Abstract: An actual operating time indicator includes: a lifting motor for lifting a load up/down; a power detection unit for detecting an input power based on a current and a voltage supplied to the motor, and converting the input power into a first voltage proportional to the input power; a voltage-to-periodic pulse conversion unit connected to the power detection unit for receiving the first voltage and converting the first voltage into the periodic pulse proportional to the first voltage; a counter unit connected to the voltage-to-periodic pulse conversion unit for counting and integrating the periodic pulse to obtain an integrated power; and a display operatively connected to the counter unit for indicating the integrated power as an actual operating time of the motor.

Abstract: A stepless speed change electric chain block includes a DC motor for driving a load sheave. The chain block comprises a phase control circuit having a variable resistor, a capacitor, a two-way trigger diode, and a triode AC switch for receiving alternating current from alternating power source to control it in phase, a full-wave-rectifier for receiving alternating current controlled in phase in the phase control circuit to convert it into direct current which is supplied into the DC motor, and mechanical brake means provided in a transmission between the DC motor and the load sheave for braking rotation of the load sheave in a winding-off direction. With this arrangement, as the speed setting for winding operation is effected only by the phase control circuit, so that the constitution of the block is simplified and inexpensive in comparison with the prior art. All the supplied power is effectively utilized for operating the chain block.

Abstract: An operating device for an electric hoist having a DC motor for raising and lowering an object, comprises a low speed adjusting setting unit (VR1) and a high speed adjusting setting unit (VR2) provided in a control box of the hoist. The operating device further comprises in the control box a two-step push-button switch (PB-U) for the raising operation for switching over the low speed adjusting setting unit and the high speed adjusting setting unit to connect either of the units (VR1 and VR.sub.2) to a speed-change control circuit by pushing the two-step push-button switch (PB-U) to either of first and second step positions, and a two-step push-button switch (PB-D) for the lowering operation for switching over the low speed adjusting setting unit (VR1) and the high speed adjusting setting unit (VR2) to connect either of the units to the speed-change control circuit by pushing the two-step push-button switch (PB-D) for the lowering operation to either of first and second step positions.