Glossary
RV, Trailer and Fleet Repair Glossary
Short answer. If a term on your estimate does not make sense, it is probably here. These are the words that show up on RV, trailer and fleet repair orders and on claim files, defined the way we would explain them at the counter.
A
- A frame tongue
- The triangular frame structure at the front of a conventional travel trailer that carries the coupler and connects to the main frame rails. It absorbs braking and hitching loads. A tongue that is out of specification will make the trailer track incorrectly and wear tires unevenly.
- Absorption refrigerator
- A refrigerator that cools using a heat driven ammonia absorption cycle rather than a compressor, running on LP or 120 volt AC. Common failure signs are poor cooling in high ambient heat, a yellow residue at the boiler indicating a leak, and sensitivity to being operated off level.
- Actual cash value
- The replacement cost of a vehicle less depreciation, which is what most policies pay on a total loss. It is calculated from comparable sales, and RV comparables are frequently drawn from listings that do not match your floor plan, mileage or option package.
- ADAS
- Advanced driver assistance systems, covering lane departure warning, adaptive cruise, blind spot monitoring, automatic braking and backup camera systems. Sprinter, Transit, ProMaster and modern commercial chassis carry them, and structural or panel repair near a sensor generally requires a scan and a recalibration afterward.
- Adjuster
- The insurance representative who evaluates a claim, approves scope and authorizes payment. Field adjusters inspect vehicles, desk adjusters work from documentation. On RV claims most work is handled at a desk, which is why photograph quality and written detail determine how fast a file moves.
- Aftermarket part
- A component made by a company other than the original supplier. Quality varies enormously in this category, from equivalent to unusable. On RV components we evaluate case by case and tell you which is which, rather than treating aftermarket as automatically acceptable or automatically inferior.
- Agreed value
- A policy structure in which the insurer and owner set the payout amount in advance rather than calculating depreciation at the time of loss. It costs more in premium and it removes the valuation argument entirely, which matters most on custom builds and low production units.
- Anode rod
- A sacrificial magnesium or aluminum rod inside a steel water heater tank that corrodes in place of the tank lining. Suburban water heaters use them and Atwood aluminum tanks generally do not. A consumed rod left unchanged is how a water heater tank fails prematurely.
- Appraisal clause
- A provision in most policies allowing either side to demand an independent appraisal when the parties cannot agree on the amount of loss. Each side selects an appraiser, and the two select an umpire. It resolves valuation disputes without litigation, and it is underused on RV total loss disagreements.
- Azdel
- A composite panel of polypropylene and fiberglass used as an interior substrate behind the outer skin in place of wood. It does not absorb water or rot, which is a real advantage, but it bonds differently than luan and requires a different adhesive strategy during repair.
B
- Basement bay
- An exterior storage compartment beneath the floor of a coach, often pass through, and on larger units insulated and heated. Basement bays commonly house the water system, the inverter and house batteries, so water intrusion into a bay is often an electrical problem as well.
- Betterment
- A deduction an insurer may apply when a repair replaces a worn component with a new one, on the reasoning that you gained remaining life you did not have. It appears most often on roof membranes, tires and awning fabric, and it is negotiable with documentation of actual condition.
- Black tank
- The holding tank for toilet waste. Common problems are level sensors that read incorrectly because of residue, a dump valve that will not seal, and cracks caused by freezing or by tank straps that have loosened and allowed the tank to flex under load.
- Blend panel
- An adjacent undamaged panel that gets partially refinished so the new color transitions gradually instead of stopping at a hard edge. Blending is what makes a repair invisible on metallics and pearls. Estimates that omit blend panels produce repairs that read as a rectangle in sunlight.
- Boondocking
- Camping without shore power, water or sewer hookups, relying on house batteries, solar, a generator and onboard tanks. Boondocking exposes weaknesses in the house electrical system quickly, which is why solar, lithium and inverter upgrades are the most requested boondocking related work.
- Bulb seal
- A hollow compressible rubber seal that closes the gap between the slide room and the sidewall when the room is fully extended or fully retracted. Over years it takes a compression set and stops rebounding, which lets water track down the inside of the wall cavity.
- Butyl tape
- A non hardening putty tape used to bed components against a surface before fastening, on windows, vents, awning rails and roof penetrations. It is the primary seal in most RV assemblies. Surface caulking over a failed butyl bed hides the problem rather than fixing it.
C
- Cabover
- The section of a Class C motorhome or truck camper that extends forward over the cab of the chassis, typically holding a bed. Cabovers are prone to water intrusion at the front seam and to structural fatigue, because the whole section cantilevers off the body.
- CCC
- Cargo carrying capacity, the difference between GVWR and the actual weight of the vehicle with full fluids and standard equipment. It is what you actually have available for gear, water, propane and people, and on many modern units it is far smaller than owners assume.
- Ceramic coating
- A liquid polymer that cures into a hard, hydrophobic layer over paint or gelcoat, making cleaning easier and slowing oxidation. It is applied after paint correction, never before, because coating over defects locks them in. It reduces maintenance and does not prevent physical damage.
- Clear coat
- The unpigmented top layer over base color that provides gloss and UV protection. Once clear coat film fails, which is what chalky paint actually indicates, polishing removes what remains rather than restoring it. The correct fix is sanding back and refinishing, not more polish.
- Converter
- A device that changes 120 volt AC shore or generator power into 12 volt DC to run house circuits and charge the batteries. A failing converter shows up as batteries that never reach full charge or 12 volt lights that dim when the coach is plugged in.
- Crossmember
- A lateral structural member spanning between the main frame rails, supporting the floor and tying the frame together. Displaced crossmembers cause floor flex, door binding and misaligned body panels. They are the component most often missed when only visible impact damage gets repaired.
D
- Deductible
- The portion of a covered loss you pay before insurance pays. On a direct billed repair, the carrier pays the shop and you pay the deductible at pickup along with any upgrades you elected outside the claim. It applies once per covered loss, not once per repair operation.
- Delamination
- Failure of the bond between the outer skin of a laminated sidewall and its core. It usually starts from an impact or a slow leak, stays invisible for months, then presents as a bubble once summer heat expands the trapped air behind the skin.
- Diminished value
- The reduction in a vehicle market value after a documented repair, even when the repair was performed correctly. Recovery varies significantly by state, policy and whether you were at fault, and it generally requires an independent appraisal rather than an assertion.
- Direct repair program
- A network arrangement in which an insurer refers claims to participating shops that have agreed to specific rates and procedures. A carrier may recommend one. In California it cannot require you to use one, and you retain the right to select your own repair facility.
- Dry weight
- The weight of a vehicle as it left the factory without fluids, propane, cargo or passengers. It is the number quoted in brochures and it is nearly useless for planning, because a loaded RV routinely weighs thousands of pounds more than its published dry weight.
E
- EMS
- Energy management system, which monitors incoming power for low or high voltage, open ground, reversed polarity and surges, and disconnects the coach when the supply is unsafe. On larger coaches it also sheds loads to keep total draw under the available amperage.
- EPDM
- Ethylene propylene diene monomer, a synthetic rubber membrane used on many RV roofs. It chalks as it ages, which is normal, and it is repaired with compatible tapes and sealants. It is bonded to the roof decking with adhesive across the full deck, not just at the edges.
F
- Feather edge
- The tapered transition sanded at the boundary of a repair area so the new material steps down gradually into the existing finish. A poorly feathered edge shows as a visible ring or halo once the panel is painted, particularly under low angle light.
- Filon
- A smooth fiberglass reinforced plastic sheet laminated to the outside of many RV sidewalls. It is lighter and cheaper than molded fiberglass and takes paint and graphics well, but it telegraphs any framing or core irregularity behind it once the bond starts to fail.
- Front cap
- The molded fiberglass or composite front end assembly of an RV, incorporating the nose, windshield surround and often the upper cabover. Caps are molded to model and are frequently special order with long lead times, which is why cap damage drives repair schedules more than labor does.
G
- Gelcoat
- A pigmented resin surface layer sprayed into the mold when a fiberglass panel or cap is made. It is the finish itself rather than paint over a substrate, which is why gelcoat damage is repaired with resin and buffing rather than filler and refinish where possible.
- Gray tank
- The holding tank for sink and shower drain water. It is less noticed than the black tank until it develops an odor, backs up into a shower pan, or leaks into the underbelly, where the damage often reaches the subfloor before an owner sees anything inside.
- GVWR
- Gross vehicle weight rating, the maximum the manufacturer permits the loaded vehicle to weigh including fluids, cargo and occupants. Exceeding it stresses axles, tires, brakes and frame. Structural and suspension damage from chronic overloading is common and is not repairable by adding capacity.
H
- Headache rack
- A protective rack mounted behind the cab of a truck to shield the rear window and occupants from shifting cargo. On flatbeds and service bodies it also carries lights and cargo control hardware. Mounting must tie into frame structure rather than only into the bed deck.
I
- Inverter
- A device that changes 12 volt DC battery power into 120 volt AC so household outlets and appliances work without shore power or a generator. Combined inverter chargers from Magnum, Xantrex and Victron handle both directions and are the heart of most boondocking electrical systems.
K
- King pin
- The vertical pin on a fifth wheel trailer that engages the hitch jaws in the tow vehicle bed. It carries the pin weight of the trailer and is a structural component. A bent or worn king pin is a safety issue, not a wear item to monitor.
L
- Landing gear
- The extendable legs that support the front of a fifth wheel or gooseneck trailer when it is unhitched, either manually cranked or electrically driven. Bent legs, stripped gearboxes and failed motors are common. Loading a trailer on landing gear that is not on firm ground bends them.
- Lap sealant
- The flexible self leveling sealant applied over roof penetrations and seams, commonly a Dicor product. It is a topcoat, not a primary seal. It shrinks and cracks under UV and heat cycling, which is why it needs inspection annually in inland Southern California.
- Lift gate
- A hydraulic or electric platform mounted at the rear of a truck or van to raise and lower cargo, from makers including Maxon, Tommy Gate and Anthony. Mounting loads are severe, and a gate cycled with corner loads will eventually tear its mounting from the rear sill.
- LKQ part
- Like kind and quality, meaning a used or recycled original equipment part sourced from a comparable vehicle. On discontinued RV components an LKQ part is frequently the only realistic option, and on molded caps it can cut a six week lead time to a few days.
- Loss of use
- Coverage for the cost of a substitute while your vehicle is being repaired. On RVs it is often limited or absent, and where it exists it may pay a daily amount well below actual rental cost for a comparable unit. Check the specific limit before assuming it applies.
- Luan
- A thin tropical hardwood plywood used as a backing substrate in many laminated RV walls and as an underlayment in floors. It is light and inexpensive. It also turns to pulp under sustained moisture, which is why water intrusion in a luan built wall spreads quickly.
M
- Macerator
- A pump that grinds waste and pushes it through a small diameter hose, allowing a black tank to be emptied without a gravity dump connection. Convenient, but sensitive to what goes into the tank, and a failed macerator usually means the tank has to be emptied conventionally.
- MPPT
- Maximum power point tracking, a solar charge controller technology that adjusts to extract the most available power from the panels across changing sun conditions. It is meaningfully more efficient than older PWM controllers, especially with higher voltage panel arrays and lithium house banks.
O
- OEM part
- A component supplied by the original equipment manufacturer or its designated supplier. On RVs the practical difficulty is that many original suppliers no longer exist or no longer produce parts for older models, which is why fabrication capability matters on units past about eight years old.
- Orange peel
- A dimpled paint surface texture resembling citrus skin, caused by spray gun setup, material viscosity, booth temperature or improper flash times. Some texture is normal on factory finishes. Excessive orange peel on a repair is a preparation and application problem and it can be corrected by wet sanding and polishing.
- Oxidation
- Surface degradation of gelcoat or paint from UV exposure, presenting as chalky, dull, sometimes powdery finish. Light oxidation on gelcoat can be compounded and polished back to gloss. Heavy oxidation on a failed clear coat cannot, because there is no intact film left to polish.
P
- Paintless dent repair
- Working a dent out from behind the panel with specialized tools so the original finish is preserved and no refinish is needed. It works on ductile metal panels where the paint is unbroken. It does not work on fiberglass, gelcoat or laminated composite construction.
- PEX
- Cross linked polyethylene tubing used for fresh water plumbing in nearly all modern RVs, joined with crimp rings or expansion fittings. It tolerates freezing better than rigid pipe but still splits when badly frozen, and failed crimps are a common slow leak source behind walls.
- Pin box
- The structural assembly at the front of a fifth wheel that holds the king pin and transfers trailer load into the frame. Some are rigid and some incorporate air or rubber cushioning. Impact damage at the front of a fifth wheel often travels into this assembly.
- PPF
- Paint protection film, a clear urethane film applied over painted surfaces to resist stone chips and abrasion. It is most useful on front caps, rock guards and high impact leading edges. It must be removed and reapplied when the underlying panel is refinished.
R
- Rear cap
- The molded rear end assembly of a coach or trailer, carrying taillights, the ladder mount and the bumper attachment. It is the most common impact point on a towed unit, and impacts there frequently separate the cap flange from the sidewall without any visible exterior crack.
- Recalibration
- The procedure that restores an ADAS sensor to correct aim and reference after repair, using either a static target setup or a dynamic road procedure depending on the manufacturer. Skipping it after a bumper, windshield or panel repair leaves safety systems reading the road incorrectly.
- Reefer body
- An insulated and refrigerated cargo body used for temperature controlled freight. Its weakness is the liner seal: once moisture penetrates the liner, the insulation soaks, the body loses thermal performance, and the panel delaminates from the inside where nobody sees it until efficiency drops.
S
- Sail switch
- A small airflow sensing switch inside a furnace that confirms the blower is actually moving air before allowing the gas valve to open. A dirty or misadjusted sail switch is one of the most common reasons a furnace blows cold air and then locks out.
- Salvage title
- A branded title issued after a vehicle is declared a total loss. It permanently reduces resale value and complicates future insurance and financing. Owners who retain a totaled unit and repair it should understand that the brand follows the vehicle regardless of repair quality.
- Schwintek
- An in wall slide mechanism using vertical toothed rails driven by motors at each side, common on shorter rooms. Its characteristic failure is loss of sync between the two motors, which racks the room. Continuing to cycle a room that is out of sync damages the rails.
- Shore power
- External AC power supplied through a campground or home pedestal, typically 30 amp or 50 amp on an RV. Shore power feeds the converter and the AC circuits directly. Damaged shore cords, corroded inlets and worn pedestal connections are a frequent source of intermittent electrical faults.
- Slide topper
- A small fabric awning mounted above a slide room that keeps debris and water off the roof of the room when it is extended. It is a wear item. A torn or sagging topper lets water pool on the slide roof, which is a common route to slide floor failure.
- Storage fee
- A daily charge for keeping a vehicle on a repair facility property beyond the active repair period, most often accruing while a total loss decision is pending. Carriers usually cover a limited number of days. Delays in the decision are exactly what drive these charges up.
- Subframe
- A secondary structural assembly bolted or welded to the main structure, carrying suspension, drivetrain or body mounting loads. Damage to a subframe often shows up as a fitment problem elsewhere, such as doors that will not close square after an impact that appeared cosmetic.
- Subrogation
- The process by which your insurer pursues recovery from the at fault party or their carrier after paying your claim. If subrogation succeeds you may recover your deductible. It is the reason your carrier wants a police report and the other party information even when you were not at fault.
- Supplement
- An addition to an approved estimate covering damage discovered after work begins, submitted with photographs, measurements and part numbers. On laminated RV bodies almost every collision claim of any size generates at least one, because the true extent of core separation is not visible until the skin is opened.
T
- Teardown
- Controlled disassembly to expose hidden damage before final repair scope is set. On an RV it means removing outer skin sections, lifting membrane at seams and pulling interior panels where structure has to be seen. It is the stage where an estimate becomes accurate.
- Total loss
- A determination that repair cost, sometimes plus salvage value, exceeds a threshold percentage of actual cash value, so the insurer pays the value instead of repairing. Ask for the valuation worksheet and the comparables behind it, because RV valuation data is far less reliable than automotive data.
- TPO
- Thermoplastic polyolefin roof membrane, an alternative to EPDM used by many manufacturers. It is generally more resistant to chalking and punctures, but it requires TPO compatible sealants and adhesives. Using EPDM products on a TPO roof produces a repair that releases within a season.
- Transfer switch
- An automatic switch that selects between shore power and generator power, preventing both from feeding the coach at once. When it fails, symptoms include the generator running with no power inside the coach, or the coach dropping power when the generator starts.
- Tri stage paint
- A three layer finish system of a base color, a translucent mid coat containing pearl or candy, and clear over the top. Matching tri stage requires spraying let down cards to determine mid coat coverage, and it is why some colors cost substantially more to repair.
U
- Unibody
- A vehicle construction in which the body and structure are integrated rather than the body bolting onto a separate frame. Most cargo and passenger vans are unibody. Structural repair on a unibody requires measurement against factory specification because there is no separate frame to reference.
W
- Wiper seal
- The flexible blade seal that sweeps the top and sides of a slide room as it moves in and out, shedding water and debris. When it hardens or rolls under, it stops sweeping and starts channeling water into the wall or onto the slide floor instead of away from it.
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