Full position safety brake for portable chain saw
AssigneeMcCulloch Corporation
InventorSidney Hirschkoff
Life of this patent
Estimating the term…
Abstract
A hand portable chain saw with a movable safety bar for actuating a chain brake has a bracket and a lineally-acting spring which together provide a detent for holding the safety bar in the nonbraking operating position, but yet accelerate the braking movement of the safety bar upon disengagement from the detent. The carrying handle for a portable chain saw encircles the top and both sides of the saw housing to enhance both operator safety and convenience. The brake-actuating safety bar on the saw has a similar wrap-around contour to ensure engagement by the operator in the event of untoward movement of the saw for essentially any sawing position.
Claims16
In a hand portable chain saw having a housing with a carrying handle, a cutting chain, a support bar projecting forwardly from the housing for supporting the cutting chain for endless movement, motive means carried by the housing for driving the cutting chain, and a safety brake for stopping the cutting chain, the improvement in said safety brake comprising
- A. safety bar means mounted on said housing for swinging movement relative to a first axis and arranged to be swung forward upon being struck by an operator, said safety bar means having a wrap-around configuration extending around the top and sides of said housing forward of said carrying handle,
- B. a flexible brake band having a first end secured to the housing and a second end coupled to said safety bar means for movement therewith such that forward swinging of said safety bar means moves said brake band into frictional braking engagement with said motive means to stop said cutting chain, and
- C. a single spring member engaged between said safety bar means and the housing at a location spaced from said first axis and for exerting resilient force longitudinal to said forward direction, said spring member being arranged constantly to bias said safety bar means forward to said braking position, and further arranged to impose yieldable latching force on said safety bar means to resist forward movement of said safety bar means and thereby prevent inadvertent brake engagement with said motive means.
In a hand portable chain saw having a housing with a carrying handle, a cutting chain, a support bar projecting forwardly from the housing for supporting the cutting chain for endless movement, motive means carried by the housing for driving the cutting chain, and a safety brake for stopping the cutting chain, the improvement in said safety brake comprising
- A. safety bar means mounted on said housing for swinging movement and arranged to be swung forward upon being struck by an operator, said safety bar means having a wrap-around configuration extending around the top and sides of said housing forward of said carrying handle,
- B. a flexible brake band having a first end secured to the housing and a second end coupled to said safety bar means for movement therewith such that forward swinging of said safety bar means moves said brake band into frictional braking engagement with said motive means to stop said cutting chain, and
- C. resiliently-acting means
- 1. engaged between said safety bar means and the housing for exerting resilient force longitudinal to said forward direction, and arranged constantly to bias said safety bar means forward to said braking position, and further arranged to impose yieldable latching force on said safety bar means to resist forward movement of said safety bar means and thereby prevent inadvertent brake engagement with said motive means,
- 2. comprising a detent member mounted to the housing for rotation relative thereto and releasably engageable with said safety bar means for applying said latching force thereto, and a lineally-acting spring engaged between said detent member and said safety bar means and providing both said bias and said yieldable latching force.
In a hand portable chain saw having a housing, a cutting chain, a support bar projecting forwardly from the housing for supporting the cutting chain for endless movement, motive means carried by the housing for driving the cutting chain, and a safety brake for stopping the cutting chain, the improvement in said safety brake comprising
- A. safety bar means mounted on said housing for swinging movement about a first axis and arranged to be swung forward along a first direction upon being struck by an operator,
- B. a flexible brake band having a first end secured to the housing and a second end coupled to said safety bar means for movement therewith such that forward swinging of said safety bar means moves said brake band into frictional braking engagement with said motive means to stop said cutting chain, and
- C. a lineally-acting spring member exerting resilient force between said safety bar means and the housing at a location removed from said first axis and directed along said first direction, said spring member being arranged constantly to bias said safety bar means forward along said first direction, and further arranged to impose yieldable latching force on said safety bar means to resist movement of said safety bar means forward along said first direction and thereby prevent inadvertent brake activation.
In a hand portable chain saw having a housing, a sawing chain mounted on an arm extending forward from the housing, motive means coupled for driving the sawing chain, a safety bar rotatable relative to the housing between a braking position and an operating position, and brake means coupled with the safety bar for brakingly engaging the motive means for stopping the sawing chain and alternatively for release from the motive means, the improvement comprising
- A. detent-engaging means mounted for movement with the safety bar along a first direction between said braking and said operating positions thereof,
- B. first arm means extending longitudinal to said first direction and rotatably mounted for rotation relative to the housing about an axis different from the rotation axis of the safety bar, and having detent means for releasable latching engagement with said engaging means when the safety bar is in said operating position, and
- C. lineally-acting spring means engaged with said first arm means and with the safety bar for urging said arm means rotatably into said latching engagement with said engaging means, and for urging the safety bar from said operating position into said braking position.
In a hand portable chain saw having
- a housing with top, bottom and sides and a carrying handle;
- a cutting chain mounted on an arm extending forward from the housing;
- motive means coupled for driving the cutting chain;
- a safety bar mounted on the housing for swinging movement between an operating position and a braking position;
- and
- a chain brake coupled with the safety bar for brakingly engaging the motive means to stop the chain and alternatively for release from the motive means;
- the improvement wherein
- A. said carrying handle comprises a housing-encircling wrap-around handle extending about the top of the housing and about the housing sides to a substantially lowermost location thereon,
- B. said safety bar comprises a housing-encircling wrap-around barrier disposed forward of said carrying handle and extending at least substantially coextensively with said handle about the top and sides of the housing, and
- C. said chain brake includes brake control means having a spring exerting resilient force between said safety bar and the housing both for biasing said safety bar from said operating position into said braking position and for imposing a yieldable latching force on said safety bar for normally holding it in said operating position.
Dependencies are inferred from the claim text.