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Radio Control Terms

This master list of RC Terms has been collected to help new and even experienced RCer’s learn or brush-up on all types of terms used in the hobby. This is a continuation of the Terms seen every issue in our magazine and we will continue to update it as time goes on; please check back often.

Alphabetically from L - Z

Lean.
When the needles on the carburetor are set such that the engine is not getting enough fuel, this is referred to as running lean. Running too lean may help fuel economy and appear to make the vehicle run better; however, it is also a sure way to shorten the life of the engine.

Lexan.
This is a clear, plastic-like material that is vacuum-formed over molds to create different body styles. These bodies are then painted on the inside so that the paint does not scratch off from less than perfect laps around the track.

Linkage (throttle, brake).
Heavy gauge wire is used to connect servo horns to throttle and break controls.

Locknut.
A nut that uses a nylon insert in order to better grip the threads of a bolt or shaft and thereby preventing it from coming loose. It is used extensively for axles and other areas where nuts must stay secure, but it may need to be removed frequently for maintenance or repair.

Mechanical Speed Control (MSC).
The MSC is a servo-driven device that uses resistors to regulate power transfer from the battery to the motor as a means of throttle control.

MHz = Megahertz.
Unit of radio frequency. Surface frequencies are75 MHz and air frequencies of 72 MHz, 27 MHz, and 50 MHz can be used for either ground or air applications. However, a FCC license is required to operate on the 50 MHz (am radio) band.

Milliamp.
(mAh) This is a rating for batteries. The higher the milliamp rating, the longer the cell can provide power. Currently, most RC batteries range from 1500 to 3300 milliamp hours.

Module used to describe the tooth pitch of a metric pinion or spur gear.
The most common modules are 1.0, .8, .6, and .4.

Muffler.
All nitro-powered cars use some type of muffler to reduce the noise output and provide pressure to the fuel tank.

Needle Valve.
A nitro engine can have from one to three adjustment needles on the carburetor. They are used to adjust the air to fuel ratio. On most engines, the needle is turned clockwise to lean the mixture (allowing less fuel and more air to enter,) and counterclockwise to richen (permitting more fuel and less air to enter.)

NiCad (or NiCd).
Rechargeable Nickel Cadmium batteries, most commonly used to power radio transmitters and receivers. Also used in stick packs in electric vehicles.

Nickel-Metal Hydride (Ni-MH).
Battery cells that do not have "cell memory" with slightly less voltage than nickel-cadmium batteries. For the average enthusiast this means less maintenance.

Nitro/Nitromethane.
This is a fuel additive that increases a model engine's performance. The ideal nitro content (measured by percentage) varies from engine to engine, but you will typically find 10 to 30 percent on the hobby shop shelf.

NORRCA.
National Organization for Racing Radio Controlled Autos. www.norcca.com.

One-Way Bearing.
This is a bearing that allows a shaft to turn in one direction only.

Outdrive.
The outdrive refers to shafts that exit the differential on either side and transmit driveline power to the drive wheels using an axle shaft or universal.

Oversteer.
The condition that’s usually present when the rear wheels lose traction before the front wheels ending up with the rear of your vehicles swinging around through turns. Adjusting shocks, stickier tires or more rear down force are some possible solutions.

Peak Charger.
When the battery has peaked, meaning it will no longer accept a charge, this type of charger reverts to a maintenance charge rate, considerably decreasing the chance of damage to the pack.

Peak.
The point at which a battery no longer accepts a charge. Energy is then converted to heat that is potentially hazardous and can be damaging to the battery pack.

Pinion Gear.
Electric RC vehicles use a pinion gear attached to the motor’s shaft to turn the spur gear which in turn spins the rest of the drive train.

Piston.
The piston fits into an internal cylindrical part of an engine called a sleeve and slides up and down during the combustion cycle. The piston turns the engine’s crankshaft via a connecting rod, converting the energy of combustion into rotational torque. The piston and sleeve of an engine are replaceable but must both be replaced at the same time.

Pitch.
In its simplest terms, this refers to the size of a gear’s teeth. For instance, a 32-pitch pinion gear has smaller teeth than a 48-pitch gear. The number represents how many teeth per inch.

Power Supply.
A device that converts 110VAC to 12VDC. Generally used to power charging equipment.
· Preload (shock). Adjusting preload on shock absorbers determines a vehicle’s ride height. It is adjusted either by clip-on spacers or by tension clamps. Threaded shock bodies use a metal ring that is rotated up or down to adjust preload.

Prototype.
A full-scale working model of an original new product or an updated version of an existing product.

Push/Understeer.
If a vehicle’s front tires don’t provide enough grip through turns the car will not turn as sharp as it should. It will appear to go straight even though the wheels are turned.

Receiver (Rx).
The servo and ESC plug into this electronic unit in an RC vehicle. The receiver converts the radio signals from the transmitter into servos and/or electronic speed controls commands.

Resistor.
The resistor is the ceramic unit on an electric vehicle’s mechanical speed control (MSC) that limits the amount of current transferred from battery to motor. It dissipates the energy as heat.

Reverse Lockout.
This is an ESC function that prevents accidental engagement of reverse function on an ESC. Reverse is generally not permitted in organized racing, in order to prevent track mishaps.

Rich.
When the needles on the carb are set such that the engine is getting too much fuel it is referred to as running rich. If you accelerate from a stop and the engine dies, you are probably running too rich and should lean out the engine's low speed idle adjustment a little (by turning the needle valve or low-end adjustment slightly clockwise).

RPM.
Measurement of engine speed; the number of rotations/revolutions per minute.

Runtime.
Total length of time a vehicle will run on a single battery pack or tank of fuel.

Servo Reversing.
This is just what it sounds like. Radios with this function allow the user to reverse the output of the servo. This is useful when you switch the radio system between vehicles that may use different servo placement or orientation.

Servo.
This is the unit that actually does the physical work inside your vehicle. A servo contains a small motor that, when activated by commands from the transmitter, moves the control linkages for steering, throttle and brakes. Some vehicles with 3-channel radios have a third servo to activate other functions, such as reverse or shifting of gears.

Servo Saver.
A device that protects the servo from excessive force that could damage its gears. It can be integrated into the control horn or the steering bellcrank.

Shock Piston.
A small plastic, brass or nylon disk that travels up and down inside an oil-filled shock body. It uses a hole or holes to regulate the rate at which the shock compresses and rebounds.

Skid Plate.
A plastic or metal (usually aluminum or titanium) plate that protects the underside of off road vehicles.

Sleeve.
The internal cylindrical part that houses the piston in a nitro engine.

Slipper Clutch.
This refers to a device found primarily in off-road vehicles that allows the spur gear to slip under excessive load. This feature protects the driveline from excessive wear and, when set properly, makes it easier to drive in loose conditions.

Spur Gear.
The large gear that meshes with a pinion gear or clutch bell to provide power to a vehicle’s drivetrain.

Stagger.
the difference between the circumferences on the left and right side tires. In oval racing, a positive stagger means the outside tires are larger than the inside.

Stinger.
The small tubular tip on the side of a tuned pipe where exhaust is expelled.

Sway Bar.
A heavy wire that attaches across either or both the front and rear of a vehicle's suspension arms. It is designed to keep equal down pressure on the left and right through turns. When the outside edge of the vehicle is pushed up through a turn the sway bar pushes down on the inside edge to keep the tires on the ground.

Synthesized Receiver.
A Receiver, utilizing crystal-free technology, that can be set to any desired frequency.

Tamiya/JST Connectors.
These electrical connectors are widely used within the hobby. The shape of the female end on the battery and the male counterpart on the electrical component prevent accidental reversing of the polarity, which would create a short circuit.

Tire Truer.
On-road racers running foam tires are likely to have a truer in their pit boxes. When the foam donuts become worn or damaged, the surface can be renewed with a tire truer, a machine that operates in the same manner as a lathe.

Toe Angle.
When seen from above, a car’s front wheels will point inward when the steering trim is set to neutral. Applies to the rear wheels as well. This provides some degree of stability. Too much toe angle will slow you down.

TQ. Top Qualifier.
The driver who turns the most laps in the shortest amount of time. In full scale racing this is known as the pole setter.

Traction Compound.
A liquid substance applied to tires to enhance traction.

Transmitter.
The part of a radio system that is used by the driver to control a vehicle. The transmitter sends signals based on a drivers input to a receiver that is mounted in a vehicle.

Transponder.
This is a small electronic device mounted in a race vehicle. It transmits a signal to a receiver located at the start/finish line. The receiver records a vehicle’s position and lap times during a race for scoring purposes.

Tuned Pipe.
This is an upgrade for any vehicle equipped with a muffler. It is designed to increase an engine’s power output. Different tuned pipes are available for different applications. Some provide increased top speed while others said off-the-line power.

Turn Marshal.
A racer who, after he has finished his race, stands at various spots around the track during the next race to turn over any vehicles that have flipped and to remove vehicles that are no longer operable, for whatever reason, from the race course.

Turnbuckle.
This is an adjustable link that has conventional threads on one end and reverse threads on the opposite end. This enables you to make vehicle adjustments without having to remove the link from a vehicle completely.

Universal Dogbone.
A universal dogbone is a driveshaft that combines a conventional dogbone and axle into a single, more efficient unit.

Zip Tie.
A term commonly used for plastic cable wraps because of the zipping sound it makes when tightened. A good pit box will always have several sizes buried among the hex wrenches and dead glow plugs.

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