Screw piles

Abstract

A screw pile stem includes a shank having an inwardly tapered portion at one end, and a helical screw on the shank, with the helical screw being of constant pitch and at least a part of the helical screw being on the tapered portion, and with a major diameter of the part of the helical screw on the tapered portion decreasing towards a small end of the tapered portion.

What is claimed is:  
     
         1 . A screw pile stem comprising: 
 a shank having an inwardly tapered portion at one end; and    a helical screw on the shank, the helical screw being of constant pitch and at least a part of the helical screw being on the tapered portion, a major diameter of the part of the helical screw on the tapered portion decreasing towards a small end of the tapered portion.    
     
     
         2 . The screw pile stem according to  claim 1 , wherein the shank has a generally cylindrical portion coaxial with and/or adjacent to the tapered portion and a part of the helical screw is on the generally cylindrical portion.  
     
     
         3 . The screw pile stem according to  claim 2 , wherein the part of the helical screw on the cylindrical portion extends about one full turn.  
     
     
         4 . The screw pile stem according to  claim 1 , wherein the part of the helical screw on the tapered portion extends at least one full turn.  
     
     
         5 . The screw pile stem according to  claim 1 , wherein the major diameter of the part of the helical screw on the tapered portion generally decreases at a constant rate.  
     
     
         6 . The screw pile stem according to  claim 1 , wherein the major diameter of the part of the helical screw on the tapered portion generally decreases at the same rate as the diameter of the tapered portion.  
     
     
         7 . The screw pile stem according to  claim 1 , wherein the shank includes: 
 a body portion; and    an end portion coupled to the body portion at one end thereof.    
     
     
         8 . The screw pile stem according to  claim 7 , wherein the tapered portion is on the end portion.  
     
     
         9 . The screw pile stem according to  claim 7 , wherein the end portion includes a cylindrical portion and a part of the helical screw is on the cylindrical portion.  
     
     
         10 . The screw pile stem according to  claim 7 , wherein all of the helical screw is on the end portion.  
     
     
         11 . The screw pile stem according to  claim 7 , wherein the body portion and the end portion include complementary coupling means by which the end portion is detachably coupled to the body portion.  
     
     
         12 . The screw pile stem according to  claim 11 , wherein the complementary coupling means are adapted to transmit forward and reverse rotational drive from the body portion to the end portion.  
     
     
         13 . The screw pile stem according to  claim 12 , wherein the cylindrical portion forms a socket on the end portion; and 
 wherein the body portion includes a spigot which is engaged in the socket, one of the socket and the spigot having a side wall with a protuberance thereon and the other of the socket and the spigot having a side wall with a complementary recess therein adapted to receive the protuberance, the protuberance being adapted to engage in the recess so as to transmit forward and reverse drive to the end portion.    
     
     
         14 . The screw pile stem according to  claim 12 , wherein the cylindrical portion forms a spigot on the end portion, the body portion includes a socket, and the spigot is engaged in the socket, one of the socket and the spigot having a side wall with a protuberance thereon and the other of the socket and the spigot having a side wall with a complementary recess therein adapted to receive the protuberance, the protuberance being adapted to engage in the recess so as to transmit forward and reverse drive to the end portion.  
     
     
         15 . The screw pile stem according to  claim 13 , wherein one of the socket and the spigot has a side wall with a plurality of protuberances thereon, and the other of the socket and the spigot has a side wall with a complementary recess therein adapted to receive the protuberances, the protuberances being adapted to engage in the recess so as to transmit forward and reverse drive to the end portion.  
     
     
         16 . The screw pile stem according to  claim 13 , wherein each of the spigot and the socket terminates at a free end, the recess opens to a respective one of the free ends, and each protuberance is adapted to enter and exit the recess through the opening to the free end upon relative axial movement of the spigot and socket.  
     
     
         17 . The screw pile stem according to  claim 16 , wherein the recess includes two circumferentially spaced-apart securing portions adapted to selectively receive therein a protuberance in which relative axial movement between the spigot and the socket is prevented.  
     
     
         18 . The screw pile stem according to  claim 17 , wherein the opening is between the circumferentially spaced-apart securing portions.  
     
     
         19 . The screw pile stem according to  claim 18 , wherein the recess has a plurality of spaced-apart axially-aligned securing portions, one of the spigot and the socket has a plurality of axially-aligned protuberances, and the protuberances are arranged to coincidentally locate in respective ones of the securing portions to prevent relative axial movement between the spigot and the socket.  
     
     
         20 . The screw pile stem according to  claim 13 , wherein at least one of the recesses is formed by pressing a portion of the side wall inwards.  
     
     
         21 . The screw pile stem according to  claim 13 , wherein partial relative rotation of the spigot and socket causes each protuberance to locate in one of the respective securing portions.  
     
     
         22 . The screw pile stem according to  claim 21 , wherein each protuberance and recess are arranged such that partial relative rotation of the spigot and the socket urges the end portion and the body portion axially together.  
     
     
         23 . The screw pile stem according to  claim 13 , further comprising: 
 a plurality of complementary circumferentially spaced-apart protuberances and recesses.    
     
     
         24 . The screw pile stem according to  claim 13 , wherein the socket has a shoulder therein, and the end of the spigot is adapted to abut the shoulder, whereby downward loads applied to the upper end of the shank are transmitted to the helical screw by the shoulder.  
     
     
         25 . The screw pile stem according to  claim 1 , wherein the shank includes extension coupling means at its other end for coupling thereto an extension stem.  
     
     
         26 . The screw pile stem according to  claim 25 , wherein the extension coupling means is adapted to engage complementary coupling means on an extension stem corresponding to the coupling means on the one end.  
     
     
         27 . A screw pile end piece adapted to be connected to a pile stem, the screw pile end piece comprising: 
 an inwardly tapered portion with at least a part of a helical screw thereon, the helical screw on the tapered portion being of constant pitch and a major diameter of the helical screw decreasing towards a small end of the tapered portion.    
     
     
         28 . The screw pile end piece according to  claim 27 , further comprising: 
 a generally cylindrical portion coaxial with and adjacent to the tapered portion; and    wherein part of the helical screw is on the generally cylindrical portion.    
     
     
         29 . The screw pile end piece according to  claim 28 , wherein the part of the helical screw on the cylindrical portion extends about one full turn.  
     
     
         30 . The screw pile end piece according to  claim 27 , wherein the part of the helical screw on the tapered portion extends at least one full turn.  
     
     
         31 . The screw pile end piece according to  claim 27 , wherein the major diameter of the part of the helical screw on the tapered portion generally decreases at a constant rate.  
     
     
         32 . The screw pile end piece according to  claim 27 , wherein the major diameter of the part of the helical screw on the tapered portion generally decreases at the same rate as the diameter of the tapered portion.  
     
     
         33 . The screw pile end piece according to  claim 27 , further comprising: 
 coupling means adapted to engage complementary coupling means on a pile stem to which the end piece is to be attached for coupling the screw pile end piece thereto, with the coupling means being adapted to receive forward and reverse rotational drive from the complementary coupling means of the pile stem.    
     
     
         34 . The screw pile end piece according to  claim 33 , wherein the cylindrical portion forms a socket which is adapted to receive therein a complementary spigot on the pile stem to which the end piece is to be coupled, with the socket having a side wall with a protuberance thereon adapted to engage in a complementary recess in the pile stem, or a recess therein adapted to receive a complementary protuberance on the pile stem so as to receive forward and reverse drive therefrom.  
     
     
         35 . The screw pile end piece according to  claim 33 , wherein the cylindrical portion forms a spigot which is adapted to engage in a complementary socket on the pile stem to which the end piece is to be coupled, the spigot having a recess therein adapted to receive a complementary protuberance in the socket, or the spigot having a protuberance thereon adapted to engage in a complementary recess in the socket of the pile stem, so as to receive forward and reverse drive therefrom.  
     
     
         36 . The screw pile end piece according to  claim 34 , wherein the socket has a side wall with a plurality of protuberances thereon adapted to engage in a complementary recess in the pile stem so as to receive forward and reverse drive therefrom.  
     
     
         37 . The screw pile end piece according to  claim 34 , wherein the spigot terminates at a free end and the recess opens to the free end, the opening being adapted to receive therethrough the protuberance of the pile stem to which the end piece is to be coupled.  
     
     
         38 . The screw pile end piece according to  claim 34 , wherein the socket terminates at a free end and the recess opens to the free end, the opening being adapted to receive therethrough the protuberance of the pile stem to which the end piece is to be coupled.  
     
     
         39 . The screw pile end piece according to  claim 37 , wherein the recess includes two circumferentially spaced-apart securing portions adapted to selectively receive therein a protuberance such that relative axial movement between the pile stem and the end piece is prevented.  
     
     
         40 . The screw pile end piece according to  claim 39 , wherein the opening is between the circumferentially spaced-apart axially-aligned securing portions.  
     
     
         41 . The screw pile end piece according to  claim 40 , wherein the recess has a plurality of spaced-apart axially-aligned securing portions.  
     
     
         42 . The screw pile end piece according to  claim 34 , wherein the recess extends only partway through the side wall of the socket.  
     
     
         43 . The screw pile end piece according to  claim 35 , wherein the recess extends only partway through the spigot.  
     
     
         44 . The screw pile end piece according to  claim 36 , wherein the plurality of spaced-apart protuberances are axially-aligned and adapted to engage in complementary securing portions of a recess in the pile stem to which it is to be coupled.  
     
     
         45 . The screw pile end piece according to  claim 34 , wherein the socket has a shoulder therein adapted to be engaged by the free end of the pile stem to which the shoulder is to be attached and to receive bearing loads therefrom.  
     
     
         46 . The screw pile end piece according to  claim 35 , wherein the spigot has a shoulder thereon adapted to be engaged by the free end of the pile stem to which the shoulder is to be attached and to receive bearing loads therefrom.  
     
     
         47 . The screw pile end piece according to  claim 34 , wherein the recess is formed by pressing a portion of the side wall inwards.  
     
     
         48 . A pile stem for screw piles, the pile stem comprising: 
 a body portion; and    two opposite end portions, with: 
 a first end portion being adapted to engage a first screw pile end piece having an inwardly tapered portion with at least a part of a helical screw thereon, the helical screw on the tapered portion being of constant pitch and a major diameter of the helical screw decreasing towards the small end of the tapered portion; and  
 a second end portion being adapted to engage a second like pile stem.  
   
     
     
         49 . In combination, a screw pile assembly comprising: 
 a screw pile end piece having an inwardly tapered portion with at least a part of a helical screw thereon, the helical screw on the tapered portion being of constant pitch and a major diameter of the helical screw decreasing towards a small end of the tapered portion; and    a pile stem adapted to be detachably coupled to the screw pile end piece.    
     
     
         50 . A screw pile stem comprising: 
 a steel stem; and    a cast end piece secured thereto.    
     
     
         51 . A screw pile end piece comprising: 
 a body formed of cast steel.