GB1584810A

GB1584810A – Fluid pressure operated percussion mechanism with remotely operable stroke control
– Google Patents

GB1584810A – Fluid pressure operated percussion mechanism with remotely operable stroke control
– Google Patents
Fluid pressure operated percussion mechanism with remotely operable stroke control

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Publication number
GB1584810A

GB1584810A
GB5300877A
GB5300877A
GB1584810A
GB 1584810 A
GB1584810 A
GB 1584810A
GB 5300877 A
GB5300877 A
GB 5300877A
GB 5300877 A
GB5300877 A
GB 5300877A
GB 1584810 A
GB1584810 A
GB 1584810A
Authority
GB
United Kingdom
Prior art keywords
valve
throttle
cylinder
return
pressure medium
Prior art date
1976-12-23
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Expired

Application number
GB5300877A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Fried Krupp AG

Original Assignee
Fried Krupp AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1976-12-23
Filing date
1977-12-20
Publication date
1981-02-18

1977-12-20
Application filed by Fried Krupp AG
filed
Critical
Fried Krupp AG

1981-02-18
Publication of GB1584810A
publication
Critical
patent/GB1584810A/en

Status
Expired
legal-status
Critical
Current

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Classifications

B—PERFORMING OPERATIONS; TRANSPORTING

B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS

B25D—PERCUSSIVE TOOLS

B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously

B25D9/14—Control devices for the reciprocating piston

B25D9/26—Control devices for adjusting the stroke of the piston or the force or frequency of impact thereof

F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES

F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES

F01L21/00—Use of working pistons or pistons-rods as fluid-distributing valves or as valve-supporting elements, e.g. in free-piston machines

F01L21/02—Piston or piston-rod used as valve members

Description

(54) FLUID PRESSURE OPERATED PERCUSSION MECHANISM WITH
REMOTELY OPERABLE STROKE CONTROL
(71) We, FRIED. KRUPP GESELLSCHAFT MIT BESCHRANKTER HAFTUNG, of 103 Altendorfer Strasse, D-4300 Essen 1, Federal
Republic of Germany, a German body corporate, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement ::
This invention relates to a fluid pressure operated percussion mechanism of the type, hereinafter termed the type specified, comprising a cylinder containing a piston which is reciprocable to make repeated impacts on a cooperating stem disposed at one end of the cylinder and à distributor valve which is operated automatically in response to the movements of the piston, and by establishment by the piston of communication between the cylinder and the distributor valve which enables pressure medium to flow between them, to reverse pressure and exhaust connections to the opposite ends of the piston and thereby cause reciprocation of the piston.
With a mechanism of this type, the impact energy imparted to the shank at each impact stroke of the piston is directly proportional to the stroke of the piston and the frequency of impact of the piston on the shank is inversely proportional to the duration of a working cycle which in turn is a function of the time occupied by changeover of the distributor valve at the end of the impact stroke and a.t the end of the return stroke of the piston.
Existing modes of adjustment of a percussion mechanism of the above type are time consuming and cumbersome because for example, a Lafette percussion drill must be moved when adjustment is required from the drilling position to an accessible position and can only be replaced with difficulty. In the case of a crusher including a hydraulic hammer the operating personnel must be continually on the alert, because at the start when the material is being broken into large individual pieces a large piston stroke is returned while later, during crushing to smaller pieces, a smaller impact energy and a corresponding smaller piston stroke are required.
The invention provides a fluid pressure operated percussion mechanism of the type specified, in which the communication between the cylinder and the distributor valve is a single channel which is unmasked by the piston on its return stroke and contains an adjustable throttle, or is afforded by a plurality of channels which are unmarked by the piston in succession on its return stroke and are alternatively selectable by a selector valve to permit pressure medium to pass from the cylinder to the distributor valve, and a selector at a station remote from the cylinder which is operable to adjust said throttle or said selector valve.
The main advantages achieved by the invention is that adjustment of the piston can easily be effected during operation of the mechanism from a remote control point.
In addition to the saving in time, this affords considerable protection to the percussion mechanism.
Embodiments of the invention are illustrated in the accompanying diagrammatic drawings, in which: Fig. 1 shows a percussion mechanism with remote control of the stroke of the piston;
Figs. 2a and 2h show other embodiments;
Figs 3a and 3b are diagrams showing an embodiment in which the changeover time of the distributor valve may be varied; and
Figs. 4a, 4b and 4c are further diagrams illustrating variants of the mechanism shown in Figs. 3a and 3b.
Fig. 1 shows a hydraulically operated percussion mechanism including a piston which is reciprocated in a cylinder 1 to cause its impact face S to impart repeated blows to a shank 11. After each impact, the piston is moved away from the impact plane EE in the direction of the arrow by admission of pressure medium under line pressure to a port 7 and thence through an annular channel 8 to an annular surface 5 on the piston. The cylinder 1 contains grooves 2a – 2d which communicate by individual channels 3a – 3d with a distributor valve 19. When the surface 5 on the piston 6 exposes, for example, the groove 2b, a pulse of line pressure PO supplied through the channel 7, can pass via the annular space 8, the groove 2b, the channel 3b, a groove 4b, a bore 9 and a channel 10 to the valve 19.This responds by changing over an alternative position in which it connects the port 7 to return pressure P,. and applies line pressure P0 to another annular surface at the rear of the piston 6 to cause the resulting differential hydraulic pressure to move the piston in an impact stroke towards the shank 11 to make a further impact in the plane EE. Reversal from the impact to the return stroke is effected by establishment of communication through the chann.el 3b, between the valve 19 and the cylinder, as described later with reference to Fig. 3b, shortly before the impact of the piston, to cause the valve 19 to change over again to apply line pressure P0 to the part 7 and return pressure Pr to the rear end of the piston.
The piston can perform different return strokes SQ. 5 . sod, determined by the position of the piston 12 of a selector valve 13, which determines which of the channels 3a – 3d wil be connected by the grooves 4a 4d to the valve 19 on the return stroke of the piston.
Fig. 1 shows the setting for the stroke st. The channel 3a is blanked off by the piston 12 and it is not until the piston has unmasked the groove 2b that line pressure can flow to the valve 19 and the latter is able to switch the piston over to the impact stroke.
The piston 12 is balanced and is acted on by two opposing forces, namely the pressure of a spring 15 and an opposing control pressure Pr which acts on the surface 16 of the piston. The pressure Pr is applied to the selector 13 through a narrow bore hose 18 from a signal generator 17, constituted by an adjustable pressure regulating valve, which is situated at a remote control station. The control pressures appropriate for the strokes s,. . . 5d of the piston 6 are marked on a scale and can be selected by adjustment of a screw 20.
Figs. 2a and 2b show simple embodiments which provide selection of only two alternative strokes sa and Sb. These include a remotely situated signal generator which consists of a manually operated 2/3 way valve 21 and a selector valve 22 which is a 2/2 way valve. In position I of the valve 21, as shown in Fig. 2a, the line 18 is connected to the tank T. The cylinder 24 has only two grooves 2a and 2b. In the position shown in Fig. 2a the valve 22 has closed the channel 3Q, so that the return stroke of the piston continues until it has unmasked the groove 2b to open a path through the channel 3b for a pulse of pressure to the valve 19. The stroke of the piston is therefore sb.
Shifting of the valve 21 to position II moves the valve 22 to position II, in which the channel 3a is open to the valve 19 and the stroke of the piston is sa.
Fig. 2b is a variant of Fig. 2a. The selector valve 25 is a 2/3 way valve and the operation is analogous to that of Fig.
2a.
Figs. 3a and 3b show another mode of control, in which the cylinder 26 has a single groove 2, through which the pressure pulse may pass to the valve 19 through an adjustable throttle 27 at the end of the return stroke of the piston 6. A determined volume V0 of pressure medium is required to move the valve 19 and this must be supplied by the pressure pulse. The valve itself is indicated symbolically by its mass m < . In position I the pressure pulse has moved mv against the pressure of a spring 28 into the position in which the piston 6 commences its impact stroke towards the shank 11. m requires, in dependence upon the degree of opening of the throttle 27, more or less time to reach position I. During this time the piston continues to travel in its return stroke a distance depending on its moment of inertia. Adjustment of the throttle 27 is therefore effective to control the energy of each individual impact and the frequency of impact. The delay effect may be considerably increased by connecting an accumulator 29 in parallel with the volume Vv of the valve 19. The throttle 27 is adjustable by a remote control 17, 18. As shown in Fig. 3b, during the impact stroke cf the piston 6 the groove 2 is connected by grooves 30 and 31 with the return line Pr. The volume Vv of pressure medium has been displaced in the direction of the arrow as the valve mass mv has been returned to position II by the pressure of the spring 28 and the accumulator 29 has discharged the volume Vsp. The entire volume Vsr + V must pass through the throttle 27 to reach the return line Pr through the grooves 2, 30 and 31. The cross sectional area of the throttle thus also determines the reversal time required by mv to return from position I to II. Increase and decrease in the reversal time of the valve at each end of the piston stroke correspond respectively to lower and higher frequencies of impact. The adjustable throttle 27 in Figs. 3a and 3b thus performs two functions. It influ ences, as the result of remotely controlled variations in its cross-sectional area, not only the time required for mv to move from II to I, but also the time required for mv to move from I to II. The embodiments shown in Figs. 4a and 4b permit of variation of one reversal time only. Fig. 4a shows control of the time required for the valve 19 to move from the return stroke to the impact stroke, which can be delayed by the throttle 27 remotely controlled through the line 18, while the pressure medium bypasses the throttle via the non-return valve 32 when it flows from the valve 19 to the cylinder. Fig. 4b shows exclusive control of the time required by the valve 19 to move from the impact to the return stroke, the pressure medium bypassing the throttle through the non-return valve 32 when flowing from the cylinder to the valve 19. Fig. 4c can be regarded as a combination of Figs. 4a and 4b. The two changeover lines are independently variable. When the piston unmasks the groove 2, the pressure medium flows through the throttle 33 and the non-return valve 34 to the valve 19. The path through the throttle 35 is blocked by the closed-non-return valve 36. When the groove 2 is connected by the groove 30 in the piston 6 with the return line (see Fig. 3b) the pressure medium can flow from the valve 19 and the accumulator 29 through the non-return valve 36 and the throttle 35, the path through the throttle 33 being blocked by the non-return valve 34. The cross sectional areas of the throttles 33 and 35 can be independently varied through the remote control channels 1 8a and 1 8b respectively. The accumulator 29 can be of such size that its influence becomes negligible upon full opening of either one or both throttles. WHAT WE CLAIM IS: - 1. A fluid pressure operated percussion mechanism of the type specified, in which the communication between the cylinder and the distributor valve is a single channel which is unmasked by the piston on its return stroke and contains an adjustable throttle, or is afforded by a plurality of channels which are unmasked by the piston in succession on its return stroke and are alternatively selectable by a selector valve to permit pressure medium to pass from the cylinder to the distributor valve, and a selector at a station remote from the cylinder which is operable to adjust said throttle or said selector valve. 2. A percussion mechanism according to claim 1, wherein the adjustable throttle controls flow of pressure medium both from the cylinder to the distributor valve and from the distributor valve to the channel. 3. A percussion mechanism according to claim 1, comprising a channel bypassing the throttle and containing a non-return valve which permits flow of pressure medium from the distributor valve to the cylinder. 4. A percussion mechanism according to claim 1, comprising a channel bypassing the throttle and containing a non-return valve which permits flow of pressure medium from the cylinder to the distributor valve. 5. A percussion mechanism according to claim 1, wherein the single channel has two branches, each containing a throttle adjustable from the remote station and a non-return valve, one such valve permitting flow of pressure medium from the cylinder to the distributor valve, and the other permitting flow of pressure medium from the distributor valve to the cylinder. 6. A percussion mechanism according to any of claims 2 to 5, which includes an accumulator connected in parallel with the distributor valve. **WARNING** end of DESC field may overlap start of CLMS **. Claims (6) **WARNING** start of CLMS field may overlap end of DESC **. ences, as the result of remotely controlled variations in its cross-sectional area, not only the time required for mv to move from II to I, but also the time required for mv to move from I to II. The embodiments shown in Figs. 4a and 4b permit of variation of one reversal time only. Fig. 4a shows control of the time required for the valve 19 to move from the return stroke to the impact stroke, which can be delayed by the throttle 27 remotely controlled through the line 18, while the pressure medium bypasses the throttle via the non-return valve 32 when it flows from the valve 19 to the cylinder. Fig. 4b shows exclusive control of the time required by the valve 19 to move from the impact to the return stroke, the pressure medium bypassing the throttle through the non-return valve 32 when flowing from the cylinder to the valve 19. Fig. 4c can be regarded as a combination of Figs. 4a and 4b. The two changeover lines are independently variable. When the piston unmasks the groove 2, the pressure medium flows through the throttle 33 and the non-return valve 34 to the valve 19. The path through the throttle 35 is blocked by the closed-non-return valve 36. When the groove 2 is connected by the groove 30 in the piston 6 with the return line (see Fig. 3b) the pressure medium can flow from the valve 19 and the accumulator 29 through the non-return valve 36 and the throttle 35, the path through the throttle 33 being blocked by the non-return valve 34. The cross sectional areas of the throttles 33 and 35 can be independently varied through the remote control channels 1 8a and 1 8b respectively. The accumulator 29 can be of such size that its influence becomes negligible upon full opening of either one or both throttles. WHAT WE CLAIM IS: - 1. A fluid pressure operated percussion mechanism of the type specified, in which the communication between the cylinder and the distributor valve is a single channel which is unmasked by the piston on its return stroke and contains an adjustable throttle, or is afforded by a plurality of channels which are unmasked by the piston in succession on its return stroke and are alternatively selectable by a selector valve to permit pressure medium to pass from the cylinder to the distributor valve, and a selector at a station remote from the cylinder which is operable to adjust said throttle or said selector valve. 2. A percussion mechanism according to claim 1, wherein the adjustable throttle controls flow of pressure medium both from the cylinder to the distributor valve and from the distributor valve to the channel. 3. A percussion mechanism according to claim 1, comprising a channel bypassing the throttle and containing a non-return valve which permits flow of pressure medium from the distributor valve to the cylinder. 4. A percussion mechanism according to claim 1, comprising a channel bypassing the throttle and containing a non-return valve which permits flow of pressure medium from the cylinder to the distributor valve. 5. A percussion mechanism according to claim 1, wherein the single channel has two branches, each containing a throttle adjustable from the remote station and a non-return valve, one such valve permitting flow of pressure medium from the cylinder to the distributor valve, and the other permitting flow of pressure medium from the distributor valve to the cylinder. 6. A percussion mechanism according to any of claims 2 to 5, which includes an accumulator connected in parallel with the distributor valve. GB5300877A 1976-12-23 1977-12-20 Fluid pressure operated percussion mechanism with remotely operable stroke control Expired GB1584810A (en) Applications Claiming Priority (1) Application Number Priority Date Filing Date Title DE19762658455 DE2658455C3 (en) 1976-12-23 1976-12-23 Pressure medium operated striking mechanism Publications (1) Publication Number Publication Date GB1584810A true GB1584810A (en) 1981-02-18 Family ID=5996418 Family Applications (1) Application Number Title Priority Date Filing Date GB5300877A Expired GB1584810A (en) 1976-12-23 1977-12-20 Fluid pressure operated percussion mechanism with remotely operable stroke control Country Status (5) Country Link JP (1) JPS5380304A (en) DE (1) DE2658455C3 (en) FR (1) FR2375008A1 (en) GB (1) GB1584810A (en) SE (1) SE429515B (en) Cited By (7) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title US4646854A (en) * 1984-11-29 1987-03-03 Fried. Krupp Gesellschaft Mit Beschrankter Haftung Hydraulic striking device US5174387A (en) * 1990-11-20 1992-12-29 Krupp Maschinentechnik Gesellschaft Mit Beschrankter Haftung Method and apparatus for adapting the operational behavior of a percussion mechanism to the hardness of material that is being pounded by the percussion mechanism US6058632A (en) * 1997-11-07 2000-05-09 Hawkins; Peter Arthur Taylor Tool holder with percussion member US8201640B2 (en) 2007-02-23 2012-06-19 Atlas Copco Rock Drills Ab Method in respect of a percussive device, percussive device and rock drilling machine US20160199969A1 (en) * 2015-01-12 2016-07-14 Caterpillar Inc. Hydraulic hammer having variable stroke control EP3328591A4 (en) * 2015-07-31 2018-12-26 TEI Rock Drills, Inc. Remote control of stroke and frequency of percussion apparatus and methods thereof FR3077753A1 (en) * 2018-02-14 2019-08-16 Montabert METHOD FOR ADJUSTING THE STROKE STROKE OF A STRIPPER PISTON OF A PERCUSSION APPARATUS, AND A PERCUSSION APPARATUS FOR CARRYING OUT SAID METHOD Families Citing this family (20) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title DE3115361A1 (en) * 1981-04-16 1982-10-28 Hydroc Gesteinsbohrtechnik GmbH, 5960 Olpe Hydraulic percussion device JPS581690U (en) * 1981-06-22 1983-01-07 古河鉱業株式会社 Impact mechanism of hydraulic rock drill JPS5869995A (en) * 1981-10-20 1983-04-26 株式会社小松製作所 Drifter apparatus of crawler drill JPS58185688U (en) * 1982-06-07 1983-12-09 株式会社小糸製作所 Crawler drill drifter device JPS604636U (en) * 1983-06-20 1985-01-14 北越工業株式会社 hydraulic rock drill JPS6123389U (en) * 1984-07-16 1986-02-12 古河機械金属株式会社 Variable stroke mechanism of hydraulic impact device FR2595972B2 (en) * 1985-07-16 1989-10-20 Montabert Ets PERCUSSION APPARATUS FR2584968B1 (en) * 1985-07-16 1989-02-17 Montabert Ets METHOD FOR CONTROLLING THE MOVEMENT OF THE IMPACT PISTON OF A PERCUSSION APPARATUS MOUSED BY AN INCOMPRESSIBLE PRESSURE FLUID, AND APPARATUS FOR IMPLEMENTING THE METHOD FR2602448B1 (en) * 1986-08-07 1988-10-21 Montabert Ets METHOD FOR REGULATING THE PERCUSSION PARAMETERS OF THE STRIKE PISTON OF AN APPARATUS MOVED BY AN INCOMPRESSIBLE PRESSURE FLUID, AND APPARATUS FOR CARRYING OUT SAID METHOD DE4019019A1 (en) * 1990-06-14 1991-12-19 Krupp Maschinentechnik METHOD FOR DETERMINING CHARACTERISTIC CHARACTERISTICS OF A STRIKE AND DEVICE FOR IMPLEMENTING THE METHOD DE4027021A1 (en) * 1990-08-27 1992-03-05 Krupp Maschinentechnik HYDRAULICALLY OPERATED IMPACT DRILLING DEVICE, ESPECIALLY FOR ANCHOR HOLE DRILLING DE4028595A1 (en) * 1990-09-08 1992-03-12 Krupp Maschinentechnik HYDRAULICALLY OPERATED PERFORMANCE FI104960B (en) * 1995-07-06 2000-05-15 Sandvik Tamrock Oy Hydraulic hammer FR2742365B1 (en) * 1995-12-13 1998-01-16 Outils Pneumatiques Globe PNEUMATIC ASSEMBLY WITH APPROACH AND COMBINED STRIKE, DESSLING UNIT COMPRISING SUCH AN ASSEMBLY, DESSLING INSTALLATION COMPRISING SUCH A UNIT, AND METHOD FOR CONTROLLING SUCH AN INSTALLATION FI114290B (en) * 2003-02-21 2004-09-30 Sandvik Tamrock Oy Control valve and arrangement on impactor FI117548B (en) * 2005-03-24 2006-11-30 Sandvik Tamrock Oy The impactor, FR2902684B1 (en) * 2006-06-27 2010-02-26 Montabert Roger METHOD FOR SWITCHING THE STROKE STROKE OF A MU-PERCUSSION APPARATUS BY AN INCOMPRESSIBLE FLUID UNDER PRESSURE, AND APPARATUS FOR CARRYING OUT SAID METHOD SE530524C2 (en) * 2006-09-13 2008-07-01 Atlas Copco Rock Drills Ab Percussion, rock drilling machine including such percussion and method for controlling percussion US9840000B2 (en) * 2014-12-17 2017-12-12 Caterpillar Inc. Hydraulic hammer having variable stroke control AT517385B1 (en) * 2015-06-15 2019-02-15 Fill Gmbh Device for coring Family Cites Families (5) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title SE339817B (en) * 1970-06-16 1971-10-18 Atlas Copco Ab DE2217507B1 (en) * 1972-04-12 1973-08-09 Bauer, Karlheinz, Dr.-Ing., 8898 Schrobenhausen Hydraulic hammer and its use for hammer drill FR2250014A1 (en) * 1973-11-07 1975-05-30 Secoma DE2512731A1 (en) * 1975-03-22 1976-10-07 Klemm Bohrtech HYDRAULIC IMPACT DEVICE US4062411A (en) * 1975-12-05 1977-12-13 Gardner-Denver Company Hydraulic percussion tool with impact blow and frequency control 1976 1976-12-23 DE DE19762658455 patent/DE2658455C3/en not_active Expired 1977 1977-12-13 SE SE7714140A patent/SE429515B/en not_active Application Discontinuation 1977-12-19 FR FR7738195A patent/FR2375008A1/en active Pending 1977-12-20 GB GB5300877A patent/GB1584810A/en not_active Expired 1977-12-22 JP JP15506177A patent/JPS5380304A/en active Granted Cited By (10) * Cited by examiner, † Cited by third party Publication number Priority date Publication date Assignee Title US4646854A (en) * 1984-11-29 1987-03-03 Fried. Krupp Gesellschaft Mit Beschrankter Haftung Hydraulic striking device US5174387A (en) * 1990-11-20 1992-12-29 Krupp Maschinentechnik Gesellschaft Mit Beschrankter Haftung Method and apparatus for adapting the operational behavior of a percussion mechanism to the hardness of material that is being pounded by the percussion mechanism US6058632A (en) * 1997-11-07 2000-05-09 Hawkins; Peter Arthur Taylor Tool holder with percussion member US8201640B2 (en) 2007-02-23 2012-06-19 Atlas Copco Rock Drills Ab Method in respect of a percussive device, percussive device and rock drilling machine US20160199969A1 (en) * 2015-01-12 2016-07-14 Caterpillar Inc. Hydraulic hammer having variable stroke control CN105782142A (en) * 2015-01-12 2016-07-20 卡特彼勒公司 Hydraulic hammer having variable stroke control EP3328591A4 (en) * 2015-07-31 2018-12-26 TEI Rock Drills, Inc. Remote control of stroke and frequency of percussion apparatus and methods thereof US10370900B2 (en) 2015-07-31 2019-08-06 Tei Rock Drills, Inc. Remote control of stroke and frequency of percussion apparatus and methods thereof FR3077753A1 (en) * 2018-02-14 2019-08-16 Montabert METHOD FOR ADJUSTING THE STROKE STROKE OF A STRIPPER PISTON OF A PERCUSSION APPARATUS, AND A PERCUSSION APPARATUS FOR CARRYING OUT SAID METHOD WO2019158849A1 (en) * 2018-02-14 2019-08-22 Montabert Method for adjusting the striking stroke of a striking piston of a percussion apparatus, and a percussion apparatus for implementing said method Also Published As Publication number Publication date DE2658455B2 (en) 1980-05-14 DE2658455A1 (en) 1978-06-29 FR2375008A1 (en) 1978-07-21 JPS614628B2 (en) 1986-02-12 DE2658455C3 (en) 1981-01-22 JPS5380304A (en) 1978-07-15 SE7714140L (en) 1978-06-24 SE429515B (en) 1983-09-12 Similar Documents Publication Publication Date Title GB1584810A (en) 1981-02-18 Fluid pressure operated percussion mechanism with remotely operable stroke control US5392865A (en) 1995-02-28 Hydraulic percussion apparatus US4062411A (en) 1977-12-13 Hydraulic percussion tool with impact blow and frequency control US4899836A (en) 1990-02-13 Hydraulic percussion instrument and method of operating same EP0035005B1 (en) 1985-05-22 A hydraulically operated impact device EP0149967B1 (en) 1988-09-21 Hydraulically actuated percussion tool WO2004073931A1 (en) 2004-09-02 Control valve and a method of a percussion device comprising two parallel inlet channels JPH0658073A (en) 1994-03-01 Hammer device US4082032A (en) 1978-04-04 Control of hydraulically powered equipment US4111269A (en) 1978-09-05 Hydraulically-powered impact tool CA1059008A (en) 1979-07-24 Impact tool US4349075A (en) 1982-09-14 Hydraulically operated impact motor US5064005A (en) 1991-11-12 Impact hammer and control arrangement therefor US4343228A (en) 1982-08-10 Hydraulic cylinder arrangement US3609969A (en) 1971-10-05 Hydraulic impact device US4343227A (en) 1982-08-10 Hydraulic percussion apparatus US4244274A (en) 1981-01-13 Cylinder control device of hydraulic cylinder apparatus CA1146443A (en) 1983-05-17 Impactor JP2759497B2 (en) 1998-05-28 Impact tool JPS6125784A (en) 1986-02-04 Stroke variable mechanism of hydraulic type striking device US6901842B2 (en) 2005-06-07 Percussion hydraulic apparatus JPH08509431A (en) 1996-10-08 Hydraulic impact hammer US5887665A (en) 1999-03-30 Striking element US3292370A (en) 1966-12-20 Power transmission apparatus US4036108A (en) 1977-07-19 Pressure fluid operated percussion tools Legal Events Date Code Title Description 1981-05-07 PS Patent sealed 1998-01-14 PE20 Patent expired after termination of 20 years Effective date: 19971219
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