FH (Frame Height)
The distance from the top of the frame to the ground. See Chassis Dimensions.
Fifth Wheel
A coupling device mounted on a tractor that contains a provision for accepting and holding the kingpin of a semi-trailer.
Final-stage Manufacturer
A person who performs such manufacturing operations on an incomplete vehicle that it becomes a completed vehicle.
FMCSR
Abbreviation for Federal Motor Carrier Safety Regulation, regulations enforced by the Office of Motor Carrier Safety. See OMCS.
FMVSS
Abbreviation for Federal Motor Vehicle Safety Standard. These regulations promulgated by the National Highway Traffic Safety Administration under Public Law 89-563 are mandatory and must be complied with when motor vehicles or items of motor vehicle equipment are manufactured and certified thereto.
Forks
A device attached to the lift bar for lifting a vehicle by an axle, frame or structural member.
Forward Control
A configuration in which more than half of the engine length is rearward of the foremost point of the windshield base and the steering wheel hub is in the forward quarter of the vehicle length.
Frame Cutoff
The standard frame on most models extends behind the rear axle, far enough to support a body mounted on the vehicle. For special-purpose bodies that may be unusually short for the wheelbase of the vehicle on which it is mounted, or in most tractor operations this frame extension behind the rear axle may be shortened. The shortest allowable extension for each vehicle is referred to as Maximum Frame Cutoff.
Frame Section Modulus
The engineering term that indicates the relative strength of frames as it relates to shape. It takes into account frame depth, flange width and material thickness. All other things being equal, the frame with the largest section modulus will have the greatest strength and stiffness, (i.e., the ability to more effectively resist sagging under loads).
Fuel Cell
A device that generates electricity via a chemical reaction between a fuel (typically hydrogen) and oxygen. Every fuel cell has two electrodes, the anode (positive) and the cathode (negative). The reactions that produce electricity occur at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes.
Full Air Brakes
Compressed air is used to provide the force required to expand the brake shoes by cam or wedge against the brake drums. Air pressure is supplied direct to chambers at the wheel position.
Full Trailer
A trailing load-carrying vehicle that is entirely supported by its own suspension system. The powered unit merely tows this type of trailer and does not directly support any of its weight. Sometimes referred to as a Pup when towed behind a truck with a mounted body or behind a tractor/semi-trailer combination. Tractor/semi-trailer/full-trailer combinations are often referred to as Doubles or Double Bottoms.
FW (Frame Width)
The overall width of the chassis frame measured outside to outside behind the cab.
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