Pancake A brake diaphragm housing on each set of dual wheels on a
semi-trailer and on most tractors.
P&D Pickup and delivery.
Payload Weight of the cargo being hauled.
Peddle Run Truck route with frequent delivery
Pigtail Cable used to transmit electrical power
from the tractor to the trailer. So named because it is coiled like a pig's
Piggyback Semi-trailer built with reinforcements to
withstand transport by a railroad flatcar.
Pintle Hook Coupling device used in double trailer,
triple trailer and truck trailer combinations. It has a curved, fixed towing
horn and an upper latch that opens to accept the drawbar eye of a trailer or
Placard A sign showing the type of hazardous
materials loaded in a vehicle.
Ply Rating (PR) Relative measure of tire casing
strength. (see Load Range)
Powertrain (Drivetrain) All the components,
including engine, which transmit the engine's power to the rear wheels: clutch,
transmission, driveline and drive axle(s)
Private Carrier Business which operates trucks
primarily for the purpose of transporting its own products and raw materials.
The principle business activity of a private carrier is not transportation.
PSI (Pounds Per Square Inch) In trucking, unit of
measurement for tire air pressure, air brake system pressure and turbocharger
PTO (Power Takeoff) Device used to transmit engine
power to auxiliary equipment. A PTO often drives a hydraulic pump, which can
power a dump body, concrete mixer or refuse packer. Some designs mount to a
standard opening on the transmission, while others attach at the front or rear
of the engine.
Pull Trailer Short, full trailer (supported by
axles front and rear) with an extended tongue.
Pup Trailer Short trailer, usually between 26 and
32 feet long, with a single axle.