Patent Publication Number: US-2011058894-A1

Title: A lock assembly for an excavator wear member

Description:
FIELD OF THE INVENTION 
     The invention relates to a lock assembly for an excavator wear member. In particular, although not exclusively, the invention relates to a lock assembly for releasably securing an excavator tooth to a nose of an excavator. 
     BACKGROUND TO THE INVENTION 
     Excavator tooth assemblies mounted to the digging edge of excavator buckets and the like generally comprise a replaceable digging tooth, an adaptor body and an adaptor nose which is secured by welding or the like to the digging edge of a bucket or the like. The tooth generally has a socket-like recess at its rear end to receivably locate a front spigot portion of the adaptor nose and a removable locking pin is generally employed to releasably secure the tooth on the adaptor. 
     In use, excavator teeth are subjected to extensive load forces along a longitudinal axis of a tooth as well as in vertical and transverse directions. A snug fit is required between the digging point and the front portion of the adaptor and also between the adaptor socket and the nose spigot portion and their respective mounting pins to avoid premature wear between the components. As the various components wear, the locking pins can loosen thereby increasing the risk of loss of a digging point or an entire adaptor/tooth combination. This necessitates considerable downtime to replace the lost wear members and where items such as locking pins are not recovered, these can cause damage and/or further downtime in downstream operations such as ore crushing and the like. 
     The greatest loads experienced by excavator tooth assemblies are vertical loads which tend to generate large moment forces capable of rotating a tooth off the front of an adaptor and/or rotating the adaptor off the adaptor nose. In addition, twisting or “yaw” loads are frequently imposed on such tooth assemblies. 
     Despite many prior art attempts to improve the mounting of a wear member to a nose of an excavator, most of these proposals suffer from one or more deficiencies. As described hereinafter, many of the prior art references relate to direct mounting of a tooth onto a nose without an intermediate adaptor but in those assemblies, the mounting systems for securing teeth directly onto excavator noses is considered analogous to the mounting of a tooth onto an adaptor. U.S. Pat. No. 4,182,058 describes an excavator tooth having a rearwardly divergent tapering socket to receive a nose having a complementary-shaped front spigot portion. Resistance to rotational moment forces is borne by a resilient steel cotter pin extending through aligned vertical apertures in the socket and spigot portions. U.S. Pat. Nos. 3,774,324, 4,338,736, 4,481,728, 4,903,420, 5,469,648, 7,100,315 and 6,735,890 all describe nose and tooth combinations wherein the nose has a generally convergently tapering spigot portion with a forward tip having a box-like configuration with at least the upper and lower surfaces thereof having faces parallel to each other and to a longitudinal axis of the nose portion. With the exception of U.S. Pat. No. 4,338,736, which describes a transverse locking pin, each of the tooth mounting arrangements is heavily reliant on a large vertical locking pin to resist rotational moment forces tending to rotate the teeth off respective noses. 
     U.S. Pat. No. 4,231,173 describes a tapered adaptor nose having a box-like free end, which engages in a mating box-like socket cavity to resist rotational moments. Opposed pairs of rearwardly extending tongues engage in corresponding recesses in the outer surfaces of the adaptor nose to resist rotational movements. Because the tongues themselves are unsupported, they possess a limited capacity to resist rotational moment forces. 
     U.S. Pat. No. 5,272,824 describes a structure similar to that of U.S. Pat. No. 4,231,173 except that the side tongues are of more robust dimensions and the upper and lower tongues are formed as box-like members with apertures to receive a vertical mounting pin passing through aligned apertures in the tooth and adaptor nose. 
     U.S. Pat. No. 4,404,760 provides flat rail surfaces on the adaptor nose to engage with mating grooves in the socket aperture of a corresponding tooth wherein the mating rail and groove surfaces are generally parallel to the longitudinal axis of the tooth. 
     U.S. Pat. No. 5,423,138 describes a generally tapered nose having a box-like front end with upper and lower transverse surfaces generally parallel to a longitudinal axis of a tooth which located directly thereon. The parallel upper and lower transverse surfaces are contiguous with upper and lower rail surfaces on each side of the nose and parallel to the longitudinal axis of the tooth. A pair of rearwardly extending side tongues locate in recesses formed in the outer side faces of the nose, ostensibly to resist rotational moment forces in the tooth. Because the side tongues are recessed to accommodate the side rail portions, the robustness of the side tongues is somewhat compromised. 
     U.S. Pat. No. 4,233,761 describes a fairly stubby tapered nose having a box-like front portion with upper and lower surfaces generally parallel to a longitudinal axis of an excavator tooth, an intermediate rearwardly diverging tapered portion and a rear portion having upper and lower surfaces extending generally parallel to a longitudinal axis of the tooth. Formed on the upper and lower surfaces of the front, intermediate and rear portions of the nose are spaced parallel reinforcing ribs which are located in mating grooves in the excavator tooth. A large vertical locking pin extends through aligned apertures in the tooth and nose between the reinforcing ribs. This structure is heavily reliant on the locking pin to resist rotational moment forces however it is considered that this configuration may be prone to failure in the rear portion of the adaptor. 
     U.S. Pat. No. 5,709,043 describes a nose/adaptor combination wherein the adaptor socket tapers convergently towards a box-like front portion having upper and lower bearing surfaces generally parallel to a longitudinal axis of the tooth, a front transverse upright bearing surface and rearwardly divergent bearing surfaces formed at obtuse angles between the converging upper and lower walls and the side walls of the socket, ostensibly to avoid areas of stress concentration. 
     U.S. Pat. No. 6,018,896 describes a pin/retainer system for locking an excavation tooth onto an adaptor wherein the retainer is inserted in the adaptor and a wedge-shaped pin is driven into aligned apertures in the tooth and adaptor to resiliently engage with the retainer. 
     United States Publication No US 2002/0000053A1 describes a mechanism for releasably retaining an adaptor into the nose of a bucket lip or the like wherein a tapered threaded socket is non-rotatably located on the inside of an aperture in the side wall of the adaptor. A threaded retaining pin extends through the threaded socket and locates in an aligned aperture in the bucket nose. 
     U.S. Pat. No. 5,337,495 describes a tooth assembly with a two-piece telescopically engageable adaptor secured to a nose with a tapered wedge pin assembly. A similar mounting system is described in U.S. Pat. No. 5,172,501 and U.S. Pat. No. 6,052,927. Other retention systems for digging points on adaptors or adaptors on noses are described in U.S. Pat. Nos. 6,119,378, 6,467,204, and 6,467,203. 
     Other devices for removably securing replaceable wear elements on earth working equipment such as a retaining pin, a bolt, a pin lock and locking blocks engageable in a top aperture in a wear member are described in U.S. Pat. Nos. 3,839,805, 3,982,339, 4,587,751, 5,088,214 and 5,653,048 respectively. 
     U.S. Pat. No. 5,937,550 describes a lock assembly for releasably securing an adaptor to a nose of an excavator support structure. The lock assembly comprises a body and a base coupled together and adapted for insertion, while coupled together, in a hole in the nose of the support structure. The length of the lock assembly is extended to secure the adaptor and is retracted to release the adaptor. While adequate for securing an adaptor to a nose of an excavator support structure, the lock described in this patent is relatively complex in design and operation leading to high costs and labour intensive extraction procedures in the field. Canadian Patent Application No 2,161,505 describes a system for removably retaining an excavation point on an adaptor with at least one flanged sleeve having a screw-threaded aperture therein, the flanged sleeve being non-rotatably locatable in a transverse bore in the adaptor before fitment of the point onto the adaptor. A screw-threaded pin is inserted into the sleeve via an aperture in the point whereby portion of the head of the pin retains the point on the adaptor. 
     Australian Patent Application No 2003264586 describes a locking pin assembly comprising a body member having a non-circular cross-sectional shape locatable in a bore of complementary shape extending laterally between opposite sides of an excavator lip mounting nose. After locating the body member in the nose aperture, an adaptor can be engaged over the nose with apertures in opposite side walls aligned with the body member. Threaded bolts engage in threaded apertures in opposite ends of the body member, the bolts each having a tapered shank portion with an enlarged boss at a free end thereof, the boss being locatable in a respective aperture in a side wall of said adaptor to prevent the adaptor from disengaging with the nose. 
     While generally satisfactory for their intended purpose, the abovementioned prior art all suffer from one or more shortcomings or disadvantages in terms of inadequate resistance to rotation of a tooth off a nose or an adaptor under the influence of vertical loads applying a rotational moment to the tooth, a predisposition to premature wear, difficulties in retention of the teeth on noses or adaptors, inadequate locking systems and unduly complicated configurations giving rise to increased fabrication costs. Furthermore, the prior art all generally rely on lock assemblies that require threaded components. Thread components in lock assemblies are generally disadvantageous as dirt and fines can infiltrate the threaded assembly thereby causing cementation and resulting in difficulties in removal. 
     OBJECT OF THE INVENTION 
     It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice. 
     DISCLOSURE OF THE INVENTION 
     In one form, although it need not be the only or indeed the broadest form, the invention resides in a lock assembly for releasably securing an excavator tooth on a nose of an excavator, the lock assembly comprising: 
     a rigid lock member having a base portion and a retaining portion extending from said base portion, the base portion adapted to be located in a retaining cavity of the nose and the retaining portion adapted to at least partially extend into a retaining aperture of the wear member 
     a resiliently deformable lock member, in use, adapted to be located within the retaining cavity of the nose to abut an upper face of the rigid lock member to thereby captively retain the base portion of the rigid lock member in the retaining cavity and the retaining portion at least partially within the retaining aperture such that side walls of the retaining portion of the rigid lock member bear against complimentary side walls of the retaining aperture of the wear member and opposed bearing faces of the base portion of the rigid lock member oppose and engage respective side walls of the retaining cavity of the nose of the excavator to thereby releasably secure the wear member on the nose of the excavator. 
     Preferably, the retaining portion of the rigid lock member has outwardly convergent side wall portions adapted to oppose and engage complimentary inwardly divergent side walls of the retaining aperture of the wear member. 
     Suitably, the resiliently deformable lock member is adapted to be deformed in order to allow passage through the retaining aperture into the retaining cavity. Optionally, the resiliently deformable lock member has at least one latch adapted to be located inwardly of a side wall of the retaining aperture. 
     Further features of the present invention will become apparent from the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein: 
         FIG. 1A  shows a perspective view of an excavator wear assembly according to an embodiment of the invention; 
         FIG. 1B  shows an exploded perspective view of the excavator wear assembly shown in  FIG. 1A ; 
         FIG. 2  shows a partial front perspective view of an adaptor forming part of the excavator wear assembly shown in  FIG. 1A ; 
         FIG. 3A  shows a rear perspective view of a tooth forming part of the excavator wear assembly shown in  FIG. 1A ; 
         FIG. 3B  shows a sectional top view of the tooth shown in  FIG. 3A ; 
         FIG. 4A  shows a front perspective view of a rigid lock member  1310  forming part of the excavator wear assembly of  FIG. 1A ; 
         FIG. 4B  shows a front perspective view of a resiliently deformable lock member forming part of the excavator wear assembly of  FIG. 1A ; 
         FIG. 4C  shows a plan view of the resiliently deformable lock member shown in  FIG. 4B ; 
         FIG. 4D  shows a rear perspective view of the resiliently deformable lock member shown in  FIG. 4B ; 
         FIG. 5A  shows a perspective view of the tooth shown in  FIG. 3A  mounted upon the adaptor shown in  FIG. 2 ; 
         FIG. 5B  shows a top sectional view of the perspective view shown in  FIG. 5A ; 
         FIG. 6A  shows a forward perspective view of the excavator wear assembly in a partially assembled position; 
         FIG. 6B  shows a rear perspective view of the excavator wear assembly shown in  FIG. 6A ; 
         FIG. 6C  shows a top sectional view of the excavator wear assembly shown in  FIG. 6A ; 
         FIG. 7A  shows a close up perspective view of the excavator wear assembly in a fully assembled position; and 
         FIG. 7B  shows an underside sectional view of the excavator wear assembly shown in  FIG. 7A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The excavator wear assembly and lock assembly therefore are described with reference to an excavator wear member in the form of a tooth releasably secured to an adaptor. The adaptor is in turn secured to a nose of an excavator bucket or the like. A skilled addressee will appreciate that the invention may be employed to releasably secure an adaptor to a nose or a tooth directly to a nose of an excavator bucket lip. 
       FIG. 1A  shows a perspective view of an excavator wear assembly  1000  according to an embodiment of the invention.  FIG. 1B  shows an exploded perspective view of the excavator wear assembly  1000 . Excavator wear assembly comprises a wear member in the form of a tooth  1100  mountable on an adaptor  1200  and a lock assembly  1300  disposed in each opposing transverse face of the tooth  1100  and the adaptor  1200  to thereby releasably secure tooth  1100  on adaptor  1200 . 
     Adaptor  1200  is suitably configured for mounting on a digging edge of an excavator by way of an adaptor socket  1210 . Adaptor socket  1210  is formed in a shape complimentary with a nose of an excavator digging edge (not shown). 
     Adaptor  1200  has aligned transverse apertures  1221  each extending through a respective opposed side wall  1220 . Aligned transverse apertures  1221  are adapted to receive an adaptor retaining pin (not shown) which extends through aligned transverse apertures  1221  and an adaptor retaining pin passage in the complimentary shaped nose (not shown) to thereby retain the adaptor  1200  on the excavator digging edge. 
     Adaptor  1200  further includes a spigot portion  1230  extending from a forward portion thereof and upper and lower mounting recesses  1201  and  1202  (lower mounting recess  1202  not shown in  FIG. 1A  or  FIG. 1B ) respectively. Additionally, adaptor  1200  has a pair of side wall mounting recesses  1203  and  1204  (not shown) located in a forward portion of each opposed side wall  1220 . 
       FIG. 2  shows a partial front perspective view of adaptor  1200 . Spigot portion  1230  has converging upper and lower rear bearing surfaces  1231 ,  1232  which terminate at substantially parallel upper and lower forward bearing surfaces  1233 ,  1234  respectively. A front bearing face  1235  is disposed between upper forward bearing surface  1233  and lower forward bearing surface  1234 . 
     Spigot portion  1230  also has a retaining cavity  1240  located in opposed side walls  1236  of spigot portion  1230 . Each retaining cavity  1240  is formed from a lower cavity  1241  and an upper cavity  1242 . Upper cavity  1242  is relatively wider than lower cavity  1242  and extends further transversely within spigot portion  1230  thereby forming a ridge  1243  between upper cavity  1242  and lower cavity  1241 . 
     A recess  1244  is formed in a floor  1241 A of lower cavity  1241  and extends through to a rear wall  1242 A of upper cavity  1242  thereby forming a groove  1241 B in a back wall  1241 C of lower cavity  1241 . The function of retaining cavity  1240  is discussed in greater detail below. 
       FIG. 3A  shows a rear perspective view of tooth  1100  and  FIG. 3B  shows a sectional top view of a portion of tooth  1100 . 
     Wear member in the form of tooth  1100  has a forwardly projecting working end  1101  and a socket cavity  1110  formed from converging upper and lower rear bearing surfaces  1111  (bit shown) and  1112  respectively. 
     Each of upper and lower bearing surfaces  1111  and  1112  terminate at substantially parallel upper and lower forward bearing surfaces  1113  (not shown) and  1114  respectively. A front bearing face  1115  is disposed between upper forward bearing surface  1113  (not shown) and lower forward bearing surface  1114 . 
     Bearing surfaces  1111 ,  1112 ,  1113 , and  1114  and front bearing face  1115  of tooth socket  1110  are configured to be complimentary with bearing surfaces  1231 ,  1232 ,  1233  and  1234  and front bearing face  1235  respectively of spigot portion  1230  of adaptor  1200 . 
     Tooth  1100  further includes upper and lower mounting projections  1101  and  1102  respectively and side mounting projections  1103  and  1104  respectively. In use, mounting projections  1101 ,  1102 ,  1103  and  1104  are adapted to be located within mounting recesses  1201 ,  1202 ,  1203  and  1204  respectively of adaptor  1200 . 
     Additionally, a retaining aperture  1120  extends through each opposed side wall  1105  and  1106  of tooth  1100 . Each retaining aperture  1120  is formed from an upper retaining aperture  1121  extending through a respective side wall  1105  and  1106 . Retaining aperture  1120  also has an upper retaining aperture  1122  extending through a respective side wall  1105  and  1106 . 
     Upper retaining aperture  1122  is relatively wider than lower aperture  1121  as shown. Furthermore, lower retaining aperture  1121  has a centre that is located rearwardly of upper retaining aperture  1122 . 
     As will be discussed in greater detail below, upper retaining aperture  1122  is adapted to at least partially align with upper retaining cavity  1242  of adaptor  1200  when tooth  1100  is located upon spigot portion  1230  of adaptor  1200  such that side walls of upper retaining aperture  1122  are encompassed by side walls of upper retaining cavity  1242 . 
     Retaining aperture  1120  further includes a recess  1123  extending inwardly along floor  1124  of lower retaining aperture  1121 . 
     Lower retaining aperture  1121  has inwardly diverging side walls  1125 A,  11258  such that the cross sectional area of lower retaining aperture  1121  is greater at socket cavity  1110  than at side walls  1105  and  1006 . 
     Furthermore, retaining aperture  1120  has a longitudinal recess  1126  forming a longitudinal bench  1127  on inwardly diverging side wall  1125 A of lower retaining aperture  1121 . Longitudinal recess also forms a forwardly located projection  1128  in a side of upper retaining aperture  1122 . 
     The function of retaining aperture  1120  will be discussed in greater detail below. 
     Excavator wear assembly  1000  further includes at least one lock assembly  1300  to releasably secure tooth  1100  on adaptor  1200 . In the embodiment, excavator wear assembly has two lock assemblies  1300  each extending through at least partially aligned retaining aperture  1120  and retaining cavity  1240  in opposed side walls as will be discussed in greater detail below. 
     Lock assembly is formed from a rigid lock member  1310  and a resiliently deformable lock member  1320 . 
       FIG. 4A  shows a front perspective view of rigid lock member  1310 . 
     Rigid lock member  1310  is preferably formed from a rigid material such as steel or the like. Rigid lock member  1310  is formed from a base portion  1311  and a retaining portion  1312  extending from base portion  1311 . 
     Base portion  1311  is configured to be received in lower retaining cavity  1241  in adaptor  1200  and retaining portion  1312  is configured to be received in lower retaining aperture  1121  of tooth  1100  as will be discussed in greater detail below. Base portion  1311  has opposing bearing faces  1314  and  1315 . 
     As shown retaining portion  1312  of rigid lock member  1310  has generally outwardly converging side walls  1313 A and  1313 B. In use, side walls  1313 A and  1313 B are configured to bear against inwardly diverging side walls  1125 A,  1125  of lower retaining aperture  1121  of tooth  1100 . 
       FIG. 4B  shows a front perspective view of resiliently deformable lock member  1320  forming part of lock assembly  1300 .  FIG. 4C  shows a plan view of resiliently deformable lock member  1320  and  FIG. 4D  shows a rear perspective view of resiliently deformable lock member  1320 . 
     Suitably, resiliently deformable lock member  1320  is formed from polyurethane or similar resiliently deformable material. Resiliently deformable lock member  1320  has a front face  1321  and a rear face  1322 . 
     Optionally, resiliently deformable lock member  1320  includes a strengthening member (not shown) located therein to provide structural support. 
     In the embodiment, two apertures  1323  extend from front face  1321  to rear face  1322 . Each respective aperture  1323  has a piercable membrane  1324  disposed therein adjacent front face  1321  and set back within aperture  1323  as shown. 
     Angled shoulders  1325  extend rearwardly from opposing ends of front face  1321 . Opposed rearwardly diverging side wall portions  1326  extend from a respective angled shoulder  1325 . 
     Angled shoulders  1327  extend forwardly from opposing ends of rear face  1322 . Opposed rearwardly converging side wall portions  1328  extend from a respective angled shoulder  1327  and terminate at a respective rearwardly diverging side wall portion  1326  as shown. 
     Each rearwardly converging side wall portion  1328  extends forward of its intersection with each respective rearwardly diverging side wall portion  1326  to form latch  1329 . 
     Resiliently deformable lock member  1320  further comprises a catch  1330  located in at least one of rearwardly diverging side wall portions  1326  as shown. Additionally, upper and lower shoulders  1331  and  1332  are located above and below respectively of both opposed rearwardly diverging side wall portions  1326  and opposed rearwardly converging side wall portions  1328 . 
     Resiliently deformable lock member  1320  is adapted to be captively retained within upper retaining cavity  1242  of adaptor  1200 . Furthermore, resiliently deformable lock member  1320  is adapted to deformably pass through upper retaining aperture  1122  as will be discussed further below. 
     In use, lock assembly  1300  releasably secures tooth  1100  on spigot portion  1230  of adaptor  1200  as discussed below. 
       FIG. 5A  shows a perspective view of tooth  1100  mounted upon adaptor  1200  and  FIG. 5B  shows a top sectional view of tooth  1100  mounted upon adaptor  1200 . 
     Socket cavity  1110  of tooth  1100  is mounted upon spigot portion  1230  of adaptor such that bearing surfaces  111 ,  1112 ,  1113  and  114  and front bearing face  1115  (all not shown in  FIG. 5A  or  FIG. 5B ) oppose and engage complimentary bearing surfaces  1231 ,  1232 ,  1233  and  1234  and front bearing face  1235  (all not shown in  FIG. 5A  or  FIG. 5B ) respectively of spigot portion  1230  of adaptor  1200 . 
     Furthermore, mounting projections  1101 ,  1102 ,  1103  and  1104  of tooth  1100  are located within mounting recesses  1201 ,  1202 ,  1203  and  1204  respectively of adaptor  1200 . 
     Retaining aperture  1120  of tooth  1100  at least partially aligns with retaining cavity  1240  of adaptor  1200 . Upper retaining aperture  1122  of tooth  1100  partially aligns with upper retaining cavity  1242  of adaptor  1200  such that such that side walls of upper retaining aperture  1122  are encompassed by side walls of upper retaining cavity  1242 . Furthermore, an outer extent of inwardly diverging side walls  1125 A and  1125 B of lower retaining aperture  1121  are encompassed by side walls of lower retaining cavity  1241  of adaptor  1200  as shown. 
     In this position, recess  1123  extending inwardly along floor  1124  of lower retaining aperture generally corresponds with recess  1244  formed in floor  1241 A of lower retaining cavity  1241  as shown. 
       FIG. 6A  shows a forward perspective view of the excavator wear assembly  1000  in a partially assembled position whereby rigid lock member  1310  is located within lower retaining cavity  1241 .  FIG. 6B  shows a rear perspective view of the excavator wear assembly  10000  shown in  FIG. 6A  and  FIG. 6C  shows a top sectional view of the excavator wear assembly  1000  shown in  FIG. 6A . 
     Rigid lock member  1310  is then located through upper retaining aperture  1122  and received in upper retaining cavity  1242 . As discussed previously, as upper retaining cavity  1242  has a greater width than lower retaining cavity  1241  and base portion  1311  of rigid lock member  1310  is configured to be received in lower retaining cavity  1241 , rigid lock member  1310  drops such that base portion  1311  is received in lower retaining cavity  1241  of adaptor  1200  as shown. 
     In this position, retaining portion  1312  of rigid lock member  1310  extends outwardly of lower retaining cavity  1241  at least partially into lower retaining aperture  1121  of tooth  1100  such that outwardly converging side walls  1313 A and  1313 B of rigid lock member  1310  oppose and are engagable with inwardly diverging side walls  1125 A and  1125 B respectively of lower retaining aperture  1121  of tooth  1100  in order to thereby bear against inwardly diverging side walls  1125 A and  1125 B. 
     Furthermore, bearing faces  1314  and  1315  of base portion  1311  oppose and are engagable with corresponding side walls of lower retaining cavity  1241  to thereby bear against the same. In this way, tooth  1100  is releasably secured to adaptor  1200 . 
       FIG. 7A  shows a close up perspective view of the excavator wear assembly  1000  in a fully assembled position and  FIG. 7B  shows an underside sectional view of the excavator wear assembly  1000  shown in  FIG. 7A . 
     Resiliently deformable lock member  1320  is then inserted through upper retaining aperture  1122  of tooth  1100  into upper retaining cavity  1242  of spigot portion  1230  of adaptor  1200 . The width of resiliently deformable lock member  1320  is greatest at the intersection of respective rearwardly diverging side wall portions  1326  and rearwardly converging side wall portions  1328  where latch  1329  is formed. This width is greater than a width of upper retaining cavity  1242 . As such, resiliently deformable lock member  1320  is deformed under a force to allow insertion into upper retaining cavity  1242 . 
     Suitably, a tool such as a screw driver or the like, may be employed to interface with catch  1330  in order to assist in levering resiliently deformable lock member  1320  into upper retaining cavity  1242 . 
     As resiliently deformable lock member  1320  is levered into place, each latch  1329  locates behind a respective side wall of upper retaining aperture  1122  of tooth  1100  to thereby secure resiliently deformable lock member  1320  in place. In this position, resiliently deformable lock member  1320  reverts to its relaxed position such that it is no longer deformed. 
     In this position, resiliently deformable lock member  1320  at least partially extends into upper retaining aperture  1122  of tooth  1100 . However, due to the shape of the rearwardly diverging side wall portions  1326 , the resiliently deformable lock member  1320  does not bear against side walls of upper retaining aperture  1122  of tooth  1100 . 
     Furthermore, the resiliently deformable lock member  1320  exerts a biasing force on side walls and top wall of upper retaining cavity  1242  and on a top face of rigid lock member  1310 . Optionally, resiliently deformable lock member may be retained within upper retaining cavity by way of an interference fit. 
     In this way, resiliently deformable lock member  1320  captively retains rigid lock member  1310  in place. 
     In this way, the lock assembly  1300  releasably secures wear member in the form of tooth  1100  on a nose of an excavator which, in the embodiment, is in the form of adaptor  1200 . 
     The point and transverse forces that tooth  1100  is subjected to during use are borne by the rigid lock member  1310  such that side wall  1125 A of tooth  1100  bears against side wall of  1313 A of rigid lock member  1310  and this force in turn is transferred to bearing face  1314  of lock member which bears against an opposed side wall of lower retaining cavity  1241  of adaptor. 
     Similarly,  1125 B of tooth  1100  bears against side wall of  1313 B of rigid lock member  1310  and this force in turn is transferred to bearing face  1315  of lock member which bears against an opposed side wall of lower retaining cavity  1241  of adaptor. 
     Due to the generally corresponding tapers in side walls  1313 A and  1313 B and side walls  1125 A and  1125 B respectively, transverse loads are similarly borne. Further, these respective tapers also accommodate for manufacturing tolerances in the respective components such that the assembly remains effective. 
     Furthermore, resiliently deformable lock member  1320  captively retains rigid lock member  1310  in place as discussed above. 
     In order to remove the lock assembly  1300  and thereby remove tooth  1100  from adaptor  1200 , resiliently deformable lock member  1320  is levered out of upper retaining cavity  1242  of adaptor  1200 . As before, a tool such as a screw driver or the like, may be used to assist this process through interaction with catch  1330 . Furthermore, each piercable membrane  1324  may be pierced in order that a tool may be inserted through each aperture  1323  to help assist levering respective latches  1329  out from behind respective side walls of upper retaining cavity  1122 . 
     Once the resiliently deformable lock member  1320  has been removed from upper retaining cavity  1242 , rigid lock member  1310  is free to move upwardly and out through upper retaining aperture  1122 . Suitably, a tool may be inserted through generally aligned recesses  1242  and  1123  to assist in this process. 
     Tooth  1100  is then free to be removed from adaptor  1200 . The excavator wear assembly of the invention and the lock assembly for securing the wear member in the form of tooth  1100  to adaptor  1200  avoid the need for threaded components and complex parts. Furthermore, the lock assembly avoids the need for heavy hammers and the like for mounting within the respective retaining apertures and retaining cavities. In this way, the invention provides for an effective method of releasably securing the tooth to the adaptor. 
     Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention. 
     It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.