Patent ID: 6473975
Filing Date: 2002-11-05
Classification: B27B,Y10T

Abstract:
A chain saw, comprising:a housing; a drive motor attached to the housing, the drive motor including a driveshaft; a chain guide adapted for movement transverse to the drive shaft; a saw chain adapted to be driven by the driveshaft for circulation around the chain guide, the transverse movement of the chain guide in a first direction tightening the chain with respect to the chain guide and driveshaft, the transverse movement of the chain guide in a second direction loosening the chain with respect to the chain guide and driveshaft; a chain guide tightener adapted for selectively clamping the chain guide to the housing to prevent the transverse movement of the chain guide and unclamping the chain guide from the housing to allow the transverse movement of the chain guide; and a blocking mechanism disposed between the housing and the chain guide tightener, wherein the blocking mechanism includes a pair of detent plates adapted for selectively engaging each other to permit the movement of the chain guide in the first direction and prevent movement of the chain guide in the second direction; wherein each detent plate includes saw tooth projections and respective projections of each detent plate can be brought into engagement with each other to interlock the detent plates, the detent plate and the saw tooth projections being integrally formed; and wherein, when the chain guide tightener is selected for unclamping the chain guide, the blocking mechanism permits the movement of the chain guide in the first direction and prevents movement of the chain guide in the second direction and when moving the chain guide in the first direction the chain guide is lifted against the chain guide tightener and chain guide plate having an elastic preload between the housing and the chain guide tightener exerts an elastic prestress on the chain guide and the detent plates when the chain guide tightener is selected for unclamping the chain guide.