CA1325562C - Reciprocating percussive device - Google Patents
Reciprocating percussive deviceInfo
- Publication number
- CA1325562C CA1325562C CA000606783A CA606783A CA1325562C CA 1325562 C CA1325562 C CA 1325562C CA 000606783 A CA000606783 A CA 000606783A CA 606783 A CA606783 A CA 606783A CA 1325562 C CA1325562 C CA 1325562C
- Authority
- CA
- Canada
- Prior art keywords
- tool
- holder
- piston
- spool
- spool valve
- 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.)
- Expired - Fee Related
Links
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
- B25D9/06—Means for driving the impulse member
- B25D9/12—Means for driving the impulse member comprising a built-in liquid motor, i.e. the tool being driven by hydraulic pressure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D17/00—Details of, or accessories for, portable power-driven percussive tools
- B25D17/08—Means for retaining and guiding the tool bit, e.g. chucks allowing axial oscillation of the tool bit
- B25D17/084—Rotating chucks or sockets
-
- 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
Abstract
ABSTRACT Fig. 1 RECIPROCATING PERCUSSIVE DEVICE
A hydraulic/pneumatic percussive device comprising a double-acting piston (60) which executes reciprocal motion and a tool or tool holder (90) which executes limited reciprocal motion due to the piston (60) striking it. The position of the tool or tool holder (90) relative to the piston stroke is maintained substantially constant by use of a spool valve which acts, through a drive gear (90B) and insert (90D) to apply greater or lesser fluid pressure to the tool or tool holder (90) in response to the axial thrust acting thereupon. The spool valve may e made adjustable to allow the maintained position of the tool or tool holder to be adjusted to cope with variations in axial thrust levels.
A hydraulic/pneumatic percussive device comprising a double-acting piston (60) which executes reciprocal motion and a tool or tool holder (90) which executes limited reciprocal motion due to the piston (60) striking it. The position of the tool or tool holder (90) relative to the piston stroke is maintained substantially constant by use of a spool valve which acts, through a drive gear (90B) and insert (90D) to apply greater or lesser fluid pressure to the tool or tool holder (90) in response to the axial thrust acting thereupon. The spool valve may e made adjustable to allow the maintained position of the tool or tool holder to be adjusted to cope with variations in axial thrust levels.
Description
1 3 2 ~ 2 ~ 1 ~ ~EG~PRDCATING PERCUSSIVE DEVICE
., The present mvention relates to hydraulically or pneumatically actuated reciprocating devices, and in particular to percussive devices such as rock drills.
United Kingdom patents GB 1526048 and GB Z157220 describe such devices having preferred embodiment6 in the form of rock drills and other percussive tools such as impactors (e.g. pav mg-breakers).
Such devioes oomprise a cylinder containing a double-actiny piston having recessed portions which co-operate with a cont~ol port formed in the cylinder wall. miS port leads to a controlling val~e arrangement which controls the reciprocation of the piston. This reciprocating motion is then imparted to a drill rod or shank adaptor axially aligned ~ith the piston. The above two patents, GB
1526048 and ~B 2157220, relate specifically to such devices in which the fre~uency of reciprocation may be varied.
In the case of rock drills and similar rotary percussive tools, ~e drill rod or shank adaptor is caused to rotate by gearing linked to a driving motor. The gearing is arranged to allow some degree of axial mov~ment of the drill rod, the generation of rotary moti~n is thus independent of the percussive mechanism. ~-In use, there is an optimum position of the drill rod relative to the stroke of the hammer piston, such that the piston strikes the drill xod just prior to the end of the piston power stroke.
Achieving this optimum positioning will result in maximlm transfer of energy to the drill bit with increased penetration rates and minimised reflected or wasted energy which can cause excessive wear of the drill bit and damage to the rock drill oomponent6.
Because of the wear of the strike faces which can occur in use together with the build up of tolerances w~lich affect the strike position, wide variations in strike position from one mach:ine to another oan result. We have appreciated that a mechanism i6 reguired to maintain the optimum 6trike position and oo~pensate for it6 possible variation depending on piston power, rock oonditions and thrust levels.
In acoordance with the present invention there is provided a -". :: . .,. :. . : : . : . :
132~
hydraulic or pneumatic percussive devi oe oompri~ing a dbuble-acting piston which executes~reciprocal motion and a t~ol ~r tool holder executing limuted reciprocal mction due t~ the pisto~ striking the said tool or holder near the end of the pi6ton pawer 6tr~ke wherein a spool valve i6 provided which in resp~nse to the axial thrust acting on the tool or holder applies a greater or lesser fluid pressure t~ the tool or holder to maintain a substantially oDnstant position thereof relative to the piston stroke.
Thus, when drilling, thrust levels will vary depen~ing on rock conditions and piston power which will vary the forces on the tool.
During mLment6 of increased force the tool will tend to nnve backwards (into the drill). By increasing the fluid pressure on the tool or taol holder, the position of the tcol or tool holder relative to the device (and hence the piston stroke) i~ maintained substantially oonstant. With a corresponding drop in pressure which occurs when drilling forces are reduced, the device maintains the optimIm strike position.
In a further preferred embodiment, the ~ystem is adjustable, to o~pe with drilling different types of rock, varying piston power, and varying thrust levels.
The invention will now be further described by way of example and with reference to the acooTpaning drawings in which:
Fig. 1 shows a sectioned part-assembly of a percussive rock drill, Fig. 2 is an enlarged view of the spool valve ass~i~bly of I ~'ig.1, ', Fig. 3 shows a variable sleeve position control used in conjunction with the 6pool ~alve of Fig. 2, Fig. 4 shows diagrammatic representations of the hydraulic circuits for the 6pool vaive of Fig.2, with (Fig. 4A) or without (Fig. 4B) the control valve of Fig.3.
; The 6truckure and operation of the drill i6 similar ~a that ofour earlier application (GB 2157220) and, where appropriate, the Bame reference numeral6 have been u6ed.
Referring initially to Fig. 1, the drill oomprise6 a hammer pi~ton 60 at it6 left h~nd end for imparting blows to a drill rod (n~t shown) retained by a Bhank adaptor 90 at it~ right h~nd end.
' ., ~:
: ~32~2 The shank adaptor 90 and drill rod are caused to rot~te hy neans of the engagement of 6pl~ned portion 86 with an internally splin~d 61eeve 88B ~*~ch m turn engages via dsgs 92B a gear 90B which incorporates an insert 90D. The gear is rDtated by a pinion 93B
which iB oQnnected to a motor output shaft 94B via splines 200. Ihe pinion is supported in bearings 201 and the motor output shaft 94B
is limited in axial movement by stop 203. The gear 90B is supported in bearings 204 and 205 which are housed in housings 206 and 207. The rotation is ind~pendent of the percussive me~hanism.
During drilling the drill steel with its bit is thrust in to the rock and the action of percussion and rotation causes it to drill a hole. The reaction from the thrust and drilling forces i~
resi6ted by the gear 90B due to its contact, by way of the insert 90D, with the shank adaptor 90. The reaction is then normally absorbed in a thrust bearing situated between the gear 90B and housing 206 (as in GB 2157220A).
qb optimise the strike position and hence the effectiveness of the percussive action the g~r 90B is in the form of a piston 90C at the left hand side which ves in a cavity 208 counterbored into housing 206. me allowable axial movement of the gear 90B is limited in its forward direction (right hand) by a thrust bearing 209 and in its rearward direction (left hand) by the rear wall of the cavity 208.
lo sense and control the axial movement of the gear 90B (and hence the shank adaptor 90) a spool 210 housed in a sleeve 211 is provided in the rear wall of the cavity 208 (see Fig.2).
Pressurised fluid either from a high pressure cavity within the machine or from an external source enters passage 212 at the rear (left hand) end of the spool 210. A central hole 210A through the spool 210 emerges at the right hand end via a smaller choke hole 210B in a hydrostatically balanced pad 210C. The balance is such that contact is maintained between the pad 210C and the pi~ton 90C
irrespective of the po6ition of the gear 90B. Connected to the central hole 210A are holes 213 which connect to a fir6t reoess 214 on the out6ide of spool 210. A ~econd re oess 215 on the outside of the 6pool 210 i~ 6eparated from the firet by a land 216.
Holes 218 in eleeve 211 connect to recess 218A. ThiB in turn . .
.
", - 4 - 132~62 connects to a passage way which links up with the tanX/return llne of the rock drill (not shown~. HDle6 219 in Rleeve 211 connect to recess 219A and to axial holes 219B which emerge into cavity 208.
In operation pressuri6ed fluid antering passage 212 forces the 6pool 210 with its hydrostatic pad 210C into contact with piston 90C. In the position 6hown the gear 90~ ~nd hence the shank 9~ are in the optim~m 6trike position. The position is maintamied by 5 virtue of the positional relationship between land 216 and hole 219 1 -metering sufficient fluid into or out of cavity 208 to maintain the required pressure acting on area al, to resist the forward thrust of the machine.
The condition of over thrusting or encountexing greater resistance to penetration will cause ~he shank 90 and gear 90B t~
move into the drill (to the left of Fig. 2) taking spool 210 with it. Now land 216 opens hole 219 and hence connects recess 214 andi hole 213 (which are pressurised) to cavity 208 via recess 219A and axial holes 219B. This raises the pressure in cavity 208 to oounter the additional forces, and causes the gear 90B and shank 90 to m~ve ~orward towards the designed strike position.
Conversely during under-thrusting conditions or sudden increased penetration into a fissure or 60fter rock the gear 90B and shank 90 will move forward ~to the right of Fig. 2). Pressure on the end of the spool at 212 will cause the spool to follow the gear hence connecting hole 219 to the tank/return line via recess 215, hole 218 and recess 218A. Pressure in cavity 208 is now r~duced and the gear 90B and shank 90 return to their correct strike position by virtue of the normal feed force from the thrusting mechanism.
The combination of the available pressure and area al of the piston section 90C of gear 90B ensures more than ample reaction force to counter any thrust levels likely to be encountered during drilling. The nett effect is optimum performance with reduced wear and hence increased relia'oility.
The sleeve 211 can be made movable (left or right) thereby altering the metering position of the spool 21~ and hence the ~trike position. Moving the sleeve forward (right) will cause the effective ~trike position of shank 90 to move forward. MbvLng the ~leeve to the left will cause the strike po~ition to move to the :
:
..
:i~: .. . , : . .. ~ .. . :.. ., .,.. :, . ~.:: .,: : . - .. . .. ., .. ,. - .. . . . . .
1325~2 .
left. The ~trike position can ~e retarded or advancsd to 6uit the dynamics of the hammer pi~ton an~ ~he type of rock being drilled.
The ~leeve 211 ~an be moved hydrauli~ally, pneumatically, mechanically or by any oo~b mationO
Gne suitable method of axially m~ving the sleeve 211 is 6hL~n in Fig. 3. Pressure in cavity 220 acts on an area a2 of the sleeve 211 and is resisted by the foroe from spring 221. Increasiny the pressure mDves the sleeve 211 to the right until a balanoed sib~ation is maintained and a new strike position achiev0d.
Fig. ~A illustra~es the hydraulic (or pneumatic) ~ystem of such a drill having a nDvable sleeve: Fig. 4B illustrates the oorresponding system for a fixed sleeve.
Although the invention has been described with particular reference tD percussive rock drills, it will be understood that possible applioationa a~re not so limited.
., !
,sl , ~ .. . ................. . .
., The present mvention relates to hydraulically or pneumatically actuated reciprocating devices, and in particular to percussive devices such as rock drills.
United Kingdom patents GB 1526048 and GB Z157220 describe such devices having preferred embodiment6 in the form of rock drills and other percussive tools such as impactors (e.g. pav mg-breakers).
Such devioes oomprise a cylinder containing a double-actiny piston having recessed portions which co-operate with a cont~ol port formed in the cylinder wall. miS port leads to a controlling val~e arrangement which controls the reciprocation of the piston. This reciprocating motion is then imparted to a drill rod or shank adaptor axially aligned ~ith the piston. The above two patents, GB
1526048 and ~B 2157220, relate specifically to such devices in which the fre~uency of reciprocation may be varied.
In the case of rock drills and similar rotary percussive tools, ~e drill rod or shank adaptor is caused to rotate by gearing linked to a driving motor. The gearing is arranged to allow some degree of axial mov~ment of the drill rod, the generation of rotary moti~n is thus independent of the percussive mechanism. ~-In use, there is an optimum position of the drill rod relative to the stroke of the hammer piston, such that the piston strikes the drill xod just prior to the end of the piston power stroke.
Achieving this optimum positioning will result in maximlm transfer of energy to the drill bit with increased penetration rates and minimised reflected or wasted energy which can cause excessive wear of the drill bit and damage to the rock drill oomponent6.
Because of the wear of the strike faces which can occur in use together with the build up of tolerances w~lich affect the strike position, wide variations in strike position from one mach:ine to another oan result. We have appreciated that a mechanism i6 reguired to maintain the optimum 6trike position and oo~pensate for it6 possible variation depending on piston power, rock oonditions and thrust levels.
In acoordance with the present invention there is provided a -". :: . .,. :. . : : . : . :
132~
hydraulic or pneumatic percussive devi oe oompri~ing a dbuble-acting piston which executes~reciprocal motion and a t~ol ~r tool holder executing limuted reciprocal mction due t~ the pisto~ striking the said tool or holder near the end of the pi6ton pawer 6tr~ke wherein a spool valve i6 provided which in resp~nse to the axial thrust acting on the tool or holder applies a greater or lesser fluid pressure t~ the tool or holder to maintain a substantially oDnstant position thereof relative to the piston stroke.
Thus, when drilling, thrust levels will vary depen~ing on rock conditions and piston power which will vary the forces on the tool.
During mLment6 of increased force the tool will tend to nnve backwards (into the drill). By increasing the fluid pressure on the tool or taol holder, the position of the tcol or tool holder relative to the device (and hence the piston stroke) i~ maintained substantially oonstant. With a corresponding drop in pressure which occurs when drilling forces are reduced, the device maintains the optimIm strike position.
In a further preferred embodiment, the ~ystem is adjustable, to o~pe with drilling different types of rock, varying piston power, and varying thrust levels.
The invention will now be further described by way of example and with reference to the acooTpaning drawings in which:
Fig. 1 shows a sectioned part-assembly of a percussive rock drill, Fig. 2 is an enlarged view of the spool valve ass~i~bly of I ~'ig.1, ', Fig. 3 shows a variable sleeve position control used in conjunction with the 6pool ~alve of Fig. 2, Fig. 4 shows diagrammatic representations of the hydraulic circuits for the 6pool vaive of Fig.2, with (Fig. 4A) or without (Fig. 4B) the control valve of Fig.3.
; The 6truckure and operation of the drill i6 similar ~a that ofour earlier application (GB 2157220) and, where appropriate, the Bame reference numeral6 have been u6ed.
Referring initially to Fig. 1, the drill oomprise6 a hammer pi~ton 60 at it6 left h~nd end for imparting blows to a drill rod (n~t shown) retained by a Bhank adaptor 90 at it~ right h~nd end.
' ., ~:
: ~32~2 The shank adaptor 90 and drill rod are caused to rot~te hy neans of the engagement of 6pl~ned portion 86 with an internally splin~d 61eeve 88B ~*~ch m turn engages via dsgs 92B a gear 90B which incorporates an insert 90D. The gear is rDtated by a pinion 93B
which iB oQnnected to a motor output shaft 94B via splines 200. Ihe pinion is supported in bearings 201 and the motor output shaft 94B
is limited in axial movement by stop 203. The gear 90B is supported in bearings 204 and 205 which are housed in housings 206 and 207. The rotation is ind~pendent of the percussive me~hanism.
During drilling the drill steel with its bit is thrust in to the rock and the action of percussion and rotation causes it to drill a hole. The reaction from the thrust and drilling forces i~
resi6ted by the gear 90B due to its contact, by way of the insert 90D, with the shank adaptor 90. The reaction is then normally absorbed in a thrust bearing situated between the gear 90B and housing 206 (as in GB 2157220A).
qb optimise the strike position and hence the effectiveness of the percussive action the g~r 90B is in the form of a piston 90C at the left hand side which ves in a cavity 208 counterbored into housing 206. me allowable axial movement of the gear 90B is limited in its forward direction (right hand) by a thrust bearing 209 and in its rearward direction (left hand) by the rear wall of the cavity 208.
lo sense and control the axial movement of the gear 90B (and hence the shank adaptor 90) a spool 210 housed in a sleeve 211 is provided in the rear wall of the cavity 208 (see Fig.2).
Pressurised fluid either from a high pressure cavity within the machine or from an external source enters passage 212 at the rear (left hand) end of the spool 210. A central hole 210A through the spool 210 emerges at the right hand end via a smaller choke hole 210B in a hydrostatically balanced pad 210C. The balance is such that contact is maintained between the pad 210C and the pi~ton 90C
irrespective of the po6ition of the gear 90B. Connected to the central hole 210A are holes 213 which connect to a fir6t reoess 214 on the out6ide of spool 210. A ~econd re oess 215 on the outside of the 6pool 210 i~ 6eparated from the firet by a land 216.
Holes 218 in eleeve 211 connect to recess 218A. ThiB in turn . .
.
", - 4 - 132~62 connects to a passage way which links up with the tanX/return llne of the rock drill (not shown~. HDle6 219 in Rleeve 211 connect to recess 219A and to axial holes 219B which emerge into cavity 208.
In operation pressuri6ed fluid antering passage 212 forces the 6pool 210 with its hydrostatic pad 210C into contact with piston 90C. In the position 6hown the gear 90~ ~nd hence the shank 9~ are in the optim~m 6trike position. The position is maintamied by 5 virtue of the positional relationship between land 216 and hole 219 1 -metering sufficient fluid into or out of cavity 208 to maintain the required pressure acting on area al, to resist the forward thrust of the machine.
The condition of over thrusting or encountexing greater resistance to penetration will cause ~he shank 90 and gear 90B t~
move into the drill (to the left of Fig. 2) taking spool 210 with it. Now land 216 opens hole 219 and hence connects recess 214 andi hole 213 (which are pressurised) to cavity 208 via recess 219A and axial holes 219B. This raises the pressure in cavity 208 to oounter the additional forces, and causes the gear 90B and shank 90 to m~ve ~orward towards the designed strike position.
Conversely during under-thrusting conditions or sudden increased penetration into a fissure or 60fter rock the gear 90B and shank 90 will move forward ~to the right of Fig. 2). Pressure on the end of the spool at 212 will cause the spool to follow the gear hence connecting hole 219 to the tank/return line via recess 215, hole 218 and recess 218A. Pressure in cavity 208 is now r~duced and the gear 90B and shank 90 return to their correct strike position by virtue of the normal feed force from the thrusting mechanism.
The combination of the available pressure and area al of the piston section 90C of gear 90B ensures more than ample reaction force to counter any thrust levels likely to be encountered during drilling. The nett effect is optimum performance with reduced wear and hence increased relia'oility.
The sleeve 211 can be made movable (left or right) thereby altering the metering position of the spool 21~ and hence the ~trike position. Moving the sleeve forward (right) will cause the effective ~trike position of shank 90 to move forward. MbvLng the ~leeve to the left will cause the strike po~ition to move to the :
:
..
:i~: .. . , : . .. ~ .. . :.. ., .,.. :, . ~.:: .,: : . - .. . .. ., .. ,. - .. . . . . .
1325~2 .
left. The ~trike position can ~e retarded or advancsd to 6uit the dynamics of the hammer pi~ton an~ ~he type of rock being drilled.
The ~leeve 211 ~an be moved hydrauli~ally, pneumatically, mechanically or by any oo~b mationO
Gne suitable method of axially m~ving the sleeve 211 is 6hL~n in Fig. 3. Pressure in cavity 220 acts on an area a2 of the sleeve 211 and is resisted by the foroe from spring 221. Increasiny the pressure mDves the sleeve 211 to the right until a balanoed sib~ation is maintained and a new strike position achiev0d.
Fig. ~A illustra~es the hydraulic (or pneumatic) ~ystem of such a drill having a nDvable sleeve: Fig. 4B illustrates the oorresponding system for a fixed sleeve.
Although the invention has been described with particular reference tD percussive rock drills, it will be understood that possible applioationa a~re not so limited.
., !
,sl , ~ .. . ................. . .
Claims (4)
1. A hydraulic or pneumatic percussive device comprising a double-acting piston which executes reciprocal motion and a tool or tool holder executing limited reciprocal motion due to the piston striking the said tool or holder near the end of the piston power stroke wherein a spool valve is provided which in response to the axial thrust acting on the tool or holder applies a greater or lesser fluid pressure to the tool or holder to maintain a substantially constant position thereof relative to the piston stroke.
2. A device according to claim 1, in which the spool valve comprises a spool movably housed in a sleeve and in which the spool surface has recessed portions cooperating with a pressurised fluid port in the inner surface of the sleeve and so shaped that movement of the spool in response to the axial thrust acting on the tool or holder directs the pressurised fluid to increase or decrease the fluid pressure applied to the tool or holder.
3. A device according to claim 1 or 2, in which the tool or holder is rotated about its axis by a drive gear connected to a motor and in which fluid pressure applied by the spool valve is directed against the drive gear which in turn transmits the resultant force to the tool or holder.
4. A device according to claim 1, in which the position of the spool valve may be adjusted, thereby adjusting the maintained position of the tool or holder relative to the piston stroke.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888817907A GB8817907D0 (en) | 1988-07-27 | 1988-07-27 | Reciprocating percussive device |
| GB8817907.2 | 1988-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1325562C true CA1325562C (en) | 1993-12-28 |
Family
ID=10641208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000606783A Expired - Fee Related CA1325562C (en) | 1988-07-27 | 1989-07-27 | Reciprocating percussive device |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1325562C (en) |
| GB (2) | GB8817907D0 (en) |
| ZA (1) | ZA895716B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI98401C (en) | 1995-10-10 | 1997-06-10 | Tamrock Oy | A method for adjusting the drilling of a drilling machine and a rock drilling machine |
| US6293309B1 (en) * | 1996-08-29 | 2001-09-25 | Twinwood Engineering Ltd | Control valve apparatus |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB261824A (en) * | 1925-08-15 | 1926-11-15 | George Henry Turton Rayner | Improvements in or relating to percussive tools |
| SE319134B (en) * | 1968-05-08 | 1969-12-22 | Atlas Copco Ab | |
| US3721095A (en) * | 1971-08-23 | 1973-03-20 | Bolt Associates Inc | Controllable force method and system of driving piles |
| US3995700A (en) * | 1975-10-14 | 1976-12-07 | Gardner-Denver Company | Hydraulic rock drill system |
-
1988
- 1988-07-27 GB GB888817907A patent/GB8817907D0/en active Pending
-
1989
- 1989-07-27 CA CA000606783A patent/CA1325562C/en not_active Expired - Fee Related
- 1989-07-27 GB GB8917175A patent/GB2221418B/en not_active Expired - Lifetime
- 1989-07-27 ZA ZA895716A patent/ZA895716B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| GB8917175D0 (en) | 1989-09-13 |
| ZA895716B (en) | 1990-04-25 |
| GB2221418A (en) | 1990-02-07 |
| GB8817907D0 (en) | 1988-09-01 |
| GB2221418B (en) | 1992-02-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3507337A (en) | Function switching arrangement for electro-pneumatic hammer drills | |
| US5056606A (en) | Damped hammer drill | |
| SU1272998A3 (en) | Drilling hydraulic percussion device | |
| US4068727A (en) | Method and device for damping the recoil of a work tool connected to a rock drilling machine | |
| US3490549A (en) | Hydraulic percussive drill | |
| US4073350A (en) | Device for damping the recoil of a work tool connected to a percussion tool | |
| US5415240A (en) | Drilling device for a rock drill | |
| EP0578623B1 (en) | Hammer device | |
| EP0080446A2 (en) | Method of controlling an impact motor and an impact motor | |
| FI114903B (en) | The rock drilling machine | |
| JPS6344513B2 (en) | ||
| HU180242B (en) | Motor driven jackhammer | |
| GB1515442A (en) | Hydraulic percussion tool with impact blow and frequency control | |
| US4563938A (en) | Pressure fluid operated percussive tool | |
| CA2329533C (en) | Hammer device | |
| AU2001274768B2 (en) | Method of opening joints between drilling components, and rock drill | |
| ZA200406502B (en) | Hydraulic rotray-percussive hammer drill | |
| US4052107A (en) | Hydraulic hammers hydraulically driven impactor | |
| EP0634559B1 (en) | Fluid driven down-the-hole drilling machine | |
| US5060734A (en) | Seawater hydraulic rock drill | |
| CA1325562C (en) | Reciprocating percussive device | |
| US4718500A (en) | Reversible percussion device for percussion tool | |
| JPH06503621A (en) | air hammer | |
| US3464500A (en) | Percussion tool control means | |
| WO2001083170A1 (en) | Method and arrangement for adjusting the percussion energy in a percussion drilling apparatus |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |