RV Terms and Definitions

12dC_thumb212-volt DC – A recreational vehicle’s low voltage, direct current system, powered by either a battery or an inverter when the RV is connected to electrical hookups or a generator.  Direct current means that the electrical current flows in one direction in the circuit.  12-volt DC powers components in the RV such as lights, water pump, LP gas furnace controls, generator starter, tank level indicators, and DC powered entertainment equipment.

110AC_thumb120-volt AC – A recreational vehicle’s alternating current system, powered by way of electrical hookups in a campground – sometimes called shore power – or from a generator.  The voltage is the same as that normally found in homes.  Alternating current means that the electrical current changes direction in the circuit, normally 60 cycles every second (60 hertz). AC powers components in the RV such as the microwave, water heater in AC mode, refrigerator in AC mode, and AC electrical outlets.

Actual weight – The measured weight of the vehicle or it’s components.  Factory or sticker weights may be averages or estimates of weight. 1

Adjustable ball mount – used to attain proper height between a tow vehicle receiver and the coupler of the trailer or other vehicle that is being towed.  Normally used with weight distributing hitches,  the ball of the adjustable ball mount may be raised, lowered or and sometimes even tilted to attain the proper tongue weight and coupler height to level the trailer or compensate for tow vehicle “squat” that happens when the weight of the trailer tongue is lowered onto the tow ball.

AGM – Absorbed Gas Mat, a type of battery using a glass mat to wick the electrolyte between the battery plates.  AGM batteries only have enough liquid electrolyte to keep the mat wet.  If the battery is broken, there is little or no liquid available to leak out.2

Airbag – term used to describe either factory installed air suspension systems on motorhomes or after market RV suspension enhancements.

Amp, RV service – AC (alternating current) service in modern RVs are rated at either 30 amps or 50 amps. The ampere is unit of measure of electrical current.  A 30 amp service provides 12ov power to the camper through through a three wire power cord – black is hot, white is neutral and green is ground.  A four wire cord is used for 50 amp service – Black and red are hot, white is neutral, and green is ground.  The two hot wires supply two separate 120v legs in the RV. If the service is wired properly, the two hot wires are of different electrical phases and can be connected to supply 240 volt service.

30 amp receptacle
30 amp plug
50 amp recepticle
50 amp plug

Amp hour (Ah) – an ampere hour is the amount of charge in a battery that will allow one amp of current to flow for an hour.  A milliampere hour (mAh)  is 1,000th of an amp hour.  It is commonly used as a measure of charge in portable electronics batteries, such as a laptop computer or notebook, and provides an indication of how long it can operate without needing to be recharged.  A battery’s amp hour rating has little significance unless qualified by the design discharge period.  Cold cranking amps and reserve capacity ratings provide better information for battery selection.

Anode rod – a sacrificial rod used mainly in metal hot water heaters.  When dissimilar metals and water combine an electrochemical process called galvanic corrosion occurs.  In this process one metal corrodes preferentially to another when both metals are in electrical contact and immersed in an electrolyte (the water in the heater). Galvanic rods are made of metal alloys that have a more active potential than the metal that would otherwise corrode, so the anode material is corroded – sacrificed –  instead.3

Arctic Pack – Original design or additions and/or modifications to an RV to enable its use in colder weather, which may include electrically heated tanks, heated mattress, added (or different) insulation, insulated and enclosed under-carriage, dual pane windows (perhaps even insulated gas-filled). May also be referred to as a “four season” or “all weather” package. Example: Lance 4 Seasons | All Weather Package.

Articulation point – A pivot point or joint between two objects that allows relative movement between the two. With recreational vehicles, the articulation point is where the tow vehicle is connected to whatever it is towing. Normally, there is just one articulation point with RVs.  However, in a triple tow situation, where a boat or other small trailer is being towed behind a camping trailer, there will be two articulation points.  RV articulation points will normally be one of the following:

  • the fifth wheel hitch and the king pin on a fifth wheel trailer or
  • the ball and coupling on a bumper or receiver type hitch.

ATV – All-terrain vehicle; defined by the American National Standards Institute as a vehicle that travels on low-pressure tires, with a seat that is straddled by the operator, along with handlebars for steering control. While ATVs are designed to handle a wider variety of terrain than most vehicles, they are not truly able to traverse all types of terrain.4

Auxiliary batteries –  another term for the house batteries.

Awning – Retractable fabric shade mounted on the side of an RV.  Patio awnings – roof-like coverings that extend from the body of the camper –  are most commonly used, providing outside shade and some protection from the elements. Manual and power operated models are available.  RV screen rooms can be connected to the awning as can decorative awning lights. Other types of awnings are also used with RVs:

  • Window awnings – shade and protection from elements over individual windows.
  • Slide-out awning; keeps off rain, snow and debris that can damage slide seals and migrate into the RV.
  • Entry door awning – shades the entrance and provides cover from the elements.
  • Outback awnings – canopy awnings that provide cover over toy hauler ramp as well and can be combined with a screen room.

ring-and-pinion-gears-4Axle ratio – The ratio of the number of turns the drive shaft makes for each rotation of the rear tires as established by the ring-and-pinion gears in the rear axle.  The gears in the axle change the direction of drive rotation by 90° from the drive shaft to the axle shafts.  The gears also multiply the force provided by the drive shaft – the torque – providing a mechanical amplification.  Higher ratio values provide more torque per rotation of the drive shaft.  For example, a 4.10:1 means that the drive shaft must turn 4.1 turns to rotate the axle one revolution.  As well, if the drive shaft is delivering 100 lb-ft to the axle, the axle gears multiply that force by the same ratio (100 x 4.1 = 410 lb-ft). Lower gear ratios in the axle provide lower torque, but higher speed for the vehicle.  With a 3.08:1 ratio, the 100 lb-ft. torque of the shaft would deliver 308 lb-ft to the axle, a 25% reduction in torque.  A higher ratio gives more torque and less road speed for a given engine RPM, with a lower fuel economy.  For fuel economy, a lower axle ratio is best.

Axle weight – The axle weight or load of a vehicle is the total weight transmitted by all the wheels on a given axle to the surface beneath it. 5

campground_thumb3Back in – a campground site with a single entrance, normally referred to as a back in site.  In the campground map segment on the right, sites 151 – 155 are designated as back in sites. Campgrounds with hookups at back in sites will normally have the hookups on or near the left side of the RV when the camper is backed in and picnic table and fire ring, if provided, on the right side.

Back-up monitoring system – camera and navigation screen used as a aid to backing up or reversing the RV.  The camera is mounted on the back of the motorhome and the screen on or near the vehicle’s dashboard.  Since the camera faces rearward, the display on the screen is horizontally reversed so that objects on the vehicle’s rear right show up on the right side of the screen and those on the rear left show up on the left – in other words, the camera output is displayed in a mirror image format oriented as a driver would see in a rearview mirror. The system can also be used in the same manner as a rearview mirror to monitor traffic behind the RV as well as anything whatever is being towed, though this may be limited due to the mounting angle of the camera and the use of a wide angle lens.6

Ball mount – the part of a ball hitch that the trailer hitch ball is attached to.  Receiver-type hitches use removable ball mounts while fixed drawbar hitches – attached to the vehicle frame – and bumper hitches have integrated holes for attaching the trailer hitch ball.

For safe and comfortable towing, the trailer should always be as level as possible. A level trailer will put less strain on the connection between the trailer and hitch. It will also help the trailer stay in line behind the vehicle. Because trailer and vehicle heights often differ, a ball mount with a Rise or a Drop may be needed.7

Basement, basement model – storage area below the floor of the recreational vehicle. Basement storage is more commonly found on Class A motorhomes, some Class C motorhomes, and the forward storage area of many fifth wheel trailers. Basement storage areas allow pass-through storage, where one or more compartments can be accessed from either side of the camper.  Basement models are RVs that incorporate large storage areas below a raised chassis.

Battery – direct current (DC) electrical power source.  RVing batteries have two applications that require different battery designs: (a) powering house or coach DC components and (b) starting power for the engine and powering chassis DC component for a motorhome or tow vehicle.

Batwing antenna – roof mounted television antenna that can be raised and lowered from the inside of the RV using a hand crank combined with a manual control used to rotate the antenna. Batwing antenna are characterized by two horizontal “wings.”

1 Changin’ Gears – Understanding RV Weights
2 BatteryStuff.com – Gel vs AGM
3Wikipedia – Galvanic Corrosion, Galvanic Anode
4 Wikipedia – All-terrain vehicle
5 Wikipedia – Axle load
6 Wikipedia – Backup camera
7 etrailer.com – Choosing the Correct Ball Mount

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