Definition
An electromechanical relay whose contacts advance one position each time the operating coil is energized, allowing a single input pulse train to switch power sequentially through several circuits. Each pulse moves a wiper or set of contacts to the next stop, and the relay holds that position until the next pulse arrives.
Plain English
A switch that clicks one step further every time it gets an electrical pulse, so each pulse connects a different circuit in turn.
Context Anchor
Seen in aircraft electrical system descriptions, especially where older or simple equipment uses one repeated signal to select among several positions or functions.
Derivation
Stepping describes the action of moving one position at a time, like footsteps. Relay comes from the Old French relayer, meaning to leave behind or pass on, used since the 1800s for an electrical device that passes a control signal from one circuit to another. Together: a relay that passes the signal on one step at a time.
Why Pilots Care
Enables reliable automatic selection of multiple channels or settings in legacy avionics without continuous manual input.
Analogy
Think of a clicking pen: each press moves the mechanism to its next position. A stepping relay does something similar electrically, advancing to the next contact with each pulse.
Intuition Check
Do not confuse a stepping relay with a transformer that steps voltage up or down. In this term, “stepping” means moving through switch positions one at a time.
Example Sentence 1
The landing gear sequencing on the older trainer used a stepping relay to extend the gear and close the doors in the correct order.
Example Sentence 2
During preflight the technician verified that the stepping relay completed its full sequence without sticking.