Educational Mechanics
Facet Gear
A toothed gear with flat faces that engages with another gear; often seen in steering gearboxes and powertrain linkages.
Fault Current
The electrical current that flows when a short circuit occurs, potentially damaging electrical components if not interrupted.
Feathering (Tyre Wear)
A wear pattern on tyres where the leading or trailing edges of tread blocks show uneven wear, often associated with incorrect wheel alignment (toe).
Feathering Plate
A plate used in some clutch designs to help guide friction linings; also refers to plates in some brake systems that reduce noise.
Ferrite
A magnetic material commonly used in transformer cores and inductive sensors in automotive electrical systems.
Fill Port
An access point provided in a reservoir, gearbox, or hydraulic circuit to add fluid to the system.
Final Drive
The last set of gears in a drivetrain that reduces rotational speed and delivers torque to the drive shafts or axle shafts.
Filter (Air / Oil / Hydraulic)
A device that removes particulates from a fluid (air, oil, or hydraulic fluid) to protect downstream components and maintain system performance.
Fire Ring (Piston)
A heat-resistant ring positioned on a piston to deflect combustion heat and protect piston surfaces.
First Motion Shaft
The shaft that first receives torque from the engine before it is distributed through the transmission or driveline.
Also - Primary shaft, Gearbox input shaft
Fixed Displacement Pump
A hydraulic pump that delivers a constant volume of fluid per revolution, used where a predictable flow rate is required.
Flat Rate Time
A standardized time allocation used by technical training and service manuals to measure how long a procedure should take; useful as an instructional benchmark, not a repair directive.
Float (Wheel Bearing)
The lateral movement permitted within a bearing assembly, allowing for expansion or contraction without binding.
Also known as "end float"
Floating Brake Caliper
A disc brake caliper that slides on guide pins to centre itself over the disc when pressure is applied, simplifying design while maintaining effective clamping.
See - Disc Brakes Explained
Flow Control Valve
A valve that regulates the rate of fluid flow in hydraulic circuits, such as in power steering or advanced suspension dampers.
Flywheel
A mass attached to the engine crankshaft that smooths pulsating torque output and provides rotational inertia; also the surface against which a clutch engages.
See: How a Clutch works and Dual Mass Flywheel
Foot Control Valve
A valve in a pneumatic or hydraulic service brake system that controls fluid or air pressure in response to driver foot input.
Forced Induction
An engine aspiration method that uses a turbocharger or supercharger to increase the mass of air entering the engine, thereby increasing power.
Fork (Transmission Selector)
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Forward Drive Ratio
The gear ratio that determines how many revolutions of the engine are needed to turn the road wheels once in a forward gear.
Four-Wheel Drive (4WD)
A drivetrain configuration that provides drive torque to all four wheels. Part-time systems lock front and rear propeller shafts, whereas full-time systems use centre differentials to allow speed differences.
See: Transmission & Driveline Overview and Transmission Wind-Up
Friction
The resistance to motion between two contacting surfaces. In vehicles, friction is harnessed in brakes to convert kinetic energy into heat and in clutches to transmit torque.
Friction Coefficient
A numerical value describing the ratio of frictional force between two surfaces to the normal force pressing them together. It influences braking performance and tyre grip.
Full Lock
The steering position where the steering wheel is turned to its maximum allowed angle, used for extreme manoeuvring.