| 摘要 |
The invention is directed to a braking arrangement for a chain saw having a housing and a guide bar mounted on the housing for accommodating a saw chain thereon. The brake arrangement includes a brake drum operatively connected to the saw chain with a brake band disposed in surrounding relationship thereto. A brake member is connected to the brake band and moves between a ready position whereat the brake band is disposed in spaced relationship to the brake drum and a released position whereat the brake band is drawn tightly around the brake drum. A brake spring resiliently biases the brake member to cause the brake member to pull the brake band tightly about the brake drum when in the released position. A latch arrangement holds the brake member in the ready position against the force of the brake spring. A cam connected to the drive motor rotates through a predetermined path. A release device opens the latch arrangement to permit rotational movement of the brake member to the released position and releases a tensioning member for movement into the path of the cam when the brake member is in the second position whereat the tensioning member follows the cam in a movement that causes the tensioning member to again coact with the latch arrangement to return the brake member to the ready position and to reclose the latch arrangement whereby the latter again holds the brake member in the ready position against the force of the brake spring. |
