GB1258060A - - Google Patents

Abstract

1,258,060. Vibrators. KEELAVITE HYDRAULICS Ltd. 13 Oct., 1969 [11 Oct., 1968], No. 48337/68. Heading F2X. [Also in Divisions G2-G3] A piston 13 is reciprocated by hydraulic pressure in chambers 17, 18 so as to apply to a pile (not shown) through a rod 2 and foot 3 a longitudinal vibratory-force with an asymmetric sawtooth waveform such that the pile is either driven or extracted. The pressure is controlled by a servo-valve 43, pipes 40, 48 being connected to a fluid source and a drain tank, respectively. Hydraulic accumulators 46, 50 are provided as shown. In the valve a spool (64), (Fig. 3 (not shown), reciprocates in response to operation of a pilot valve 61, Fig. 4, by a torque motor 62, which is controlled by a unit 87 according to signals from a unit 84 and transducers 77, 78 detecting the positions of the spool (64) and spools (68, 69) in the pilot valve. The unit 84 compares and amplifies signals from a wave generator 85 and a transducer 82 detecting the position of the rod 2. Adjustment of the generator determines the waveform of the vibratory force. Alternatively, two piston elements are attached to a common rod, Fig. 5 (not shown), a valve in place of the valve 43 causing pressure application to both of the pistons to drive the rod in one direction and to only one piston to drive the rod in the opposite direction. More than two piston elements may be provided. Apparatus with a plurality of piston areas may comprise a system similar to that shown in Fig. 4.