Operating Principles of Electomatic Gearcases

The Electramatic gearcase consists of an arrangement of a switch and electromagnetic coils (electric clutches) instead of a mechanical linkage to accomplish shifting of the stern drive into forward, neutral, or reverse. When the engine is running, both the forward and reverse gears freely revolve in opposite directions on the propeller shaft until one gear or the other is engaged. The gears have a helically wound steel spring (the clutch spring) locked to them. When the remote control unit is shifted to a forward position, an electric; switch in the control box closes the circuit (green wire) to the forward: electromagnetic coil in the gearcase. When the electric coil is energized, electromagnetism instantly attracts and anchors the free end of the clutch spring to the flange of the clutch hub. The revolving gear causes the spring to wrap around the hub, creating a direct coupling with' the propeller shaft. It can be seen that motive power is transmitted through the pinion gear, forward gear, clutch and propeller shaft to the propeller. Forward drive is thus retained until the remote control unit is returned to a neutral position. Shifting into reverse causes an identical action (as described above) to happen on the reverse coil, clutch and gear, assembly.