Patent Description:
Existing locking pliers such as <CIT>, <CIT> comprise two robust handles connected to two robust jaws, and a locking mechanism connected to the two jaws. The handles can be squeezed to close the jaws. The locking member is attached to an over centre linkage which when utilized prevents the lower handle from pivoting from its closed configuration and until opened retaining the jaws in a closed position. The clamping width of the jaws is adjusted by an adjustment screw, the adjustment screw further determining the clamping pressure exerted upon the clamped workpiece. As the clamping pressure has to be pre-set it can take several attempts to correctly adjust the screw to the required position in order to clamp the workpiece the best way. The clamping width of the jaws once set by the adjusting screw is finite, any movement, vibration or relaxing of the clamped material normally results in the failure of the clamping action. This is most prevalent when the device is used to initially clamp bodywork parts during a panel beating process prior to welding or bolting the panels being worked on. Inadvertent over pressure applied by the clamping jaws usually results in damage or distortion of the clamped parts.

USD742194 shows a set of pliers having a toothed strut with a locking mechanism attached to one operating arm. As the arms are closed the teeth "ratchet" past the lock. As the operating arms are not designed to resiliently deform during robust operation, the toothed arc of the strut remains in substantially the same locking angle relative to the locking mechanism.

<CIT> comprises pliers or clamps having a bow or arcuate portion to permit limited flexing of one of the handles. A pivotal strut is retained between the handles and the strut is slidably held in a channel within one handle and pivotally held within the other handle. The pivotal end of the strut has a toothed arc, which acts with a switched pawl to lock or unlock the handle positions relative to one another. Compression of the handles closes the gap between the fixed and moveable jaws, the moveable jaw sliding up a clamp bar portion until the jaws robustly contact the workpiece, the further operation of the handles resulting in the clamping of the workpiece, the resilient arcuate portion acting to impose a limited sprung grip upon the workpiece, further usefulness imported by the locking action of the pawl teeth within the strut arc teeth when the pawl is switched into its ratchet locking position retaining the handles substantially in their closed position providing a limited spring grip upon the workpiece. The arc of the toothed strut in conjunction with the corresponding toothed arc of the pawl being capable of compensating for the changes in angles of one handle relative to the other as the resilient portion flexes as differing pressures are applied to the handles during use, any normal locking switch being rendered suspect as the angle of one locking tooth to the other changing as the handle flexes, which may prevent the teeth interlocking sufficiently to provide a dependable locking mechanism.

<CIT>, <CIT> and <CIT> each discloses a hand operated gripping tool comprising a first handle connected with said first handle, a second handle pivotably connected with said first handle to permit relative pivoting movement of said first and second handles and a second jaw connected with said second handle. The first and second jaws are removable jaws that are push-fit attachable to the respective said handle.

<CIT> discloses a device for attaching/detaching a shaft snap ring and a hole snap ring comprising a hand operated gripping tool comprising a first handle, a first jaw connected with said first handle, a second handle pivotably connected with said first handle to permit relative pivoting movement of said first and second handles and a second jaw connected with said second handle,.

The invention provides a hand operated gripping tool comprising a first handle, a first jaw connected with said first handle, a second handle pivotably connected with said first handle to permit relative pivoting movement of said first and second handles and a second jaw connected with said second handle, wherein one of said first jaw and second jaws is a removable jaw and said removable jaw is push-fit attachable to the respective said handle, said removable jaw comprises an outboard portion defining a gripping region and an inboard portion that projects from said outboard portion and is received by the respective said handle, said inboard portion comprises a first part and a second part disposed opposite said first part to define a slot between said first and second parts, said respective handle defines respective recesses to receive said first and second parts and said recesses define a blade that complementarily engages in said slot when said removable jaw is push-fit attached to said respective handle, characterised in that said blade comprises a leading end provided with a plurality of formations that complementarily engage a plurality of formations defined by said removable jaw to define a plurality of selectable orientations of said removable jaw with respect to the respective said handle.

Some examples further comprise a locking mechanism by which said removable jaw is lockable to the respective said jaw.

In some examples said locking mechanism comprises a snap-fit mechanism.

In some examples said snap-fit mechanism comprises a detent mechanism.

In some examples each of said first and second jaws is a said removable jaw.

In order that the invention may be well understood some examples will now be described with reference to the drawings, in which:.

Following is a listing of the various components shown in the drawings. For the ready reference of the reader the reference numerals have been arranged in ascending numerical order.

<FIG> illustrate examples of multi jaw pliers <NUM> that will be described to provide background to the invention.

<FIG> illustrates multi jaw pliers <NUM> shown at rest. The pliers <NUM> comprise a head portion <NUM> comprising a first jaw <NUM> and a second jaw, which in this example are each detachable jaws <NUM>. The detachable jaws <NUM> may be of various shapes and sizes according to the operator's requirements, the drawings showing but a few variations.

The detachable jaws <NUM> each have gripping faces <NUM> and interlocking tongues <NUM> that are engaged within the detachable jaw recesses <NUM> of the respective lower jaws <NUM>, <NUM> and locked in position by the jaw locking pins <NUM> engaged within the interlocking tongue recesses <NUM>.

The handle portion <NUM> comprises a first handle <NUM> and second handle <NUM> (with clenching portions <NUM>) and are pivotal around the jaw pivot pin <NUM>. The handles <NUM>, <NUM> are contiguous to their corresponding lower jaw elements <NUM>, <NUM>. The handles <NUM>, <NUM> with their corresponding jaws <NUM>, <NUM> (detachable jaws <NUM>) are pivotal around the jaw pivot pin <NUM>.

<FIG> and <FIG> illustrate an example of a detachable jaw <NUM>. <FIG> illustrates a one piece forged/machined, cast, Metal Injection Moulded or other manufactured example of the detachable jaw <NUM>. It is obvious that the one piece detachable jaw <NUM> could be also for example plastic injection moulded for use on easily marked workpieces <NUM> (not shown). The detachable jaw <NUM> comprises a gripping face <NUM>, abutment faces <NUM>, interlocking tongues <NUM>, interlocking tongue recesses <NUM> and a lower jaw web aperture <NUM>. Further shown is the jaw locking pin <NUM>, comprising a locking face <NUM>, unlocking face <NUM>, control axle <NUM> and operating slot <NUM>.

<FIG> shows a further example of construction of detachable jaw <NUM> comprising metal layers that can be stamped or fine blanked to form a laminate like construction, using rivets or the like as fixings <NUM> through the jaw assembly holes <NUM>. The detachable jaw comprising a gripping face <NUM>, abutment faces <NUM>, inter-locking tongues <NUM> with inter-locking tongue recesses <NUM>. Further shown is the jaw locking pin <NUM> comprising a central axle <NUM>, outer axle <NUM>, locking face <NUM>, unlocking face <NUM>, outer face <NUM> with an operating slot <NUM> or alternately a threaded bore <NUM> for the use with corresponding screws <NUM>, which when locked within the threaded bore <NUM> can usefully be used for the appropriate rotation of the said locking pin <NUM>. Although many differing types of detachable jaw <NUM> attachment could be utilised the laminated example shown is the simplest and most cost effective, comprising of outer plates <NUM> and inner plate <NUM>.

<FIG> illustrates another multi jaw pliers <NUM> having first and second jaws comprising detachable jaws <NUM> with gripping faces <NUM>. The detachable jaws have interlocking tongues <NUM> for engagement within the lower jaw <NUM>, <NUM> engagement slots <NUM> and are locked in position by the jaw locking pin <NUM> engaged within the corresponding interlocking tongue recess <NUM>. The locking pin <NUM> is shown in this illustration with an operating slot <NUM>, the unlocking faces <NUM> illustrated aligned with the engagement slots <NUM> inner profile, thereby allowing the detachable jaw <NUM> interlocking tongue <NUM> to be inserted or removed as required into the appropriate engagement slots <NUM> within the lower jaws <NUM>, <NUM>. When the appropriate detachable jaw <NUM> is incorporated within the chosen lower jaw <NUM> or <NUM>, its abutment faces <NUM> will robustly adjoin similarly profiled lower jaw abutment faces <NUM> and lower jaw outer plates <NUM>. In best practice the lower jaws engagement slots <NUM> further comprise a lower jaw web <NUM>, which usefully strengthens the attachment construction. It is obvious that the interlocking tongue <NUM> etc. can be alternately affixed the lower jaws <NUM>, <NUM> and the lower jaw engagement slots <NUM> be within the detachable jaws <NUM>.

<FIG> shows the multi jaw pliers <NUM> of <FIG> as comprising a pivotal strut <NUM> encompassed by a strut spring <NUM> and shows the head portion <NUM>, handle portion <NUM> and the pivotal strut <NUM> with a corresponding pivotal switch <NUM>. The jaw <NUM>, <NUM> closure can be usefully enhanced by the incorporation of the pivotal strut <NUM> and corresponding switch <NUM> for locking the handles <NUM>, <NUM> in the operated closed position. The operation of the switch <NUM> releases the strut <NUM> locking function allowing the strong strut spring to propel the handles into their open position. As an added safety feature, the handles <NUM>, <NUM> have to be first compressed to release the tension between the strut toothed face <NUM> and the switch toothed engagement <NUM> (<FIG>) before the switch <NUM> can disengage the locking teeth <NUM>. The handles <NUM>, <NUM> are usefully biased towards the open position by the strut spring <NUM>.

Though a non-essential integer the most cost effective method of manufacture and assembly of the majority of the multi jaw pliers <NUM> construction is, as illustrated, a laminate like composition made from cut or stamped generally planar metal plates <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, affixed as required by suitable fixings <NUM> through assembly holes <NUM>, <NUM>, <NUM> to the adjoining layers of plate. The first handle <NUM> comprises outer plates <NUM> and inner plate <NUM> and the second handle <NUM> comprises outer plates <NUM> and inner plate <NUM>. The first and second jaws <NUM>,<NUM> comprises a first jaw <NUM> outer lower jaw <NUM> contiguous with the second handle outer plates <NUM>.

<FIG> and <FIG> illustrate the incorporation of dual bowed bend promoting portions <NUM> into the handle portion <NUM>, the head portion <NUM>, and a further pivotal link <NUM> with a corresponding locking switch <NUM>. The jaw <NUM>,<NUM> closure can be usefully enhanced by the incorporation of the sprung pivotal link <NUM> and corresponding switch <NUM> for locking the handles <NUM>, <NUM> in the operated closed position, the operation of the switch <NUM> releasing the strut <NUM> locking function. As an added safety feature, as shown in <FIG>, the handles <NUM>, <NUM> have to be first compressed to release the tension between the link toothed face <NUM> and the switch toothed engagement <NUM> (<FIG>) before the switch <NUM> can disengage the pivotal link teeth <NUM>. The handles <NUM>, <NUM> are usefully biased towards the open position by the link spring <NUM> and the pivotal switch <NUM> or swivel lock <NUM> is further usefully biased by the switch spring <NUM> or link spring <NUM>.

As illustrated in <FIG> and <FIG>, in order to provide a method of adjusting the clamping pressure exerted by the jaws <NUM>, <NUM> the pivotal link <NUM> is rotatable around its axle pin <NUM> when the handles <NUM>, <NUM> are clenched closing the jaws <NUM>, <NUM> upon the workpiece <NUM> etc. As the handles <NUM>, <NUM> are further activated, pivoting around the pivot pin <NUM>, the pivotal link teeth <NUM> "ratchet" over the corresponding teeth <NUM> on the pivotal actuator <NUM>, according to the closing pressure C applied. When the operator has reached the level of gripping force G required and releases the applied grip C from the handle grips <NUM> the ratchet teeth <NUM>, <NUM> engage in a locking manner. The flex induced within the living spring portions <NUM> and clamping the jaws <NUM>, <NUM> upon the clamped parts <NUM> is retained by the pivotal link <NUM> retention by the pivotal actuator <NUM> lock teeth <NUM> upon the strut teeth <NUM>. As further illustrated in <FIG> the retained pivotal link <NUM> thereby comprises the base of a triangular elastic potential energy structure A, the bend promoting portions <NUM> further comprising the sides of the triangle A and the jaw pivot pin <NUM> as the apex, this formation usefully acts via the connected jaws <NUM>, <NUM> to provide clamping pressure to the said jaws <NUM>,<NUM> upon the workpiece <NUM>, this gripping force G pressure being advantageously resilient in nature.

As further illustrated in <FIG>,<FIG>,<FIG> and <FIG> the pivotal switch <NUM> has an axle <NUM>. The pivotal link <NUM> comprises in this iteration a toothed face <NUM> and an opposite back face <NUM>.

As shown in <FIG>, a compression spring <NUM> circumscribes the pivotal link <NUM> and urges, when allowed, the handles <NUM>,<NUM> apart towards an open at rest position. The switch <NUM> in this example is a wedging arrangement comprising a toothed wheel <NUM> having an axle <NUM> confined within elongate slots <NUM> within the toothed handle switch housing <NUM>. When the pliers <NUM> have been operated and the jaws <NUM>, <NUM> are forcefully closed C and thereafter the handles <NUM>, <NUM> relaxed, the axle <NUM> is propelled up the slots <NUM> towards the pivotal link <NUM>, wherein it robustly wedges the axle <NUM> and therefore the toothed wheel <NUM> against the pivotal link toothed face <NUM>, usefully locking the jaws <NUM>,<NUM> in the operated closed position.

Some examples may provide a more immediate locking action with minimal loss of elastic potential energy during the switching process, wherein the toothed wheel switch <NUM> is provided having an internal positional arc <NUM> encompassing a corresponding inner toothed wheel <NUM> with a central axle <NUM>, the arc <NUM> having an inner smooth unlocking surface <NUM> and an opposite toothed inner locking surface <NUM>. The toothed wheel <NUM> is able to traverse within the limitations of its retention of its axles <NUM> within the switch elongate slots <NUM>. The toothed wheel <NUM> being optimally kept in constant sprung engagement with the corresponding teeth <NUM> of the pivotal link <NUM> by the switch housing guide block face <NUM> projecting the toothed wheel <NUM> up the angled elongate slots <NUM> towards the link teeth <NUM>. The axle <NUM> in best practice is robustly attached to the toothed wheel <NUM> although it is not a requirement. The axle <NUM> and its attached toothed wheel <NUM> during the actuation of the handles <NUM>, <NUM> sequence can freely rotate within the switch <NUM> internal arc <NUM> and restricted confines of the elongate slots <NUM> within the corresponding toothed wheel switch housing <NUM>, as the toothed wheel <NUM> is in the jaw <NUM>,<NUM> closure sequence rotated anti clockwise down the elongate slots <NUM> by its interaction with the toothed strut <NUM>. The elongate slots <NUM> are set at an appropriate angle relative to the strut toothed face <NUM> such that, as the handles <NUM>, <NUM> are compressed the toothed wheel <NUM> and its axle <NUM> rotate anti clockwise down the elongate slots <NUM> away from any locking action upon the strut toothed face <NUM>. When the handle portions <NUM>, <NUM> gripping force is released the bowed portions <NUM> elastic potential energy causes the toothed strut <NUM> to rotate the engaged toothed wheel <NUM> and axle <NUM> clockwise up the angled elongate slots <NUM> towards the toothed strut <NUM>, until it is robustly wedged by the converging elongate slot <NUM> angles upon the corresponding toothed strut <NUM>, locking the handles <NUM>, <NUM> and thereby jaws <NUM>, <NUM> closed upon the clamped workpiece <NUM> in a usefully robust sprung gripping action. In order to unlock the jaws <NUM>,<NUM>, the toothed wheel's <NUM> axle's <NUM> locked position within the elongate slots <NUM> can be usefully transmuted by the operation of the pivotal switch <NUM> having an integral arc unlocking surface <NUM> designed to act upon the periphery of the toothed wheel <NUM> yet not impede its rotation. As shown in <FIG>, <FIG> the operation of the toggle lever <NUM> pivoting the switch <NUM> around its switch pivot pin <NUM> bringing the smooth unlocking surface <NUM> of the integral arc <NUM> forcefully into contact with the toothed wheel <NUM> periphery in the release direction, as an inbuilt safety lock measure the handles <NUM>, <NUM> must first be operated enough to relieve the locking force of the toothed wheel axle <NUM> within the elongate slots <NUM> upon the toothed strut <NUM>, the simultaneous operation of the switch actuator <NUM> allowing a smooth unlocking action as the handle <NUM>, <NUM> pressure C and therefor jaw <NUM>, <NUM> clamping pressure is further relieved.

<FIG>, <FIG>, <FIG> illustrate the lock/unlock positions of a cost-effective swivel lock <NUM>, wherein the mechanism can be set to allow the handles <NUM>, <NUM> to either move freely relative to one another when utilised or be conveniently locked in their last operated position. For demonstration purposes the handle outer top plate <NUM> is removed to show the workings of the inner switch <NUM>.

<FIG> shows the pliers <NUM>, illustrating the switch <NUM> in the locking position, with workpieces <NUM> clamped between the jaws, whereas the switch <NUM> urged by the strut spring <NUM> acting against the spring operating face <NUM> resiliently rotating around the switch pivot pin <NUM> till the switch teeth <NUM> engage the corresponding pivotal strut teeth <NUM> usefully locking the said strut <NUM> between swivel lock <NUM> and the opposing guide block face <NUM>. The switch locking stop <NUM> which also comes into contact with the toothed strut face <NUM>, can be either smooth or similarly toothed to the strut toothed face <NUM>, the said stop <NUM> preventing unwanted switch <NUM> travel after the locking has taken place.

<FIG> and10 further show the pliers <NUM>, illustrating the switch <NUM> in the locked/unlocked position, the actuator <NUM> depressed swivelling the said switch <NUM> substantially smooth guide portion <NUM> into contact with the pivotal strut toothed face <NUM> allowing the pivotal strut <NUM> to move freely under the resilient pressure of the strut spring <NUM> until the pliers <NUM> are in their open position.

<FIG> illustrates a multi-jaw pliers <NUM> with the resilient bend promoting portions <NUM> incorporated within the detachable jaws <NUM>.

<FIG> show an embodiment of multi jaw pliers <NUM> according to the invention, illustrating the switch <NUM> in the locking position, with workpieces <NUM> clamped between the detachable jaws <NUM>. The detachable jaws <NUM> are capable of being usefully rotated into differing toothed positions or angles and thereafter robustly locked in the required position or further removed and replaced with the requisite shaped jaw <NUM> for the job application. The detachable jaw or jaws <NUM> have outer plates <NUM> with a shorter inner plate <NUM> configured to form a recess <NUM> between the outer plates <NUM> into which can be retained the corresponding lower jaw inner plate <NUM>. The detachable jaw inner plates <NUM> have toothed castellations or engagement teeth <NUM>, which when incorporated into the correspondingly profiled lower jaw engagement teeth <NUM> form a robust jaw structure <NUM>, <NUM>. The jaw locking screw <NUM>, when operated, clamps the outer plates <NUM> upon the lower jaw inner plate <NUM> further adding to the overall integrity of the jaw <NUM>, <NUM>. The detachable outer jaw plates <NUM> have a through hole in one and a screw hole in the other, the lower jaw inner plate <NUM> having in best practice an appropriately shaped hole to allow the jaw locking screw <NUM> to be slackened, allowing the detachable jaw <NUM> to be partially withdrawn and reinserted into different jaw engagement teeth <NUM>, <NUM>, usefully altering, as required, the angle of detachable jaw <NUM> relative to the lower jaw <NUM>, <NUM>. It is best practice to have the screw holes in the detachable part <NUM> of the jaws <NUM>, <NUM> as if screw thread <NUM> wear occurs it ensues in the least expensive part.

<FIG> shows the pliers <NUM>, illustrating the swivel lock switch <NUM> in the locked position, the strut spring end <NUM> acting against the spring operating face <NUM> rotating the said switch <NUM> around the switch pivot pin <NUM> meshing the switch teeth <NUM> with the strut teeth <NUM> in a locking manner. During the closure of the jaws <NUM>, <NUM> the strut teeth <NUM> in contact with the switch teeth urge the swivel lock switch <NUM> out of toothed <NUM>, <NUM> engagement rotating the switch <NUM> against the resilience of the strut spring <NUM> in a ratchet like manner.

In some examples a set of multi jaw pliers comprises a head portion incorporating gripping faces within the opposing jaws for the clamping of the desired workpiece, pivotal handle portions and a toothed strut positioned between the handles. Bow shaped resilient portion or portions can be usefully incorporated within either or both the jaw or handle portions, when the pliers are operated these resilient portions impart a useful sprung pressure upon the clamped workpiece by the gripping face of the jaws. The jaws can be usefully locked in the required clamping position upon the workpiece, in one example by a toothed strut pivotally attached to one handle and conveniently being locked or unlocked according to the switch operation on the opposing handle.

In some examples a set of pliers comprises a head portion incorporating gripping faces within the opposing jaws for the clamping of the desired workpiece, pivotal handle portions and a sprung toothed link positioned between the handles. Bow shaped resilient portion or portions can be usefully incorporated within either or both the jaw or handle portions, when the pliers are operated these resilient portions impart a useful superior sprung pressure upon the clamped workpiece by the gripping face of the jaws. The jaws and bend promoting portion are contiguous with each individual handle and gripping portion. The jaws can further be usefully locked in the required clamping position upon the workpiece by a toothed strut pivotally attached to the fixed handle and conveniently being locked or unlocked according to the locking switch pivotal within the opposing moving handle.

Some examples may further comprise clamping widths within its specification that are automatically adjusted, the locking pressure can be further be usefully determined by the operator by the straightforward gripping pressure of the handles, the simple release of the handles initiating the locking of the jaws upon the clamped parts.

Some examples may further comprise a plurality of bowed resilient portions within either or both handles providing superior constant jaw clamping pressure of the part or parts clamped whilst normally preventing surface damage to the parts clamped. Examples of the multi jaw pliers work on a reasonable range of workpiece sizes and shapes whilst utilizing superior sprung gripping force of the workpiece. Furthermore, the main parts are capable of being stamped in order to further reduce their manufacturing cost.

Some examples may include a compression spring encompassing the pivotal link, this spring conveniently propels the handles towards their open position when the switch is unlocked and the handles are relaxed. The strong spring further largely prevents lateral movement of the moving handle down the pivotal strut during the initial clenching of the handle, ensuring that the moving handle can usefully pivot around the switch pivot in the first instance until the converging jaws both contact the workpiece. This spring can be further usefully utilized to operate the switch.

Some examples may include a pivotal switch whereas the guide block which is required to remain substantially opposite the switch teeth is incorporated within a pivotal switch housing instead of being typically statically affixed to the handle outer plates.

Some examples may include a swivel lock or actuator situated within the switch housing, the swivel lock comprising a toggle lever, a toothed engagement portion, a pivot bore, a spring abutment face, smooth guide portion and a spring stop portion.

The housing and its internal pivotal switch both rotate according to the operated movement and angle of the toothed strut. The pivotal switch pivoting as required around the switch pivot pin ensuring the cage switch remains in complete engagement and alignment with the corresponding toothed strut at all times, thereby ensuring positive engagement between the teeth of the toothed strut and the teeth of the switch. The rotation of the switch with the toothed strut therefore being capable of compensating for the obscure changes in angles as one handle pivots relative to the other and as the handle bend promoting portions flex as differing pressures are applied to the handles during use, any normal locking switch being rendered suspect as the angle of the strut teeth to the switch teeth and the guide block change as the handles pivot and flex which can and does prevent the teeth interlocking sufficiently to provide a dependable locking mechanism.

The housing integral smooth guide block guide face providing sufficient span against the opposing smooth surface of the strut back face to ensure the adjoining surfaces remain substantially parallel in all situations.

When the plier grips are operated, the handles are propelled towards one another, the strut being pivotal at the fixed end around its pivot pin. The strut locking teeth semi- engaging the swivel lock toothed engagement portion, this engagement of the switch teeth and the corresponding toothed strut further rotating the swivel lock and its corresponding teeth out of engagement with the strut engagement teeth in a ratchet like manner, against the resilience of the strut spring, the generally smooth back face of the toothed strut being robustly positioned opposite the switch teeth by the switch cage guide block. When the required gripping pressure is attained and the handle clenching grip pressure is relaxed, the resiliently bowed portions move towards their initial pre-stressed position whereby the swivel lock is rotated within the cage housing by the switch teeth engagement with the strut teeth aided by the corresponding strut spring. This action expediently engages the locking interaction between the strut teeth and the switch teeth, the locking stop whether smooth or toothed preventing undue travel. The clamping action of the jaws being determined by the remaining resilience of the bowed portions, the elastic potential energy. The resultant jaw resilient closing force is largely proportional to the force applied to the handles and the pivotal dimension ratio between the handles and jaws less any small losses incurred during the switch locking procedure, the pivot being the jaw fulcrum pin.

Some examples may include a more immediate locking action cage switch incurring minimal loss of elastic potential energy during the switching process, comprising a switch housing with parallel outer laminates through which are situated the pivot pin holes, the inner recess or strut channel incorporating the guide block and the outer face incorporating a strut spring guide. The strut channel containing a pivotal actuator having an internal arc encompassing a corresponding inner toothed wheel with a central axle, the arc having an inner smooth unlocking surface and an opposite toothed inner locking surface, the actuator pivotally operated by a toggle lever around the switch pivot pin. The toothed wheel is able to traverse within the limitations of the retention of its axles within the switch cage elongate slots. The toothed wheel being optimally kept in constant sprung engagement with the corresponding teeth of the locking strut by the switch inner (toothed or smooth) locking surface, projecting the toothed wheel up the angled elongate slots towards the strut teeth. The axle in best practice is robustly attached to the toothed wheel although it is not a requirement. The axle and its attached toothed wheel during the actuation of the handles sequence can freely rotate against the ratchet like action of the sprung toothed locking surface within the switch internal arc and restricted confines of the elongate slots within the corresponding cage housing laminates. The elongate slots are set at an appropriate angle relative to the locking strut teeth such that, as the handles are compressed in the final clenching sequence the toothed wheel and its axle in one example rotate anti clockwise up the elongate slots away from any locking action upon the toothed strut. When the handle portions gripping force is released the bowed portions elastic potential energy causes the toothed strut to rotate the partially pre-engaged toothed wheel clockwise down the angled elongate slot within the cage housing outer laminates, towards the toothed strut teeth, until it is robustly wedged by the converging elongate slot angles upon the corresponding toothed strut, locking the handles and thereby jaws closed upon the clamped workpiece in a usefully robust sprung gripping action. In order to unlock the jaws the toothed wheels locked position within the elongate slot can be usefully transmuted by the operation of the pivotal actuator toggle lever, the pivotal actuator having an integral arc unlocking surface designed to act upon the periphery of the toothed wheel yet not impede its rotation. The operation of the toggle lever pivoting the pivotal actuator around its switch pivot pin bringing the smooth unlocking surface of the positional arc forcefully into contact with the toothed wheel periphery in the release direction, as an inbuilt safety lock measure the handles must first be operated enough to relieve the locking force of the toothed wheel axle within the elongate slots upon the toothed strut, the simultaneous operation of the toggle lever allowing a smooth unlocking action as the handle pressure and therefor jaw clamping pressure is further relieved.

As it is commercially prudent to have a clicking noise to accompany the jaw closure and locking procedure the pivotal actuator inner locking surface can be further toothed, the interaction of the tooth or teeth with the corresponding rotating toothed wheel providing a typical ratchet like sound, the switch rotating as required around the switch pivot pin against the resilience of the strut spring.

In a further iteration in order to provide a more versatile and useful device, the jaw working profiles or outer jaw can be interchanged with other outer jaws with differing working profiles in order to provide a cost-effective equivalent to several set of differing pliers required for different jobs. These interchangeable jaws being usefully locked or unlocked from robust engagement within the lower jaws as required, providing one locking handle set capable of use with a cost-effective range of differing jaws as required.

In one example the lower jaws comprising of a laminate like construction in order to provide a lower cost method of retaining the locking swivel pin which comprises a central axle rotatable within a corresponding thickness and bore within the lower jaw inner plate. The locking swivel pin having a further reduced circumference hereafter termed outer axles, largely level in height to the lower jaw outer plates which have corresponding circular cut out profiles such that the said swivel pin is laterally held within the lower jaw by the outer plates whilst capable of rotation within its afforded enclave. The outer end face of the locking swivel pin can usefully incorporate a screwdriver slot or other drive profile for the required rotation of the said pin, one further alternative being the use of known large head screws screwed into corresponding threads within the said swivel pin, the screw heads adding to the integrity of the outer and inner jaw structure, the screws usefully locked in the correct tolerance position by know locking fluid. The locking swivel pin outer axles comprising a spherical locking face and a generally flat unlocking face, the spherical locking face can be further appropriately cam shaped in order to increase the locking mechanism proficiency. The locking swivel pin is located partially within the lower jaw interlocking tongue recess, by rotating the locking swivel pin the profile of the locking swivel pin outer axle can be chosen to either present a locking or unlocking face into the tongue recess.

Claim 1:
A hand operated gripping tool comprising a first handle (<NUM>), a first jaw (<NUM>) connected with said first handle, a second handle (<NUM>) pivotably connected with said first handle to permit relative pivoting movement of said first and second handles and a second jaw (<NUM>) connected with said second handle,
wherein one of said first jaw and second jaws is a removable jaw and said removable jaw is push-fit attachable to the respective said handle,
wherein said removable jaw comprises an outboard portion defining a gripping region and an inboard portion that projects from said outboard portion and is received by the respective said handle, and
wherein said inboard portion comprises a first part and a second part disposed opposite said first part to define a slot (<NUM>) between said first and second parts, said respective handle defines respective recesses to receive said first and second parts and said recesses define a blade (<NUM>) that complementarily engages in said slot (<NUM>) when said removable jaw is push-fit attached to said respective handle,
characterised in that said blade (<NUM>) comprises a leading end provided with a plurality of formations (<NUM>) that complementarily engage a plurality of formations (<NUM>) defined by said removable jaw to define a plurality of selectable orientations of said removable jaw with respect to the respective said handle.