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RC Glossary


New to the RC Hobbies? What does buggy, bulkhead, nitro mean in radio control car hobbies? Check out the glossary for remote control cars below.


  • Pan Car --
  • "In RC terms, this is a car that is made from a flat """"pan"""" of graphite or fiberglass, with an independent front suspension and straight-axle rear """"pod"""". These cars are rear-wheel drive only and use foam tires. RC Formula 1 cars fall into this category, although the front suspension uses much longer arms and the chassis is narrower. HPI no longer makes pan cars at this time."

  • Panasonic --
  • A manufacturer of batteries around the world. Until recently, with the release of their 3000 mAh capacity Ni-MH type cells, they were considered to be behind Sanyo in quality. The recent release of Sanyo's own nickel-metal hydride batteries will be the first direct competition of nearly identical batteries from these manufacturers in over a decade.

  • Parallel (Battery Wiring) --
  • Rare in RC, this refers to assembling a battery pack with the cells connected in a positive (+) to positive (+) and negative (-) to negative (-) configuration. This increases capacity (run time) without increasing voltage (power). A 6 cell, 1200 MAH NiCad battery pack wired in parallel would only produce 1.2V, but would provide 7200 MAH.

  • Parallel (Motor Wiring) --
  • Refers to the method of attaching 2 motors to a single speed controller. With parallel wiring, both motors are connected directly to the controller - positive (+) to positive (+) and negative (-) to negative (-). This method basically causes both motors to act as a single motor at 1 / 2 the number of turns (thus 2 38T motors would act as 1 19T motor), which results in faster speeds at the expense of torque and run time. This doubles the amp draw of the motors, but both motors will still spin at the same RPM. Also note that the halved motor turn is used to determine if your speed controllers motor limit would be exceeded.

  • Pattern Winding (Brushed Motor) --
  • A method of winding the wire around an armature in a stepped or triangular pattern to help balance the armature.

  • Pawl (Type) 2 Speed Transmission --
  • A type of 2 speed tranny that uses a spring loaded 'finger' on the second gear hub that engages the gear once a certain RPM is reached. Pawl type transmissions tend to be lighter, easier to adjust, and have fewer parts than clutch type transmissions. However, pawl type trannys tend to engage harder, which may not be suitable for low traction surfaces. The engagement point is adjusted by spring tension - more tension = later (harder) engagement, less tension = sooner (softer) engagement.

  • PCM íVPulse Code Modulation --
  • A type of transmitter and receiver that is even less prone to glitching than FM radio systems. Although more expensive than FM radios, PCM radios were very popular until FM radios got cheaper and almost as glitch-free.

  • Peak --
  • The point where a rechargeable battery is fully charged and more voltage would only create damaging heat or venting.

  • Peak Charger --
  • The recommended type of charger for nickel-cadmium batteries. Although not recommended for nickel metal-hydride batteries, these chargers can charge these types of batteries, but they must be monitored for temperature (so they don't rise above 110 degrees Fahrenheit) and voltage.

  • PGR --
  • Abbreviation for Primary Gear Ratio.

  • Pillow Ball íV Pillow Ball Suspension --
  • A pillow ball is basically an over sized ball stud, used to hold the knuckles (hubs) to the arms on pillow ball (A arm) type suspensions. Screwing the pillow balls in or out of the arms adjusts camber and track width. The hubs on pillow ball suspensions are held in place with pillow ball retainers (big azz hex head retaining screws), and plastic or nylon spacers (a.k.a. bushings).

  • Pilot Shaft --
  • Refers to the end of the crankshaft that the flywheel and clutch assembly attaches to. There are 2 basic types of pilot shafts used for RC engines - the standard (fully threaded) pilot shaft and the smooth ground pilot shaft (a.k.a. an SG - Smooth Ground, or IPS - Integrated Pilot Shaft). The standard pilot shaft often requires a sleeve or screw on pilot shaft for clutch mounting, while the smooth ground styles readily accept clutches. The later tends to reduce vibration compared to standard shafts, and is currently the industry standard for nitro engines.

  • Pinch Bolt --
  • A bolt with a rounded concave indention on the shaft - used to hold the carb in place on most nitro engines. The bolt is inserted through a hole in the block's carb neck and situated so the carb can be inserted and keyed to the indent. The bolt is then tightened (with a nut), cinching the carb in place. Do not overtighten the pinch bolt, as this could crack or damage the carb body.

  • Pinch Zone --
  • A nitro engine's sleeve tapers in near the top to help the piston seal the combustion chamber and improve compression. If you rotate an engines crank, you will notice increased resistance as the piston reaches TDC and passes through this tapered area, which is known as the pinch zone. As the engine heats up and the parts expand, this resistance becomes less noticeable. A common rule of thumb to quickly see if an engine is still in good condition is to rotate the crank and judge how much resistance is felt at the pinch zone - if its hard to turn the crank past TDC, you're makin' power, if you dont feel any resistance, you may have a really cool paper weight.

  • Pinion Gear --
  • In electric RC cars, this is the gear that attaches to an electric motors output shaft, which in turn spins the spur gear, turning the rest of the drive train. Pinion gears are rated by pitch (such as 32P, 48P or 64P), and usually have the total number of teeth stamped somewhere on the face (i.e. a 13T pinion would have 13 teeth). Always use a pinion with the same pitch as the spur gear. Using a pinion with fewer teeth increases acceleration, while using a pinion with more teeth increases top speed. Pinions are available in 1 tooth increments (12T, 13T, 14T, ect). The clutchbell of a nitro engine may also be refered to as a pinion.

  • Pipe Hanger --
  • A length of wire used to suspend a tuned pipe in the desired location, and designed to flex or give during impacts to prevent damage to the pipe. The wire is attached to the pipe and chassis with either a 'loop and bolt' system, setscrews, or collars. Music wire is usually used to make pipe hangers, but clothes hanger wire makes an excellent pipe hanger in a pinch.

  • Piston (Brake) --
  • Found on nitro and gas models that use cam style brakes - a brake piston transfers motion from the cam to the calipers, pressing them against the brake or pad to slow the model down. Brake pistons are usually free floating, small brass cylinders.

  • Piston (Engine) --
  • The part of a nitro or gas engine that seals the combustion chamber and transfers the explosive power of the fuel to the crankshaft via the connecting rod.

  • Piston (Shock) --
  • The thick disc that attaches to the end of the shock shaft and slides up and down inside the shock body. A shock piston will have one or more holes drilled through it that allows the shock fluid to pass through as the piston moves inside the shock. These holes, along with the shock fluid weight and spring rate, affect the shocks damping (bound and rebound) rate. Basically, more holes (or larger holes) allow the fluid to pass through quicker, speeding up the damping rate. Fewer holes (or smaller holes) restrict the fluid, slowing down the damping rate.

  • Piston Locker --
  • A cylindrical tool that is threaded into the glow plug hole of a nitro engine to prevent the crank from turning while the clutch nut is loosened or tightened. This performs the same function as a flywheel wrench, but many prefer the wrench since it doesn't put pressure on the connecting rod.

  • Piston Port --
  • Refers to the holes in some piston skirts that allow the air/fuel mixture trapped below the piston to reach other ports in the engine. If the wrist pin mounting holes suddenly become piston ports, you may have a problem.

  • Piston Skirt --
  • The lower 'hollow' portion of the piston that helps keep the piston aligned with the sleeve. There is usually a cut out in the piston skirt to allow clearance for the back plate while the piston is at BDC.

  • Pit Box --
  • What you use to haul tools, spare parts, and supplies to the track or area where you are going to run. A pit box may be as simple as a cardboard box, or a multi-drawer, RC specific wheeled behemoth.
    Either way, stock it with everything you need and plaster it with as many decals as you can (this adds valuable style points).

  • Pit Lane --
  • The area on the side of a track that is reserved for models that require refueling, tuning, or repairs. The pit lane is usually located directly in front of the drivers stand.

  • Pit Towel --
  • A towel or mat you place your model on while wrenching or inspecting. A pit towel helps to prevent small parts or screws from bouncing away, soaks up oils and grease, and protects your work surface. Many companies offer RC specific pit towels, but in a pinch, those fancy guest towels your mother / wife / girlfriend are so proud of will also work.

  • Pitch - P --
  • "The measure on a pinion gear or spur gear of how many teeth fit per inch. On a 64-pitch gear, 64 teeth will fit within one inch; on a 48-pitch gear, 48 teeth will fit in one inch. HPI offers both 64-pitch and 48-pitch gears for electric cars. HPI Nitro cars use a unique pitch called """"one module"""", abbreviated by """"1M"""" in part descriptions. It is a metric pitch that is ideal for Nitro cars, which run on dirty parking lots. Nitro cars also suffer from engine vibrations, which can loosen."

  • Pivot-Ball Suspension --
  • A type of suspension system brought to scale Touring Cars from 1/8 scale Nitro cars. Instead of the more common lower suspension arm/upper turnbuckle link, the pivot-ball suspension uses inner hinge pins and screws on the outer pivots that adjust camber and track. The caster is adjusted by moving clips on the inner upper hinge pin.

  • Planetary Gears --
  • Commonly found in diffs, this gear system consists of a series of small gears revolving around a larger center gear (much like the planets revolving around the sun, only much, much smaller). This is commonly used with enclosed diffs, where the diff is integrated into the gear train inside a tranny case (such as with 3 gear trannys).

  • Play --
  • See Mesh

  • Plugging Pulse --
  • Refers to the wave of pressure created by the convergent cone in a tuned pipe. This wave of pressure is returned to the engine at around the speed of sound, 'plugging' the exhaust port just before it closes and pushing over scavenged air/fuel mixture back into the combustion chamber. The effect of the plugging pulse may be referred to as 'supercharging'.

  • Pole Position --
  • A start position for a race where a car is in the very front of the starting grid. Usually the most desirable position to start from, because other cars must pass you to be in the lead.

  • Polycarbonate --
  • A.K.A. Lexan. A flexible, durable plastic molded using the vacuum forming process. Polycarbonate is the status quo for RC bodies.

  • Polystyrene --
  • A rigid plastic used in the injection molding process for some scale RC bodies (a.k.a. 'hard bodies') and scale details. Most buggy and truggy wings are also molded from polystyrene.

  • Pork --
  • Refers to the un-needed excess weight on a model. For RC, pork is usually measured in grams or fractions of an ounce - for the government, it's usually measured in billions of dollars. Unless someone owns you (and the ride you rode in on), the weight of your ride can easily be reduced - the government is a different story.

  • Port --
  • The openings or passageways in a nitro engine's sleeve and crankcase that transfer the air/fuel mixture and exhaust gasses while the engine is running. Ports are opened and closed by the piston as it moves up and down in the sleeve (the induction port is opened and closed by the crank's rotation). The port position, area, and shape affect engine timing and performance. In gas engines (fuelies), the intake and exhaust ports are conventional valve operated openings above the combustion chamber. Nitro engines are commonly rated by the number of ports in the sleeve - unless otherwise noted, the number usually does not include the crank or exhaust ports, but does include satellite and guide ports. Either way, more ports do not guarantee more power.

  • Port --
  • An opening in the sleeve of a nitro engine.?Modifying the port size and shape can affect the power and fuel consumption of an engine, but the modification is best left to a professional.

  • Port Area --
  • This basically refers to the size of a port in a nitro engine, which affects the amount of air/fuel transferred and timing.

  • Port Duration --
  • The amount of time a port remains open - usually measured in degrees of crank rotation.

  • Port Timing --
  • The points where a port opens and closes - usually measured in degrees of the cranks rotation from TDC (Top Dead Center). Note than some ports are open (or closed) at the same time. A timing wheel is the usual and easiest to understand method of determining port timing.

  • Porting --
  • A method of hopefully gaining more power from a nitro engine. If done correctly, you can get more power. If not done correctly, you will have possibly more power but much worse fuel consumption. If done very badly, the engine will not run at all!?

  • Potentiometer (Servo) --
  • The electrical unit inside a servo that senses where the output shaft currently is and sends voltage to the servo motor until the shaft reaches the desired position.

  • Power Pack --
  • "Refers to the battery pack used to power the motor on electric models. For 1:8 to 1:12 scale, power packs are usually LiPo or sub C stick, flat, or saddle packs. But micro models commonly use 1/2A receiver packs as power packs. The power pack may also be referred to as the """"on board battery"""", since it is on board the model."

  • Power Up --
  • Refers to turning your radio system on. Always turn on your transmitter (radio) before your receiver (model), and always make sure your frequency isn't being used in the area before powering up.

  • Pre Load --
  • The amount of tension on a shock spring. Pre load affects the models ride height, and is adjusted using clip on spacers, clamps, or rotating collars (such as those on threaded shock bodies). Contrary to popular belief, pre load does not affect spring rate (unless you are using dual rate springs).

  • Pre Load Clip- Pre Load Spacer - Spring Clip - Spring Spacer --
  • A 'C' shaped clip that snaps onto the shock body between the spring collar and upper spring cap to make quick pre load adjustments. These clips are available in sets of varying thicknesses to increase or decrease pre load. Threaded shock bodies don't use pre load spacers (unless you're just too lazy to turn the pre load collar).

  • Pressure Fitting --
  • The small 'nipple' that the fuel tubing of nitro and gas models slides onto, which may be replaceable or integrated into the part. The 'barbed' cone-like shape prevents the tubing from sliding off due to pressure. Pressure fittings are commonly found on needle valve assemblies, pipes, and fuel tanks - as well as fuel filters, boost bottles, and a variety of tubing connectors.

  • Pressure Line --
  • The tube that runs from the tuned pipe or muffler to the fuel tank on nitro powered models. The pressure line transfers back pressure from the exhaust to the fuel tank, which forces the fuel from the tank into the carb.

  • Pressure Plate --
  • The thick metal 'disc' that applies pressure to the diff rings of a ball diff assembly or pads of a slipper clutch as the adjustment nut is tightened. For ball diffs, the pressure plate may be integrated into the hub or drive cups.

  • Primary Gear Ratio - PGR --
  • A ratio found by dividing the number of teeth on the spur gear by the number of teeth on the pinion / clutch bell (72T spur / 25T pinion - 72 / 25 = 2.9:1 PGR). This ratio can be multiplied by the internal gear ratio (IGR) to find the final drive ratio (FDR). Note that the primary drive ratio can easily be altered by exchanging the spur or pinion / clutch bell.

  • Prime --
  • Refers to pumping just enough fuel to the carb of an engine to get the engine started. This may be done with a primer bulb (if your ride is equipped with one) or by placing your finger over the exhaust stinger and turning the engine over until fuel reaches the carb.

  • Pullstarter --
  • A mechanism that allows the starting of a Nitro car engine without the need for a separate engine starter box. Because it is permanently attached to the engine, the engine must sit higher in the car, which affects its center of gravity. It also can affect the rotating weight of the engine itself, however this and the center of gravity affect will not concern anyone but the most serious racer.

  • Punch --
  • "In RC terms, this means the same thing as acceleration. Driving """"full punch"""" means you are on the throttle all the time!"""

  • Push --
  • See Understeer

  • Pushrod (Linkage) --
  • The rod or wire used to connect the servo horn to the item the servo operates - such as connecting the throttle servo to the carb. The pushrod converts the servos rotational movement to linear movement. Pushrods are usually made of thick, sturdy wire (a.k.a. piano wire).

  • Pushrod (Suspension) --
  • A turnbuckle or tube used on off road models that utilize cantilever type suspensions. The pushrod transfers motion from the suspension arms to the cantilevers (which transfers the motion to the inboard shocks).

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