Small Engines Chapter 6
Inductive field coil
A coil of wire attached to a segmented iron core that produces a magnetic field when current is passed through it.
Governor droop curve
A combination of rpm decrease and maximum brake horsepower curves.
Speed sensing device
A governor system component attached through linkage to the throttle plate of the carburetor to sense changes in engine speed.
Governed idle spring
A governor system component that has a low spring rate that offsets some of the force from the speed sensing device to improve governor sensitivity at low rpm.
Governed idle
A governor system function that allows an engine to accept light to moderate loads at idle speed without stalling the engine.
Mechanical governor system
A governor system that uses a gear assembly that meshes with the camshaft or other engine components to sense and maintain the desired engine speed.
Electronic governor system
A governor system that uses a limited angle torque motor in place of the governor spring and speed sensing device.
Governor blade
A movable metal or plastic blade which deflects air from flywheel fins to act as the speed sensing device of a pneumatic govornor system.
Applied load
A resistive force opposing engine forces.
Armature
A rotating part of an electric motor consisting of a segmented iron core or pemanent magnet mounted on the motor shaft.
Governor system
A system that maintains a desired engine speed regardless of the load applied to the engine.
Pnuematic governor system
A system which uses force from moving air produced by rotating flywheel fins to sense engine speed.
Dither effect
An effect based on the theory that less time is required to accelerate mass that is already in motion.
L A T
Limited angle torque motor, A direct current motor used to control governor system components in an electronic governor system.
Governor droop
The amount of rpm decrease between top no load governed speed and the rpm where power is delivered.
Governor spring
The component that pulls the trhottle plate toward the wide open throttle position.
Spring rate
The force necessary to stretch the spring one unit of length.
Force differential
The measured difference in forces acting on a single object.
Free length
The overall dimension of the spring when unloaded.
Governed speed
The speed obtained at the balance point between the forces of the speed sensing device and the governor spring.
Resonance
The state of the vibration wave frequency being equal to the natural vibration wave frequency of the component.
Top no load speed
The top speed setting an engine achieves without any parasitic load from equipment components.
Hysteresis
The undesirable motion of governor system components caused by engine vibration and governor system friction characteristics.
Hunting
The undesirable quick changing of engine rpm when set at a desired speed.
Surging
The undesirable slow changing of engine rpm in a cyclical pattern when set at a desired speed.
