Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Pi"

PIB: Acronym for Product Information Bulletin. General information on a product.

Pick: See
Prospector's pick

Pick and finishing hammer: Pick and finishing hammer

A widely used type of body hammer with a pointed end on one side and a shallow domed end for finishing on the other side

Picker: See
Electro picker

Picker set: See
Lock picker set

Pick hammer: A hammer with a round head for conventional planishing and a small pick-shaped head for working away in sharp or tight corners. It should not be confused with a Bullet-point pick hammer, which has a more blunt pick, nor with a Pein hammer

Picking: See
Panel picking

Pickle park: Trucker slang for a rest area as in "I don't often park overnight in the pickle parks."

Pickle park pinger: Trucker slang for a CB with a roger-beep as in "I don't care much for them pickle park pingers."

Pickling: The removal of oxide or mill scale from the surface of a metal by immersion, usually in an acidic or alkaline solution

Pickling attack: The initial chemical reaction between phosphating solutions and metal surfaces in phosphate treatment

Pickum-up: Trucker slang for pick-up truck, light truck as in "Watch out for that pickum-up truck broke down in the right lane."

Pickup

A utility truck with a closed cab and an open box. In Australia it is called a utility or ute.
The transfer of material, as between bearing and shaft, caused by friction and heat due to lack of oil; can lead to seizure.
A Pick-up coil
A Yoke -- a triangular metal piece used to connect the main brake cable with the stirrup cable in a bicycle's centerpull brake system

Also see
Balanced-armature Pick-up
Magnetic Pick-up
Oil Pick-up
Profile Ignition Pickup
Transistorized Ignition With Inductive Pick-up
Transistorized Ignition With Magnetic Pick-up

Pick-up

A utility truck with a closed cab and an open box. In Australia it is called a utility or "ute."
The transfer of material, as between bearing and shaft, caused by friction and heat due to lack of oil; can lead to seizure.
A Pick-up coil or Yoke.

Also See
Magnetic pick-up
Magnetic pick-up assembly
Magnetic pick-up tool
Oscillating pick-up ignition system
Transistorized ignition with inductive pick-up
Transistorized ignition with magnetic pick-up

Pick-up assembly: See
Magnetic pick-up assembly

Pickup camper: See
Truck camper

Pickup coil: See
Pick-up coil.

Pick-up coil: The coil in which Voltage is induced in an Electronic ignition. Inputs signal to the electronic control unit to open the primary circuit. Consists of a fine wire coil mounted around a permanent magnet. As the reluctor's ferrous tooth passes through the magnetic field, an alternating current is produced, signaling the electronic control unit. Can operate on the principle of metal detecting, magnetic induction, or Hall Effect. It is also referred to as a stator or sensor.

Pick-up ignition: See
Oscillating pick-up ignition system

Pick-up ignition system: See
Oscillating pick-up ignition system

Pick-up module: A trigger-activated device which sends a signal to the ignition unit of an electronic ignition system

Pick-up pipe: See
Oil pick-up pipe

Pick-up screen: See
Oil pump strainer

Pick-up tool: A tool with a flexible or rigid shaft and a claw type pick-up end; used to retrieve small objects from hard-to-reach areas.
Also see
Magnetic pick-up tool

Pickup Truck: See
Large Pickup Truck
Small Pickup Truck

Picture: See
Scavenging picture

Picture machine: Trucker slang for a radar as in "Watch out for the picture machine at the corner of 9th and Wilcox."

Picture taker: Trucker slang for police with radar as in "There's a picture taker at the 27 mile marker."

PID: Acronym for Parameter Identification Location

PID SUP: Acronym for Parameter Identification Supported

Piece: See
Blanking piece
Breaking Piece
Distance piece
Extension
Pole piece
Sill end piece

Pien hammer: See
Ball pien hammer

Pierce-Arrow

A vehicle brand of which the following models are classic cars:

1921 Series 32
1922 and up Series 33
All models from 1925

Pierced steel planking: PSP

(PSP) A sheet of steel about 30cm wide and about one meter long with a series of holes and ridges. When placed under the driving wheels of a vehicle that is stuck in sand or snow, it helps to give traction.
Also see
Sand channels
Sand ladders
Sand tracks

Piezoelectric

Property of quartz crystal that causes it to vibrate when a high frequency (500 kHz or higher) voltage is applied. Concept is used to atomize water in a humidifier.
Having the ability to generate a voltage when mechanical stress is applied, as in a piezoelectric crystal.

Piezoelectric ignition: A system of Ignition that employs the use of a small section of Ceramic-like material. When this material is compressed, even a very tiny amount it emits a high Voltage that will fire the plugs this system does not need a Coil, points or Condenser.

Piggyback

A semitrailer built with reinforcements to withstand transport by a railroad
The way empty log trailers are carried on the bed of a tractor such that no axles touch the ground. Also may refer to other kinds of vehicles carried on the rear of a power unit in a manner that axles do touch the road.

Also see
flatcar
TOFC

Piggyback cargo: Truck carrying motor vehicles piggyback-style on a power unit. The trucks being carried have their front axles off the ground resting on the vehicle in front. Several vehicles may be hitched together in this way. This category is also used for wreckers towing a vehicle. Piggyback also refers to the way empty log trailers are carried on the bed of a tractor such that no axles touch the ground. Also may refer to other kinds of vehicles carried on the rear of a power unit in a manner that axles do touch the road.

Pig iron: Produced in blast furnaces, pig iron is the raw material for practically all iron and steel products; contains about 3-5 percent carbon
Also see
Bessemer Pig Iron

Pigment: Finely ground powders in the paint that give it its color.

Pigtail: A cable used to transmit electrical power from the tractor to the trailer. So named because it is coiled like a pig's tail.
Also see
Wiring pigtail

Pike: A broad highway designed for high-speed traffic
Also see
Turnpike

Pile: This is a steel or concrete bar which is driven into the ground to form part of the foundations for a building.
Also see
Bearing Pile
Cast-in-situ Concrete Piles
Scrap pile

Pile caps: The structure built on top of piling to support the bridge beams.

Pile Voltage Transformer: See
Carbon Pile Voltage Transformer

Piling

The build-up of metal on a contact breaker point. The opposite is Pitting
A heavy beam of timber, concrete, or steel driven into the earth as a foundation or support for a structure.

Pill: A jet in the fuel-return line which establishes the mixture

Pillar: A shaft or upright member or support holding up the roof. Also called a Post. The A-post holds up the windshield. The B-post is behind the front door about in the middle of the side of the roof. The C-post holds up the rear window. In station wagons, another post is placed between the B-post and the last post so that it becomes the C-post and the last post is the D-post.
Also See
A-pillar
B-pillar
C-pillar
Center pillar
D-pillar
Dogleg pillar
Dogleg pillar
Door pillar switch
Door pillar
Hinge pillar reinforcement
Hinge pillar
Latching pillar
Roof pillars
Windshield pillars

Pillared hardtop: See
Four-door pillared hardtop

Pillar jack: See
Tower jack

Pillar light: A courtesy light mounted on the central pillar within the passenger compartment

Pillar reinforcement: See
Hinge pillar reinforcement

Pillar switch: See
Door pillar switch

Pillion pad: A backrest pad which is mounted behind the seat on a motorcycle.

Pilot

A small fuel flame used to ignite the fuel at the main burner.
When you want to drill a large hole into a piece of metal, the drill will have difficulty making the cut properly. So if you drill a small hole first, the larger hole will be easier to make. The small hole is a pilot hole or a pilot bore.
If you are mating two pieces of metal (like the cylinder head to the cylinder) with a gasket in between, it can be difficult to line things up properly. So a temporary rod or stud is inserted to make it easier. Once it is lined up, the rod or stud is removed. The rod or stud is a pilot.
A person who operates an airplane.

Also see
Automatic Pilot
Circuit Pilot
Proved Pilot
Test Pilot

Pilot bore: See
Pilot

Pilot bearing: A small bearing in the center of the flywheel end of the crankshaft, which carries the forward end of the clutch shaft. The British term is spigot bearing.
Also see
Clutch pilot bearing.

Pilot car: A car specifically marked to lead traffic through a construction or work zone.

Pilot circuit: Secondary circuit used to control a main circuit or a device in the main circuit.

Pilot hole: When using a large drill bit, it is sometimes hard for the drill to cut through the metal and do it evenly in a straight line. A pilot hole is first made with a small bit. Then, when you use the large bit, the drilling is much easier.

Pilot house: The enclosed space on the navigating bridge from which a ship is controlled when under way.

Pilot jet: A jet in the idling circuit of a fixed jet carburetor which measures and admits fuel

Pilot operated absolute: See
POA suction throttling valve

Pilot operated absolute valve: (POA) A suction throttling device used on some GM and Ford air conditioner system.

Pilot point: Similar to a "B" point, a pilot point is a small (perhaps 1/8" to 1/4") unthreaded blunt portion at the end of a sheet metal or drive screw.

Pilot Program: See
California Pilot Program

Pilot shaft: A dummy shaft that is placed in a mechanism as a means of aligning the parts. It is then removed and the regular shaft installed.

Pilot valve: A small valve used to control action of a larger valve

Pin: A small cylinder used for fastening something or as a pivot.

Also See
Alignment Pin
Anchor Pin
Blow Pin
Bonnet pin
Carbon pin
Clevis Pin
Cotter pin
Dowel pin
Escutcheon pin
Floating piston pin
Fulcrum pin
Gudgeon pin
Gudgeon pin boss
Gudgeon pin circlip
Gudgeon pin end
Guide Pins
Hair pin
Hitch pin
Hood Pin
Hood pin kit
Hood pins
Kingpin
Locating pin
Lock pin
Lynch Pin
Pad retainer pin
Pawl
Piston pin
Piston pin circlip
Piston pin end
Quick Release Hitch Pin
Roll pin
Safety Pin
Shear pin
Slotted Pin
Spiral wrapped pin
Split pin
Taper Pin
Tri pin
Worm and taper pin
Wrist pin

Pin boss: See
Gudgeon pin boss
Piston boss

Pinch-off pliers: See
Hose pinch-off pliers

Pinch Point

A sharp conical point, usually of 45 degrees included angle, formed by a pinching operation.
Traffic calming measure where sections of the road are narrowed to reduce speed

Pin circlip: See
Gudgeon pin circlip
Piston pin circlip
Wrist pin circlip

Pin Clip: See
Hitch Pin Clip

Pin Cotter: See
Hair Pin Cotter

Pin end: See
Gudgeon pin end
Piston pin end
Wrist pin end

Ping: See
Pinging.

Pinging: A metallic rattling sound produced by the engine during heavy Acceleration when the Ignition timing is too far advanced for the grade of fuel being burned. The noise is caused by vibrations in the Cylinder walls, Head, and Piston. When an engine pings, the normal, controlled even spread of the Flame front is disrupted by the spontaneous Combustion of pockets of fuel. Their collision sets off the pressure waves that result in the pinging sound. Pinging can be caused by bad Timing, inadequate octane rating, incorrect Fuel-air mixture, a Hot spot in the Combustion chamber caused by a glowing piece of Carbon, or an overheat condition. Also called Knocking.
Also see
Detonation.

Pinhole: See
Rust pinhole

Pinholing: Tiny bubbles in the paint finish that are often grouped together. It is caused by trapped solvents, moisture or air released from the film. Compare Solvent pop

Pinion: A small, tapered gear which meshes with a larger gear or rack. It is found in two primary places in an automobile the Differential pinion and the Rack and pinion steering.
Also See
Crown wheel and pinion
Differential Pinion
Drive pinion
Inertia pinion
Rack and pinion gearbox
Ring and pinion

Pinion carrier: That part of the rear axle assembly that supports and contains the Pinion gear shaft.

Pinion gear: Pinion gear

The smaller of two meshing gears. A pinion gear is used in a Starter motor to engage the Flywheel ring gear and also rides along the surface of the Steering rack (a rod with grooves cut in it to mesh with the gear)
Also see
Rack and pinion gearbox.

Pinion gearbox: See
Rack and pinion gearbox

Pinion shaft: Pinion shaft

A short drive shaft in the rear axle connecting the prop shaft to the crown wheel via the final drive pinion

Pinion steering: See
Rack and pinion steering

Pinking: A British term for Pinging

Pin kit: See
Bonnet pin kit
Hood pin kit

Pin lock: Pin lock

A pin with a hole at one end through which a Hair pin cotter is thrust to secure it in place.

Pinned piston ring: A steel pin, set into the Piston, is placed in the space between the ends of the ring. The ring is thus kept from moving around in the Groove.

Pinned ring: A steel pin, set into the Piston, is placed in the space between the ends of the ring. The ring is thus kept from moving around in the Groove.

Pinning: Procedure for repairing cracks in the combustion chamber using threaded pins

Pin punch: A tool with a parallel shaft for use with a hammer to drive out pins, shafts, rivets, etc. Compare Drift punch

Pin slider caliper disc brake: A disc brake design with a sliding caliper. The major components are caliper (a casting with one cylinder and piston), caliper frame (casting), guide pins, Teflon or rubber sleeves/bushings. The caliper floats on the sleeves over the guide pins. The guide pins are threaded or riveted to the caliper frame. The caliper frame is bolted to the suspension

Pin spanner: A wrench with pins on forked ends, used to turn an Adjustable cup on a Bottom bracket of a Bicycle.

Pin Spring And Retainer: See
Hold-down Pin Spring And Retainer

Pinstripe: A thin, precisely contoured lines along certain body features; they may extend along the whole car and finish off in elaborate, bouquet-like designs. Striping usually refers to simple decorative lines, e.g., on motorcycle tanks, while pinstriping mostly refers to custom work, i.e., more elaborate and sharply curved lines

Pinstriping: A thin, precisely contoured lines along certain body features; they may extend along the whole car and finish off in elaborate, bouquet-like designs. Striping usually refers to simple decorative lines, e.g., on motorcycle tanks, while pinstriping mostly refers to custom work, i.e., more elaborate and sharply curved lines

Pinstriping tool: A painting tool used to apply thin, precise lines on the body, e.g., on motorcycle tanks and to enhance car body contours.

Pintaux nozzle: A pintle-type diesel fuel injector nozzle with a hole in the side through which a very small amount of fuel is sprayed when the needle valve is partly opened at low pressure, before the main hole comes into use

Pintle

The needle of the injection valve in a diesel fuel injector.
A vertical bolt or pin in a towing bracket, to which the towbar is attached.
The top of some types of valves
The pins or bolts that hinge the rudder to the gudgeons on the rudder post or sternpost

Pintle Hook: A coupling device used in a 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.

Pintle nozzle: An injector nozzle containing the Pintle

Pin wrench: A wrench with a pin that can be fitted into a hole in a nut to exert extra pressure

Pioneer roads: Temporary access ways used to facilitate construction equipment access when building permanent roads.

PIP: Acronym for Profile ignition pickup

Pipe: A tube used to transfer liquid or gas. Rigid conduit of iron, steel, copper, brass, aluminum, or plastic.
Also See
Balance pipe
Blast Pipe
Brake pipe
Breather pipe
Bustle Pipe
Chain pipe
Discharge pipe
Distributor Pipe
Downpipe
Exhaust pipe
Feed pipe
Flexible brake pipe
Front pipe
Gas Forced-air Heat Pipe
Hawse pipe
Heater air pipe
Impact pipe
Induction pipe
Intake pipe
Kickup pipe
Lake Pipes
Lakes Pipes
Oil breather pipe
Oil pick-up pipe
Outlet pipe
Overflow pipe
Side pipe
Sounding pipe
Suction pipe
Tail pipe
Y-pipe

Pipe Caps: A cap that threads onto a pipe (like a nut) to seal one end.

Pipe Fitting: Any form of connecting parts which join together pieces of pipe.

Pipe Gas Forced-air: See
Heat Pipe Gas Forced-air

Pipe Plug: A short piece of threaded pipe, slotted, square head or socket, used to close up one end of a pipe fitting

Pipes: See
Exhaust system
Lake pipes
Lakes pipes

Pipe Thread: American Standard pipe threads are tapered 1 inch in 16, or 3/4 inch per foot. They are 60 degree threads, of National form with flat or rounded top and bottom.
Also see
American Standard Pipe Thread
British Standard Pipe Thread

Pipework: A system of Pipes

Pipe wrench: An Adjustable wrench with serrated jaws. The most common type of pipe wrench is the so-called Stilison wrench. Also called a monkey wrench.
Also see
Chain pipe wrench

Piping

A system of Pipes.
A rubber or plastic strip inserted between two removable panels, i.e., between a bolt-on fender and the body, to cover up the joint and to prevent water getting in; with the piping inserted, only the round bead along the upper edge of the piping is visible
A seam in upholstery where the edge of the material is folded over a cord

Pip mark: A little dot or indentation which indicates the top side of compression ring

Piquet, Nelson: A three-time, World Driving Champion from Brazil and is considered one of the all-time great Formula One drivers

Piston: Click image to supersize
piston

A round or cylindrical plug, which closed at one end and open at the other. It slides up and down in the Cylinder. It is attached to the Connecting rod and when the fuel charge is fired, will transfer the force of the Explosion to the Connecting rod then to the Crankshaft.
Also See
Accumulator piston
Alloy piston
Articulated Pistons
Autothermic piston
Belted piston
Brake piston
Cam-ground piston
Charging piston
Collapsed piston
Damper piston
Deflector piston
Displacement Piston
Flat-topped piston
Flat-top piston
Floating piston pin
Floating piston
Flow Check Piston
Full-skirt piston
Hydraulic Piston
Molybdenum piston ring
Operating piston
Oval piston
Oversize piston
Pent crown piston
Pinned piston ring
Primary piston
Pump Reciprocating Single Piston
Secondary piston
Slipper piston
Split skirt piston
Stepped piston

Piston bore: The diameter of the hole in the cylinder block in which the piston moves back and forth between top dead center (TDC) and bottom dead center (BDC)

Piston boss: The built-up area around the Piston pin hole.
Also see
Boss.

Piston Caliper: See
Four Piston Caliper

Piston charging pump

The function of the piston of the two-stroke engine to pre-compress the fresh charge induced into the crankcase.
A separate piston used in earlier two-stroke engine designs to provide a supercharging effect

Piston clearance: The distance between the piston and the cylinder wall.

Piston collapse: A reduction in the diameter of the Piston skirt caused by heat and constant impact stresses.
Also see
Collapsed piston.

Piston compression ring: A ring which surrounds the Piston and fits in a grove in the piston. It is designed to seal the burning fuel charge above the piston. Generally there are two compression rings per piston and they are located in the two top Ring grooves. They also help to transfer heat from the piston into the Cylinder walls and subsequently to the Water jacket surrounding the Cylinder.
Also See
Grooved compression ring
Tapered compression ring

Piston compressor: A compressor in an air-conditioning system with one or more pistons arranged in either an in-line, axial, radial, or V-configuration

Piston crown: Piston crown

The very top of the piston. The piston crown transmits the pressure created during the ignition of the air/fuel mixture to the piston pin, then to the connecting rod, and from there to the crankshaft. The diameter of the piston crown is slightly smaller than the piston skirt. Also called Piston dome.

Piston-crown combustion chamber: Click image to supersize
Piston-crown Combustion Chamber

The volume in the cylinder above the piston on the compression stroke that is used in diesel truck engines and in some European gasoline automobile engines. The advantage in simply machining a flat surface on the cylinder head is offset by the added cost of machining the bowl in each piston and by increased piston weight.

Also See
Hemispherical combustion chamber
Bathtub combustion chamber
Wedge combustion chamber
Squish combustion chamber

Piston damper: A small damper piston in an SU or Stromberg carburetor which reduces the movement of the large air piston in the venturi

Piston diaphragm: A flexible membrane which displaces under pressure, imparting movement to the piston in a Stromberg carburetor

Piston displacement

Amount (Volume) of air displaced by a Piston when moved through the full length of its stroke.
Volume obtained by multiplying area of cylinder bore by length of piston stroke.

Also see
Displacement.

Piston dome: The top surface of a Piston. It is often shaped for better combustion and to prevent a valve from contacting the surface.
Also see
Piston crown
Piston head.

Piston engine: A form of internal combustion engine. It is a heat engine in which the expansion of gas causes (by the explosion or a fuel and air mixture or the introduction of steam) a piston inside a cylinder to move and turn a crank shaft.

Piston expansion: Because pistons are usually made of aluminum and the cylinder walls are made of iron, the piston will expand more rapidly than the cylinder when they get hot. Some type of compensation needs to be made for this expansion or the piston will seize in the cylinder.

Also See
Split skirt
T-slot
Steel strut
Cam-ground piston

Piston extension screw: A stroke limiting screw between the primary piston and secondary piston stop

Piston head: That portion of the Piston above the top ring.

Also See
Piston dome
Piston crown

Piston land: That portion of the Piston which is between the Ring grooves.

Piston lands: That portion of the Piston which is between the Ring grooves.

Piston lifter: A pin in the base of the piston chamber in an SU or Stromberg carburetor, used to check the strength of the mixture and the free movement of the piston

Piston material: The materials from which pistons are made are grey cast or light alloys; most light alloys consist of an aluminum-silicon alloy

Piston pin: Piston pin

A steel pin that is passed through the Piston, it is used as a base upon which to fasten the upper end of the Connecting rod. It is round and may be hollow. Also called wrist pin or gudgeon pin.
Also see
Floating piston pin

Piston pin boss: See
Piston boss.

Piston pin circlip: A Circlip which is used on either end of the piston pin to hold the pin in place. Also called snap ring.

Piston pin end: The small end of the connecting rod through which the piston pin is inserted

Piston Pump: See
Reciprocating Single Piston Pump

Piston ring: A metal, split ring installed in the Groove on the outside wall of the Piston. The ring contacts the sides of the Ring groove and also rubs against the Cylinder wall thus sealing the space between the piston and the wall. Poor rings can cause poor Compression and severe Blowby. Often seen as blue smoke out the Exhaust pipe.
Also See
Compression ring
Dykes ring
Molybdenum piston ring
Oil control ring
Pinned piston ring

Piston ring, chrome: See
Chrome ring

Piston ring clamp: A special automotive tool used for installing pistons. The clamp is slipped over the piston and when tightened, compresses the piston rings into the piston grooves. With the piston rings compressed, the piston can be installed into the cylinder by light tapping

Piston ring end gap: The distance left between the ends of the ring when installed in the Cylinder.

Piston ring expander: A spring device placed under a Piston ring to hold it snugly against the Cylinder wall.
Also see
Expander.

Piston ring flutter: The oscillations of a piston ring which mainly occur at high engine speed and thus can cause breakage

Piston ring gap: See
Piston ring end gap.

Piston ring groove: One of the channels into which the piston rings reside.

Piston ring groove cleaner: A special automotive tool to remove carbon and varnishes from piston grooves before installing piston rings

Piston ring job: Reconditioning the Cylinder and installing new rings.

Piston ring, oil control: See
Oil control ring.

Piston ring, pinned: See
Pinned piston ring

Piston ring pliers: A pliers-like special automotive tool used to spread and slip piston rings over a piston for removal and installation

Piston ring ridge: That portion of the Cylinder above the top limit of ring travel. In a worn cylinder, this area is of a smaller diameter than the remainder of the cylinder and will leave a ledge or Ridge that must be removed.

Piston ring side clearance: The space between the sides of the ring and the ring Lands.

Piston ring stop: A pin pressed into the ring grooves of a two-stroke engine in order to prevent the rings from rotating, which would allow the open ends to become jammed in the ports

Piston rocking: See
Piston slap

Piston rod: A shock absorber rod which operates the piston in a telescopic damper

Piston seal: A fluid seal on a disc brake caliper piston

Piston seizure: A sudden stalling of the engine, caused by the piston becoming stuck in the bore; this is often caused by overheating or lack of lubrication and often leaves severe score marks in the cylinders and on the skirt of the piston.

Piston skirt: Piston skirt

The portion of the Piston below the rings and Bosses. It absorbs the thrust caused by the Crankshaft as it makes contact with the Cylinder wall. (Some engines have an Oil ring in the skirt area, though not common.)

Piston skirt expander: A spring device placed inside the Piston skirt to produce an outward pressure which increases the diameter of the skirt.

Piston skirt expanding: Enlarging the diameter of the Piston skirt by inserting an Expander, by Knurling the outer skirt surface, or by Peening the inside of the Piston.

Piston slap: The condition caused by too much Clearance between the Piston and the Cylinder walls. The piston rattles or slaps against the wall of the cylinder. It makes a hollow, muffled, bell-like sound. Also called piston rocking.

Piston speed: The speed of the piston for a given engine rpm

Piston spring: A coil spring in an SU carburetor which counteracts the upward movement of the piston

Piston stops: Tabs, or protrusions, on a backing plate positioned to prevent the wheel cylinder pistons from leaving the wheel cylinder.

Piston thrust: The pushing action of the piston which occurs at the sides of the piston 90° away from the piston pin as it pushes against the cylinder wall.

Piston Tool: See
Brake Piston Tool

Piston top: See
Piston crown

Piston-type compressor: A compressor in an air-conditioning system with one or more pistons arranged in either an in-line, axial, radial, or V-configuration

Piston-valve engine: A two-stroke engine that relies on the ports in the cylinder walls to control admission and exhaust of the air/fuel mixture; it is not equipped with other control elements such as rotary valves

Pit

Area at a race track for fueling, tire changing, making mechanical repairs, etc.
Small craters in the surface of metal.

Also See
Borrow Pit
Catch Pit
Cockpit
Inspection pit

Pitch

The back and forth rocking motion of a vehicle which compresses the front springs and extends the rear springs so that the nose of the vehicle is down while the tail is up. Then the action reverses so that the nose is up and the tail is down (i.e., dive and Squat).
The distance between two adjacent threads on a bolt or screw measured at the outside diameter of the threads.
The distance, measured parallel to its axis, between corresponding points on adjacent thread forms in the same axial plane and on the same side of the axis.
The distance between a point on one gear tooth and the same point on the next gear tooth.
The quality of sound with respect to the frequency of vibration of the sound waves.
The angle at which something is tilted.
In Britain, a parking space or site for a trailer, camper, etc.

Also See
Auto Coarse Pitch
Axial Pitch
Coarse pitch
Variable pitch stator

Pitch circle: (PC) the circumference on which the centers of the wheel bolt holes are located

Pitch circle diameter: (PCD) The diameter of the stud holes/bolt holes for fixing the wheel to the hub. The pitch circle (PC) is usually shown as a double number, e.g., 5-5.5. The first number indicates the number of holes, and the second, the diameter of the PC

Pitch control: See
Bump stop

Pitch diameter: On a straight thread the diameter of the coaxial cylinder the surface of which would pass through the thread profiles at such points as to make the width of the groove equal to one-half of the basic pitch. Approximately half way between the major and minor diameters.

Pitch gauge: See
Screw pitch gauge

Pitch Line: A generator of the cylinder or cone of a screw thread specified in the definition of pitch diameter.

Pitch Pulley: See
Variable Pitch Pulley

Pitch stator: See
Variable pitch stator

Pitman arm: A short lever arm Splined to the Steering gear Cross shaft, the pitman arm transmits the steering force from the Cross shaft to the Steering linkage system. In this way rotary motion of the Steering wheel is turned to lateral movement of the arm. The British term is drop arm.
Also see
Idler arm.

Pitman shaft: See
Rocker shaft

Pitot tube: A tube for measuring the pressure and velocity of a fluid flow; in some CVTs, used in conjunction with a valve arrangement to control ratio changes

Pit road: The paved roadway that leads into the pit area from the racetrack.

Pits

Area at a race track for fueling, tire changing, making mechanical repairs, etc.
Cavities extending from the surface into the metal as a result of pitting corrosion or rust.

Also see
Shallow pits

Pit stop

A stop at the pits by racer, for fuel, tires, repairs, etc.
Colloquial term for going to the toilet.

Pittards: Leather A high quality, natural, supple, and quick drying leather

Pittards leather: A high quality, natural, supple, and quick drying leather

Pitted: Eroded Contact breaker points

Pitting: Surface damage to a metal in the form of pits or holes. The opposite is Piling

Pitting corrosion

A corrosion process resulting in Pits
Deep corrosion in localized spots on an object--even stainless steel. Dirt or grease on certain portions of the object may block oxygen from that surface, thus impeding the passive film which protects stainless from corrosion.

Pitting factor: The ratio of the depth of the deepest pit to the average penetration as calculated from weight loss

PIV: Acronym for Peak Inverse Voltage

Pivot: A pin or shaft about which a part moves. The place at which a lever swivels. A lever cannot work without a pivot.
Also see
Low pivot swing axle
Pedestal Pivot

Pivot axis: See
Kingpin axis

Pivot bolt: A bolt on which the arms of Caliper brakes pivot and which also serves as the means for mounting the brakes on the bike Frame. Also called Mounting bolt.

Pivot pin: See
Kingpin

Pivot ring: See
Fulcrum ring

Pivot swing axle: See
Low pivot swing axle