Abstract: A braking arrangement for a motor-driven chain saw is disclosed. The braking arrangement is actuable by a releasing device and is held in the release position against a spring force by means of a latching device. The braking arrangement includes a brake band holding member to which a brake band is fastened. The brake band can be tightened around a clutch drum of the motor-driven chain saw by means of an ancillary chain brake device provided in addition to the chain brake device, so that the clutch drum is brought to an immediate stop. This braking action occurs also if the releasing device of the chain brake device is not actuated. In this way, the chain brake device remains activated thereby enabling it to act during operation of the chain saw, for example, in the event that the motor-driven chain saw kicks back while the saw chain is running.

Abstract: A pipe scraping tool for cleaning scale and other deposits from the exterior surfaces of pipes. The tool includes a plurality of inverted "U"-shaped scraper members each of which is carried by one of a series of interconnected hinged links, each link (preferably rectangular in shape) having a straight edge at each end thereof. These straight edges and the type of links used avoid excessive lateral movement of the links. The inverted "U"-shape of the scraper members provides relatively closely spaced cutting edges. The substantial length of the legs of the inverted "U"s helps avoid clogging of the tool by providing substantial exit spaces, for scale and other debris removed from the pipe exterior surfaces, between the cutting edges and the structure supporting those cutting edges, as well as between the cutting edges and the hinges that interconnect the links that carry the scraper members.

Abstract: A handle and skid assembly for attachment to the saw bar of a chain saw. A handle component extends upwardly and rearwardly from the skid assembly and includes a pair of handgrips. The ground engaging skid assembly includes forwardly directed arms with one having an article engaging edge which guides the saw chain diagonally into cutting engagement with the article. An open area defined by the remaining arm receives a portion of the sawed article. The two-piece skid assembly includes protective flanges adjacent the runs of the saw chain.

Abstract: A chain saw bar having an elongated shape, a saw chain guideway around substantially the length of the perimeter thereof, with a matching saw chain sprocket in the nose thereof, and calculated points of variation in strength in the interior of the bar at points removed from the sprocket, the points of variation in strength acting so that if the bar is subjected to an excessive bending force, the bar will tend to become bent initially at one point of variation in strength and with increased bending force at a subsequent point of variation in strength. In this way, extreme bending of the bar at one location and pinching of the sprocket are minimized.

Abstract: An emergency braking system of a chain saw including a hand guard located in front of a front handle bar, and an inertia trigger. The hand guard is pivotally supported by a body of the chain saw and urged by the biasing force of a spring to move downwardly so that its lower end is located in spaced juxtaposed relation to a lever of an actuation device. The inertia trigger is pivotally supported at one end thereof by the hand guard and biased so as to thereby prevent the hand guard from moving downwardly.

Abstract: A sprocket wheel for driving a saw chain of a chain saw including a pair of annular sprocket wheel members of the same shape and configuration each formed on one side surface thereof with elevated surface portions of a number which is one-half the desired number of the teeth of the sprocket wheel produced as an end product by joining the sprocket wheel members together in such a manner that the one side surfaces thereof having the elevated surface portions face each other.

Abstract: An air filter for a motor-driven tool such as a portable motor-driven chain saw includes a prefilter through which aspirated air flows into a chamber partly defined by a cover that can be secured to the housing of the motor-driven tool. From this space, the air flows through a main air filter to the carburetor of the motor. The main air filter and the prefilter are configured as a one-piece double filter unit.

Abstract: A chain saw is provided with an oil pump for supplying oil to the saw chain. The pump includes a piston immersed in a chamber formed in the housing of the saw and rotatable by a gear rigidly connected to the piston and rotated by another gear driven by a motor. The gear connected to the piston has an inclined end face which wobbles upon the rotation of the gear and is pressed by a helical spring against a supporting ball which is positioned in a recess of a flange bolt manually turnable from the outside of the housing. The path of adjustment of the supporting ball is greater than the diameter of the piston. The working pressure generated by the spring is translated directly to the piston.

Abstract: A braking arrangement for a motor-driven chain saw is disclosed. The braking arrangement is actuable by a releasing device and is held in the release position against a spring force by means of a latching device. The braking arrangement includes a brake band holding member to which a brake band is fastened. The brake band can be tightened around a clutch drum of the motor-driven chain saw by means of an ancillary chain brake device provided in addition to the chain brake device, so that the clutch drum is brought to an immediate stop. This braking action occurs also if the releasing device of the chain brake device is not actuated. In this way, the chain brake device remains activated thereby enabling it to act during operation of the chain saw, for example, in the event that the motor-driven chain saw kicks back while the saw chain is running.

Abstract: A motor-driven chain saw is electrically operated by means of a universal motor and has two brake systems operating independently of one another. A mechanical brake system serves as a safety brake and when actuated, the mechanical brake system brings the saw chain to a standstill instantaneously. The second brake system is an electric coasting brake, which when the switch is released stops the saw chain quickly but without recoil. The electrical braking is effected by reversing the polarity of one pole coil of the field winding and short-circuiting it with the rotor winding.

Abstract: An assembly for the attachment of a cutter blade into a chain saw. The saw consists of a frame including controls and drive mechanism as well as a protruding cutter blade (2) encircled by an endless toothed chain that receives its motive power from the shaft of a motor mounted to the frame. The cutter blade (2) and the power transmission unit (16) to be connected to the saw shaft are mounted to an auxiliary frame (18). The auxiliary frame (18) has fasteners (17) and the saw frame is fitted with counterparts (10, 11) for attaching the auxiliary frame (18) into the saw frame (1) using the fastener (17) so that the transmission unit (16) is in power transmitting connection with the saw shaft (4).

Abstract: A chain saw having reduced transmission of vibration includes an internal combustion engine, a crankcase, and a crankshaft; a support assembly, the support assembly including a frame and at least one manual gripping handle; and a vibration isolation system for connecting the engine and the support assembly and inhibiting the transmission of vibration. The vibration isolation system comprises: a front vibration mount having an axis parallel to the crankshaft for connecting the crankcase to the front of the frame and a rear vibration mount having an axis parallel to the crankshaft for connecting the cylinder of the engine to the rear of the frame. The front vibration mount and the rear vibration mount are disposed so that a first imaginary line connecting their axes intersects an imaginary vertical plane containing the crankshaft at a point above the crankshaft.

Abstract: The invention is directed to a motor-driven chain saw wherein a sprocket for a saw chain and a drive wheel for an oil pump are rotatably journalled on the crankshaft. The oil pump pumps oil for lubricating the saw chain and guide bar. The sprocket and the drive wheel are driven via a clutch drum. In this arrangement, a detachable resilient connecting member is provided to connect the drive wheel of the oil pump to the clutch drum at the peripheral wall of the latter. The resilient connecting member protects the drive wheel and the oil pump from excessive wear.

Abstract: An electro-mechanical brake in a motor saw requires electric energy for the operation of the brake. This energy can, according to the invention, be surplus energy in the ignition system of the saw. Surplus energy exists usually only when the r.p.m. exceeds a certain value. A capacitor is charged by current from the system and is prepared to discharge through a coil to actuate the brake on a signal from a kickback sensor.

Abstract: The invention is directed to a motor-driven apparatus such as a motor-driven chain saw or the like. It includes a lubricating-oil pump and an oil supply for a work tool and is equipped with a device for interrupting the supply of oil to the tool. This facilitates use of the chain saw apparatus with an accessory attachment work tool such as a hedge trimmer, drilling tool or the like for which a flow of lubricating oil is unnecessary.

Abstract: The invention is directed to a braking arrangement for a chain saw and includes a brake band and a brake drum which form friction partners with their associated friction surfaces during braking. At least the friction surface of one of the friction partners includes a material which is resistant to conversion to martensitic structure. Particularly suitable materials are those having a cubic face-centered lattice structure, such as, for example, austenitic steel or chrome-nickel steel.

Abstract: Front handle support means of a portable chain saw having a built-in internal combustion engine serving as a source of motive force includes a handle support arm connected to one lateral side of a machine frame and extending upwardly to support at its upper end one end of a handle pipe of a front handle. A projection is formed integrally at an upper end portion of the handle support arm and extends forwardly to support a hand guard. A plurality of shock absorbers are mounted on an inner side of the handle support arm to connect the internal combustion engine therethrough to the machine frame.

Abstract: A safety device for a chain saw conventional in its overall construction is disclosed which comprises mainly a brake lever pivotally supported by the housing of the chain saw and arranged to stop the cutting chain when the brake lever is actuated either by inertia or by engagement with the operator's hand. The brake lever is formed with a cam surface adapted to press an engaging member connected to the drive shaft out of meshing engagement with an interlocking wheel for driving the cutting chain so as to shut off the driving power to be transmitted to the interlocking wheel. The brake lever also includes a braking member secured thereto and adapted for movement therewith in synchronism with the arcuate movement of the cam surface, into frictional braking engagement with the interlocking wheel for effecting a brake effect on the cutting chain.

Abstract: A throttle cushion of a portable power-driven machine has a sleeve-like elastic cushioning member fitted on the portion of a trigger engageable with a throttle valve actuating rod.

Abstract: A guide bar extension member coupled to a guide bar of a chain saw for selectively lengthening or shortening the cutting bar for cutting different size pieces of timber, for example. In its preferred form, the guide bar comprises a sectional guide bar assembly which is separable at the high point of its curved periphery into rear and forward guide bar portions with an extension element of a predetermined length inserted therebetween.

Abstract: Disclosed is a receptacle for use in a portable power driven machine, which is arranged such that a flexible elastic hose at least partly provided with a coiled portion is allowed to stay within the receptacle by being drawn thereinto from a liquid take-out port, said hose being mounted with a filter at its free end; and the length of said hose allowed to stay within the receptacle is made greater than a distance covering from the liquid take-out port to a liquid inlet port of the receptacle.

Abstract: An air cleaner in which an end of a flexible air intake pipe is mounted on a receiving member sealingly surrounding an intake port of a carburetor, the other end of the air intake pipe is clamped by an end portion of an air intake pipe retainer engaging with a bottom opening of a case member, a retaining claw for engaging with a frame edge of the body is formed at a bottom portion of the case member and the bottom portion of the case member is fastened by a screw at a position remote from the retaining claw.

Abstract: An automatic brake operating device to be used on a motor chain saw provided with a clutch drum around which there is a pretensioned brake band. By use of a spring and a toggle joint the band can be switched between a free position and a braking position. The toggle joint is operated between two corresponding positions by an inertia mass for releasing and a stirrup for resetting. The mass and the stirrup are individually movable and capable of triggering the brake independent of each other.

Abstract: A chain saw safety-brake system including a pivotable member, and a screw located in side-by-side relation to the pivotable member and having a brake band connected thereto at one end. The screw can be operated from outside of the chain saw to adjust the length of the brake band. The pivotable member and the screw are assembled with a lock lever for locking a clutch drum and contained in a casing to provide a packaged unit.

Abstract: Disclosed is a sawdust discharge port which is arranged such that a side wall of a cover member covering a body frame of a chain saw and opened at its lower end and forming one of the constituent elements of the discharge port has a substantially flat outer surface, and an inner surface forming an inclined surface whose lower end edge portion is gently inclined inwardly and downwardly, thereby to permit the side wall to gradually increase in thickness toward its lower end.

Abstract: A braking device for braking the saw chain of a portable motor-driven chain saw having a safety device which has a mass member, a locking lever being provided which is pivotably mounted on the hand guard lever and bears the mass member at its free, sprung end, co-operating by its other end with a control cam which bears against the brake lever and via which the braking operation of the rotating saw chain is controlled, in such a way that the braking operation of the rotating saw chain is automatically initiated, if an uncontrolled acceleration takes place, by the saw rolling down the timber trunk to be sawn at the moment when the saw becomes jammed, with the consequence that the resulting braking force counteracts the accelerating force, so that the recoil angle of the saw is reduced.

Abstract: A chain saw safety braking assembly includes a sensing arm pivotally mounted to the housing and having a protrusion. A portion of the sensing arm is located in front of the gripping handle and is arranged to move from a first position to a second position in response to being struck by an appendage of the operator. A flexible brake band is disposed around the peripheral surface of a brake drum, and includes a first end anchored to the housing and a second end coupled to the sensing arm protrusion, such that when the sensing arm moves from the first position to the second position the flexible brake band is moved from a position free of the brake drum to a frictional braking relationship with the brake drum. A latch is rotatably mounted to the housing and is adapted to releasably engage the protrusion on the sensing arm. A spring anchored to the housing cooperates with the latch such that the latch yieldably holds the sensing arm in either the first or the second position.

Abstract: The invention is directed to a safety arrangement for a power-driven portable tool such as a motor-driven chain saw or the like. The portable tool has a housing equipped with two handles both of which are grasped by the operator to hold and guide the tool during use thereof. One of the handles is a bail handle mounted at the forward part of the housing. The safety arrangement includes two switches associated with respective ones of the handles. The switches are operatively connected to the motor so as to cause the same to be operative only when both switches are closed. At least a portion of one of the contacts of the bail handle switch is displaceable from a first position whereat the bail handle switch is open to a second position whereat the switch contacts come into mutual contact and the bail handle switch is closed.

Abstract: A drive sprocket for use with an elongate, endless saw chain, the sprocket being a substantially cylindrical member having pockets spaced circumferentially thereabout for receiving drive tangs on the saw chain with sprocket edge margins adjacent the tang-receiving pockets providing support for bottom surfaces of the side links of the saw chain. The pockets have enlarged clearing portions opening radially outwardly from the sprocket which are wider than remainder portions of the pockets. The clearing openings are configured and positioned to allow debris to clear radially from the pockets.

Abstract: A cutting apparatus designed to produce an oscillating force which is transmitted to a cutting element, said cutting element having a plurality of cutting teeth disposed at intervals in a complete circle around the periphery of the cutting element. The direction of cutting of the cutting teeth of said cutting element is alternated in opposite directions so that when to the cutting element is applied an oscillatory force, half of the cutting teeth will cut in one direction and the other half in the opposite direction. Thus the cutting apparatus disclosed herein is designed to work with any oscillating flexible cutting element of the type described above.

Abstract: An emergency braking device for a chain saw having a clutch drum drivingly connected to the engine crank shaft through a centrifugal clutch. The emergency braking device includes a braking band wound around the clutch drum and connected at its one end to a stationary part of the chain saw. The other end of the braking band is connected to an actuator having a lever member. The emergency braking device further includes a hit switch member adapted to be rotated when hit by an inertia action of an inertia member disposed in the vicinity of a front handle so as to surround the lever member. As a kick-back takes place in the chain saw, the inertia member hits the hit switch member which in turn drives the lever member to actuate the actuator thereby to tighten the braking belt to quickly brake the clutch drum.

Abstract: A power-driven portable machine such as a chain saw. The machine has a liquid crystal display device incorporated in a detachable cover member of a supporting assembly which is connected with a driving assembly including a prime mover such as internal combustion engine through vibration damping members.

Abstract: The invention is directed to a power chain saw incorporating a braking device having a release handle. The chain saw includes a carrying handle spaced a distance from the release handle. At least one of the handles is made of a plastically deformable material and can be deformed so as to cause the spacing between the handles to be adjusted within predetermined limits.

Abstract: A hand-guided, motor driven working device with at least one working tool, especially a portable power chain saw. The device has a venting device for the fuel tank, with the venting device comprising a flexible tube, which projects from the upper part of the tank chamber. The free end of the tube is closed except for a labyrinth-like passage or opening. The tube is arranged at least partially within a covering or sheathing, and the tube is guided to an essentially dirt- and contamination-free chamber located as far as possible from the tank, the tool, and the motor.

Abstract: A suction silencer for suppressing generation of noise caused by gas or air sucked by a machine such as a compressor, internal combustion engine or the like. The suction silencer has amounting seat by which it is mounted on the suction side of a machine such as an internal combustion engine. The mounting seat has an opening leading to the suction port of the machine. An inversed conical surface protrudes from the peripheral edge of the opening. A lid member is attached to cover the inversed conical surface such that a small gap is left between the inner surface of the lid member and the large-diameter end of the inversed conical surface. The lid member has an inversed conical member which projects into the space defined by the conical surface so that an annular passage is formed between the inversed conical surface and the peripheral surface of the inversed conical member.

Abstract: A centrifugal clutch for power saws. The clutch includes a rotating driven centrifugal weight carrier, and a clutch drum which is concentric to the axis of rotation of the carrier. At least one centrifugal weight engages the clutch drum at predetermined speed of the carrier. The centrifugal weight is coupled with at least one return weight in such a manner that the return weight opposes the pressing force of the centrifugal weight when the speed increases over a certain level.

Abstract: A safety device on a power saw which is provided with two handles, especially for a power chain saw. The saw has a brake which engages a drive member of the cutting tool of the saw under the effect of a force retainer; the brake is held in the ineffective or inoperative position by a stop which is actuated by operating elements associated with the two handles. The stop is locked in its locking position and is releasable by means of an adjustment device which is driven by an energy source supplied by the engine of the saw, and is controlled by a control device which is connected to the operating elements which are embodied as key or contact switches.

Abstract: A portable power tool includes a manually actuable safety lever and an inertial safety system for activating a brake of the tool to provide a more effective safety arrangement. A first spring applies the brake when the safety lever contacts the hand, wrist or arm of an operator during "kick-back" or like violent movement of the tool. A second spring is operable independently of the safety lever for also releasing the first spring. An inertia mass is displaceable effectively independently of the safety lever when the brake is in the inoperative condition. This inertia mass releases the second spring, so releasing the first spring and applying the brake, upon occurrence of "kick-back" or the like. Preferably, the second spring operates a hammer release mechanism for striking a locking lever releasably retaining the safety lever. A band brake of a chain saw or circular saw may particularly be operated in this manner.

Abstract: The invention concerns a chain saw for a tree cutting device.This chain is composed of cutting links (2) having two cutting teeth (6) located on either side of the longitudinal axis of the chain, one of the teeth being basically in the plane of the chain and the other tooth being displaced with respect to the plane of the chain, and the cutting links being so placed that the chain presents, on either side of its longitudinal axis, successively, a tooth displaced on one side of its plane, a tooth in its plane, a tooth displaced on the other side of its plane, a tooth in its plane, and so forth.

Abstract: An exhaust muffler for a two-cycle opposed cylinder engine of simultaneous ignition type having two cylinders opposing to each other in the horizontal direction. The muffler has conical members disposed to oppose to exhaust ports of the cylinders, the exhaust ports being arranged in a side-by-side relation. The conical members form conical annular discharge passages leading from respective exhaust ports. The discharge passages have flattened peripheral outlets of different opening areas. The flows of the exhaust gas from respective cylinders are introduced through the flattened peripheral outlets of the discharge passages into a common diffusion chamber, so that the attenuation of the pressure waves and release of heat of exhaust gas are promoted to reduce the exhaust noise of the engine.

Abstract: A chain saw having front and rear handles disposed at the front and rear parts of an engine block for driving a saw chain. The front and rear handles are connected at their one ends to the engine block in a vibration absorbing manner through respective vibration damping members. The other ends of the front and rear handles are arranged to oppose to each other at two points and are connected to each other at these two points in a vibration absorbing manner through respective vibration damping members. At least one of the vibration damping members connecting the other ends of the handles is fixed to the engine block.

Abstract: A motor-driven chain saw having a plurality of units including an engine-saw unit, a casing, a multiplicity of fuel tanks, and filter elements for fuel and lubricant. The filter-tank unit is provided with a top portion and a bottom portion which restricts spacings for a direct location of the filter elements. The filter-tank unit is provided with a fixed pipe system for the fuel and lubricant between the spacings and the auxiliary apparatus constituting a carburetor and lubricant pump.

Abstract: A chain saw having a saw chain adapted to be driven by an engine. The engine has a cylinder and a crank case separable from each other. The crank case has cooling air guide walls formed integrally therewith and extending along the upper and lower sides of the cylinder.

Abstract: A power chain saw comprises a cylinder block and a crank-case having a forwardly extending housing formed integrally therewith, a carburetor is incorporated into the housing and a main handle is located on the power unit on its upper side and extends longitudinally between the rear end and the forward upper portion of the power unit.

Abstract: A muffler for a portable engine for a chain saw or the like including separable dish shaped members having mating peripheral edges which, when interfitted one within the other, form a hollow shell. Exhaust gas inlet and outlet openings are formed in an end wall of one of the members and a deflector member is mounted exterior of the shell and is adapted to redirect the flow of exhaust gas leaving the muffler outlet openings so that the exhaust gas flows generally in the same direction as engine cooling air flow over the engine and the muffler. A shield is mounted on the shell and has a major portion spaced from the muffler shell to form a cooling air flow passage. The separable shell members, deflector, shield and a tubular diffuser disposed within the shell are held in assembled relationship on the engine by removable threaded fasteners.

Abstract: A stabilizer bar for a hand held tool which extends laterally from the handle of the tool to receive and mate with the thumb to stabilize the hand grip of the tool. The stabilizer bar may be cylindrical and eccentrically adjustable to adjust to the comfort of the user's hand or may be provided with an elliptical body likewise adjustable for comfort. Furthermore, the stabilizer bar may be slidable through the handle of the tool to accommodate right or left handed grips.

Abstract: A pruning and clearing apparatus comprises a guide bar mounted on a handle. The saw chain of the guide bar is driven by means of a hydraulic motor and a separate portable drive unit comprising a hydraulic pump driven by an internal combustion engine and provided with an oil cooler. The hydraulic pump is connected to the hydraulic motor by lines arranged in the handle.

Abstract: A manually portable chain saw (10) having a gripping handle (18), a cutting chain (26), a sensing arm (30), and a motive force mechanism (14), features a releasable bistate mechanism (39a) for stopping cutting chain movement in response to forward movement of the sensing arm (30). The releasable bistate assembly (39a) captures an end of a brake band (40) for longitudinal movement in the direction of the brake band (40) and transverse movement in the direction of the long axis of the sensing arm (30). Independent adjustment of the forces on the sensing arm (30) and on the latch mechanism (49), and positive braking action are achieved. Separate spring biases (50, 52) are employed against the sensing arm (30) and the latch mechanism (49) respectively.

Abstract: A portable motor chain saw with a safety braking device to protect against kick-back, recoil or centrifugal movements of the saw. The saw includes a handle supported against the motor housing by damping elements, and also includes a locking device which on the one hand is connected with the handle, and on the other hand engages against a hand guard in such a way that it is released under the influence of relative movement, of the motor housing with respect to the handle, caused by a kick-back or centrifugal movement, consequently releasing the hand guard. The locking device has an abutment surface extending transverse to the direction of centrifugal movement, and this abutment surface cooperates with a projection directed against it.

Abstract: A saw chain guide device for a chain saw in which an end face of each of side plates disposed adjacent to a drive sprocket of the saw chain terminates extremely adjacent to a tooth tip circle of the drive sprocket of the saw chain, and an edge portion extending beyond the end face and along the tooth tip circle of the toothed sprocket is integrally formed with at least one of the side plates confronting outerside of the chain saw.