RV Camping - Glossary of RV Terms

RV Camping - Beginner's Guide to RVs and Motor Homes

Glossary of RV Terms

120 AC/12 DC/LP-gas: The power sources on which RV refrigerators operate; 120 AC is 120-volt alternating current (same as in houses); 12 DC is 12-volt direct current (same as in motor vehicles); LP-gas. Some RV refrigerators can operate on two of the three sources, others on all three.

Adventure Travel: Any participatory human powered activity. Adventure travel usually takes place in an outdoor setting. Trips are generally in small groups, comprised of people desiring to be unique and independent.
Axle Ratio: Ratio between pinion and ring gears in the differential that multiply torque provided by the engine. It describes the number of driveline revolutions required to turn the axle one time. With a 4.10:1 axle, the driveline turns 4.1 times for each full axle revolution. Higher numbers mean more torque and less road speed for a given engine speed; i.e., a 4.10:1 ratio provides more torque than a 3.73:1.

AWR: Axle Weight Rating. Please read our Weight and Loading pages for more information.

Black Water: The toilet water stored in a holding tank under an RV.

Boondocking: Camping in your RV without water or electrical hook-ups. The term is also used among campers who like to enjoy all of nature, regardless of the terrain while avoiding redundant commercial campground fees. Please read our Boondocking page for more information.

BTU: British Thermal Unit. A measurement of heat that is the quantity required to raise the temperature of one pound of water 1 degree Fahrenheit. RV air-conditioners and furnaces are BTU-rated. A one-ton Air conditioning unit is the equivalent of 12,000 BTU.

Caravan: A group of three or more RVs traveling together. Like a miniature version of a 16-wheeler "convoy".

Chassis: The framework that supports the body and engine of an RV.

Class A Motor Home: Motor home that range from 24'-40' in length.

Class B Motor Home: Also known as camping conversion vans, Class B Motorhomes are built within the dimension of a van but with modification to provide basic living accommodations. Models usually range from 16'-21' in length.

Class C Motor Home: Motorhomes that range from 16'-32' in length.

Converter: A device for changing 120-volt AC into 12-volt DC electrical power.

Curb Weight, or Net Weight: should be the weight of the unit as it is sitting on the lot, without the personal load you will be adding. Please read our Weight and Loading pages for more information.

Dinghy: A car or other vehicles that is towed behind an RV. Also known as the toad.

Dry Weight: Dry Weight is a very imprecise term. Some manufacturers say it means "nothing wet" in it. Others will say it's without options. Dry Weight is the empty weight of the vehicle or trailer. Dry weight may or may not include the weight of appliances, slide outs, etc. Please read our Weight and Loading pages for more information.

Fan Switch: A normally open switch that closes at a preset temperature, causes the furnace to run for a short time after the thermostat opens, allowing the furnace to cool down.

Fifth-Wheel Trailers: Towable RV that is designed to be coupled to a special hitch that is mounted over the rear axel in the bed of a pickup truck.

Full-Timers: RVers who live in their RV year around.

Furnace Ignition Control Board: When powered, initiates gas valve opening and spark sequence which lasts approximately 7 seconds. Older models are 1 try, thermostat must be cycled off for at least 10 seconds before another ignition cycle is attempted. Newer boards are 3 try, will attempt to ignite 3 times at approximately 60 second intervals.

Folding Camper or Fold-Down: Also known as a "pop-up" or "camping" trailer. A towable RV in which the upper half collapse to make a compact, lightweight unit.

Gas Pressure: Liquid Propane Gas pressure must be 11" of water column (6.25 oz per sq. in.), checking and adjusting requires a manometer.

Gray Water: The water drainer from the sinks and shower in an RV.

Gross Axle Weight Rating (GAWR): Maximum to which the axle can be loaded, according to the manufacturer; includes all weight placed on all tires on a given axle. Each axle has a separate rating. It assumes the load is equal on both sides -- which virtually never happens. 10% of the overweight RVs exceed a tire rating without exceeding GAWR. That happens because of a load imbalance in the RV. Please read our Weight and Loading pages for more information.

Gross Combined Weight Rating (GCWR): Maximum allowable combined weight of the tow vehicle and the trailer, according to the vehicle manufacturer; includes the weight of both vehicles plus all fuel, water, supplies and passengers. It means the maximum weight rating of a towing vehicle and a towed unit in combination. GCWR takes into consideration such things as the drive train capacity (i.e. engine, transmission, drive shaft and differential), gearing, braking capacity, suspension, and axle loading. When integrating a tow vehicle with a trailer, either a fiver or travel trailer, add the GVWR of the trailer with the GVWR of the tow vehicle. If they add up to more than the GCWR of the tow vehicle it a bad match. The only solution is to pick a lighter trailer or a bigger tow vehicle. The same applies to a self contained unit and a towed unit, either four wheels down or on a dolly. Each of the big three pickup truck manufacturers (Chevrolet, Dodge and Ford) state in their literature a "Trailer Towing Capacity" as well as an alternate method for determining maximum allowable trailer weight. The published towing capacity is maximum allowable trailer GVWR, but usually requires extra optional features - called a towing package, and other options such as a particular engine or rear axle ratio. Please read our Weight and Loading pages for more information.

Gross Vehicle Weight Rating (GVWR): Maximum to which a vehicle can be loaded, according to the manufacturer; includes dry weight of the vehicle plus all fuel, water, supplies and passengers. Please read our Weight and Loading pages for more information.

Hitch Weight: Amount of a trailer's weight that rests on the tow vehicle; should be 10 to 15 percent with conventional trailers, 15 to 20 percent for fifth-wheels. Please read our Weight and Loading pages for more information.

Holding Tanks: Tanks that hold the black (toilet) and gray (sink, shower, lavatory) water. Their capacity determines how long an RV can be used without hookups. Please read our Plumbing System page for more information.

Hookups: Campground facilities for connecting an RV to 120-volt AC "shore power," water, sewer, cable TV and telephone service. Full Hookups: Refers to water, electricity and sewer at an RV site.

Igniter Electrode: Similar to a spark plug, 2 versions, 3 probe (remote sense) or 2 probe (local sense).

Inverter: A device for changing 12-volt DC into 120-volt AC power. Kilowatt (kw): A measurement of electrical power; each kilowatt equals 1000 watts. Please read our Electrical Systems page for more information.

Jalousie Windows: A window that opens up by cranking the bottom section out to about a 45 degree angle, allowing ventilation while protecting from light rain. Most RV windows slide up and down or side to side, which could allow rain to get into the RV.

Laminate: A sandwich of structural frame members, wall paneling, insulation and exterior covering, adhesive-bonded under pressure and/or heat to form the RV's walls, floor and/or roof.

Light Weight RV: The are the RVs that are designed to be easily towed behind most SUVs, Minivans, light-duty trucks and even certain cars!

Limit Switch: Furnace safety switch, a normally closed switch that opens if it gets to hot, opening turns off power to the gas valve and igniter board.

LPG: Liquefied Petroleum Gas: Propane is one formulation and butane is the other. Propane fuels RV appliances, such as the stove and refrigerator. Please read our Gas System page for more information.

Motorhome or Motor Home: A RV built on or as an integral part of a self-propelled motor vehicle chassis, combining transportation and living quarters in one unit.

Net Carrying Capacity (NCC): The amount of cargo, passenger and fluid weight that can be added to an RV without exceeding its GVWR. The NCC label in an RV may not include the weight of dealer- or factory-installed options already on the vehicle. Subtract UVW from the GVWR and the result is what can be added to the factory weight. Please read our Weight and Loading pages for more information.

Newbie: Someone new to the RV world.

Payload Capacity: is the difference between the actual weight and the GVWR of the vehicle or trailer. Options and accessories may add weight that is taken from the payload capacity, leaving you with less margin than you think you have. Ask the dealer to provide proof of the units weight before you finalize the sale. Then do the math and calculate what the remaining payload capacity really is. Please read our Weight and Loading pages for more information.

Pop-up Trailer: Also known as a Folding Trailer, great for first timers due to its simplicity and relatively low cost.

Pull-Through: RV campsites that allow vehicles to drive straight in and hook up without having to back in.

RBR: Really Big Rig.

RV: Recreational Vehicle is a motorized or towable vehicle that combines transportation and temporary living accommodations for travel, recreation and camping. An RV in America does not generally refer to off-road vehicles or snowmobiles. There are all types and sizes of RVs for any budget or need. They range from camping trailers costing a few thousand dollars to luxurious motorhomes with prices well into six figures. Please read our Caravan / RV Classes & Definitions page for more information.

Slideout: An option in many RVs where a portion of the unit can expand to create more room in the RV.

Snowbirds: RVers who live in the warmer, southern regions of the country during the winter months.

Soft Adventure: Soft adventure travel requires less physical risk, little or no experience and offers more convenience in terms of sleeping arrangements and cuisine.

Time Delay Relay: Same function as fan switch, only has its own heater.

Towable: RVs designed to be towed by a motorized vehicle (car, van, or pickup truck) and of such size and weight as not to required special highway movement permit. Towable RVS do not required permanent on-site hook-ups.

Travel Trailer: A Towable RV with an A-frame and coupler that are attached to a ball mount on the tow vehicle.

Truck Camper: A unit loaded onto or affixed to the bed or chassis of a pickup truck.

Underbelly: The RV's underfloor surface, which is protected by a weatherproofed material

Unloaded Vehicle Weight (UVW) or Dry Weight: Weight of the vehicle without manufacturer's or dealer-installed options and before adding fuel, water or supplies. How much the vehicle weighs when it leaves the factory. Please read our Weight and Loading pages for more information.

Van Conversion: This is a fully loaded van and the smallest of the fully enclosed motorhomes. They are constructed on a van chassis with elevated roof lines but no modifications to the length or width of the original chassis. Gross vehicle weights are in the 6,000 to 8,000 range with heights of 7 to 8 feet and lengths of 17 to 19 feet.

VBR: Very Big Rig.

Wet Weight: Weight of a vehicle with full fuel and freshwater tanks. Wet Weight should, but may not, include the weight of the LPG (propane or butane) in the tanks, and fresh water. (Water weight is 8.34 lbs./U.S. Gallon so a 100 Gallons weighs 834 lb.) Please read our Weight and Loading pages for more information.

Wheelbase: Distance between center lines of the primary axles of a vehicle. If a motorhome includes a tag axle, the distance is measured from the front axle to the center point between the drive and tag axles.