Socketed boss having means for retaining a tool shank

A mineral mining pick boss having a socket therein for the reception of a shank of a mineral mining pick and a locking arrangement for retaining the shank, the locking arrangement comprising a plug received in a bore extending through the boss transversely of the socket the arrangement being such that the bore intersects the socket, the plug comprising a body of a resilient material (e.g. neoprene) having bonded into the periphery thereof at spaced locations a plurality of metallic members one of which protrudes from the bore into the socket for frictional engagement with the shank of the tool so as to retain the tool in position, the other(s) of the metallic members being disposed within the bore, and the arrangement of the metallic members being such that the plug may be removed from the bore, rotated and re-inserted to change the metallic member which protrudes into the socket.

This invention relates to means for holding a shank of a tool in a socket, 
and is particularly but not exclusively for use in retaining a mineral 
cutter pick in a socket in mining machinery. 
It is known to retain a mineral cutter pick in a socket by means of a 
resilient plug which forces a metal pin against the shank of the pick, the 
shank being formed with a surface such that the pin exerts a frictional 
force which tends to keep the cutter pick pulled down on its seating. An 
arrangement of this type is shown for example in the complete 
specification of U.K. Pat. No. 895,764. 
Prior constructions of this type require a rather large diameter of 
resilient plug which limits the applications of such locks. They also 
require relatively frequent replacement of the plugs, since the pins tend 
to wear fairly rapidly. 
It is an object of the present invention to provide an improved lock for 
retaining a shank in a socket. 
The present invention accordingly provides a boss having a socket therein 
for the reception of a shank of a tool and a locking arrangement for 
retaining the shank, the locking arrangement comprising a plug received in 
a bore extending through the boss transversely of the socket the 
arrangement being such that the bore intersects the socket, the plug 
comprising a body of a resilient material having bonded into the periphery 
thereof at spaced locations a plurality of metallic members one of which 
protrudes from the bore into the socket for frictional engagement with the 
shank of the tool so as to retain the tool in position, the other(s) of 
the metallic members being disposed within the bore, and the arrangement 
of the metallic members being such that the plug may be removed from the 
bore, rotated and re-inserted to change the metallic member which 
protrudes into the socket. 
The invention also encompasses a mineral mining machine provided with one 
or more bosses as defined above.

Referring to FIG. 1, a mineral cutter pick of known type has a shank 10 in 
which is formed a groove having a sloping shoulder 12 transverse to the 
direction of motion, in use, of the cutter pick. The shank 10 of the 
cutter pick is received in a metal boss 14 which in use is secured as by 
welding to a cutter drum or chain of a minimg machine. The boss 14 has a 
socket 16 passing therethrough and dimensioned to receive the shank 10 of 
the pick. 
A bore 18 is formed through the boss 14 in a direction at right angles to 
the socket 16. The bore 18 has the form of three superimposed cylinders. 
The bore 18 receives a locking plug comprising metal rods 22 and 20 bonded 
into a body of neoprene 24, as seen in greater detail in FIGS. 2 and 3. 
The rods 20 and 22 are shorter in length than the neoprene body 24, the 
latter being extended at its ends as indicated at 24a to cover the ends 
of the rods 20, 22. 
In use, the shank 10 of the cutter pick may be inserted downwardly into the 
socket 16. During such insertion the rod 20 which projects into the socket 
is forced back against the neoprene body 24 and is then sprung against the 
shoulder 12. Because of the inclination of the shoulder 12, the neoprene 
body 24 exerts a resilient force causing the rod 20 to frictionally engage 
the shoulder and force the pick downwardly to bring a shoulder 26 on the 
pick into abutment with the top of the boss 14. 
When the rod 20 becomes worn to an unacceptable extent, the entire plug 20, 
22, 24 may be withdrawn and replaced turned through 180.degree. to bring 
the other rod 22 into use. The provision of a second rod such as 22 
received in a part-cylindrical surface of the bore 18 also resists any 
tendency of the plug to rotate under load. Also, the resilient portions 
24a act to seal the ends of the bore 18 to prevent the ingress of dirt and 
so assist in reducing wear. 
The embodiment of FIG. 4 is similar, except that the neoprene body 24 has 
bonded therein four metal rods 20, 20', 22 and 22' set 90.degree. apart. 
FIGS. 5 and 6 illustrate an embodiment in which the bore 18 is of 
substantially triangular section, and receives a neoprene body 50 which is 
also substantially triangular and has three metal rods 52, 54, 56 bonded 
into its apices. As seen in FIG. 6, here again the neoprene body extends 
over the ends of the rods to seal the bore. 
Finally, FIG. 7 shows a neoprene body 70 of generally square section seated 
in a corresponding bore and having metal rods bonded in its corners. 
It will be appreciated that metallic bodies in forms other than rods may be 
used, for example bodies with part-cylindrical surfaces extending from the 
resilient body but having flattened portions extending into the resilient 
body to assist in bonding.