CA2048374A1 - Hydraulic hammer - Google Patents
Hydraulic hammerInfo
- Publication number
- CA2048374A1 CA2048374A1 CA002048374A CA2048374A CA2048374A1 CA 2048374 A1 CA2048374 A1 CA 2048374A1 CA 002048374 A CA002048374 A CA 002048374A CA 2048374 A CA2048374 A CA 2048374A CA 2048374 A1 CA2048374 A1 CA 2048374A1
- Authority
- CA
- Canada
- Prior art keywords
- piston
- pressure
- hydraulic
- drill
- passage
- Prior art date
- 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.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
Abstract
ABSTRACT
This invention concerns hydraulic hammers which have particular but not exclusive application in down-the-hole drills. The basis of the invention is that the hammer assembly includes means for applying intermittent hydraulic pressure on one side of the piston and compressible means for constantly applying pressure to/the opposite side of the piston. In the down-the-hole drill application the compressible means will be a gas and either this gas or the hydraulic fluid used to flush the drill bit.
This invention concerns hydraulic hammers which have particular but not exclusive application in down-the-hole drills. The basis of the invention is that the hammer assembly includes means for applying intermittent hydraulic pressure on one side of the piston and compressible means for constantly applying pressure to/the opposite side of the piston. In the down-the-hole drill application the compressible means will be a gas and either this gas or the hydraulic fluid used to flush the drill bit.
Description
If ~DF~AUL .~lAb~
"AN HYDRAULIC XAM~ER~
INTRODUCTION TO THE_INVENTION
This invention relates to an hydraulic hammer assembly used in jack hammers and drilling machines, particularly but not exclusively, down-the-hole drilling machines. ~-~
BACRG~OUND Ol~ THE INVENTION
, Conventional hydraulic hammers utilise a high pressure pump and~ reservoir with fluid from the pump passed through a pressure operated valve which directs ~low to :: .
..
~ /one or ', .
_ 3 _ c~o~
one or other side of a piston in a piston and cylinder assembly. The piston forms t~e hammer for striking the drill bit.
There must be means for connecting the pump to the hammer and to return the hydraulic fluid, usually oil, back to the reservoir. This is usually a high pressure flexible hydraulic hose. A hose of this type cannot be used in down-the hole hammer assemblies.
It is an object oP the present invention to provide an hydraulic hammer which does not require an internal valve to control flow direction of the fluid passid the piston.
SUMMARY OF THE INVENTION
According to this invention there is provided an hydraulic hammer assembly comprising a piston and cylinder assembly with means for applying intermittent hydr~ulic pressure to one side of the piston and compressible means for constantly applying pressure to the opposite side of the piston.
JThe invention -~ , "'' ~' ~ .
,' ~ ' ' ' ' 2~37~
The invention al30 provide~ the compressible means tobe mechanically supplied by mean~ of a spring or the like or alternatively through a compressible fluid.
The intermittent hydrauli~ pressure can be supplied through an intermittently operated valve controlling a supply o~ fluid under substantially constant pressure.
Further features of this invention provide for the valve to be a rotary valve or a sliding valve and for there to be included means for rotating the hammer anvil.
Still further features of this invention provide for the hammer assembly to be part of a down-the-hole drill with the pressures applied to the piston provided by fluid transported through separate passages in the drill rods, for the intermittent pressure fluid to be used for flushing the drill bit or ~or the intermittent pressure to be supplied through two different fluids.
In the latter ~ase a second piston slidably operating in a sleeve will be provided.
~The invention , : : . ' ~:
- 5 - 2~ 7~
The invention also provides for th~ constant pressure supply fluid to be used for flushing the drill bit in an assembly as defined above.
BRIEF D~8CRIPTION_O~ THE DRAWING~3 These and other features of this invention will become apparent from the following descripkion of some examples of the invention wherein reference will be made to the accompanying drawings in which Fig 1 is a longitudinal section through a down-the-hole drill assembly;
Figs 2 and 3 show modifications to the assembly of Figure l;
Figs 4 and 5 show alternative valve assemblies for . _ the intermittent fluid pressure supply and Fig 6 shows one form of drill rod suitable for use with the down-the-hole drill described.
/DETAILED DESCRIPTION
' . . ..
` ' ' ' ' . ~' ' , .
~ETATLED ~E8CRIPTI~Ie_pY_~ W~
As illustrated in Figure 1 the hammer assembly 1 has a bit 2 at the free end and a backhead 3 secured to a drill rod 4. A casing 5 extends between the backhead 3 and the bit 2 which has a passage 6 for flushing fluid to pass through.
The casing 5 houses an inner sleeve 7 and a hammer in the form o~ a piston 8. The backhead end of the piston 8 extends as a stem 9 from the remainder of the piston and engages in the backhead 3 to form a sliding seal therewith.
The bore 10 through the backhead 3 is co-axial with a pressure fluid passage 11 in the drill rod 4.
The drawing al50 shows passages formed in the hammer assembly for flushing fluid which can conveniently be .~_ . ^ .
compressed air. The passages extend as shown at 12 through the backhead 3, and as shown at 13 between the casing 5 and inner sleeve 7 extending between the backhead 3 and bit 2. Apertures 14 are provided through the bit end of the inner slePve 7 and the outer end of ~ /passage 12 : ~ .
' '. . :' ~ :
' ~, !
~ " ' ` , ' ' ' , ' ' . ~ ~
~ 7 ~ 7 ~
passage 12 communicates with a passage 15 in the drill rod 4 for the supply of compressed air.
The compressed air can be supplied at constant pressure throu~h the passages and apertures above described to act on the bit striking surface 16 of the piston 8 to constantly tend to raise the piston 8 from and to the ~it 2.
When the piston 8 is raised from the bit 2 khe compressed air can also act as a flushing fluid through the passage 6.
A chamber 17 is formed in the inner sleeve 7 around the stem 9 of the piston 8. The chamber 17 communicates through a passage 18 in the backhead 3 to ambient atmosphere.-A pressure fluid 19 acts through the bore of the drillrod 4 and backhead 3 as described below to enable the hammer assembly to operate.
The passage 18 to atmosphere is provided to prevent a build up of pressure in the chamber 17 which could /occur if .
, ' ' ' ~4~7~
occur i~ there is leakage either from the compressed air path through the assembly or of the pressure fluid passed the stem 9 of piston 8.
Figure 2 illustrates the inclusion of a second piston s.eparating the pressure ~lu:id 19 column into two sections thus enabling two different types of ~luid to be used.
Figure 3 illustrates a further modification wherein a gas accumulator is formed by a stem 21 on the striking end of piston 8 in sliding engagement with a sealing bush 22 providing an oil filled chamber 23 which is in communication with the passages 13 between inner sleeve 7 and casing 5. These passages are sealed at the backhead end.
With gas under pressure introduced into passage 13 movement of the piston will enable the gas to expand or compress and always provide a pressure on the piston 8 tending to lift the piston 8 from the bit 2.
Flushing medlum in this construction can be provided by the pressure fluid l9 passing through an axial bore 24 /through the . .
: ` ` ~
. . .
. :
: ' ' - 9 - 2~ ~ 37 throuqh the piston 8 ~nd prefer~bly a restriction 25 in the form of a suitable plug is provided in the bore 24 to limit the flow o~ pressure fluid 19 to the bit.
To enable the pressure fluid 19 to act intermittently on the piston 8 with a greater force than that provided by the compressed gas in passage 13 a pressura pump ~not shown) and valve assembly are provided at the drill head.
Suitable valves are illustrated in Figures 4 and 5 of the drawings.
Referring firstly to Figure 4 the valve assembly 26 consists of a valve body 27 which has a passage 28 closed at one end 29 which is connected to a motor 30 for rotation. The open end of the valve is in alignment with the fluid passage 11 in the drill rod 4.
The body 27 rotates in a valve housing 31 which has a high pressure inlet port 32 from the pressure pump and ~ an outlet port 33 connected to the reservoir for fluid for the pump.
~ /The body - ~ ~
' ' .
:
", .
~ '; ' -- 2~8~
The body 27 hai3 a radial port 34 through the wall thereof and rotation of body 27 by the motor 30 in the housing 31 will bring port 34 alternately into alignment with ports 3~ and 33. This has the result, in operation, of pressure of.the pressure fluid down the drill rods intermittently varying from maximum pump pressure to exhaust pressure. Each time maximum pressure is exerted down the column of pressure fluid 19 the constant gas pressure acting in the oppositP
direction on piston 8 is overcome and piston 8 is caused to strike the inner end of the bit 2. When the pump pressure on the pressure fluid is released the gas pressure will cause a return stroke of the piston.
' Figure 4 also illustrates a stepped piston 35 in the pressure fluid column to separate the fluid used through the pump from that in the drill rods 4. This will enable the former to be a suitable oil while the latter is watPr. If the bore through tbe backhead 3 and end of the piston 8 are chromium plated or otherwise rendered rust resistant water can be used directly in the hammer assembly 1. This will avoid the necessity for the second piston 20 illustrated in Figure 2. ~-.
.
/In Figure . ~
- : .
8 ~ 7 ~
In Fiyura 5 a suitable slidillg valve assembly 36 is shown. The assembly con~ists of a sliding stepped valve member 37 movable in a valve casing 38 which is in communication with the column of pressure ~luid 19.
Inlet and exhaust ports 39 andl 40 are provided for connection to the delivery of the pressure pump and the reservoir for pump fluid respectively.
Reciprocation of valve member 37 will enable pump delivery pressure to be alternately applied to and relieved from the pressure fluid 19. This in turn will cause operation of the hammer assembly as described above.
With this type of valve a relief valve should also be used when the inlet port is closed. To overcome unnecessary energy loss an accummulator can be included in the system. It will be appreciated however that alternative porting arrangements can be used to avoid ._ the necessity for the relief valve.
~ I~ will be understood that the methods of applying thP
intermittent pressure supplied through the pressure fluid 19 to the piston 8 need not be effected - /hydraulically as ` ~ - 12 - 2~37~
hydraulically as set forth in the above example. I may be applied by mechanic~lly reciprocating a piston to cause pressure and release of pressure in the fluid 19.
This arrangement could readily be set up by those skilled in the art and would also preferably include the relief valve and accumulator re~erred to above.
Also the examples given above describe the use of a compressible fluid to provide a constant pressure on the piston to raise it from the bit. Mechanically resilient means such as compression springs or blocks of suitable resilient material recessed to extend and contract into the piston or drill bit may also be used.
Fiyure 6 shows a form of drill rod 4 which can conveniently be used with this invention.
'.
The drill rod 4 has an inner pipe 41 which is used as tha drive rod and provides the passage for the pressure fluid 19. An outer pipe 42 is welded at 44 to the inner pipe 41 and this welding can conveniently take place at the position on the drill rod where flat~ 43 are formed to enable the rods to be manipulated with spanners.
' /This will ' :`
~ . , .
: : :
- 13 ~ 7~
This will readily be understood by those who make such drill rods.
It is to be understood that the invention above described can be widely varied from the specific examples described and illustrated without departing from the scope of the invention. The drill rod assembly and pressure fluid valving can be varied as can the shape and configuration of the hammer assembly components. What is essential is that there be different pressures applied to each side of the hammer piston.
/CLAIM~:
.
: . ~ ~ . .
: ,
"AN HYDRAULIC XAM~ER~
INTRODUCTION TO THE_INVENTION
This invention relates to an hydraulic hammer assembly used in jack hammers and drilling machines, particularly but not exclusively, down-the-hole drilling machines. ~-~
BACRG~OUND Ol~ THE INVENTION
, Conventional hydraulic hammers utilise a high pressure pump and~ reservoir with fluid from the pump passed through a pressure operated valve which directs ~low to :: .
..
~ /one or ', .
_ 3 _ c~o~
one or other side of a piston in a piston and cylinder assembly. The piston forms t~e hammer for striking the drill bit.
There must be means for connecting the pump to the hammer and to return the hydraulic fluid, usually oil, back to the reservoir. This is usually a high pressure flexible hydraulic hose. A hose of this type cannot be used in down-the hole hammer assemblies.
It is an object oP the present invention to provide an hydraulic hammer which does not require an internal valve to control flow direction of the fluid passid the piston.
SUMMARY OF THE INVENTION
According to this invention there is provided an hydraulic hammer assembly comprising a piston and cylinder assembly with means for applying intermittent hydr~ulic pressure to one side of the piston and compressible means for constantly applying pressure to the opposite side of the piston.
JThe invention -~ , "'' ~' ~ .
,' ~ ' ' ' ' 2~37~
The invention al30 provide~ the compressible means tobe mechanically supplied by mean~ of a spring or the like or alternatively through a compressible fluid.
The intermittent hydrauli~ pressure can be supplied through an intermittently operated valve controlling a supply o~ fluid under substantially constant pressure.
Further features of this invention provide for the valve to be a rotary valve or a sliding valve and for there to be included means for rotating the hammer anvil.
Still further features of this invention provide for the hammer assembly to be part of a down-the-hole drill with the pressures applied to the piston provided by fluid transported through separate passages in the drill rods, for the intermittent pressure fluid to be used for flushing the drill bit or ~or the intermittent pressure to be supplied through two different fluids.
In the latter ~ase a second piston slidably operating in a sleeve will be provided.
~The invention , : : . ' ~:
- 5 - 2~ 7~
The invention also provides for th~ constant pressure supply fluid to be used for flushing the drill bit in an assembly as defined above.
BRIEF D~8CRIPTION_O~ THE DRAWING~3 These and other features of this invention will become apparent from the following descripkion of some examples of the invention wherein reference will be made to the accompanying drawings in which Fig 1 is a longitudinal section through a down-the-hole drill assembly;
Figs 2 and 3 show modifications to the assembly of Figure l;
Figs 4 and 5 show alternative valve assemblies for . _ the intermittent fluid pressure supply and Fig 6 shows one form of drill rod suitable for use with the down-the-hole drill described.
/DETAILED DESCRIPTION
' . . ..
` ' ' ' ' . ~' ' , .
~ETATLED ~E8CRIPTI~Ie_pY_~ W~
As illustrated in Figure 1 the hammer assembly 1 has a bit 2 at the free end and a backhead 3 secured to a drill rod 4. A casing 5 extends between the backhead 3 and the bit 2 which has a passage 6 for flushing fluid to pass through.
The casing 5 houses an inner sleeve 7 and a hammer in the form o~ a piston 8. The backhead end of the piston 8 extends as a stem 9 from the remainder of the piston and engages in the backhead 3 to form a sliding seal therewith.
The bore 10 through the backhead 3 is co-axial with a pressure fluid passage 11 in the drill rod 4.
The drawing al50 shows passages formed in the hammer assembly for flushing fluid which can conveniently be .~_ . ^ .
compressed air. The passages extend as shown at 12 through the backhead 3, and as shown at 13 between the casing 5 and inner sleeve 7 extending between the backhead 3 and bit 2. Apertures 14 are provided through the bit end of the inner slePve 7 and the outer end of ~ /passage 12 : ~ .
' '. . :' ~ :
' ~, !
~ " ' ` , ' ' ' , ' ' . ~ ~
~ 7 ~ 7 ~
passage 12 communicates with a passage 15 in the drill rod 4 for the supply of compressed air.
The compressed air can be supplied at constant pressure throu~h the passages and apertures above described to act on the bit striking surface 16 of the piston 8 to constantly tend to raise the piston 8 from and to the ~it 2.
When the piston 8 is raised from the bit 2 khe compressed air can also act as a flushing fluid through the passage 6.
A chamber 17 is formed in the inner sleeve 7 around the stem 9 of the piston 8. The chamber 17 communicates through a passage 18 in the backhead 3 to ambient atmosphere.-A pressure fluid 19 acts through the bore of the drillrod 4 and backhead 3 as described below to enable the hammer assembly to operate.
The passage 18 to atmosphere is provided to prevent a build up of pressure in the chamber 17 which could /occur if .
, ' ' ' ~4~7~
occur i~ there is leakage either from the compressed air path through the assembly or of the pressure fluid passed the stem 9 of piston 8.
Figure 2 illustrates the inclusion of a second piston s.eparating the pressure ~lu:id 19 column into two sections thus enabling two different types of ~luid to be used.
Figure 3 illustrates a further modification wherein a gas accumulator is formed by a stem 21 on the striking end of piston 8 in sliding engagement with a sealing bush 22 providing an oil filled chamber 23 which is in communication with the passages 13 between inner sleeve 7 and casing 5. These passages are sealed at the backhead end.
With gas under pressure introduced into passage 13 movement of the piston will enable the gas to expand or compress and always provide a pressure on the piston 8 tending to lift the piston 8 from the bit 2.
Flushing medlum in this construction can be provided by the pressure fluid l9 passing through an axial bore 24 /through the . .
: ` ` ~
. . .
. :
: ' ' - 9 - 2~ ~ 37 throuqh the piston 8 ~nd prefer~bly a restriction 25 in the form of a suitable plug is provided in the bore 24 to limit the flow o~ pressure fluid 19 to the bit.
To enable the pressure fluid 19 to act intermittently on the piston 8 with a greater force than that provided by the compressed gas in passage 13 a pressura pump ~not shown) and valve assembly are provided at the drill head.
Suitable valves are illustrated in Figures 4 and 5 of the drawings.
Referring firstly to Figure 4 the valve assembly 26 consists of a valve body 27 which has a passage 28 closed at one end 29 which is connected to a motor 30 for rotation. The open end of the valve is in alignment with the fluid passage 11 in the drill rod 4.
The body 27 rotates in a valve housing 31 which has a high pressure inlet port 32 from the pressure pump and ~ an outlet port 33 connected to the reservoir for fluid for the pump.
~ /The body - ~ ~
' ' .
:
", .
~ '; ' -- 2~8~
The body 27 hai3 a radial port 34 through the wall thereof and rotation of body 27 by the motor 30 in the housing 31 will bring port 34 alternately into alignment with ports 3~ and 33. This has the result, in operation, of pressure of.the pressure fluid down the drill rods intermittently varying from maximum pump pressure to exhaust pressure. Each time maximum pressure is exerted down the column of pressure fluid 19 the constant gas pressure acting in the oppositP
direction on piston 8 is overcome and piston 8 is caused to strike the inner end of the bit 2. When the pump pressure on the pressure fluid is released the gas pressure will cause a return stroke of the piston.
' Figure 4 also illustrates a stepped piston 35 in the pressure fluid column to separate the fluid used through the pump from that in the drill rods 4. This will enable the former to be a suitable oil while the latter is watPr. If the bore through tbe backhead 3 and end of the piston 8 are chromium plated or otherwise rendered rust resistant water can be used directly in the hammer assembly 1. This will avoid the necessity for the second piston 20 illustrated in Figure 2. ~-.
.
/In Figure . ~
- : .
8 ~ 7 ~
In Fiyura 5 a suitable slidillg valve assembly 36 is shown. The assembly con~ists of a sliding stepped valve member 37 movable in a valve casing 38 which is in communication with the column of pressure ~luid 19.
Inlet and exhaust ports 39 andl 40 are provided for connection to the delivery of the pressure pump and the reservoir for pump fluid respectively.
Reciprocation of valve member 37 will enable pump delivery pressure to be alternately applied to and relieved from the pressure fluid 19. This in turn will cause operation of the hammer assembly as described above.
With this type of valve a relief valve should also be used when the inlet port is closed. To overcome unnecessary energy loss an accummulator can be included in the system. It will be appreciated however that alternative porting arrangements can be used to avoid ._ the necessity for the relief valve.
~ I~ will be understood that the methods of applying thP
intermittent pressure supplied through the pressure fluid 19 to the piston 8 need not be effected - /hydraulically as ` ~ - 12 - 2~37~
hydraulically as set forth in the above example. I may be applied by mechanic~lly reciprocating a piston to cause pressure and release of pressure in the fluid 19.
This arrangement could readily be set up by those skilled in the art and would also preferably include the relief valve and accumulator re~erred to above.
Also the examples given above describe the use of a compressible fluid to provide a constant pressure on the piston to raise it from the bit. Mechanically resilient means such as compression springs or blocks of suitable resilient material recessed to extend and contract into the piston or drill bit may also be used.
Fiyure 6 shows a form of drill rod 4 which can conveniently be used with this invention.
'.
The drill rod 4 has an inner pipe 41 which is used as tha drive rod and provides the passage for the pressure fluid 19. An outer pipe 42 is welded at 44 to the inner pipe 41 and this welding can conveniently take place at the position on the drill rod where flat~ 43 are formed to enable the rods to be manipulated with spanners.
' /This will ' :`
~ . , .
: : :
- 13 ~ 7~
This will readily be understood by those who make such drill rods.
It is to be understood that the invention above described can be widely varied from the specific examples described and illustrated without departing from the scope of the invention. The drill rod assembly and pressure fluid valving can be varied as can the shape and configuration of the hammer assembly components. What is essential is that there be different pressures applied to each side of the hammer piston.
/CLAIM~:
.
: . ~ ~ . .
: ,
Claims (13)
1. An hydraulic hammer assembly comprising a piston and cylinder assembly with means for applying intermittent hydraulic pressure to one side of the piston and compressible means for constantly applying pressure to the opposite side of the piston.
2. An hydraulic hammer as claimed in claim 1 in which the compressible means is a resilient mechanical means.
3. An hydraulic hammer as claimed in claim 1 in which the compressible means is provided through a compressible fluid.
4. An hydraulic hammer as claimed in any one of the preceding claims in which the intermittent hydraulic pressure is provided through a column of liquid to which hydraulic pressure is applied through an intermittently operated valve controlling a supply of fluid under substantially constant pressure.
/5. An hydraulic
/5. An hydraulic
5. An hydraulic hammer as claimed in any one of claims 1 to 3 in which the intermittent hydraulic pressure is applied through a column of liquid to which pressure is applied by a mechanically reciprocated piston acting on the column of liquid.
6. An hydraulic hammer as claimed in claim 4 in which the valve is a rotary valve.
7. An hydraulic hammer as claimed in claim 4 in which the valve is a sliding valve.
8. A down-the-hole drill including an hydraulic hammer as claimed in any one of the preceding claims.
9. A down-the-hole drill as claimed in claim 8 in which the pressures applied to the piston are provided by fluid transported through separate passages in the drill rods.
10. A down-the-hole drill as claimed in claim 9 in which the passage for the liquid applying the intermittent pressure to the piston includes a passage for flushing the drill bit.
/11. A down-the-hole
/11. A down-the-hole
11. A down-the-hole drill as claimed in any one of claims 9 or 10 in which the passage for the liquid to apply intermittent pressure to the piston includes a separating piston enabling different fluids to be used in the hammer and in the drill rods.
12. A down-the-hole drill as claimed in claim 9 in which the passage for applying a constant pressure to the piston includes a passage for flushing the drill bit.
13. A down-the-hole drill substantially as described with reference to the Figs 1 and 2 and 4 and 6 or Figs 1 and 3 and 5 and 6 of the accompanying drawings.
DATED THIS DAY OF 1991.
DATED THIS DAY OF 1991.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA90/6166 | 1990-08-06 | ||
| ZA906166 | 1990-08-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2048374A1 true CA2048374A1 (en) | 1992-02-07 |
Family
ID=25580234
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002048374A Abandoned CA2048374A1 (en) | 1990-08-06 | 1991-08-02 | Hydraulic hammer |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU8163291A (en) |
| CA (1) | CA2048374A1 (en) |
| DE (1) | DE4125880A1 (en) |
| GB (1) | GB2246803A (en) |
| SE (1) | SE9102290L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2913365C (en) | 2007-11-20 | 2017-01-24 | National Oilwell Varco, L.P. | Circulation sub with indexing mechanism |
| GB201101033D0 (en) | 2011-01-21 | 2011-03-09 | Nov Downhole Eurasia Ltd | Downhole tool |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3995700A (en) * | 1975-10-14 | 1976-12-07 | Gardner-Denver Company | Hydraulic rock drill system |
| FI56430C (en) * | 1975-10-20 | 1982-08-09 | Tampella Oy Ab | SLAGANORDNING DRIVEN AV EN TRYCKVAETSKA |
| GB1556754A (en) * | 1976-12-10 | 1979-11-28 | Af Hydraulics | Hydraulically-actuated percussive device with overstroke damping |
| ES464093A1 (en) * | 1977-11-12 | 1978-12-16 | Luis Miguel Castejon Castan | Fluid arrangement |
| SE8205029L (en) * | 1981-11-05 | 1983-05-06 | Ingersoll Rand Co | HYDRAULIC DRIVE FORM AND RETURN MACHINE |
-
1991
- 1991-08-02 CA CA002048374A patent/CA2048374A1/en not_active Abandoned
- 1991-08-05 GB GB9116841A patent/GB2246803A/en not_active Withdrawn
- 1991-08-05 AU AU81632/91A patent/AU8163291A/en not_active Abandoned
- 1991-08-05 DE DE4125880A patent/DE4125880A1/en not_active Withdrawn
- 1991-08-05 SE SE9102290A patent/SE9102290L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| GB2246803A (en) | 1992-02-12 |
| GB9116841D0 (en) | 1991-09-18 |
| SE9102290L (en) | 1992-02-07 |
| SE9102290D0 (en) | 1991-08-05 |
| AU8163291A (en) | 1992-02-13 |
| DE4125880A1 (en) | 1992-02-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |