Motor-driven tape measure construction - has housing which encloses drive motor, power source and various safety devices

摘要

A motor driven tape measure has a housing (1) in the form of an inverted Y. The upper part of the housing has a removable cover plate which includes a battery box (19) which serves as the power source for the motor. The upper part of the housing has a hole through it to provide a hand grip (7). The upper surface carries the operating controls such as the motor switch (10) and speed control (12, 13). It also has display devices for number of turns and battery state (18). The tape measure also has a drive motor and reduction gear with a high reduction ratio, as well as a torque limiter. Other safety devices (89, 90, 91) monitor the end of the tape optically and magnetically.