Truck Accidents Glossary: P

P & D: Pickup and delivery.

Payload: Weight of the cargo being hauled.

Peddle Run: Truck route with frequent delivery stops.

Pigtail: Cable used to transmit electrical power from the tractor to the trailer. So named because it is coiled like a pig's tail.

Piggyback: Semitrailer 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 dolly.

Ply Rating (PR): Relative measure of tire casing strength. (see Load Range)

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. (see For-Hire Carrier)

PSI (Pounds Per Square Inch): In trucking, unit of measurement for tire air pressure, air brake system pressure and turbocharger boost.

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 semitrailer, usually between 26 and 32 feet long, with a single axle.