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: The invention is directed to a saw chain for a motor-driven chain saw which includes cutting links, side connecting links, driving links and safety links. Each safety link has an upper edge defining a wave-like contour that prevents chips from accumulating during the cutting action. The cutting links and safety links of the saw chain are arranged with respect to each other so that overlap is avoided between the tail end of the rearward projection of the safety link and the forward projection of the depth limiter of the cutting tooth. This affords the advantage that cutting chips do not become jammed therebetween.

Abstract: The invention is directed to a safety arrangement for a saw chain which includes cutting links. A first safety mark is formed in the outside surface of the upwardly-extending portion of the rearmost wall of the cutting link. This first safety mark is disposed at a predetermined distance from the trailing edge of the cutting link and extends in a direction substantially parallel thereto. A second safety mark is formed in the wall of the depth limiter and extends from the leading edge of the cutting link to a notch between the depth limiter and the cutting tooth. The second safety mark is disposed at a predetermined distance below the engaging edge of the limiter.

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 saw chain for chain saws, particularly portable power chain saws, comprising chain members which are pivotally connected with each other. At least some of the chain members are provided with a safety marking to show the extent of wear.

Abstract: A rotor for a centrifugal clutch which rotor is designed as an axially laminated packet and is provided with a central supporting element carrying at least two circular segmental centrifugal weights respectively having one end thereof connected to the supporting element by an elastic supporting member.

Abstract: A motor chain saw in which serially arranged clutches are interposed between the motor output shaft and the chain of the saw. The clutches include a centrifugal clutch and a mechanically controlled clutch. The mechanically controlled clutch has at least one drive element having an engaged position and a disengaged position and is acted on by centrifugal force urging it toward the position which it occupies. A spring urges the device element toward engaged position with a force less than the centrifugal force which acts on the drive element above a certain speed. The mechanically controlled clutch includes at least one control operable to move the drive element in at least disengaging direction during rotation of the clutch.