Tool driving or impacting – Impacting devices – With means to cause or control advance of hammer head
Patent
1993-12-09
1995-01-10
Smith, Scott A.
Tool driving or impacting
Impacting devices
With means to cause or control advance of hammer head
173138, 173211, B25D 1706
Patent
active
053798490
DESCRIPTION:
BRIEF SUMMARY
This invention relates to hydraulic ram assemblies particularly, but not exclusively, for use in hydraulic hammers for driving piles into the ground.
Accordingly, a first aspect of the present invention is a hydraulic ram assembly comprising an outer tubular casing having an apertured end and a closed end, an inner tubular casing extending inwardly into and through the aperture of the apertured end of the outer casing with the outside of the inner casing being made liquidtight with the apertured end, the inner casing having its inner end open and its outer end closed, the inner casing being secured adjacent to its open end to the outer casing, and through the closed end of which a piston rod of a piston is movable longitudinally of the inner casing, a series of ports being provided in the inner casing to enable fluid communication between the insides of the inner and outer casings, the outer end of the piston rod being adapted for a work purpose, a floating piston being provided in the outer casing biased away from the closed end thereof, the floating piston having an axial bore and having secured thereto a formation having an axial passage and a series of axially offset channels, the outer end of the formation adapted to abut and seal against the inner open end of the inner casing, the axial passage housing a floating valve body, the valve body being biased towards and to close off the axial bore at its formation end, at least one fluid inlet being provided at or towards the closed end of the outer casing and at least one fluid outlet being provided in the outer casing at or towards the open end of the inner casing.
Further accordingly, a second aspect of the present invention is a hydraulic hammer comprising an elongate framework having two opposed longitudinal members, means to support the framework in an upright orientation, a hammer tracking the longitudinal members and being for longitudinal movement lengthwise of the framework, and a pair of hydraulic ram assemblies carried in a balanced arrangement about the hammer and adapted to provide a raising movement to the hammer sequentially to each falling movement of the hammer under gravity, each ram assembly being as described in the next preceding paragraph.
A position-adjustable position switch mechanism is preferably provided at the predetermined extent of movement of the distal end of the piston rod of one of the ram assemblies arranged in parallel to permit fluid to escape from or to allow flow of fluid into the ram assemblies respectively.
Preferably, the elongate framework is a carriage mounted between and tracking two masts. The carriage is preferably connected through a flexible element with a winding drum carried at the end of the masts to be uppermost in use. Each mast desirably has a length-extendible foot at the ends intended to be lowermost in use, each foot desirably having a shoe.
Preferably also, the masts are carried on a mobile base unit, and are desirably carried on a platform body of a truck, the base unit having a chassis supported by tyres or tracks.
Preferably further, the end of the floating piston to which the formation is secured, is recessed to form a chamber. The end of the valve body abutting against the bore is desirably of frusto-conical shape. The holes in the wall of the inner casing are preferably spaced from the closed end a distance less than the thickness of the piston head. The piston head is desirably in sealing contact with the inside surface of the inner casing. The floating piston is desirably in sealing contact with the inside surface of the outer casing.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a longitudinal cross-sectional view of a hydraulic ram assembly according to the present invention;
FIG. 2 is a schematic side view of a hydraulic hammer according to the present invention; and
FIG. 3 is a perspective view of a hammer mount on a mobile base unit carried on a truck.
Referring to FIG. 1 of the drawing
REFERENCES:
patent: 1792888 (1931-02-01), Benedict
patent: 1825632 (1931-09-01), Kroakovsky et al.
patent: 2899934 (1959-08-01), Salengro
patent: 3905428 (1975-09-01), Nishimura et al.
patent: 4056150 (1977-11-01), Meijer
patent: 4776408 (1988-10-01), Elkin et al.
patent: 5152352 (1992-10-01), Mandanis
Greigg Edwin E.
Greigg Ronald E.
Smith Scott A.
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