US3664390A - Safety means for power-driven chain saws - Google Patents

Safety means for power-driven chain saws Download PDF

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Publication number
US3664390A
US3664390A US82342A US3664390DA US3664390A US 3664390 A US3664390 A US 3664390A US 82342 A US82342 A US 82342A US 3664390D A US3664390D A US 3664390DA US 3664390 A US3664390 A US 3664390A
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United States
Prior art keywords
lever arm
engine
safety means
saw
handle
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Expired - Lifetime
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US82342A
Inventor
Leif Erling M Mattason
Karl Garry Kenneth Fredriksson
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Husqvarna Forest and Garden AB
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Jonsereds Fabrikers AB
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
    • B27B17/00—Chain saws; Equipment therefor
    • B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
    • B27B17/083—Devices for arresting movement of the saw chain

Definitions

  • a safety means comprising switch and brake means adapted to break the ignition current of the engine and stop the saw chain, and actuating means which is situated in a position in front of the handle of the saw and arranged to be operated by the hand of the operator in case of an accident to bring said switch and brake means into operation to stop the engine and the saw chain.
  • the object of the present invention is to provide safety means to prevent such accidents.
  • the safety means according to the invention comprises a lever arm which is arranged to be swung about a pivot axis and part of which is situated in front of the side of the handle facing the blade and is spaced from the handle, a brake means connected to the lever arm and adapted, when the lever arm is swung about the pivot axis, to be urged against a member driven by the engine, such as a member partaking in the rotation of the drive wheel, to brake said member and thus the saw chain, and actuating means arranged on the lever arm and adapted, when the lever arm is swung towards the blade, to actuate a switch for breaking the ignition current of the engine.
  • the power-driven chain saw illustrated in the drawing is a conventional chain saw which can be modified by simple measures for easy incorporation of the safety means therein.
  • the chain saw comprises a housing 1 for an internal combustion engine (not shown).
  • a drive wheel 4 for a saw chain 5 guided on the blade 6 is coupled to the outgoing shaft 2 of the engine by a clutch 3.
  • a U-shaped handle 7 is mounted on the housing 1 and extends across the top of the housing.
  • a lever arm 8 is mounted on the housing for pivotment about journals 9 so placed on the engine housing that the pivot axis of the lever arm 8 will be situated rearwardly of the handle 7.
  • the lever arm 8 includes a part 17 which is obliquely forwardly directed from the pivot axis 9 and extends forwardly past the handle 7, and a part 18 which is bent at an angle obliquely upwardly away from said part 17 and is substantially parallel to the corresponding lateral limb of the handle 7.
  • the outer end of the obliquely upwardly bent part 18 is thus situated on the front side of the handle 7, Le, forwardly of the side of the handle facing the blade 6.
  • a rod is pivoted to the lever arm 8 and slidably guided in a guide in the engine housing, for example a bore formed in said engine housing and opening into an annular space between the engine housing and the periphery of the clutch housing 3.
  • a brake shoe 11 which is connected to the rod 10 and provided with a brake lining on the side facing the circumferential surface of the clutch housing 3.
  • the lever arm 8 is normally kept in a position of rest with the brake shoe 11 at some distance from the periphery of the clutch housing 3 by a return spring 12 which is a coil spring wound about the rod 10 and interposed between the engine housing 1 and the lever arm 8.
  • the lever arm 8 has a projection 13, for example at the angular bend between its two straight portions, to cooperate with a switch 14 located on the engine housing.
  • the switch 14 is arranged and disposed in such a manner that by actuation of the switch the pro ection 13 breaks the ignitlon current of the engine when the lever arm 8 is swung forwardly and before the brake shoe 11 comes into braking engagement with the periphery of the clutch housing 3.
  • the lever arm 8 carries a rod 15 which extends across the engine housing and is spaced such a distance from the handle 7 that should the saw operator's hand slip or move forward in any other unintentional manner towards the lever arm 8 and the rod 15 or should the saw as a result of a throw turn counterclockwise about the handle 7, the rod 15 actuated by the operators hand will be swung towards the blade, whereby the above described safety means comprising the switch 14 and the brake means 10, 11 is made operative so that the ignition current of the engine is broken and in immediate conjunction therewith the brake is applied for braking the living force of the engine, transmission and chain so that the chain is rapidly stopped.
  • the lever arm 8 may be in the form of a Ushaped member which surrounds the upper part of the engine housing as does the U-shaped handle.
  • the lever arm is composed of two parts which are detachably connected together at 16.
  • the brake rod 10 having the brake shoe 11 is secured to one part 17 of the lever arm as is the actuating means 13 for the switch 14.
  • the other part 18 of the lever arm carries the transverse rod 15.
  • the upper part 18 of the lever arm can be swung at the hinge connection 16 towards the handle 7 so that the saw operator can move his hand freely.
  • safety means comprising a lever arm which is arranged to be swung about a pivot axis and part of which is situated in front of the side of the handle facing the blade and is spaced from said handle, a brake means connected to the lever arm and adapted, when the lever arm is swung about the pivot axis, to be urged against a member driven by the engine, and actuating means arranged on the lever arm and adapted, when the lever arm is swung towards the sword, to actuate a switch for breaking the ignition current of the engine.
  • Safety means as defined in claim 1, wherein the pivot axis of the lever arm is disposed on the engine housing rearwardly of the handle.
  • lever arm is composed of two parts so as to include a first part carrying said brake means and said actuating means for the switch, and a second part which is hinged to the first part and has a rod extending across the engine housing, and said second part can be swung about the hinge connection to a position in which the rod is not in the way of the saw operators hand.
  • Safety means as defined in claims 1 and 2, wherein the brake shoe is connected to a rod which is slidable in a guide connected to the engine housing and pivoted to the lever arm.
  • Safety means as defined in claims 1, 3 and 5, wherein a return spring is interposed between the lever arm and the engine housing to return the lever arm and the brake means to inoperative position.

Abstract

In a chain saw driven by an internal combustion engine a safety means comprising switch and brake means adapted to break the ignition current of the engine and stop the saw chain, and actuating means which is situated in a position in front of the handle of the saw and arranged to be operated by the hand of the operator in case of an accident to bring said switch and brake means into operation to stop the engine and the saw chain.

Description

United States Patent Mattsson et al.
[451 May 23, 1972 [54] SAFETY MEANS FOR POWER-DRIVEN CHAIN SAWS [72] Inventors: Leif Erling M. Mattsson; Karl Garry Kenneth Fredriksson, both of Brastad, Sweden [73] Assignee: Jonsereds Fabrikers Aktiebolag, Jonsered,
Sweden [22] Filed: Oct. 20, 1970 21 Appl. No.: 82,342
[30] Foreign Application Priority Data Oct. 29, 1969 Sweden ..14771 [52] US. Cl. ..l43/32 R, 143/17 C [51] Int. Cl ....B27b 17/02, 827g 19/00 [58] Field ofSearch ..l43/32 R, 32 B, 32 D, 32 L, 143/43 R, 43 A, 17 C, 157 R, 159 R [56] References Cited UNITED STATES PATENTS 1,189,603 7/1916 Michener ..143/17 C UX 1,617,565 2/1927 Bens ..143/32 3,292,673 12/1966 Gregory ..143/43 Primary ExaminerDonald R Schran Attomey-Karl W. Flocks ABSIRACT In a chain saw driven by an internal combustion engine a safety means comprising switch and brake means adapted to break the ignition current of the engine and stop the saw chain, and actuating means which is situated in a position in front of the handle of the saw and arranged to be operated by the hand of the operator in case of an accident to bring said switch and brake means into operation to stop the engine and the saw chain.
6 Claims, 1 Drawing Figure SAFETY MEANS FOR POWER-DRIVEN CHAIN SAWS This invention relates to safety means in power-driven chain saws which comprise an engine housing with a handle and a blade forming a guide for a saw chain driven by the engine via a drive wheel.
in certain circumstances, such as when felling is done at difficulty accessible sites and under bad weather conditions, the handling of such power-driven chain saws is always associated with risks of accidents. Thus, the saw operator may slip for some reason or other, reaching out with his hand so that it touches the rapidly moving saw chain. On sawing with the pushing, i.e., non-pulling, chain run it may happen that the saw is thrown back, particularly at the application thereof, if the engine has not been run up to full speed before application of the saw. Similar phenomena may occur on sawing with the pulling chain run, if the outgoing run is jammed. For instance on trimming trees when the saw is moved from below against a branch in an upward direction it has also happened that when the resistance to sawing suddenly ceases and the applied pull is not simultaneously decreased, that the sword is abruptly thrown upwards so that the chain hits the saw operator in the head.
The object of the present invention is to provide safety means to prevent such accidents. To this end the safety means according to the invention comprises a lever arm which is arranged to be swung about a pivot axis and part of which is situated in front of the side of the handle facing the blade and is spaced from the handle, a brake means connected to the lever arm and adapted, when the lever arm is swung about the pivot axis, to be urged against a member driven by the engine, such as a member partaking in the rotation of the drive wheel, to brake said member and thus the saw chain, and actuating means arranged on the lever arm and adapted, when the lever arm is swung towards the blade, to actuate a switch for breaking the ignition current of the engine.
The invention will be described more in detail hereinbelow with reference to the accompanying drawing which illustrated a side elevation of a power-driven chain saw having safety means according to the invention.
The power-driven chain saw illustrated in the drawing is a conventional chain saw which can be modified by simple measures for easy incorporation of the safety means therein.
The chain saw comprises a housing 1 for an internal combustion engine (not shown). A drive wheel 4 for a saw chain 5 guided on the blade 6 is coupled to the outgoing shaft 2 of the engine by a clutch 3. A U-shaped handle 7 is mounted on the housing 1 and extends across the top of the housing. A lever arm 8 is mounted on the housing for pivotment about journals 9 so placed on the engine housing that the pivot axis of the lever arm 8 will be situated rearwardly of the handle 7. The lever arm 8 includes a part 17 which is obliquely forwardly directed from the pivot axis 9 and extends forwardly past the handle 7, and a part 18 which is bent at an angle obliquely upwardly away from said part 17 and is substantially parallel to the corresponding lateral limb of the handle 7. The outer end of the obliquely upwardly bent part 18 is thus situated on the front side of the handle 7, Le, forwardly of the side of the handle facing the blade 6. A rod is pivoted to the lever arm 8 and slidably guided in a guide in the engine housing, for example a bore formed in said engine housing and opening into an annular space between the engine housing and the periphery of the clutch housing 3. Located in said annular space is a brake shoe 11 which is connected to the rod 10 and provided with a brake lining on the side facing the circumferential surface of the clutch housing 3. The lever arm 8 is normally kept in a position of rest with the brake shoe 11 at some distance from the periphery of the clutch housing 3 by a return spring 12 which is a coil spring wound about the rod 10 and interposed between the engine housing 1 and the lever arm 8.
The lever arm 8 has a projection 13, for example at the angular bend between its two straight portions, to cooperate with a switch 14 located on the engine housing. The switch 14 is arranged and disposed in such a manner that by actuation of the switch the pro ection 13 breaks the ignitlon current of the engine when the lever arm 8 is swung forwardly and before the brake shoe 11 comes into braking engagement with the periphery of the clutch housing 3.
At its outer end the lever arm 8 carries a rod 15 which extends across the engine housing and is spaced such a distance from the handle 7 that should the saw operator's hand slip or move forward in any other unintentional manner towards the lever arm 8 and the rod 15 or should the saw as a result of a throw turn counterclockwise about the handle 7, the rod 15 actuated by the operators hand will be swung towards the blade, whereby the above described safety means comprising the switch 14 and the brake means 10, 11 is made operative so that the ignition current of the engine is broken and in immediate conjunction therewith the brake is applied for braking the living force of the engine, transmission and chain so that the chain is rapidly stopped.
The lever arm 8 may be in the form of a Ushaped member which surrounds the upper part of the engine housing as does the U-shaped handle. Preferably, the lever arm is composed of two parts which are detachably connected together at 16. The brake rod 10 having the brake shoe 11 is secured to one part 17 of the lever arm as is the actuating means 13 for the switch 14. The other part 18 of the lever arm carries the transverse rod 15. In cases where the safety means 10, 11 and 14 is not desirable or where said means would impede a certain type of work, the upper part 18 of the lever arm can be swung at the hinge connection 16 towards the handle 7 so that the saw operator can move his hand freely.
What we claim and desire to secure by Letters Patent is:
1. In a power-driven chain saw having an engine housing with a handle thereon, and a blade forming a guide for a saw chain driven by an internal combustion engine via a drive wheel, safety means comprising a lever arm which is arranged to be swung about a pivot axis and part of which is situated in front of the side of the handle facing the blade and is spaced from said handle, a brake means connected to the lever arm and adapted, when the lever arm is swung about the pivot axis, to be urged against a member driven by the engine, and actuating means arranged on the lever arm and adapted, when the lever arm is swung towards the sword, to actuate a switch for breaking the ignition current of the engine.
2. Safety means as defined in claim 1, wherein the member driven by the engine is a member partaking in the rotation of the drive wheel for the saw chain.
3. Safety means as defined in claim 1, wherein the pivot axis of the lever arm is disposed on the engine housing rearwardly of the handle.
4. Safety means as defined in claim 1, wherein the lever arm is composed of two parts so as to include a first part carrying said brake means and said actuating means for the switch, and a second part which is hinged to the first part and has a rod extending across the engine housing, and said second part can be swung about the hinge connection to a position in which the rod is not in the way of the saw operators hand.
5. Safety means as defined in claims 1 and 2, wherein the brake shoe is connected to a rod which is slidable in a guide connected to the engine housing and pivoted to the lever arm.
6. Safety means as defined in claims 1, 3 and 5, wherein a return spring is interposed between the lever arm and the engine housing to return the lever arm and the brake means to inoperative position.

Claims (6)

1. In a power-driven chain saw having an engine housing with a handle thereon, and a blade forming a guide for a saw chain driven by an internal combustion engine via a drive wheel, safety means comprising a lever arm which is arranged to be swung about a pivot axis and part of which is situated in front of the side of the handle facing the blade and is spaced from said handle, a brake means connected to the lever arm and adapted, when the lever arm is swung about the pivot axis, to be urged against a member driven by the engine, and actuating means arranged on the lever arm and adapted, when the lever arm is swung towards the sword, to actuate a switch for breaking the ignition current of the engine.
2. Safety means as defined in claim 1, wherein the member driven by the engine is a member partaking in the rotation of the drive wheel for the saw chain.
3. Safety means as defined in claim 1, wherein the pivot axis of the lever arm is disposed on the engine housing rearwardly of the Handle.
4. Safety means as defined in claim 1, wherein the lever arm is composed of two parts so as to include a first part carrying said brake means and said actuating means for the switch, and a second part which is hinged to the first part and has a rod extending across the engine housing, and said second part can be swung about the hinge connection to a position in which the rod is not in the way of the saw operator''s hand.
5. Safety means as defined in claims 1 and 2, wherein the brake shoe is connected to a rod which is slidable in a guide connected to the engine housing and pivoted to the lever arm.
6. Safety means as defined in claims 1, 3 and 5, wherein a return spring is interposed between the lever arm and the engine housing to return the lever arm and the brake means to inoperative position.
US82342A 1969-10-29 1970-10-20 Safety means for power-driven chain saws Expired - Lifetime US3664390A (en)

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SE14771/69A SE348964B (en) 1969-10-29 1969-10-29

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US (1) US3664390A (en)
AT (1) AT305599B (en)
CA (1) CA925001A (en)
CH (1) CH518783A (en)
DE (1) DE2051664A1 (en)
ES (1) ES384879A1 (en)
FI (1) FI54070C (en)
FR (1) FR2066575A5 (en)
GB (1) GB1280805A (en)
NO (1) NO133964C (en)
SE (1) SE348964B (en)

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739475A (en) * 1971-10-19 1973-06-19 Mc Culloch Corp Chain saw safety method and apparatus
US3793727A (en) * 1972-10-04 1974-02-26 Mcculloch Corp Chain saw safety method and apparatus
US3839795A (en) * 1973-04-26 1974-10-08 Mc Culloch Corp Chain saw safety method and apparatus
DE2440483A1 (en) * 1973-08-29 1975-03-13 Husqvarna Ab CHAINSAW
JPS5140699A (en) * 1974-10-03 1976-04-05 Kyoritsu Kk Chensoono hanpatsuanzensoochi
US3974566A (en) * 1975-09-08 1976-08-17 Mcculloch Corporation Method and apparatus for arresting movement of a chain saw cutter chain
US4152833A (en) * 1977-06-22 1979-05-08 Crow, Lytle, Gilwee, Donoghue, Adler And Weineger Chain saw braking mechanism
WO1982000437A1 (en) * 1980-08-08 1982-02-18 Overy C Switch-brake interlock for chain saw
US4335514A (en) * 1980-08-08 1982-06-22 Black & Decker Inc. Switch-brake interlock for chain saw
US4385442A (en) * 1980-02-08 1983-05-31 Andreas Stihl Portable power chain saw
US4419857A (en) * 1981-08-07 1983-12-13 Outboard Marine Corporation Lawn mower with combined engine brake and ignition control
US4432139A (en) * 1980-10-28 1984-02-21 Andreas Stihl Safety device on a power saw
WO1984003650A1 (en) * 1983-03-14 1984-09-27 Victor A Grogan A chain saw safety switch
US4573556A (en) * 1983-05-20 1986-03-04 Aktiebolaget Electrolux Actuator for the release of an automatic emergency brake of a hand-operated powered tool
US4651423A (en) * 1986-04-23 1987-03-24 Grogan Victor A Chain saw cutting chain safety stop
AU576035B2 (en) * 1985-01-29 1988-08-11 Kenneth Wallmark Braking device for chain saw
US5101567A (en) * 1991-06-27 1992-04-07 Cool James E Chain saw electric all-stop safety switch
US5150523A (en) * 1991-07-11 1992-09-29 Ryobi Motor Products Corporation Deadman switch arrangement for a hedge trimmer
US5305528A (en) * 1992-04-17 1994-04-26 Textron Inc. Power tool braking system
US5791057A (en) * 1995-09-04 1998-08-11 Makita Corporation Electromotive chain saw
US20100147544A1 (en) * 2008-11-20 2010-06-17 Yamabiko Corporation Work Apparatus With Internal Combustion Engine
US8601919B1 (en) 2000-11-06 2013-12-10 William C. King Method of braking a chain saw
CN104227791A (en) * 2013-06-13 2014-12-24 安德烈·斯蒂尔股份两合公司 Work implement with an internal combustion engine

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3608523A1 (en) * 1986-03-14 1987-09-17 Bosch Gmbh Robert QUICK STOP DEVICE FOR STOPPING A SAW CHAIN OF A PORTABLE MOTOR CHAIN SAW
DE3640162A1 (en) * 1986-11-25 1988-05-26 Franz Rebhan HOUSING FOR A MOTOR CHAINSAW
DE3821874A1 (en) * 1988-06-29 1990-01-18 Black & Decker Inc Chain saw
DE3932137C2 (en) * 1989-09-27 1998-07-02 Stihl Maschf Andreas Device for actuating a brake device for stopping a motor-driven working tool of a working device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1189603A (en) * 1915-04-21 1916-07-04 Charles E Michener Saw.
US1617565A (en) * 1921-04-23 1927-02-15 Chain Saw Corp Tree-sawing apparatus
US3292673A (en) * 1963-08-27 1966-12-20 Rockwell Mfg Co Power operated portable hand saw

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1189603A (en) * 1915-04-21 1916-07-04 Charles E Michener Saw.
US1617565A (en) * 1921-04-23 1927-02-15 Chain Saw Corp Tree-sawing apparatus
US3292673A (en) * 1963-08-27 1966-12-20 Rockwell Mfg Co Power operated portable hand saw

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3739475A (en) * 1971-10-19 1973-06-19 Mc Culloch Corp Chain saw safety method and apparatus
US3793727A (en) * 1972-10-04 1974-02-26 Mcculloch Corp Chain saw safety method and apparatus
US3839795A (en) * 1973-04-26 1974-10-08 Mc Culloch Corp Chain saw safety method and apparatus
DE2440483A1 (en) * 1973-08-29 1975-03-13 Husqvarna Ab CHAINSAW
JPS5140699A (en) * 1974-10-03 1976-04-05 Kyoritsu Kk Chensoono hanpatsuanzensoochi
US3974566A (en) * 1975-09-08 1976-08-17 Mcculloch Corporation Method and apparatus for arresting movement of a chain saw cutter chain
US4152833A (en) * 1977-06-22 1979-05-08 Crow, Lytle, Gilwee, Donoghue, Adler And Weineger Chain saw braking mechanism
US4385442A (en) * 1980-02-08 1983-05-31 Andreas Stihl Portable power chain saw
WO1982000437A1 (en) * 1980-08-08 1982-02-18 Overy C Switch-brake interlock for chain saw
US4335514A (en) * 1980-08-08 1982-06-22 Black & Decker Inc. Switch-brake interlock for chain saw
US4432139A (en) * 1980-10-28 1984-02-21 Andreas Stihl Safety device on a power saw
US4419857A (en) * 1981-08-07 1983-12-13 Outboard Marine Corporation Lawn mower with combined engine brake and ignition control
WO1984003650A1 (en) * 1983-03-14 1984-09-27 Victor A Grogan A chain saw safety switch
US4573556A (en) * 1983-05-20 1986-03-04 Aktiebolaget Electrolux Actuator for the release of an automatic emergency brake of a hand-operated powered tool
AU576035B2 (en) * 1985-01-29 1988-08-11 Kenneth Wallmark Braking device for chain saw
US4651423A (en) * 1986-04-23 1987-03-24 Grogan Victor A Chain saw cutting chain safety stop
US5101567A (en) * 1991-06-27 1992-04-07 Cool James E Chain saw electric all-stop safety switch
US5150523A (en) * 1991-07-11 1992-09-29 Ryobi Motor Products Corporation Deadman switch arrangement for a hedge trimmer
US5305528A (en) * 1992-04-17 1994-04-26 Textron Inc. Power tool braking system
US5791057A (en) * 1995-09-04 1998-08-11 Makita Corporation Electromotive chain saw
USRE37832E1 (en) 1995-09-04 2002-09-10 Makita Corporation Electromotive chain saw
US8601919B1 (en) 2000-11-06 2013-12-10 William C. King Method of braking a chain saw
US20100147544A1 (en) * 2008-11-20 2010-06-17 Yamabiko Corporation Work Apparatus With Internal Combustion Engine
US8469001B2 (en) * 2008-11-20 2013-06-25 Yamabiko Corporation Work apparatus with internal combustion engine
CN104227791A (en) * 2013-06-13 2014-12-24 安德烈·斯蒂尔股份两合公司 Work implement with an internal combustion engine
EP2813702A3 (en) * 2013-06-13 2014-12-24 Andreas Stihl AG & Co. KG Working machine with a combustion engine
US9353721B2 (en) 2013-06-13 2016-05-31 Andreas Stihl Ag & Co. Kg Work implement with an internal combustion engine
RU2655823C2 (en) * 2013-06-13 2018-05-29 Андреас Штиль АГ унд Ко. КГ Working tool with an internal combustion engine

Also Published As

Publication number Publication date
FI54070C (en) 1978-10-10
AT305599B (en) 1973-03-12
FR2066575A5 (en) 1971-08-06
FI54070B (en) 1978-06-30
CA925001A (en) 1973-04-24
CH518783A (en) 1972-02-15
SE348964B (en) 1972-09-18
DE2051664A1 (en) 1971-05-06
NO133964C (en) 1976-08-04
GB1280805A (en) 1972-07-05
ES384879A1 (en) 1973-03-16
NO133964B (en) 1976-04-20

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