Safety braking apparatus for portable chain saw

Claim 2

In a chain saw of the type including a housing, a guide bar projecting from said housing, a cutting chain mounted to run on said guide bar, and motive means carried by said housing coupled to said cutting chain for propelling said cutting chain around said guide bar, the improvement comprising, in combination: a safety lever pivotally mounted on said housing for movement from an operating position to a braking position; a brake band having a first end portion coupled to said safety lever, a second end portion coupled to said housing, and an intermediate portion disposed for frictional engagement with said motive means in response to movement of said safety lever from said operating position to said braking position; a latching member pivotally mounted on said safety lever for rotational movement relative to said force transmitting safety lever, said latching member having a first end portion disposed for releasable engagement with said safety lever and a second end portion disposed in releasably latching engagement with said housing; and, a spring member engaged intermediate said housing and said latching member, said spring member exerting a yieldable force on said safety lever which constantly biases said safety lever for movement from said operating position to said braking position, said spring member also exerting a yieldable latching force on said latching member and cooperating with said safety lever for holding said second end portion of said latching member in releasably latching engagement with said housing for resisting movement of said safety lever and thereby preventing inadvertent frictional engagement of said brake band with said motive means when said safety lever is in said operating position, and said spring member cooperating with said safety lever for permitting rotation and disengagement of said latching member from said housing as said safety lever rotates from said operating position to said braking position in response to an external actuating force acting on said safety lever.

Claim 3

The chain saw combination as defined in claim 1, said spring member comprising a lineally acting coil spring compressively seated intermediate said housing and said latching member, said lineally acting coil spring having a first end portion engaging said first end portion of said latching member and a second end portion engaging said housing.

Claim 4

The chain saw combination as defined in claim 1, said spring member comprising a lineally acting coil spring compressively seated intermediate said housing and said latching member, the first end of said brake band being enclosed by and extending through said lineally acting coil spring.

Claim 5

The chain saw combination as defined in claim 1, said first end of said brake band being bifurcated thereby defining a central passage, the first end portion of said latching member projecting through said central passage and engaging said safety lever.

Claim 6

The chain saw combination as defined in claim 4, said safety lever having a recess receiving the bifurcated end portions of said brake band and an anchor pin bridging said recess, said bifurcated end portions of said brake band being secured to said anchor pin.

Claim 7

The chain saw combination as defined in claim 1, said safety lever having a pin projecting orthogonally with respect to said safety lever, said latching member being mounted on said pin for rotational movement of said first and second end portions relative to said safety lever.

Claim 8

The chain saw combination as defined in claim 1, said housing having a latch pin and a roller carried by said latch pin for engaging the second end portion of said latching member.

Claim 9

The chain saw combination as defined in claim 1, said latching member comprising a central body portion pivotally mounted on said safety lever, said first and second end portions projecting from said central body portion in substantially orthogonal relation relative to each other, said first end portion defining a lever arm for engaging said spring member and transmitting the yieldable latching force exerted by said spring, and said second end portion having a detented surface for engaging said housing.

Claim 10

The chain saw combination as defined in claim 8, said housing having a latch pin and a roller carried by said latch pin for releasably engaging said detented surface of the second end portion of said latching member, and said second end portion having an inclined surface for engaging said roller as said latching member rotates relative to said safety lever.

Claim 11

In a chain saw of the type including a housing, a guide bar projecting from said housing, a cutting chain mounted to run on said guide bar, and motive means carried by said housing coupled to said cutting chain for propelling said cutting chain around said guide bar, the improvement comprising, in combination: a safety lever pivotaly mounted on said housing for movement from an operating position to a braking position; a brake band having a first end portion coupled to said safety lever, a second end portion coupled to said housing, and an intermediate portion disposed for frictional engagement with said motive means in response to movement of said safety lever from said operating position to said braking position; a latching member pivotally mounted on said safety lever for rotational movement relative to said force transmitting safety lever, said latching member having a first end portion disposed in releasably latching engagement with said housing and having a second end portion defining a moment arm relative to the pivotal axis of said latching member for transmitting a latching force to said first end portion and to said safety lever; and, a spring member engaged intermediate said housing and said latching member, said spring member exerting a yieldable force on said safety lever which constantly biases said safety lever for movement from said operating position to said braking position, said spring member also exerting a yieldable latching force on said latching member and cooperating with said safety lever for holding said second end portion of said latching member in releasably latching engagement with said housing for resisting movement of said safety lever and thereby preventing inadvertent frictional engagement of said brake band with said motive means when said safety lever is in said operating position, and said spring member cooperating with said safety lever for permitting rotation and disengagement of said latching member from said housing as said safety lever rotates from said operating position to said braking position in response to an external actuating force acting on said safety lever.

Claim 12

In a chain saw of the type including a housing, a guide bar projecting from said housing, a cutting chain mounted to run on said guide bar, and motive means carried by said housing coupled to said cutting chain for propelling said cutting chain around said guide bar, the improvement comprising, in combination: a safety lever pivotaly mounted on said housing for movement from an operating position to a braking position; a brake band having a first end portion coupled to said safety lever, a second end portion coupled to said housing, and an intermediate portion disposed for frictional engagement with said motive means in response to movement of said safety lever from said operating position to said braking position; a latching member pivotally mounted on said safety lever for rotational movement relative to said force transmitting safety lever, said latching member having a first end portion disposed in releasably latching engagement with said housing and having a second end portion defining a moment arm relative to the pivotal axis of said latching member for transmitting a latching force to said first end portion and to said safety lever; and, a spring member engaged intermediate said housing and said latching member, said spring member exerting a yieldable force on said safety lever which constantly biases said safety lever for movement from said operating position to said braking position, said spring member also exerting a yieldable latching force on said latching member and cooperating with said safety lever for holding said second end portion of said latching member in releasably latching engagement with said housing for resisting movement of said safety lever and thereby preventing inadvertent frictional engagement of said brake band with said motive means when said safety lever is in said operating position, and said spring member cooperating with said safety lever for permitting rotation and disengagement of said latching member from said housing as said safety lever rotates from said operating position to said braking position in response to an external actuating force acting on said safety lever.

Claim 13

The chain saw combination as defined in claim 10, said spring member comprising a torsion spring having a first end portion coupled to said latching member and a second end portion coupled to said housing.

Claim 14

The chain saw combination as defined in claim 11, said torsion spring being mounted in coaxial relation with the pivotal axis of said safety lever.

Claim 15

The chain saw combination as defined in claim 11, said safety lever being pivotally mounted to said housing by means of a pivot pin projecting intermediate said housing and said safety lever, said torsion spring being mounted in coaxial relation with and enclosing said pivot pin.

Claim 16

The chain saw combination as defined in claim 11, said latching member being pivotally mounted to said safety lever by means of a pivot pin projecting intermediate said latching member and said safety lever, the first end portion of said torsion spring being coupled to the moment arm portion of said latching member at a point opposite the longitudinal centerline of said pivot pin.