

24. A safety wheel block as claimed in any one of claims 7-23, wherein the leverage member is integrally formed with the pivoting arrangement.

25. A safety wheel block as claimed in any one of claims 1-24, wherein the pivoting arrangement comprises a pair of plates spaced apart by at least one transverse strut.

26. A safety wheel block as claimed in any one of claims 7-25, wherein the leverage member comprises a pair of plates spaced apart by at least one transverse strut.

27. A safety wheel block as claimed in any one of claims 7 -26, wherein the leverage member comprises a pair of spaced apart plates, between which is supported one or more selected from the first wheel and the second wheel.

28. A safety wheel block as claimed in any one of claims 1-27, wherein the pivoting arrangement is pivotally coupleable to the base assembly by means of an axle arrangement.

29. A safety wheel block as claimed in claim 28, wherein the pivoting arrangement comprises an axle that is received or receivable into a complementary aperture in the base assembly.

30. A safety wheel block as claimed in claim 28, wherein the base assembly comprises an axle that is received or receivable into a complementary aperture in the pivoting arrangement.

31. A safety wheel block as claimed in any one of claims 20-30, wherein the clamping formation on the base assembly is adapted and configured to clamp the rope against the second wheel on angular movement of the support assembly caused by the operational loss of tension at the tension end of the rope.

32. A safety wheel block as claimed in any one of claims 20-30, wherein the clamping formation on the base assembly is adapted and configured to clamp the rope against the first wheel.

33. A safety wheel block as claimed in any one of claims 20-32, wherein the clamping formation on the base assembly is adapted and configured to clamp the rope against a clamping formation on the pivoting arrangement.

34. A safety wheel block as claimed in any one of claims 1-33, wherein the base assembly includes securing formations for securing the base assembly to a securing point.

35. A safety wheel block as claimed in claim 34, wherein the securing point is raised relative to the object to be lifted.

36. A safety wheel block as claimed in any one of claims 1-35, wherein the safety wheel block includes at least one selected from a sensor or switch for detecting pivotal movement of the pivoting arrangement. Received at IPONZ 29 November 2010 -23-

37. A safety wheel block as claimed in any one of claims 1-36, wherein the safety wheel block includes at least one actuation device for actuating the restraining arrangement to at least partially restrain movement of the rope.

38. A safety wheel block as claimed in any one of claims 37, wherein the safety wheel block includes a power input arrangement for powering one or more selected from the sensors, actuation device and restraining arrangement.

39. A safety wheel block as claimed in claim 38, wherein the power input arrangement is one or more selected from an electrical plug, or a receiving conduit for pressurised fluid.

40. A safety wheel block as claimed in any one of claims 37-39, wherein the safety wheel block includes a power supply for powering one or more selected from the sensors, actuation device and restraining arrangement.

41. A safety wheel block as claimed in claim 40, wherein the power supply is one or more selected from a. a compressor b. a hydraulic power pack, and c. a generator.

42. A safety pulley wheel block as claimed in any one of claims 1-41, wherein the axes of any two or more of the first wheel, second wheel and pivot axis of the pivoting arrangement are parallel to each other.

43. A safety pulley wheel block as claimed in any one of claims 1-42, wherein the rope applies forces to the first wheel and/or second wheels in a direction normal to their axes of rotation.

44. A safely pulley wheel block as claimed in any one of claims 1-43, wherein the rope apphes forces to the pivoting arrangement in a direction normal to its pivoting axis.

45. A safety pulley wheel block as described in the accompanying specification, with our without reference to the accompanying figures.