shunt circuit (electrical circuit). A parallel circuit, or a circuit in which there are more than one path for electrons to flow.
shunt ohmmeter. A type of ohmmeter used for measuring very low values of resistance. Voltage across the meter is adjusted until the meter pointer deflects full scale. Then, the unknown resistor is connected in parallel (in shunt) with the meter. The resistance of the unknown resistor is indicated by the decrease in the current flowing through the meter.
shunt winding. Field coils in an electric motor or generator that are connected in parallel with the armature.
shunt-wound generator. An electrical generator whose field windings are connected in shunt (parallel) with the armature winding. Most aircraft generators are shunt-wound, because their output voltage can be controlled by varying the amount of current flowing through the shunt-connected field winding.

shunt-wound motor. A commutator-type electric motor in which the field windings are connected in shunt (parallel) with the armature. Shunt-wound motors do not have a large amount of starting torque, but they operate at a relatively constant speed, and they do not need to have a mechanical load connected to them to prevent them from overspeeding.
Shunt-wound motors are used for blowers and other low-torque applications.
shut-off valve (fluid power system component). A valve used in a fluid power system to shut off the flow of fluid.
shuttle valve (fluid power system component). A type of automatic selector valve installed in a critical portion of a fluid power system. Fluid for normal operation of the system flows through the shuttle valve into the actuating cylinder. But if the normal system pressure fails, emergency fluid pressure can be directed into the actuator through the shuttle valve.