Tool driving or impacting – Impacting devices – Selective axial direction of impact
Patent
1981-02-25
1989-04-11
Yost, Frank T.
Tool driving or impacting
Impacting devices
Selective axial direction of impact
175 19, B25D 916
Patent
active
048197416
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The invention relates to the construction equipment, and more particularly to percussion devices.
The device according to the invention may find application, e.g. in making holes in soil for a trench-less laying of under-ground engineering lines.
The invention may further be used in impact equipment for driving casings into soil, making cast-in-place piles and soil sampling in conducting engineering geological investigations.
BACKGROUND OF THE INVENTION
Known in the art are percussion devices (cf. British patent specification No. 1170167, publ. Mar. 14, 1967), comprising a casing, a striker accommodated in the casing for reciprocations under the action of fluid under pressure and a fluid distribution system enabling the reciprocations of the striker and causing the striker to impart blows to the casing either toward the front- end part of the casing (forward movement function) or toward the rear-end part of the casing (rearward movement function).
The distribution of fluid under pressure for both functions of the device is controlled by a control member which is movably coupled to the striker. The control member may be installed in two positions with respect to the casing - in the front- end or in the rear-end position, the control member controlling the distribution of fluid under pressure to enable the forward movement function when in one position and controlling the distribution of fluid under pressure to enable the rearward movement function when in the other position.
The control member is coupled to the casing by means of a tube communicating with a source of fluid under pressure, having a helical groove cooperating with a helical groove of a flange attached to the casing. Fluid under pressure is fed to the tube by means of a flexible conduit connected to the tube.
Two pairs of stops are provided on the tube and flange to limit the displacement of the control member when the tube rotates in the flange. The tube is caused to rotate in the flange by imparting rotary motion to the flexible conduit.
The flexible tube should be rotated to bring the control member to the position enabling the forward movement function of the device. The tube is thus caused to move together with the control member to the front-end position until the engagement of the front-end stops of the tube and flange. Upon the admission of fluid under pressure the striker starts reciprocating in the casing and imparting blows thereto which are directed toward the front-end (head) part of the casing, and the entire device moves through the soil leaving a hole therebehind.
To switch the device over for rearward movement function (reversal), fluid under pressure should be shut-off. Then the flexible conduit should be rotated in the opposite direction. The control member is thus caused to move together with the tube toward the rear-end position owing to the provision of helical grooves on the tube and flange until the rear-end stops of the tube and flange engage one another; in this position the control member enables reciprocations of the striker in the casing so as to impart blows thereto in the direction toward the rear-end (tail) part of the casing, and the entire device is caused to move under the action of such blows in the opposite direction through the hole, that is the device works in the rearward movement function.
For switching the device over back for the forward movement function, the control member should be moved back to the front-end position as described above.
The above-described devices are characterized by difficulties encountered in reversing, because with considerable length of a hole and flexible conduit and with an unstable hole (when driving holes in loose soils) the transmission of rotary motion to the tube through the flexible conduit is extremely difficult. The helical grooves of the tube and flange may also be clogged to result in jamming and this also hampers the reversal.
Still another feature of known devices is associated with failure to maintain the pre-set function, that is with the
REFERENCES:
patent: 4078619 (1978-03-01), Sudnishnikov et al.
Chepurnoi Nikolai P.
Cherednikov Evgeny N.
Karavaev Andron T.
Kostylev Alexandr D.
Nazarov Nikolai G.
Wolfe James L.
Yost Frank T.
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