Patent Application
20090129863
The invention relates to a breaking tool, with a raking and levering capacity, in addition to a linear impact hammer, and an attachment means for same.
In particular, the present invention relates to a breaking tool adapted for attachment to known plant machinery including excavators, wheeled loaders and the like
Reference throughout the specification is made to the invention as relating to breaking tools in the form of gravity drop hammers although this should not be seen as limiting.
Gravity drop hammers are primarily designed for surface breaking of exposed rock and generally consist of a weight capable of being raised to a height within a housing before release. The weight falls under gravity to strike a surface to be broken, either directly (thus protruding through an aperture in the hammer housing) or indirectly via a striker pin.
The present invention is discussed herein with respect to rock breaking devices produced by the applicant including the devices described in PCT/NZ03/000236 and PCT/NZ03/000237 featuring a drop hammer lock and drive mechanism for a powered drop hammer respectively. U.S. Pat. No. 4,383,363 describes a rock breaking apparatus known as, and herein referred to as the Terminator™ and New Zealand patent application No. 540097 describes a striker pin and drop-weight apparatus designed to be attached to an excavator or the like. The term gravity drop hammer is thus used herein to encompass powered drop hammers in addition to those powered solely by gravity.
In operation of the above-mentioned machines it is often desirable to move or lever rock and other material with the hammer or striker pin. Movement of the material can be achieved by placing the hammer or pin against the material and pushing or pulling with the excavator. However, with existing hammers the coupling between the hammer and excavator, known as the mounting plate, is a substantial distance from the striker pin so the pulling forces at the striker pin are low and difficult to control. This large separation between the striker pin and the mounting plate coupling with the excavator also increases the likelihood of generating high uncontrolled forces that can damage the hammer. Mounting the hammer at a distance from the striker pin thus causes time consuming, inaccurate and inconvenient operation of the hammer for the operator.
A rock breaking apparatus described in the applicant's New Zealand patent application No. 540097 can also perform levering and raking in addition to performing surface breaking tasks of conventional hammers.
Raking refers to using the excavator to pull surface rock horizontally along the ground using the side of the pin. The rock can be loose above the ground surface or be friable enough to be drawn towards the excavator after pressing or driving the point of the pin into the in-situ rock. When raking it is necessary for the hammer/arm assembly to remain locked relative to each other. The linkage geometry to maintain such a locked position requires far greater strength than conventional mounting methods, though ideally the linkage should still utilise standard components.
Levering is a particularly useful action of the rock breaking apparatus aforementioned. Levering refers to the driving of the point of the striker pin or hammer into non-friable in-situ rock creating or exploiting a crack. Once the crack is established, the operator can lever the hammer and pin through actuation of one end of the boom attached to the excavator and extract the rock from the ground or widen the cracks further. In such applications it is an important advantage to have the maximum torque and thus leverage available to pry intractable rocks.
Another advantage of being able to lever a powered hammer or breaking device is being able to apply the impact point at positions away from the top surfaces of the material to be broken. This is an important advantage of the applicant's previous inventions described in PCT application numbers PCT/NZ03/000235, PCT/NZ03/000236 and PCT/NZ03/000237. Often the rock requires fine manipulation to correctly position the hammer impact over a seam or weak point. In such scenarios, delivering high power in combination with fine control close to the striker pin provides a significant advantage.
Some existing earth working devices are capable of pivoting to allow the device to operate away from the vertical. Such a device is described in WO98/07952 by Persson. This device comprises pivotable links coupled to a drilling rig to pivot the rig by operation of a hydraulic ram. This allows the rig to be pivoted to drill at an angle away from the vertical. However, the device is unsuited for levering action due to the geometry of the linkage limiting the degree of applicable torque to unfeasibly low levels.
The theoretical maximum lifting capacity of an excavator is the moment resolved about the ends or sides of the tracks without tipping the excavator. The allowable lifting moment is a percentage of the tipping moment. However, not all this moment is available for lifting. The excavator arm and hammer assembly extending from the excavator apply a moment to the excavator which must be subtracted from the maximum lifting moment and is governed by;
Thus by minimising the counterproductive inherent tipping moment created by a)-b) above, the capacity of the excavator to resist any additional moments generated during levering and raking operations without tipping over is increased.
The impact energy of the drop hammer, divided by the mass of the excavator is herein defined as the power-to-weight ratio. A greater power-to-weight ratio implies either more breaking power for a given excavator size or a smaller excavator for a given breaking power. The profitability of a system is thus increased by a higher power-to-weight ratio.
Existing gravity drop hammers are attached to excavators via a wing and mounting plate arrangement attached to the excavator arm. These mounting plates must be custom made for each drop hammer and excavator to ensure the geometrical proportions of the plate are correct. The mounting plate and associated fixings on the drop hammer also add substantial weight to the drop hammer, thereby reducing the power-to-weight ratio and absorbing more moment capacity of any given excavator. The wing and mounting plate also increase the distance from the excavator to the centre of gravity of the drop hammer, which also reduces the power-to-weight ratio and absorbs more lifting moment capacity for a given excavator and arm extension.
In many regions globally, excavation, demolition and quarry operations are restricted from using explosives due to the elevated risks of explosives theft by unauthorized parties including rebels, terrorists and the like. Urban encroachment on quarries and mines has also made the use of explosives difficult and expensive in many regions due to community opposition to ground vibration. Obtaining the necessary permissions or consents from the relevant authorities to use explosives for laying roads, railways and pipelines has also become extremely difficult or impossible to achieve due to the above discussed factors. In such regions, it is thus desirable for a rock breaking machine to also be capable of levering embedded rocks, widening cracks, breaking rock faces and raking without the use of explosives.
It is thus desirable to provide a tool for a carrier such as an excavator, capable of striking a surface to be broken, hammered or compacted about a substantially linear axis and which is also capable of applying a torque and side load to an object substantially laterally to said axis to lever and rake rocks or other material.
It is also desirable to provide a tool that is readily attachable to standard excavator arms, enabling cost to be minimised by permitting different tools/implements to be fitted as required.
It is further desirable for the weight of the attachment mechanism of the tool and the distance between the implement and the excavator arm to be minimised.
It would be a yet further advantage for the implement to enable high forces to be applied about the levering pivot point when the implement is attached to an excavator, without damaging the tool or excavator.
There are many linkage systems and implements designed for attaching to earth working machines including those described in WO96/33315, WO90/03473, JP2000132448, JP2002145911, JP2001257017, JP05034057, JP09364906, JP63125843, JP11344858, DE19702624, EP0887475, EP1013835, EP0325358, EP0386904, EP0818581, U.S. Pat. No. 3,529,740, U.S. Pat. No. 3,743,126, U.S. Pat. No. 4,381,167, U.S. Pat. No. 4,486,141, U.S. Pat. No. 5,405,237, U.S. Pat. No. 5,609,464, U.S. Pat. No. 5,592,762, WO01/016433, WO02/22966, WO2004/016864, WO2004/027162 and WO2004/057114.
However, none of the devices described in these documents achieve the objectives of the present invention, i.e. to
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
According to one aspect of the present invention there is provided an impact hammer for breaking, levering and raking material, said hammer including:
Preferably the implement includes a hammer mechanism of the type described in PCT application numbers PCT/NZ03/000235, PCT/NZ03/000236, PCT/NZ03/000237, New Zealand Patent Application No. 540097 or U.S. Pat. No. 4,383,363 (incorporated herein by reference). However, it should be appreciated that the present invention is equally suited to other powered hammer mechanisms, gravity drop hammers or the like.
In one embodiment, the tool and movable mass are formed as a single item. In such embodiments, the movable mass performs breaking operations by travelling along said impact axis (under assistance or by gravity alone) until one end projects from the hammer housing to strike the target surface. However, such hammer configurations are not usable for levering or raking operations unless the movable mass tool is secured relative to the hammer housing by a tool lock. Locking the tool rigidly to the hammer prevents the tool being forced back inside the hammer during raking or levering operations. Thus, in a further embodiment, the hammer further includes a tool lock capable of rigidly fixing the tool to the hammer with one end of said tool projecting from the hammer to form said striker pin for use during raking and levering operations.
In alternative embodiments, the hammer is formed with a separate moveable mass and a tool (known as a ‘striker pin’) coupled to the hammer. During breaking operations, the tip of the striker pin projecting from the hammer is placed in contact with the target surface and the mass is propelled (again either by gravity or under assistance) to strike the opposing end of the striker pin which transfers the impact via the external striker pin tip to the target surface. It will be appreciated the tool may be coupled to the hammer in a variety of configurations, which allow the impact from the movable mass to be transferred directly to the work surface without impacting a high shock load to the hammer housing and carrier. Thus, slideable couplings are required to allow a degree of tool travel along the impact axis, whilst retaining the striker pin from falling out completely of the hammer. In a preferred embodiment, the slideable coupling includes at least one retaining pin engagable with a corresponding projection or indentation to define limits of allowable travel of the striker pin along the impact axis. Alternatively, the coupling may be formed by a resilient mounting, or biasing means such as an elastomeric coupling or spring, buffer or the like.
Thus, as used herein, the term ‘tool’ is defined as including a striker pin coupled to the hammer and a movable mass used directly for breaking operations capable of being locked to the hammer by a tool lock for raking and levering operations.
Throughout the specification, reference is made to the hammer being attached to an arm of a carrier in the form of an ‘excavator arm’. However, this should not be seen to be limiting as the hammer may be attached to any suitable machine including other demolition, quarrying or rock working machines.
Preferably said first link includes a pair of arms spaced apart to receive the hammer therebetween. The use of two (preferably symmetrically configured) arms increases the strength and structural integrity of the first link. Although the use of a single arm may be implemented, such a configuration places limitations on the torque that may be applied during levering actions without twisting and bending the single arm about the arm's longitudinal axis. In alternative embodiments said first link may include a pair of jaws or other encircling members pivotally coupled to the hammer. Configuring the hammer attachment to the carrier arm to allow the hammer to effectively pass ‘through’ the attachment, rather than attaching to the side or end of the hammer, provides significant control and strength advantages.
It can be seen that in an alternative embodiment, said quaternary pivot axis may be coaxial with said primary pivot axis. However, typical excavator arms are configured with the primary pivot point at a distal end of the arm with the quaternary pivot point and second link located at an intermediate position between the primary pivot point and the drive.
In one embodiment, a drive in the form of a hydraulic ram is used to provide force to the first and second links to pivot the hammer about said primary axis. However it should be appreciated that other mechanisms may be used such as pneumatic rams, or any other form of drive or drives, capable of extending a rod or arm, either directly or indirectly via supplementary linkages. A pair of drives may be used for example, placed symmetrically on opposing lateral sides of the carrier arm and individually acting on corresponding control linkages passing either side of the hammer. Herein reference will be made to the operation of a hydraulic ram and actuator mechanism as used in preferred embodiments of the present invention, though this is exemplary only and should not be seen to be limiting in any way.
Upon extension of the drive, the first and second links pivot at their first ends about the secondary and quaternary pivot axes respectively. Both links also pivot at their common connection to the drive about the tertiary pivot axis. The angle subtended between the first and second links at the tertiary pivot point on the opposing side to the drive increases as the drive extends thus forcing the tertiary pivot axis away from the carrier operating arm. This applies a torque to the hammer about the primary pivot axis causing the hammer to pivot about same, moving the hammer tip towards the carrier.
Preferably the first link is pivotally coupled to the outermost edge of the hammer relative to the excavator arm, thereby maximising the distance (herein referred to as ‘torque distance’) between the primary pivot and secondary pivot axes. The torque applied to the implement for a force of given magnitude is dependant on the direction of the force applied by the hydraulic ram via the first link and the ‘torque distance’. The greatest torque for a given force and torque distance is achieved when the direction of the applied force (i.e. the angle of the first link) is orthogonal to the axis of the torque distance. Maximising the torque of the present invention is one key aspect of ensuring maximum productivity and effectiveness.
The present invention also relies on the specific location of the primary pivot axis with respect to the tool head tip. It is desirable to locate the primary pivot axis as close as practicable to the tool head tip, to maximise levering and raking ability. Prior art attachment of hammers place the primary pivot axis at some distance from the tool head as levering and raking operations fall outside their intended usage. In the present invention, the attachment point for the primary pivot axis is deliberately configured to lie close to the tool head tip. It has been found that for effective levering and raking operation, the primary pivot point is located in a region between the tool head and a line subtended orthogonally from the impact axis from the end of the tool distal to the tool face. In embodiments with a fixed tool in the form of a striker pin coupled to the hammer, this distance is typically very close to the nose block of the hammer.
In embodiments using a tool lock to lock the movable mass, the opposing end of the tool to the tool head is typically further separated than that of a striker pin configuration. However, it still provides a readily definable cut-off, beyond which placement of the primary axis pivot point provides no worthwhile levering or raking effectiveness.
Another advantage of coupling the first link to the furthermost side of the implement is that it maximises the range of angle through which the implement may rotate about the main pivot and thus maximises the range of levering ability.
In preferred embodiments the length of the first and/or second links is adjustable. Therefore, the length of the links can be extended or reduced to respectively accommodate a larger or smaller implement. Also, by increasing the length of a link, the maximum achievable angle of rotation of the implement about the main pivot is also increased.
In one embodiment, the length of the first and/or second links is adjustable, preferably by providing at least one locking mechanism to lock the length of the link for any given incremental change in length.
In preferred embodiments each arm of the first link is formed from two or more joined segments. Preferably each arm is formed from first and second segments each having a plurality of apertures incrementally spaced apart on a longitudinal axis for receipt of one or more bolts, lugs, pins, rivets or the like.
In one embodiment for example, the two segments may be joined by lining up two pairs of apertures on each of the first and second segments. A bolt is passed through at least one of the apertures and nuts screwed onto the bolts and tightened. The two segments are thus joined together and locked in place. Bolts can be applied to any number of apertures to increase the strength of the attachment. The length of the first link may be varied by aligning different apertures and joining the two segments.
Preferably the control linkage includes a tie member bridging the arms of the first link. The tie member maintains the arms parallel and minimizes any tendency of the hammer to rotate or pivot about the longitudinal axis of the first link, thereby twisting the first link and potentially damaging same. Preferably the tie member is substantially rigid and is attached to each arm of the first link.
In preferred embodiments the linkage on the excavator arm will be provided with a first and/or second link of adjustable length.
A further important requirement for the effective levering and raking of material is the application of an even torque and power during the operational range of rotation of the hammer about the primary axis. A consistent power delivery is affected by the angle between the control linkages though the range of rotation of the hammer. In a preferred embodiment, said first and second link subtend an angle between 60-150° at the tertiary pivot axis on the opposing side to said drive during rotation of the hammer about the primary axis.
It will be appreciated the present invention may be considered to reside in both a hammer substantially as hereinbefore described attachable to a carrier and control linkage for attaching known hammers to a carrier and a method of attaching same.
Thus, according to a further aspect, the present invention includes a control linkage attachable to an impact hammer for breaking, levering and raking material and a carrier,
said hammer including:
Thus, by the simple replacement of the conventional first link of an existing control linkage with a replacement first link of the present invention, a suitable impact hammer may be operated in the advantageous raking and levering manner described herein.
Thus, the hammer can be attached to existing excavators with minimal adaptation of the excavator resulting in significant cost savings by replacing the need for multiple excavators with a single excavator with interchangeable implements. The costly, time consuming and problematic fitment of existing drop hammers to excavators via a customised wing and mounting plate fitment, configured to fit both the existing first and second links of the excavator arm is thus also circumvented.
According to a further aspect, the present invention includes a carrier having an articulated operating arm attached to an impact hammer for breaking material, said hammer including:
According to a further aspect of the present invention, there is provided a method of attaching a hammer substantially as hereinbefore described to a carrier arm, said method including the steps of;
The replacement first link may be of a fixed size, dimensioned to for attachment between a known carrier arm linkage configurations. Alternatively, the first link may be of adjustable length enabling a given impact hammer to be readily fitted to a range of carrier arms of differing geometries.
Minimising the lateral separation of the hammer and the carrier arm provides the further benefit of reducing the counterproductive inherent tipping moment created by the attached hammer before any additional moments are generated during levering and raking operations. Thus, according to one embodiment, the separation of the primary pivot axis orthogonally from the impact axis is less than the overall length of said tool.
Therefore, it can be seen that the present invention offers significant advantages over the prior art including;
Further aspects and advantages of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:
a) shows a preferred embodiment of the present invention in the form of an impact hammer attached to a carrier arm;
b) shows a prior art impact hammer attached to a carrier arm;
c) shows a cross section through XX shown in
d) shows a further embodiment with an alternative control linkage arrangement to that shown in the embodiment illustrated in
a-c) shows side elevations of a preferred embodiment of the present invention shown in
a-c) shows side elevations of a preferred embodiment of the present invention through the range of motion of the impact hammer about the primary axis, with the secondary pivot axis located on the impact axis of the impact hammer;
a-c) shows side elevations of a prior art embodiment through the range of motion of the impact hammer about the primary axis, with the secondary pivot axis located the adjacent side of the hammer relative to the carrier arm;
a-c) shows an enlarged view of the control linkage shown in
a-c) shows an enlarged view of the control linkage shown in
a-c) shows an enlarged view of the control linkage shown in
a-c) shows a prior art process of attaching an impact hammer to a carrier arm, and
a-c show the process of attaching the embodiment illustrated in
The present invention is primarily adapted for use with impact hammers (1) such as gravity drop hammers, powered drop hammers, hydraulic hammers and the like. Although specific implementations of such designs differ, each generally includes some form of movable mass located within the hammer housing and capable of linear reciprocating movement for along an impact axis (14). The hammer (1) includes an elongate tool received within the hammer (1) having two opposed ends and a longitudinal axis coaxial with the impact axis (14). One end of the tool projects from the hammer (1), to form an operative tool head for use during said levering and/or raking operations. Depending on the construction of the hammer (1), the tool may take different forms. In one embodiment, the movable mass and the tool may be formed as a single element which is locked from movement to the hammer (1) during levering and raking with one end of the tool projecting from the hammer (1) to form the tool head. It will be appreciated however that in such embodiments (not shown), a hammer tool lock (as described in the inventors international application PCT/NZ03/000236 incorporated herein by reference) is required to fix the tool relative to the hammer housing during raking and levering operations.
In an alternative embodiment (as shown in
Thus, depending on the construction of the hammer (1), the tool may be formed as a moveable weight and locked from movement during levering and raking; or, the tool is formed as a separate element (i.e. the striker pin (23)) distinct from the movable weight
The hammer (1) in
The hammer (1) is attached to the carrier arm (2) at a primary pivotal attachment point (6) attached to the hammer (1) at a distal end of the operating arm (2) for pivotal movement about a primary pivot axis (6) orthogonal to said impact axis (14).
The articulated control linkage (3) provides a means for effecting pivotal movement of the hammer (1) about said primary axis (6) in response to movement from a drive in the form of a hydraulic ram (7) attached to said operating arm (2).
The first link (4) is pivotally attached to the hammer at a first end to form a secondary pivot axis (8) parallel to said primary axis (6), said first link (4) also being pivotally attached at a second end to said second link (5) forming a tertiary pivot axis (12).
The second link (5) is pivotally attached at a first end to form a quaternary pivot point axis (13) on the carrier operating arm (2), said quaternary pivot axis (13) being parallel to said secondary (8) and tertiary (12) axes, said second link also being pivotally attached at a second end to said second end of the first link (4) at said tertiary pivot axis (12) and to said drive (7), preferably coaxial with said tertiary pivot point axis (12). The first link (4) is comprised of a pair of arms (4a, 4b) passing either side of the hammer (1) as shown in
In
In an alternative embodiment shown in
The present invention differs from the prior art (as shown in
In operation; extension or retraction of the hydraulic ram (7) acts to pivot the first and second links (4, 5) in opposing directions about the secondary pivot axis (8) and quaternary pivot axis (13) respectively. Both links also pivot in opposite directions about the tertiary pivot axis (12). As the ram (7) extends, the first and second links (4, 5) are splayed apart at the tertiary pivot axis (12) and thus the angle subtended therebetween is increased whilst the secondary pivot axis (8) is pushed out away from the carrier arm (4). The force from the drive (7) acting along the first link (4) applies a torque to the hammer (1) at the secondary pivot axis (8), causing the hammer (1) to pivot about the primary pivot axis (6) towards the carrier.
Thus, the hammer (1) may not only be operated to break rock, concrete or other material by percussion impacts of the striker pin (23) along the impact axis (14), but also to rake or lever material by a pivoting and locking action about the primary pivot axis (6). Such actions may also be employed by prior art methods of attaching a hammer (1) to an excavator arm (2), though the prior art configurations used pose several shortcomings.
Moreover, in the prior art, the hammer (1) body is mounted further outboard from the arm (2) further increasing the position of the center of gravity of the hammer (1) and arm (2) assembly away from the carrier body (not shown), thereby increasing the tipping moment of the excavator and thus decreasing the ability to lever and rake material. This is contrasted in
The relatively small attachment base of the wing (16) to the mounting plate (9) (resultant from the smaller torque distance (17)) and the increased separation (16) requires the wing (16) and mounting plate (9) to be made sufficiently robust to support the hammer (1) in operation without deformation and thus adding substantial weight to the hammer (1) and carrier (2) arm assembly. This increase in weight reduces the power-to-weight ratio of the hammer and carrier.
It will be appreciated that levering performance advantages are obtained by moving the secondary pivot axis (8) further outboard away from the primary pivot axis (6). However, it will also be seen that there is a significant trade-off in performance in some configurations for different portions of the pivotable range of the hammer (1).
In more detail,
In each of
It will be seen that the greatest torque distance (17) is present in the embodiment in
It will also be seen that despite a comparable range of movement for the hammer (1) about the primary axis (6) for the embodiments of
The range of movement in the series a)-c) in
In the torque triangle (27), it will be readily apparent that the torque applied to the primary pivot axis (6) by force acting on secondary pivot point (8) via the first link (4) is optimised when:
It will be seen that in the preferred embodiment in
In contrast, compared to the embodiment of
Moreover, the effective power delivered by the drive (7) to provide leverage with the striker pin (23) is a function of the rate of movement of the drive (7) compared to the rate of movement of the striker pin (23). This is governed by the angle ω formed by the control linkage (3) at the tertiary pivot (8) where optimum values of ω are over approximately 70°. Assuming the use of a drive (7) with the same power in the embodiments in
Again, it will be seen that in contrast, the preferred embodiment in
Thus, to optimise the mechanical advantage applied to lever the rock (29), it is desirable to make the distance (33) from the striker tip (31) to the intermediate position (32) a minimum, compared to the distance (34) between the intermediate position (32) and the secondary pivot axis (8). In addition to employing an increased torque distance (17), the levering power is also optimised (as per the embodiment of
Minimising the distance (35) between the striker tip (31) to the primary pivot axis (6) also optimises the raking ability of the hammer (1) and arm (2) assembly in addition to minimising the shock loading on the carrier during conventional percussion impacts on the striker pin (23).
A further advantage of the present invention is its ability to be attached to a standard carrier arm with minimal modification and engineering effort. This is illustrated in
Ensuring the correct geometry to match the particular carrier arm (2) and hammer (1) requires measurement of the distance between the primary pivot axis (6) and secondary pivot axis (8) with the hydraulic ram (7) fully contracted and also measuring the angle formed by a line between the secondary and tertiary pivot axes (i.e. the torque distance (17)) with respect to the vertical. Accurate geometry measurements can be difficult for unqualified staff to perform, leading to expensive delays from misaligned mounting plates (9). A wing (16) portion must also be attached or have been manufactured as part of the hammer (1) to facilitate mounting of the hammer (1) to the mounting plate (9).
Different carriers may have different configurations and thus requirements for mounting the hammer (1) to the carrier arm (2). This means that an individual mounting plate (9) must be made for each type of carrier, typically requiring around a month to design, manufacture and deliver from the date of measuring. It has been found in practice up to ten percent of mounting plates are mis-measured, typically requiring the mounting plate (9) to be taken offsite for remanufacture.
In contrast, attachment of a hammer (1) using the present invention (as shown in
Thus, it can be seen that by providing a first link (4) of adjustable length, the control linkage (3) can be adjusted onsite to fit any particular hammer (1) or carrier arm (2) with little operational downtime and minimal engineering, thus the present invention offers substantial cost savings over the state of the art.
In prior art hammer (1) attachments as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 540097 | May 2005 | NZ | national |
| 543739 | Nov 2005 | NZ | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/NZ06/00115 | 5/16/2006 | WO | 00 | 7/7/2008 |
