Caravan chassis explained (2023)

Everything you wanted to know about caravan chassis but were afraid to ask

Advances in caravan technology have been subtle rather than revolutionary over the years, but one steady change we have noticed is the move away from the time-honoured timber frame/aluminium cladding body fitted on steel chassis to a more integral (and lighter) structure with a strong, rigid composite fibreglass or aluminium body on a lightweight chassis.

Despite their stronger and sexier-looking composite body, these new-wave caravans still need a chassis.

But why is a chassis so important on a caravan -- and how do you best look after yours?

Caravan chassis explained (1)

A sturdy steel chassis provides the backbone of most caravans

What is a caravan chassis?

A chassis is a frame that supports the body and typically onto which things like the suspension, jockey wheel, stabiliser legs, water tanks and coupling are attached. You can’t have a caravan without some kind of chassis, but there are a few variations on the theme...

The most common set-up involves longitudinal chassis beams made from Rectangular Hollow Section (RHS) 150mm x 50mm steel, while the cross beams often are Square Hollow Section (SHS) 50mm x 50mm.

You’ll see this set-up (or a version thereof) on just about all Aussie-made vans. Other (lighter) vans, such as the European models, use a C-channel chassis main beam.

Caravan chassis explained (2)

The heavier the caravan, the stronger the chassis!

Many caravan chassis have extra strengthening in the form of A-frame gussetting, which is extra steel welded to the longitudinal beams. There’s also the A-frame reinforcement plate, which is additional sheet steel welded onto the longitudinal beams at what can be a weak point on a caravan chassis, where the A-frame beams meet the main chassis structure.

Risers are sections of RHS welded onto the top (or underneath) the parallel chassis side sections. This allows the body to have more clearance and as wheel wells are higher, there’s the opportunity for both a flat floor inside the van and more wheel travel off-road.

Most chassis are stitch-welded, which is a short run of welding at about 400mm intervals.

Caravan chassis explained (3)

Latest Coromal chassis uses rivets instead of welds

Lightweight European caravan chassis

The Europeans do chassis very differently. Generally tow vehicles in Europe are smaller, more fuel efficient and lighter then tow vehicles in Australia so, accordingly their caravans have to be designed with low mass paramount.

This is reflected in their chassis design; today you won’t find any RHS steel chassis under a caravan made in Europe. Instead, there will be C-channel longitudinal chassis lengths, with the only cross bracing being the torsion beam suspension.

Many don't have the chassis cross beams used on Aussie vans for extra rigidity and strength simply because they don’t need it. The van’s rigidity is gained from the composite body and this chassis set-up is strong enough for the maximum 2000kg that these vans weigh.

Caravan chassis explained (4)

Euro caravan bodies are generally lighter and stronger, so chassis doesn't have to do as much work

Some European chassis are even bolted together rather than welded, to save some weight -- such as the new AL-KO chassis.

While we’re not focussing on body construction here, it’s important to explain how a composite body can take over some of the chassis’ responsibility for strength. The walls, roof, floor and furniture in a composite body design are usually all interlocked in place and then bonded - providing a solid, unitary body structure.

What can’t a caravan body do?

The one crucial thing a composite, interlocked body can’t do is adequately support suspension, or provide a platform for the coupling to attach to. But who knows what future technology might serve up...

Meanwhile, as Aussie caravans have become larger and better equipped in recent years so too have they increased in weight. Interest is growing in shaving weight off caravans, including by reducing chassis/body weight. The Aussie manufacturers have begun to eye off what the Europeans have been doing for years and applying some of their chassis-construction methods.

Some manufacturers have done this by using C-channel steel cross-beams instead of SHS sections. Others have gone a step further by using C-section steel with cut-outs, reducing weight without compromising on strength.

Caravan chassis explained (5)

Cut-outs help reduce chassis weight

You’ll notice that most of these C-channel beams and cut-outs are not cut straight but have a curled-over section at the cut-out openings or at the tips of the C-channel beams. This is done for added strength.

Another way to reduce weight has been to build a van with a strong composite body. As the chassis does not then have to do all the work, it can be built lighter.

However, as yet there hasn't been a huge weight saving by building composite vans with lighter steel chassis, especially when it comes to large (22 foot-plus) off-road tandems. The weight saving is about 200-300kg over a regular large Aussie van.

There are several reasons why Aussie van chassis haven’t made a wholesale move to Euro-like construction. Probably the biggest reason is that it's cheaper and easier to weld up a RHS/SHS chassis that can be used across a range of caravan bodies; it also doesn’t need as much engineering and varying changes in chassis size to account for high-stress areas of the chassis.

Caravan chassis explained (6)

Keep an eye on rust formation before it becomes a problem

What type of galvanising is best?

DuraGal and SupaGal steel use galvanised zinc coatings to prevent the steel from rusting. Done before the chassis has been welded together, DuraGal is zinc coating applied only to external surfaces while SupaGal is zinc applied to both internal and external surfaces of the steel.

When the chassis is welded together, zinc can also be applied to the external welds -- internally though, the welds can corrode as they aren't zinc-protected.

Hot-dipped galvanising, which is a process of dipping the finished chassis into a tank of molten zinc, is the best way to rustproof a chassis. However, it does add a bit of weight to the chassis -- about five per cent, although that can vary according to how much of the coating remains in the hollow sections of the chassis.

Two large, identical chassis can be several kilos apart in weight as different amounts of zinc have settled in each.

Looking after your chassis

There isn’t much involved with chassis maintenance. Although there isn’t much to go wrong, the chassis isn’t an entirely set-and-forget item. It still needs periodic checking and a small amount of maintenance.

If you’re buying an older, second-hand van or if you have owned your van for a while it won’t hurt to check the A-frame for rust. Obvious signs of corrosion on the weld seam, and if tapping the box section reveals a hollow sound in some sections but not others, may indicate serious rust problems. Get it checked out by a caravan specialist.

If you’re spending a lot of time camping near the sea or if you’re towing on the beach, don’t just wash your van’s shiny side. The chassis should be rinsed with plenty of water, especially if it has been exposed to sea water on the beach.

Caravan chassis explained (7)

Most chassis are galvanised but salt is still the enemy

The gas bottle holders don’t normally cause problems but with large 9kg bottles fitted you may need to occasionally check the frame’s stiffness and for any signs of broken welds.

The handbrake lever pin needs to be greased, and the handbrake cable needs to be checked for fraying.

The tow coupling also needs cleaning and re-greasing occasionally to provide a smooth trouble-free movement when coupling/de-coupling.

The spring holding the lock-down clip must be in good condition, or the safety margin given by the clip could become compromised. While an unlikely scenario, you don’t want to risk the caravan de-coupling on a bumpy road because the coupling release safety clip was broken.

The tow coupling head needs the securing bolts checked for tension - they should never be loose. If you're uncertain what torque to apply to tighten these bolts, then check with your caravan manufacturer.

Some tow vehicles do not tow some caravans very well, but a lot of that can be down to chassis set-up. Make sure that the A-frame is not sitting too low when coupled to the vehicle’s towball, or not only will the caravan not tow well but also the A-frame will scrape against the road on dips such as those when entering or exiting driveways.

Caravan chassis explained (8)

Many Australian chassis are hand welded

Flipping the towbar shank over (where possible -- some shanks are not designed to do this) or replacing the shank with one that sets the coupling point higher can help deliver a more level, and safer towing rig.

In some cases a Weight Distribution Hitch will be needed -- if so, make sure there's space on the appropriate points on the van chassis' A-frame for the WDH collars to fit.

While a scrape or two won’t harm the A-frame (it can remove any zinc coating and encourage corrosion though), a solid thump against the road can cause all sorts of problems.

The chain links could become damaged and while the A-frame structure is usually very solid, it could transfer shocks through the towbar and the caravan, causing further damage. However, making use of the different height adjustments on a WDH can make the geometry more acceptable.

Lastly, safety chains should be inspected for wear to the links or any other indications of deterioration.


What is the chassis on a caravan? ›

The chassis of a caravan is widely described as being the skeletal backbone of your caravan. It is a metal frame that acts as the foundation of the caravan body and is where several parts of the caravan such as the jockey wheel and stabiliser legs are attached to. There are different grades of steel used for chassis.

How do I check my caravan chassis? ›

Where can I find my caravan VIN Number? Your Vehicle Identification Number (VIN), sometimes called a chassis number, or a CRiS number, can be found on the main door to the habitation area, in the bottom right-hand corner of each window, (on occasion this may exclude the front windows depending on the model).

What is a caravan answer? ›

Britannica Dictionary definition of CARAVAN. [count] 1. a : a group of people or animals traveling together on a long journey especially through the desert. b : a group of vehicles (such as cars or wagons) traveling together.

How much weight does galvanising add to a caravan chassis? ›

Typically, galvanising adds around five percent to the overall weight of the chassis. The intense heat can warp the steel though, and that needs to be taken into account by the caravan chassis manufacturers.

What are the 4 types of chassis? ›

There are several types of chassis, differing in their construction and the way in which other components, such as the drivetrain and body, are assembled.
  • Ladder frame chassis. Ladder frame chassis is one of the oldest types of chassis. ...
  • Backbone chassis. ...
  • Monocoque chassis. ...
  • Tubular chassis.
Dec 27, 2022

How do you identify a chassis? ›

Door. Your car's chassis number is often printed on the driver's side door. There will be a metal strip found on the B-pillar of the car which will have the number printed on it. This can be seen when the driver's side of the door is opened.

What does a chassis number look like on a caravan? ›

The Caravan VIN

The VIN will be dotted around the caravan. It will be stamped onto the A Frame, either etched onto or have a no-tamper sticker on windows and can be found in some gas lockers. The 17 digit code has 3 main parts, each of which can be broken down into more information.

Where is the chassis on a van? ›

You can locate the chassis number of the car under the spare wheel in the boot. Upon lifting the spare wheel, you can spot the VIN or the chassis number of the vehicle.

Why is it called a caravan? ›

The word caravan comes from the Persian karwan meaning "group of desert travelers." A caravan can be a large group of people traveling together in one long line. It's also the term used for a camper that has a living area in it.

What is caravan in simple terms? ›

a group of travelers, as merchants or pilgrims, journeying together for safety in passing through deserts, hostile territory, etc. any group traveling in or as if in a caravan and using a specific mode of transportation, as pack animals or motor vehicles: a caravan of trucks; a camel caravan.

What is special about caravan? ›

It provides the means for people to have their own home on a journey or a vacation, without relying on a motel or hotel, and enables them to stay in places where none is available. However, in some countries campers are restricted to designated sites for which fees are payable.

Can you drill into caravan chassis? ›

Holes should not be drilled in chassis flanges unless it is the practice of the original equipment manufacturer (OEM) to do so.

Will a galvanized chassis rust? ›

A fully hot-dipped, galvanised chassis provides, by far, the highest levels of protection from rust and corrosion. This should be the only option considered if siting a caravan in exposed locations such as coastal areas.

Do you need to paint a galvanised chassis? ›

Painting a galvanized chassis is somewhat controversial, many argue that it doesn't adhere and it doesn't add any protection. On the other hand, a galvanized chassis is attractive to thieves. Let us know what you think below. However, a galvanised chassis can be painted, using commercially available products.

What is the most used chassis? ›

A monocoque is a shell around the car made by using both chassis as the frame in a single construction. This is the most commonly used chassis right now due to the number of advantages of has over the other two chassis.

What chassis do most cars use? ›

Monocoque Chassis

This type of chassis is the most common type of chassis used in modern passenger cars. This single body type structure makes up all the components and mechanical parts. All the exterior components like seats, suspension, engine, transmission, and body panels are directly connected to the chassis.

What are the 3 main parts of under chassis? ›

Vehicle's under chassis have 3 Main Parts:
  • Clutch. Connecting to Engine to Drive shaft to transmit power from the engine to each wheels.
  • Steering. Steering wheel, control and shoulder arm, and wheel control are the 4 parts of vehicle's steering. ...
  • Suspension.

How do you decode a chassis number? ›

Decoding your VIN
  1. The first character tells you where in the world the vehicle was built. ...
  2. The second character denote the manufacturer.
  3. The third character tells you the vehicle type or division.
  4. The fourth through the eighth characters tell you the vehicle brand, body style, engine size and type, model, and series.

What is chassis details? ›

Vehicle Identification Number, chassis and engine number are unique identification numbers of your vehicle. VIN is an alphanumeric code of 17 characters. Decoding this number will help you identify the manufacturing year and month of a vehicle's model. Similarly, a chassis number is the last six-digit number of VIN.

Do chassis have VIN numbers? ›

A car's VIN number is sometimes called its chassis number. They are the same - the Vehicle Identification Number is stamped to the chassis of the car and so is fixed to that model in question.

Does a caravan have a chassis number? ›

Caravans and light trailers must have their individual vehicle identification number (VIN) clearly stamped, embossed, or otherwise permanently marked on a substantial part of the frame or chassis.

How do you check if a caravan is stolen? ›

Contact the police

If you have installed a tracking system contact them to let them know so they can trace where the caravan is. Stolen caravans are listed on a number of systems including the PNC (Police National Computer), CRIS, and insurance databases, so historic checks can be made by officers.

Are all chassis numbers the same? ›

All modern motor vehicles are distinguished by a specific Vehicle Identifying Number, or a VIN. Like a fingerprint but for a car, no two VINs are the same.

What is an example of a chassis number? ›

For example, Chassis (Frame) Number SV30-0169266 breaks down as "V30" identifying the model as Toyota Camry/Vista x30; "S" identifying the engine (4S-FE), and "0169266" being the serial number of the vehicle.

How does a chassis number look like? ›

The chassis number is the last six digits of your car's Vehicle Identification Numbers (VIN), so you need to find the VIN to determine the chassis number. Cars and motorcycles list the VIN in different places, so where you look will depend on the type of vehicle you have.

What is the difference between the chassis and the frame? ›

So, the chassis is the load-bearing part of the frame – the 'frame', then, is the rest of the structural body of the car. This is what you imagine when you think of cars being put together on assembly lines - the skeleton frame of a car.

How can I tell what year my caravan is by chassis number? ›


You will find the VIN number either in the window, door or A frame. It has 17 digits and in more modern caravans is scratched into the window, so it cannot be removed. The 10th character of your VIN number denotes how old your caravan is.

What is VIN chip on a caravan? ›

VIN CHIP™ is a theft deterrent and identification system for touring caravans designed to deter criminals looking to steal touring caravans and to help aid the identification and recovery process. The VIN is the first thing the police look for to identify a touring caravan.

What is the American word for caravan? ›

The American word is trailer.

What is a caravan called in America? ›

What is a caravan called in America? Depending on the style/model, in America, Caravans are called campers, trailers, fifth wheels, and pop-ups. If the unit has a motor, it is called a camper, RV (Recreational Vehicles), Class A, or Class C.

What is another word for caravan? ›

synonyms for caravan
  • cavalcade.
  • convoy.
  • expedition.
  • procession.
  • band.
  • campers.
  • safari.
  • train.

How does caravan work? ›

Caravan is a two-player game in which both players have three piles of cards, also known as caravans. The goal is to bring the total value of each pile to between 21 and 26 using your deck of cards. If a caravan goes over 26, it is no longer valid and you can restart the pile.

What is the old meaning of caravan? ›

For the first 70 years of its use in English, caravan referred to merchants or pilgrims travelling together, with their goods carried by camels. In the mid 18th century the term was used in the US to refer to groups of travellers, traders or emigrants travelling through the Western states with their horses and wagons.

What are two examples of a caravan? ›

7 Types of Caravans
  • Regular Caravan. These are your run of the mill caravans, probably the kind that first comes to mind when you think of caravans. ...
  • Pop-up Caravans. ...
  • Tent Trailer. ...
  • Camper Trailer. ...
  • Pop-out Caravans. ...
  • Fifth-Wheelers. ...
  • Motorhome.
Apr 6, 2020

Who uses caravan? ›

caravan, a group of merchants, pilgrims, or travelers journeying together, usually for mutual protection in deserts or other hostile regions.

Why do people use caravans? ›

Flexibility – Caravaning offers a level of flexibility that is hard to find with other forms of travel. With a caravan, you can go wherever you want, whenever you want, and stay for as long as you want. There's no need to worry about hotel bookings, flights, or schedules.

Why did people use caravans? ›

Caravans were used mainly in desert areas and throughout the Silk Road, where traveling in groups aided in defense against bandits as well as helped to improve economies of scale in trade.

What engine do you need to pull a caravan? ›

What's the best engine size for towing a caravan? As a general rule, you'll need an engine size of at least 2000cc to tow a caravan. However, this will vary depending on the weight of your caravan and your car.

Are caravan chassis galvanised? ›

Brand new static caravans will usually have galvanised chassis. The underside of your static caravan should be inspected when siting it and then regularly, about twice a year, especially before and after the winter season.

Are all caravan chassis galvanised? ›

Caravans nowadays are built on a galvanised AL-KO or BPW chassis fitted with related running gear. The advantage of these galvanised products is the fact that they're virtually maintenance-free.

What are caravan chassis made of? ›

Most caravan, camper trailer and fifth wheeler chassis are made of steel, usually rectangular hollow section (RHS) steel.

How do you stop chassis rust? ›

Chemical Rust Treatments

Chemical Treatments are one of the primary ways of protecting your vehicle against rust. They work by spraying a waxy coating against any exposed metal which adds another layer of protection against rust. There are some panels (such as the inner part of the roof) which are unable to be sprayed.

How do I protect my static caravan chassis? ›

Painting your chassis with a zinc paint such as Zinga will reduce the potential of rust and corrosion from sea salt or in the event of flooding. Zinga will also increase the lifespan of your holiday caravan as Zinga (Zinger) offer greater protection than hot dipped galvanising.

Will rustoleum paint stick to galvanized metal? ›

Touch up galvanized surfaces with Rust-Oleum High Performance V2100 System Galvanizing Compound Spray. This 93% pure zinc coating provides maximum corrosion resistance and excellent adhesion and durability on galvanized metal.

Can you paint straight onto galvanised steel? ›

Unfortunately, paint does not adhere to galvanised steel. That's because the layer of zinc on the metal, which is designed to reduce corrosion, also rejects paint, causing it to peel away and shed.

Do you need to sand galvanized steel before painting? ›

Sand the entire metal surface thoroughly, including crevices and dents. Wipe the entire surface with the tack cloths. Apply the primer as directed, covering the entire surface of the metal. It's best to start at the top and work down, section by section.

What does the chassis consist of? ›

The chassis comprises the following components: wheels, wheel carrier, wheel bearing, brake, wheel suspension, axle support, suspension (including anti-roll bar)...

What is the function of chassis? ›

The chassis has a function to support the vehicle's engine and transmission loads as well as components and passengers in the car. Another function is to maintain the shape of the car so that it remains rigid and does not deform when used.

How do I read my chassis number? ›

Decoding your VIN
  1. The first character tells you where in the world the vehicle was built. ...
  2. The second character denote the manufacturer.
  3. The third character tells you the vehicle type or division.
  4. The fourth through the eighth characters tell you the vehicle brand, body style, engine size and type, model, and series.

What is chassis number code? ›

A vehicle identification number (VIN) (also called a chassis number or frame number) is a unique code, including a serial number, used by the automotive industry to identify individual motor vehicles, towed vehicles, motorcycles, scooters and mopeds, as defined by the International Organization for Standardization in ...

Is A VIN the same as a chassis number? ›

The Vehicle Identification Number (VIN) or Chassis Number can be found on the dashboard, driver's side door and on the registration certificate. All cars and light commercial vehicles built after 1981 have a unique 17-character VIN that provides access to valuable information about that vehicle's history.

What does a VIN or chassis number look like? ›

What does the VIN number look like? The VIN is 17 characters long and is comprised of both digits and capital letters. If your VIN appears to be any shorter than this, it may be a model manufactured before 1981, when VINs were between 11 and 17 characters.

Do galvanized chassis rust? ›

Fully Galvanised Chassis

A fully hot-dipped, galvanised chassis provides, by far, the highest levels of protection from rust and corrosion. This should be the only option considered if siting a caravan in exposed locations such as coastal areas.

What is Supergal chassis? ›

DuraGal and SupaGal steel use galvanised zinc coatings to prevent the steel from rusting. Done before the chassis has been welded together, DuraGal is zinc coating applied only to external surfaces while SupaGal is zinc applied to both internal and external surfaces of the steel.


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