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RV Talk 101 by: Mark J Polk

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I guess because I work in the RV Industry and around RVs almost everyday I take some things for granted. One of those things is RV terminology. When you hear these terms everyday you just assume that everybody understands them. It would not be uncommon for a typical conversation between two RVers at the campground to go something like this.

“Hi my name's Fred. Nice rig you got there.” “Thanks Fred, I'm Joe. It's a new pusher my wife and I just got. This is our maiden voyage with it.” Fred replied, “We still have our Class C, it works better for us with the kids. I told my wife we'd upgrade when we're empty nesters and can go full timing.” Joe said, “Well I've seen some Class A's that aren't as nice as that, you have two slides and a full basement.” “We don't have any complaints, it's 29 feet long and with the Triton V10 it has plenty of power. I do wish the holding tanks were bigger, it seems like I'm dumping them all the time.” Joe said, “We had the same problem with our fiver we traded in. I told the wife this time we're getting bigger holding tanks, pass through storage, 50-amp service and filon with aluminum frame construction. No more stick and tin for us. I couldn't keep up with the black streaks.” Fred said, “I know what you mean. Fiberglass sidewalls are the only way to go, but I'm a little concerned about delamination. My neighbor's Class A is only four years old and it's already delaminating.” Joe replied, “That crossed my mind too. You really need to keep an eye out for any water damage. When we bought the new motor home I had a 20 X 40 foot shelter built to store it under and keep it out of the elements. I'm not sure which is worse, what I paid for the shelter or paying to have some delamination repaired.” “Hey Joe, is that the dinghy you tow behind your motor home?” “Yes, we just got that too.” Fred said, “I didn't know you could tow that model with all four wheels on the ground.” Joe replied, “That's why we got it. I didn't want to use a dolly and it only weighs 2,800 pounds. With the motor home fully loaded we can tow it and not worry about exceeding our Gross Combined Weight Rating (GCWR).” Fred asked, “Did you have to make any driveline modifications to tow it with all four wheels on the ground?” Joe said, “No, and there are no speed or distance restrictions.” “Well Joe it was nice meeting you, I better finish with the campground hook ups.” “Nice meeting you Fred. Why don't you and your wife stop by later.” “We'll do that.”

Now, for an RVer with some experience this conversation makes perfectly good sense, but for the new RVer it may be a bit confusing. To help clear things up I'd like to offer some common RV terms that you will encounter during your RVing experiences.

30 Amp, 120-volt electrical system - Most RVs are designed with 30 Amp, 120 Volt electrical systems, and some of the larger RVs with more appliances and two roof A/Cs use a 50 Amp, 120 Volt electrical system. What this basically means is, for everything to operate properly the manufacturer intends the RV to have a 30 or 50 Amp electrical service supplied to the RV.


Aluminum Frame Construction -When the RV framing is made of aluminum as opposed to wood.

Artic Package - An RV that is equipped with additional insulation and heated holding tanks for winter camping.

Awning - A canvas or vinyl covering mounted to the side of an RV that provides shade. Some awnings are retractable and use a spring-loaded roller tube. Other awnings must be rolled out by hand and are supported by poles, rope tie downs and stakes.

Axle Ratio - The number of times the drive shaft must turn to turn the axle one time. If you have a 3.73:1 axle ratio the drive shaft turns 3.73 times for each full turn of the axle. The higher the numeric value of the axle ratio the better the vehicle will tow, and the higher the numeric value the more gas you will use.


Backup Monitor - A monitor located in the driver's view that is attached to a small camera on the back of a motor home. It is used to assist in backing the motor home and to monitor what is happening behind you while you are traveling.

Ball & Ball Mount - Hitch balls have three basic measurements, the ball diameter, the shank diameter and the shank length. Ball diameter sizes come in 1 7/8”, 2” and 2 5/16”. The ball size must be the right size for the coupler on the trailer you are towing, and be rated to tow the trailers GVWR. The ball mount is the removable portion of the hitch that slides into the hitch receiver. For Weight Carrying (WC) hitches it may be necessary to find a ball mount with a drop or rise to help level the trailer when its hooked up to the tow vehicle. An adjustable ball mount is used for heavier trailer applications. Adjustable ball mounts allow the ball to be raised, lowered or tilted to compensate for trailer tongue weight and to attain proper height adjustments. Adjustable ball mounts are normally used with Weight Distributing (WD) hitches.

Basement Storage - Storage compartments or storage area located below the floor of the motor home. You access the storage from outside. Some storage areas are referred to as pass through storage, which means it goes from one side of the RV to the other with no dividers, and can be accessed from either side.

Black Water Holding Tank - A tank mounted under the RV that collects water and waste from the toilet. When the tank is ¾ or more full it is emptied or dumped into an approved dump station or campground sewer. The black water tank is treated with chemicals to control odor and assist in breaking down waste.

Brake Controller - An electronic controller that is normally mounted under the dashboard of the tow vehicle, but within hands reach of the driver. The controller is designed to activate the trailer brakes when the tow vehicle brakes are applied. It also has a manual over ride that can be used to activate the trailer brakes without using the vehicle brakes.

Break-away Switch - A switch that is wired into the trailers brake system. It is attached from the trailer to the tow vehicle by a cable lanyard. In the event that the trailer and vehicle separate the cable pulls a pin from the switch and the trailer brakes are activated. The switch must have a 12-volt source to operate.

Bumper Pull - A term used to describe towing a travel trailer or pop-up, also referred to as a pull behind.


Cab over - The portion of a class C motor home that extends over the vehicle cab. It is usually designed as a bed.

Campground Hook-Ups - When you hook-up or connect your RV to the campground electric, water and sewer utilities. This would be considered a full hook-up. Some campgrounds may only offer one or two of these connections.

Cargo Carrying Capacity (CCC): is the maximum permissible weight of personal belongings and cargo that can be added to the RV. CCC is equal or less than GVWR minus UVW, full fresh water weight, and full LP gas weight.

City Water Connection - A water connection, on the outside of the RV, that is used when you have an external water supply, such as at a campground. A potable water hose is used to connect the water supply to the city water connector on the RV.

Class A or Type A motor home - They are the largest of the motorized RV's ranging in size from 25 to 45 feet. Commonly referred to as a conventional motor home they are the ones you see that look similar to a bus, and depending on the price they can be equipped with features like washers and dryers, multiple slide out rooms, satellite dishes, home entertainment systems and much more.

Class B or Type B motor home - They are the smallest of motorized RV's ranging in size from16 to 20 feet. They are conversion vans that have been modified and equipped with sleeping, eating and bathroom facilities and amenities found in other RVs in a compact size.

Class C or Type C motor home - They are also referred to as mini-motor homes and are built on a cutaway van chassis. They range in size from 20 to 31 feet.

Converter - An electrical device that converts 120-volt AC power into 12-volt DC power. With the exception of the roof air conditioner, microwave, TV and the electric mode of the refrigerator almost everything in an RV operates on 12-volt DC power supplied by a battery. When you're plugged in to a 120-volt electrical source the converter changes the 120-volts AC to 12-volts DC so everything can operate without draining the battery(s). The converter also has a battery charger that will keep the battery(s) topped off when you are plugged in to a 120-volt power source.

Coupler - Located on the front of the trailer A-frame the coupler attaches the trailer to the ball on the hitch.


Deep Cycle Battery - Often referred to as the auxiliary battery(s) or house battery, it is used to supply 12-volt DC power to the appliances and accessories in the RV. Unlike an automotive starting battery they are designed to hold a charge longer and be discharged repeatedly. The RV battery(s) is charged when the motor home is running, or in the case of a trailer, when the tow vehicle is running, if a charge line was wired in to the trailer plug. It is also charged when the RV is plugged in to a 120-volt power source and by an onboard generator.

Delamination - When the filon, (fiberglass panel) separates from the luan backing used to construct fiberglass sidewalls on an RV. This is usually caused by water damage.

Demand Water Pump - The onboard water system that operates off of a 12-volt demand pump. When you have potable water in your fresh water holding tank and the pump is turned on it pressurizes the onboard water system. When you open a faucet and the water pressure drops the pump cycles on and off to maintain a constant pressure.

Diesel Pusher - A motor home with a rear mounted diesel engine. Often times referred to as a pusher.

Dinghy - A term used for the vehicle you are towing behind the motor home.

Dry Camping - Camping in an RV without any utility hook-ups (water, electric, sewer).
You can still use all 12-volt appliances and accessories as long as the deep cycle battery(s) has a charge. You can also use the onboard water system with the 12-volt demand pump and if you have a generator you can use the 120-volt appliances and recharge the auxiliary battery(s). This is what makes an RV fully self-contained.

Dry Weight - Dry Weight (DW) or Unloaded Vehicle Weight (UVW) is the actual weight of the RV as built at the factory. The DW does not include passengers, cargo, fresh water, LP gas, fuel or after market accessories.

DSI- Direct Spark Ignition (DSI), is a system used to ignite the burner on a propane appliance with the touch of a button. It is commonly used on RV refrigerators, furnaces and on some water heaters.

Ducted A/C and Heat- When the A/C and heat is supplied throughout the RV using a ducting system. A/C is ducted in the ceiling and the heat is ducted in the floor.

Dually- A pickup truck with two tires on each side of the rear axle.

Dump outlet-Where both holding tanks terminate into one main outlet. This is where you connect the RV sewer hose to dump or empty the gray and black water holding tanks.

Dump Station - An area designated and approved for dumping or emptying your gray and black water holding tanks.


Electric brakes - Trailer brakes are electric and are activated when the tow vehicle brakes are applied by means of a brake controller installed in the tow vehicle.

Empty Nester - When all of the children are finally out of the house.

Equalizing Hitch - An equalizing hitch, or weight distributing hitch uses additional hardware (spring bars and brackets) to distribute a percentage of the trailer's tongue weight to the axles on the tow vehicle and the axles on the trailer. Trailer tongue weight should be 10 to 15 percent of the loaded trailer weight.


Fifth Wheel Trailer - A trailer with a raised front that extends over the bed of a pickup truck. A special hitch is mounted in the bed of the truck , over the rear axle, to tow a fifth wheel trailer.

Filon - A type of fiberglass sheeting used on RVs with fiberglass sidewall construction.

Fiver - Another term used for a fifth wheel trailer.

Folding Camping Trailer - Also known as a pop-up or tent trailer. They are the smallest of RV's with collapsible ends and sides for ease of towing and storage.

Fresh Water Fill -An opening on the outside of the RV where you can fill the fresh water holding tank with potable water to use when you are traveling or dry camping.

Fresh Water Holding Tank - A tank mounted under or in the RV that stores potable water for use while traveling or dry camping. To pressurize the system and use the water in the holding tank you turn the 12-volt demand pump on.
Full Hook-Up - A full hook-up means you connect the RV to the campground electric, water and sewer facilities. In addition to this it can also include cable TV and phone line connections.

Full-Timers / Full-Timing - Terms used for RVers that live and travel in their RV full time. Some full timers sell everything and live in their RVs 100% of the time. Other full timers that spend the majority of their time on extended RV trips choose to maintain a house or residence they can return to in between trips.


Generator - Commonly used on motor homes a generator produces 120-volt AC power. A generator allows you to use 120-volt appliances when you are not plugged into an external electrical source. Generators are rated in kilowatts. For example a 5 KW generator is 5,000 watts.

Genset - A short term for a generator set.

Gray Water Holding Tank - A tank mounted under the RV that collects wastewater from the sinks and shower. When you dump or empty your holding tanks you should always dump the black tank first, and then dump the gray tank. This will assist in rinsing out the flexible sewer hose.

Gross Axle Weight Rating (GAWR): Is the maximum allowable weight that an axle is designed to support. The tow vehicle and trailer each have GAWRs.

Gross Combined Weight Rating (GCWR): The maximum permissible weight of the tow vehicle and trailer combined when both are fully loaded for travel.

Gross Vehicle Weight Rating (GVWR): is the maximum permissible weight of the vehicle when fully loaded for travel. The tow vehicle and the trailer each have GVWRs.

Gross Vehicle Weight or Gross Trailer Weight (GVW), (GTW): This is not a rating; this is the actual weight of the tow vehicle or trailer when they are fully loaded for travel.


Heat Strip - An electric heating element in a roof mounted air conditioner. These are usually used on pop-ups or other trailers that do not have a furnace. A heat strip will take the chill off, but is not designed to actually heat the trailer.

Hitch Receiver - The hitch receiver is mounted to the frame of the tow vehicle. The ball mount slides into the receiver. There are five classes of hitch receivers based on the maximum amount of weight the receiver can handle.

Hitch Weight - Hitch weight or Tongue Weight (TW) is the amount of weight pressing down on the vehicle's hitch from the coupler of the trailer when the trailer is fully loaded for travel. For trailers that weigh over 2,000 pounds TW should be 10 to 15 percent of the loaded trailer weight. For fifth wheel trailers hitch weight should be 15 to 20 percent of the loaded trailer weight.

Hydraulic Leveling Jacks - Used for leveling an RV, typically a Class A motor home, they are leveling jacks that operate using hydraulics and are controlled by levers or a touch pad normally located near the drivers seat.


Inverter - An electrical device that changes12-volt DC power into 120-volt AC power.
It is used to power 120-volt appliances or electronics such as a microwave or TV when you don't have access to an external 120-volt power source. The amount of power that is available depends on the storage capacity of your battery(s) and the wattage rating for the inverter.


Kilowatts - Power generators are rated in kilowatts. Each kilowatt equals 1,000 watts.


LP Gas - Liquid propane or liquefied petroleum is the gas used for RV appliances. Typically it is used for the range burners, oven, water heater and the LP gas mode of the refrigerator. LP gas is stored in cylinders or bottles on trailers and in tanks mounted to the frame of motor homes.

LP Gas Leak detector - LP gas leak detectors are audible alarms that warn you of a potential gas leak. They are normally located close to the floor level of the RV because LP gas is heavier than air and will settle towards the floor.


MH - Abbreviation for Motor Home.

Monitor Panel - Allows you to check or monitor the fluid levels in the gray, black and fresh water holding tanks. You can also check the condition of the auxiliary battery(s) and on some monitor panels the propane level.


NADA Book - The RV edition of the National Automobile Dealers Association (NADA) book is used by RV dealers to determine used RV values.


OEM - Abbreviation for Original Equipment Manufacturer

Overhang - The portion of the motor home that extends from the rear axle to the rear of the motor home.


Park Model - An RV trailer designed to be taken to a location such as a campground or resort area and set up permanently. A park model trailer has more household type features and amenities than a travel trailer.

Pilot Flame- The pilot flame is a small flame used to light the main burner of an LP gas fired appliance. The pilot flame heats a thermocouple control that opens the flow of gas to the burner.

Porpoising - A term used to describe the up and down movement of an RV when traveling.

Portable Toilet or Porta Potty - A portable RV toilet with a fairly small water tank and holding tank. When the holding tank is full it can be removed and emptied at a dump station.

Pull Through Site - A campground site that requires no backing. The site is designed for you to drive or pull through.

Refer - A short term for your RV refrigerator.

Regulator - LP gas regulators control or regulate the LP gas flow through all appliances, and maintain the proper operating pressure in the LP gas system.

Rig - A term RVers use for their RV.

RV - Abbreviation for Recreation Vehicle. A Recreation Vehicle combines transportation and living quarters for recreation, camping, and travel. They can be classified in two basic groups, motorized RVs and towable RVs. Motorized RVs include Class A, Class B and Class C motor homes. Towables include pop-ups, travel trailers, fifth wheels and truck campers.

RVDA - Recreation Vehicle Dealers Association

RVIA - Recreation Vehicle Industry Association


Safety Chains - Safety chains are used on trailers in case of a hitch failure. One end of the chain is attached to the trailers A-frame, and the other end to a permanent fixture on the tow vehicle, normally the receiver. The chains are crossed “X” to form a saddle that would prevent the coupler from contacting the road surface in the event of a separation.

Screen Room - A screened in enclosure that attaches to the exterior of an RV. They provide protection from insects and rain. Screen rooms are most commonly used with pop-ups.

Sewer hose - A flexible hose that attaches to the RV sewer outlet and the campground sewer used to dump or empty holding tanks. You should have a 10' and 20' hose available with necessary sewer hose attachments.

Sewer hose donut - A plastic or rubber ring used to get a good seal between the sewer hose and the campground sewer connection. Sewer hose donuts are required at many campgrounds.

Shore Power - Shore power is a term used for plugging the RV in to an external 120-volt power source such as at a campground.

Slide-In - A truck camper that slides in to the bed of a pickup truck.

Slide-Out - A section of the RV that slides out to provide you with additional living space. Some RVs have multiple slide outs.

Slider Hitch - A 5th wheel hitch used with short wheel base pickup trucks. With short wheel base trucks the front of the 5th wheel trailer can make contact with the cab of the truck when turning to sharp. A slider hitch has two positions. One for normal driving conditions and one for maneuvering where turns are required.

Snowbird -RVers that head south for the winter.

Stabilizer Jacks - Jacks that are used on the corners of an RV to stabilize it when it is set up at the campground. Some are mounted to the frame of the RV and others are portable. Stabilizer jacks are not designed to level the trailer

Stick and Tin - An RV with wood framing and corrugated aluminum exterior.

Surge Brakes - A hydraulic braking system used on some lightweight trailers. Surge brakes activate when the trailer surges or pushes against the hitch ball when slowing down.

Sway Control - A device used to help control trailer sway. There are two basic types of add on sway control, friction and cam action.


Tag Axle - A non-drive axle located behind the rear drive axle that is used to support the weight of the RVs overhang.

Three Way Refrigerator - An RV refrigerator that can operate off of 12-volt DC, 120-volt AC and LP gas.

Toad - Another term used for the vehicle towed behind a motor home. Also called a dinghy.

Tongue Jack - The jack mounted on the A frame of the trailer that supports the front of the trailer and is used to raise and lower the trailer when hitching and unhitching.

Tongue Weight -Tongue Weight or Hitch Weight is the amount of weight pressing down on the vehicle's hitch from the coupler of the trailer when the trailer is fully loaded for travel. For trailers that weigh over 2,000 pounds TW should be 10 to 15 percent of the loaded trailer weight.

Tote tank - A portable tank used to dump the contents of a holding tank in to and then transport it to a dump station to be emptied.

Tow Bar - A tow bar is used to connect a towed vehicle to a motor home when the vehicle is towed with all four wheels on the ground.

Tow Dolly - A trailer used to tow a vehicle behind a motor home when the vehicle cannot be towed with all four wheels on the ground. Two of the vehicles wheels are on the tow dolly and two are on the road surface.

Toy Hauler - An RV that has a ramp door on the back and cargo space to load motorcycles, ATVs or other toys inside.

Transmission Oil Cooler - A small heat exchanger or radiator designed to protect your transmission from overheating. Automatic transmission fluid circulates through the oil cooler and is cooled by the airflow.

Travel Trailer - An RV that is towed by a car, van, or pickup, by means of a hitch. Travel Trailers are a popular choice among RVers because of the wide array of floor plans available. Whether it's for two people or eight you can find a model that will suit your needs. They range in size from 15 to 37 feet and offer all the comforts of home. They can be unhitched from the tow vehicle when you arrive at your destination.

Truck Camper - Truck campers are campers loaded onto the bed of a pickup truck. The tailgate is removed and the truck camper is attached to the truck with tie-downs. This makes for a very versatile RV that can access back roads and remote areas other RVs can't get to.

TT - Abbreviation for travel trailer.

TV - Abbreviation for tow vehicle.


Water Pressure Regulator - A water pressure regulator is used to prevent too much water pressure from entering the RV and damaging the plumbing system. You attach the pressure regulator to the campground water supply and then attach one end of your drinking hose to the regulator and the other end to the city water inlet on the RV.

Weight Carrying Hitch - When all of the tongue weight of the trailer is supported by the hitch itself. WC hitches are normally used for lighter trailer applications. Too much weight directly on the hitch can affect the steering and handling of the tow vehicle.

Weight Distributing Hitch - when additional hardware is used to distribute a percentage of the trailers tongue weight to the axles of the tow vehicle and the axles of the trailer. WD hitches are used to tow heavier trailers and allow the tow vehicle to handle better. Also referred to as an equalizing hitch.

Wheelbase - The distance between the centerlines of the primary axles of a vehicle.

Wide Body - An RV that is wider than 8'. The majority of RVs are 8' wide. A wide body RV is usually 8' 6” wide.
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Well that about does it. This list is not all-inclusive, but if you learn these terms you will soon be talking RV talk.

Happy Camping,


Copyright by Mark J. Polk owner of RV Education 101

RV Expert Mark Polk, seen on TV, is the producer & host of America's most highly regarded series of DVD's, videos, books, and e-books.http://www.rveducation101.com/

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