Non-electrical control for sewing machine speed regulator

摘要

A sewing machine driven by an electric motor has a regulating circuit for the speed of the motor, installed in the frame of the machine, and an arrangement for controlling the circuit. Part of the control arrangement is also installed in the machine frame and this is connected by non-electrical means to the control organ outside the frame.The electrical circuit includes a circuit breaker inside the frame, connected to the operator's switch or pedal. The non-electrical means of operation form part of a pneumatic control system which includes a push-rod operating the variable resistance, fixed at one end of a bellows inside the frame. The other end of the bellows is attached to a flexible pipe connected to a means of compressing air. Alternatively, the variable resistance may be regulated by a pushrod attached to a cable mechanically.Eliminates the danger that through deterioration of the foot switch, the operator could come into direct contact with the supply from the mains.