The present invention relates to a machine for driv ^¬ ing a pile into the ground, said machine comprising a mobile frame, compartments for ballast, a in relation to the mobile frame transversely displaceable second frame carrying a mast having a driving head with a hat-shaped portion fixed against rotation for contacting the top of the pile, a first means for moving the driving head towards the top of the mast and a second means for moving the driving head towards the foot of the mast, thereby driving down the pile.

From GB Patent No. 633,758 a machine of this type is known, said machine having a rectangular, mobile supporting frame, which by means of wheels at each frame corner may be driven over the building site on rails laid out in advance. The transversely displaceable frame carries two ballast boxes and a vertical, stationary mast supported by inclined stays. The driving head is pulled down by a wire, the ends of which are carried over two-part winch drums. This machine has the drawback that it has to be driven over the building site on rails, whereby the driving of piles not standing in a row becomes difficult, as the rails have to be relaid several times. Furthermore, piles cannot be driven down close to a wall, as the mast can only be moved within the area defined by the rails, and it is not possible either to drive down inclined piles with this known machine.

From US Patent No. 3,717,205 a machine for the drill¬ ing of for instance oil or gas wells is known. The machine has a mobile frame with a mast, which can be lifted from a transport position to a working position, and a table movable along the mast, said table being adapted to hold and to rotate the drill string. By means of an arrangement of cables and a winch drum fitted in the mast it is possible to move the table along the mast with a view to adjusting the weight applied by the drill string to the drill head working in the bore hole. Such a machine is not usable for driving down piles.

It is the object of the invention to provide a machine of the kind mentioned by way of introduction and which does not have the drawbacks known from the machines described above. The machine according to the invention differs from the ones mentioned by way of introduction in that the mobile frame is self-propelled and adapted to move over the ground by means of crawler tracks, in that the second frame is a sledge displaceable transversely to the moving direction of the mobile frame, which travelling direction corresponds to the longitudinal direction of the machine, said sledge carrying a bracket, in which the mast is suspended tiltably about a longitudinal axis and pivotally about a transverse axis from a horizontal into a sloping or a vertical working position, that the transverse sledge is carried by a longi¬ tudinal sledge displaceable lengthwise to the frame, said longitudinal sledge being carried itself by the mobile frame, and in that the longitudinal sledge is displaceable from a position, in which the mast is located at the centre of the machine, to a position, in which the mast is located at the front of the machine.

This makes it possible to move the machine freely over the building site and to drive down piles in any posi¬ tion. Owing to the fact that the mast is displaceable to the front of the machine, it becomes possible for instance to drive down piles close to a wall, and by tilting or pivoting the mast, it becomes possible to drive down a pile vertically, even though the surface of the ground of the piling site is not horizontal. The pivotable mast also makes the driving down of inclined piles possible.

In other embodiments the machine may have means for moving and locking the bracket in relation to the transverse sledge, the transverse sledge in relation to the longitudi¬ nal sledge, and the longitudinal sledge in relation to the frame, respectively, and the means for moving and locking the bracket, the transverse sledge, and the longitudinal sledge are hydraulic cylinders. The use of such means has the effect that the adjustment of the mast over the place,

where a pile is to be driven down, can take place essential ^¬ ly faster than is the case with the known machine, where corresponding adjusting and locking movements take place manually. The use of hydraulic cylinders has the advantage that the cylinders may be used both for displacing the various elements to new positions and to hold them in these positions.

In other embodiments the mast may have a U-shaped cross-section adapted to surround the pile at three of its sides, the driving head may be displaceably guided in the mast, and a holder displaceable along the mast may be provided, said holder being an opening, rectangular frame with a supporting block at each frame side to contact the pile. These measures all aim at preventing slender piles from bending during the driving down. This is possible part¬ ly on account of the fact that they may find support against the mast, partly on account of the fact that the driving head is guided in the mast in such a way that it cannot move to the side, for instance on account of an ex- centric load.

The opening frame also prevents the pile from bend¬ ing. The frame is used in the following way. When the pile has been positioned in the mast, the frame is placed at a height above the ground, which corresponds to about half the length of the pile, and is then closed tightly around the pile. During the driving of the pile the frame is carried along down the mast, in which it is guided. When the pile has been driven so far down that the frame is just above the ground, the frame is removed and the pile may now be driven down to its final position without any risk of bending or buckling.

A preferred embodiment of the invention is characte¬ ristic in that the second means is a chain, which from an anchor point at the foot of the mast is taken directly over a sprocket wheel on the driving head to a second sprocket wheel at the foot of the mast, and from there to a third sprocket wheel mounted in the mast, said third sprocket wheel being driven by a motor. By using a chain as a pulling

means a safer transfer of the force to the pile is achieved than is the case when using a wire, and by letting in an ^¬ other embodiment the straight runs of the chain be substan¬ tially parallel to the longitudinal axis of the mast and by letting them run inside the mast or along the exterior thereof, the mast will not be subjected to bending moments during driving of a pile.

According to another embodiment the first means for moving the driving head towards the top of the mast is the chain, which from the motor-driven third sprocket wheel is taken via a sprocket wheel in the top of the mast over an upper sprocket wheel on the driving head to an anchor point at the top of the mast. Thereby it becomes unnecessary to take up the free end of the chain on a chain drum corre- sponding to the winch drums in the known machine. Further¬ more, it is achieved that the chain only runs inside or along the mast, thereby making it possible in an uncompli¬ cated way to pivot and/or tilt the mast. By choosing a hy¬ draulic motor a particularly simple construction is at- tained.

In another preferred embodiment the machine according to the invention is characteristic in that the second means for moving the driving head towards the foot of the mast is a hydraulic jack, of which one end is coupled to the driving head, and the other, which faces the top of the mast, is fastened to a locking head displaceably guided in the mast, said locking head having spring-loaded locking pawls engag¬ ing a plurality of projecting locking members placed in the mast. By using such a hydraulic jack, a so-called climbing cylinder, for driving the pile into the ground, a simplifi¬ cation of the machine is attained in comparison with the above described embodiment, in which the pile is driven into the ground by traction or pulling. However, when using the hydraulic jack it is not possible to drive long piles in one step. The described embodiment also has the advantage that it is easy to enclose all moving parts, whereby the work of maintaining the machine is reduced.

In a modified embodiment of the machine the second

means for moving the driving head towards the foot of the mast is a wire, which from a winch drum on the mast is taken over a pulley in the top of the mast to an eye on the locking head, and in that the eye on the locking head is movable and connected with the locking pawls in such a way that they are released from engagement with the projecting locking members in the mast, when the locking head and the driving head are lifted by means of said wire.

In further embodiments the driving head may comprise a measuring cell for measurement of the driving force applied to the pile, and the measuring cell may be a weigh ^¬ ing cell, which is inserted between the body of the driving head and a movable plate in the hat-shaped portion, said plate forming a pad for the top of the pile during the driv- ing down of the pile. In the last-named embodiments it is possible to measure the piling force applied during the entire driving operation of the pile. By comparing this measurement with a measurement of the length, the pile has been driven, and the inclination of the pile and lateral di- rection during the driving, information becomes available, which could otherwise only be obtained by a subsequent trial loading of the pile. As the information is available immediately after the pile has been driven, a considerable saving of time and costs is achieved, because a subsequent trial loading may be omitted.

The invention will be explained in detail in the fol¬ lowing by means of a embodiment and with reference to the drawing, in which

Fig. 1 is a side view of a machine according to the invention,

Fig. 2 is a somewhat schematic partial view seen in the direction III-III in Fig. 1,

Fig. 3 is a somewhat schematic partial view seen in the direction III-III in Fig. 1, Fig. 4 is a side view of the mast of the machine ac¬ cording to Fig. 1,

Fig. 5 is a front view of a driving head,

Fig. 6 is a side view of a driving head according to

Fig. 5,

Fig. 7 is a sectional view along the line VII-VII in Fig. 2,

Fig. 8 is a view similar to Fig. 3 showing the machine with a hydraulic jack,

Fig. 9 is a sectional view of the mast along the line IX-IX in Fig. 8,

Fig. 10 is a cross-section of the mast with inserted pile showing a holder for the pile, and Fig. 11 is a partial cross-sectional view along the line XI-XI in Fig. 6.

The machine shown in Fig. 1 of the drawing has a frame 1 with wheels provided with crawler tracks 2. The frame also carries a housing or an enclosure 3, which is shown schematically, and comprises compartments 4 and 5 for ballast as well as a compartment 6 for equipment such as diesel engines for propulsion, fuel tanks, electric genera¬ tors, etc. necessary for the operation of the machine. The machine has a mast 7 suspended in a bracket 8 in such a way that it can pivot about horizontal trunnions 9 journalled partly in the bracket 8 and partly in side plates 10 on each side of the mast. By means of two hydraulic cylinders 11, which at their lower ends are connected with the bracket 8 and with their upper ends via a pin 28 is hinged to the side plate 10, the mast 7 may be swung from the illustrated ver¬ tical position to a transport position 12. The mast 7 may also by means of the working cylinders 11 be placed in an inclined position 13 for driving down inclined piles, just as it may be placed in a position 14, in which the mast is leaning a bit forwards, for instance at an angle of 5" with vertical.

Fig. 2 shows schematically a part of the frame 1 forming a platform, which carries a diesel engine 16, which runs a hydraulic pump 17 driving a hydraulic motor or a hy- draulic jack, as will be explained later. For the sake of clarity neither the construction of the frame nor of the housing 3 is shown.

As can best be seen in Fig. 3 the frame has at each

side a longitudinal rail 27, on which a longitudinal sledge 21 may slide lead by guides 26 at each end of the sledge and moved by hydraulic cylinders 25.

The longitudinal sledge carries a transverse sledge 20, which by means of rails and guides (not shown) may slide on the longitudinal sledge 21 transversely to the machine. The adjustment of the position of the sledge 20 is carried out by means of transversely arranged hydraulic cylinders 24, which as shown in Fig. 2 are hinged at one end to the transverse sledge 20 and at the other end to the longitudi¬ nal sledge 21. The transverse sledge 20 has an opening, in which a plate or cradle 18 is pivotally suspended about a horizontal longitudinal axis 19. The plate 18 carries the bracket 8 and the lower ends of the previously mentioned hydraulic cylinders for swinging the mast from a working po¬ sition into a transport position. The mast 7 can as in¬ dicated with dot-and-dash lines 28 in Fig. 3 be tilted ap¬ prox. 5* from side to side by means of vertical, hydraulic cylinders 23, the lower ends of which are connected with the transverse sledge 20 and the upper ends of which are hinged to fittings 22 welded to the bracket 8.

By means of the arrangement described above it becomes possible to tilt the mast from side to side, to swing it from vertical to horizontal, to displace it from side to side and to displace the the whole mast from the centre of the machine to its front edge as indicated in dotted lines at 26 in Fig. 2.

The mast has as shown schematically in Fig. 7 a U- shaped cross-section formed by a rear plate 51 and flanges 52, which have on the inner side substantially closed por¬ tions defined by a front plate 53 and inner and outer panels 54, 55, respectively, the facing edges 56 of which form a slot for the body 31 of the driving head. Fig. 7 shows that the pile during the driving is lying completely inside the U-profile of the mast and any bending of the pile during the driving is thus limited in three directions. As explained below with reference to Fig. 10 the machine may have a holder movable along the mast, said holder preventing the

pile from bending in any direction during the driving opera¬ tion.

In the mast is movably placed a driving head 30 with a body 31 and a hat-shaped portion 32 to receive the top of a pile 70. Fig. 4 shows the body 31 of the driving head 31, which during its movement in the mast is guided in the slot formed between the edges 56 of the panels 54 and 55.

In the embodiment described in the following the machine is adapted to drive a pile into the ground by traction by means of a chain drive. In another embodiment, which will be described later, the machine is adapted to press a pile into the ground.

As shown in Fig. 4 a chain 40 is at one end anchored in a point 41 at the foot of the mast and from there taken over a lower sprocket wheel 37 on the driving head to an¬ other sprocket wheel 43 at the foot of the mast and from there to a motor-driven sprocket 40 located in the side plate 10. From there the chain 40 is guided over a wheel 45 to a sprocket wheel 46 at the top of the mast, from where the chain is passed around an upper sprocket wheel 38 on the driving head to an anchor point 47 at the top of the mast.

The driving head with sprocket wheels is shown in de¬ tail in Figs. 5-7, which show that the sprocket wheels 37 and 38 are journalled on trunnions 35 and 36, respectively, welded to the side edge of the body 31 of the driving head in such a way that the sprocket wheels and the chain are po¬ sitioned in the above-mentioned, substantially closed por¬ tions inside the flanges 52 of the mast.

Fig. 8 shows the embodiment in which the machine is adapted to press a pile into the ground, in which embodiment the mast 7 has a driving head 30, the body 31 of which as described above is guided in slots in the mast. In this em ^¬ bodiment the driving head is embodiment suspended from a locking head 85 by means of a double-acting hydraulic jack 80 with a piston rod 81 and a cylinder 82. The locking head 85 has a box-shaped body 86, which on two opposite sides has a pair of wings 87 (Fig. 9) extending into the slots formed between edges of panels 54 and 55, thereby guiding the

locking head during its movement in the mast. Between the wings 87 in each pair of wings a locking pawl 88 is pivotally mounted on a pivot 89 carried by the wings. Between the locking pawl 88 and the body 86 of the locking head a compression spring 90 is arranged, said spring press¬ ing the locking pawl towards the flange 52 on the mast, said flange carrying on its inner side a plurality of projecting members 91 equidistantly spaced over the whole length of the mast. The locking head 85 is suspended in a wire 92, which in a manner not shown is taken over a pulley in the top of the mast to a winch drum placed on the mast. The wire 92 is fastened in a longitudinally displaceable eyebolt 93, which has an end stop 94. Furthermore, a wire 95 is attached to the end stop and carried over rollers 96 to the locking pawls 88.

The arrangement works in the following way. A pile to be driven is placed in the mast, and the driving head 30 with the locking head 85 is lowered gainst the top of the pile by means of the wire 92. On account of the weight of the driving head and the locking head, the eyebolt 93 is drawn so far out of the locking head, that the end stop 94 prevents any further movement. Due to this the wire 95 has pulled the locking pawls against the locking head in such a way that the pawls go clear of the locking members 91 in the mast.

The hydraulic jack is now charged with oil under pressure and extends to lift the locking head. Thereby the load on the wires 92 and 95 is relieved in such a way that the locking pawls 88 are pressed against the sides of the mast by the springs and engage the locking members 91, whereby the locking head is prevented from moving further upwards. This causes the pile to be pressed down until the hydraulic jack has reached its full length. The oil flow is then reversed to contract the jack, whereby the locking head assisted by its own weight slides down along the mast until the oil flow is reversed again and the described cycle re¬ peated.

Fig. 10 shows a holder 71 for the pile 70. In closed

condition the holder 71 forms a frame 72 with three sides 74, 75, 76, which are fixed, and one side 77, which can be swung on a hinge 78 on the side 76 and which can be kept in closed position by means of a bolt (not shown), which is inserted through an eye 79 and a corresponding eye 80 on the side 74. Each frame side carries a support block 73, which, when the frame is closed, rests against the pile 70. The frame sides 74 and 76 carry guides 91 having surfaces 92 abutting the edges 56 of panels 54 and 55 and are thus guided by these edges during the movement of the holder along the mast.

As shown best in Fig. 11 the driving head 30 carries a housing 33 for a weighing cell 60 for measuring the driv ^¬ ing force applied to the pile 70. The weighing cell is con- nected with a measuring instrument by means of a cable 61 threaded through a bore 61 in the housing 33. The weighing cell rests with its under side against a pressure plate 63 transferring the force to the pile via a pressure pad 64 having a spherical protrusion 65. The pressure plate 63 and the pressure pad 64 fit loosely into a recess 66 in the driving head in such a way that the entire piling force is transferred from the housing 33 through the weighing cell 60 to the top of the pile.