Apparatus for driving and/or extracting piles

Claim 2

Vibratory pile driving apparatus including a motor arranged to impart to a pile forces of non-symmetric waveform wherein the motor comprises a double acting hydraulic cylinder and ram assembly, one of the two moving elements having means of connection to a pile, valve means for controlling the flow of pressurized working fluid to and from the working chamber and a waveform generator for supplying a control signal continuously to adjust the valve means so that fluid flows to and from said assembly to produce an acceleration to said ram in one direction relative to said cylinder which is greater than in the opposite direction.

Claim 3

Apparatus as claimed in claim 1 in which the piston has surfaces of equal area facing in the opposite directions and the valve means is arranged to supply fluid to the areas facing in opposite directions at different rates.

Claim 4

Apparatus as claimed in claim 2 which includes means for comparing said control signal with a measured value signal representing a quantity dependent on the supply of fluid and for adjusting the supply of fluid in dependence upon the comparison.

Claim 5

Apparatus as claimed in claim 3 which includes a transducer for determining the relative positions of the ram and cylinder and supplying the measured value signal in dependence on such determination.

Claim 6

Vibratory pile-driving apparatus comprising a double acting hydraulic cylinder-and-ram assembly, one of the two moving elements of the assembly having means of connection to a pile, a servovalve for controlling the supply of pressurised working fluid to and from the working chambers of the assembly, actuating means for the servovalve, and a closed loop control system comprising a position transducer arranged to provide a measured value signal representing the instantaneous position of the ram relative to the cylinder, means for supplying an input signal of asymmetric waveform, means for comparing the measured value signal with the input signal and for delivering a command signal dependent upon the deviation determined by the comparison, and means for supplying the command signal to the actuating means.

Claim 7

Vibratory pile-driving apparatus comprising a double acting hydraulic cylinder-and-ram assembly, one of the two moving elements of the assembly having means of connection to a pile, a servovalve for controlling the supply of pressurised working fluid to and from the working chambers of the assembly, actuating means for the servovalve, and a closed loop control system comprising a position transducer arranged to provide a measured value signal representing the instantaneous position of the ram relative to the cylinder, means for supplying an input signal of asymmetric waveform, means for comparing the measured value signal with the input signal and for delivering a command signal dependent upon the deviation determined by the comparison, and means for supplying the command signal to the actuating means.

Claim 8

Vibratory pile-driving apparatus comprising a mass adapted to be connected to a pile and to be movable longitudinally thereof and motor means comprising a double acting hydraulic cylinder-and-piston ram assembly, the piston having a first series of surfaces facing in one direction and a second and identical series of surfaces facing in the opposite direction, one of the two moving elements of the assembly having means of connection to the pile, the motor means being arranged in reciprocate the mass relative to the pile longitudinally thereof and to impart vibratory forces to the pile, the motor means being arranged to impart, or being adjustable to impart, to the pile forces of non-symmetrical waveform, and valve means for controlling the supply of pressurized working fluid to and from the working chamber of the assembly, the valve means being arranged to supply fluid to a number of the first series of surfaces for movement of the piston in one direction and to a different number of the second series for movement of the piston in the opposite direction so that the acceleration of the movement of the piston in one direction relative to the cylinder is, or can be caused to be, greater than in the opposite direction.

Claim 9

Vibratory pile-driving apparatus comprising a mass adapted to be connected to a pile and to be movable longitudinally thereof and motor means comprising a double acting hydraulic cylinder-and-piston ram assembly, the piston having a first series of surfaces facing in one direction and a second and identical series of surfaces facing in the opposite direction, one of the two moving elements of the assembly having means of connection to the pile, the motor means being arranged in reciprocate the mass relative to the pile longitudinally thereof and to impart vibratory forces to the pile, the motor means being arranged to impart, or being adjustable to impart, to the pile forces of non-symmetrical waveform, and valve means for controlling the supply of pressurized working fluid to and from the working chamber of the assembly, the valve means being arranged to supply fluid to a number of the first series of surfaces for movement of the piston in one direction and to a different number of the second series for movement of the piston in the opposite direction so that the acceleration of the movement of the piston in one direction relative to the cylinder is, or can be caused to be, greater than in the opposite direction.