| 摘要 |
A coilable tape rule includes a pair of rollers that are convexly rounded in both axial and transaxial planes, about which rollers the measuring blade moves during passage through the casing and which cause the blade to turn on its longitudinal axis so as to reorient its width dimension to a perpendicular relationship to the axis of coiling. The blade is of concavo-convex cross section and cooperates with the rollers for tracking control and to enhance the smoothness and reliability of extension and retraction.
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