Momentary Control (Hold-to-Run)
This is the mode of operation in which the movement continues as long as the button is pressed and the command is cut immediately when the button is released. In lifting and handling applications this is the default and safe behaviour; the machine is expected to stop the moment the operator's hand comes off the command.
In momentary control the transmitter broadcasts the command frame over and over as long as the button is held down. When the button is released this transmission stops or the command field empties; since the receiver sees no valid command it releases the relevant relay and the contactor drops out.
The safety value of this behaviour has two layers:
- Requirement for deliberate action: movement continues only through the continuous will of the operator. If the remote control is dropped, if the operator faints or takes their hand away, the movement stops by itself.
- Overlap with signal loss: going out of range, a flat battery or the device switching off produce the same result — no command, no movement.
For this reason latching outputs are not used in crane, hoist and platform applications; a latched output keeps the movement going even if the operator lets go of the remote control and creates a direct safety risk.
One price of momentary control is that on long movements the operator has to keep the button pressed. This is not a disadvantage but the design itself; disabling this requirement by mechanically fixing the button must absolutely never be done.
The context in which this term is used: Wireless Crane Remote Control Selection Guide