Stay safe on the road with this guide to caravan towing components — from towbars to breakaway systems — and why each one is essential for safe, legal travel.
It is easy to take for granted connecting a caravan to a tow vehicle. Simply put, it’s just a matter of hooking up the coupling, attaching the safety chains and joining any electrical connections required. In reality, there are many components and variables that go into this system for safe and legal towing.
In this article, we go through the mechanical components in the system. A key takeaway is that the entire system is only as good as the weakest link in the chain, metaphorically and literally speaking.
Towbar assemblies
The towbar is the major structure that attaches to the tow vehicle chassis. Usually made from structural steel and requiring compliance with relevant Australian standards, the towbar has significant dynamic loads imposed on it through the rigours of towing.
Towbars are fitted to specific mounting points provided by vehicle manufacturers and must be installed using high-tensile bolts and torque settings specified by the vehicle and/or towbar manufacturer. A compliant towbar will include a rating plate indicating its maximum towing capacity and the maximum allowable towball mass. It is important to understand that the towbar load ratings are not the same as the tow vehicle’s tow load ratings. In most instances, the towbar will have the same rating as the tow vehicle. However, I have come across instances where the towbar rating was less than the actual tow vehicle rating, and the car owner may need to upgrade the towbar to achieve the desired towing capacity.
The towbar assembly is bolted to the chassis
When shopping for a brand-new tow vehicle, it is worth checking if the car comes with a towbar as standard. If it doesn’t, having one fitted will take up some of your payload and, of course, add cost. Factory towbars are often integrated into the vehicle’s aesthetics and electrical systems. However, quality aftermarket towbars are widely used, especially in the 4WD market. They often provide additional features such as reinforced recovery points, integrated trailer wiring plugs and/or high-mounted receivers for better offroad clearance.
Although extremely rare, it is possible for the towbar to detach from the car, which renders the caravan also detached from the tow vehicle. Clearly, this is highly undesirable, so it is recommended to regularly inspect the bolts and the integrity of the bar, including rust or fatigue from age.
Tow tongues/ball mounts
The tow tongue (also known as a ball mount) is the removable component that connects directly into the towbar hitch receiver and carries the towball/pin. Being removable allows tow tongues of different lengths, rises and drops to be used. Increasing the tow tongue length pushes the trailer further away, which can solve some clearance problems, such as preventing the boot or trailer door from hitting the coupling or reducing the chance of jackknifing. However, longer tongues increase the leverage the caravan exerts on the tow vehicle, imparting greater forces. It is important to check whether a longer tongue is suitable for your application. In some instances, a longer tongue may not be allowed or have a lower tow and download rating than a shorter tongue.
Rises and drops are used to position the towball/pin at a suitable height so that the caravan sits level for stable towing. Some tongues are fixed and simply have different bends to achieve different heights. It is important to know that some tongues are reversible, but not all are designed to be used upside-down or may have lower ratings. Other tongues are adjustable through repositioning bolts in a variety of holes. These are particularly useful if you tow different trailers or if you occasionally carry heavy loads in the rear of the vehicle that alters its ride height.
Fixed and adjustable tow tongues
Tow tongues have their own rating separate from the towbar. Care should be taken when swapping a tow tongue to ensure it has an adequate rating; otherwise, it can compromise your overall tow rating. In other words, it could become the weak link in the chain.
Tow tongues are secured to the towbar receiver with a pin. Many pins are simply held in place with a clip, while others have a lockable end on the pin. ‘Belts and braces’ versions have both a clip and a lockable end. The simple clip versions are very reliable, but they are also more vulnerable to human tampering. At a minimum, the tow tongue could be stolen as it is easy to slide out a pin. In theory, this shouldn’t happen if best practice is followed — removing the tow tongue when not towing. If you had a lock on your coupling but not on the tow tongue, a thief could ‘unhitch’ your van at the towbar receiver. Sure, it would not be easy to tow the van away, but thieves can be creative. Perhaps the most sinister is sabotage, where someone just removes the pin but leaves the tow tongue in the receiver. This potentially could cause a catastrophic detachment of the van from the car. We will discuss the other fail safes in the towing system in a bit, but theoretically, it could happen.
Anti-rattle bolts are often used in receiver hitches to reduce movement and noise. However, their use is generally discouraged when towing. In fact, some manufacturers explicitly prohibit the use of anti-rattle bolts while towing. The nut welded to the towbar to retain the anti-rattle bolt can break away, the bolt itself can break inside the nut, or potentially, the tongue or receiver can be compromised.
Anti-rattle bolt
Anti-rattle bolts are not permitted when towing for some brands
Towballs/pins and couplings
The physical connection between the tow vehicle and caravan is achieved by joining the towball/pin and the coupling. The towball or tow pin is attached to the tow tongue with a robust nut and the coupling is welded/bolted to the caravan A-frame. By far, the two most popular connectors are the 50mm ball coupling and the Cruisemaster DO35 coupling. The 50mm ball has been around for decades and does a very serviceable job with tow ratings up to 3500kg.
50mm and 70mm towball couplings
While the DO35 is a comparative newcomer, it is now the most common setup I see on the vans I review. When hitched, the DO35 coupling is technically able to rotate 360 degrees on the roll axis and appreciably more than a ball coupling in the pitch axis. This improves offroad performance and can make it easier to couple and uncouple on uneven ground. Hopefully, you will never need to experience its greatest advantage. In the event of a violent trailer sway event, it is possible for the caravan to roll over. When a ball coupling is used it is possible for the caravan to flip the car over due to limited roll articulation. In the case of a DO35, it is possible for the caravan to tip over while the vehicle remains upright due to the 360-degree roll articulation.
The DO35 latching mechanism is easy to use and provides a very positive click when it is engaged. However, human error is still possible where the coupling is dropped over the pin, and the operator neglects to engage the latch. In these cases, it is possible for the van to travel some distance on the car until a big enough bump bounces it off.
Cruisemaster DO35 coupling
A peculiarity of Australian Standards gives the DO35 coupling (and other offroad couplings) an advantage over 50mm ball couplings. When the tow vehicle is loaded, the towball must be able to be fitted to a height of between 350mm and 460mm off the ground to be compliant. This height limit is not stipulated for other types of hitches. With many caravans and tow vehicles sitting higher these days, keeping the towball height under 460mm is often not possible.
We have focused on the 50mm ball and the DO35 as they are applicable for vans up to an ATM of 3500kg. However, for vans above 3500kg ATM there are larger, higher rated, scaled up versions available, namely the 70mm ball coupling and the DO45 coupling.
For the record, there are a number of other offroad style couplings on the market, but the truth is we rarely come across them. Also, there are some engineering/suspension companies that mandate a specialised coupling to be used when they provide a tow vehicle gross combined mass (GCM) upgrade.
Like all components in the system, couplings should be regularly monitored for any signs of deterioration and lubricated where appropriate.
Specialised coupling for GCM upgrade
Safety chains
Safety chains are your first line of defence in keeping the caravan attached if the coupling connection fails. Caravans with a less than 2500kg aggregate trailer mass (ATM) require at least one compliant safety chain, while caravans above 2500kg require two independently connected chains. Chains must be of sufficient rating and either welded to the drawbar or affixed using a mechanical coupling method that meets the relevant standards.
Best practice is to cross the chains under the coupling to create a cradle. This helps prevent the A-frame from hitting the ground in the event of a coupling failure. The chains must not drag on the ground during normal towing and should be long enough to permit full articulation during turns without placing excessive tension on the links.
Chain maintenance is often overlooked, but essential. Check for rust, deformation and damaged links, and replace any components that show signs of weakening. Chains should be stored off the ground when not in use to avoid corrosion — fortunately many A-frames have a handy place to hook the chains.
Safety chain connections
Safety chains are only as good as the hardware used to connect them to the tow vehicle. Most towbars feature welded-on chain attachment points. The conventional connection device is a D-shackle or bow shackle. Australian standards designate a number of criteria, including a break limit 1.5 times the caravan’s ATM. Generally, the break limit is six times the working load limit. Chain hooks with spring-loaded gates are also gaining popularity as an alternative to shackles, as they are more user-friendly to connect and disconnect. Standards and regulations around their use do not necessarily align. Much commentary on the subject suggests best practice is to use an appropriate shackle, while others suggest there is no issue with using hooks, provided they meet the required strength ratings. When caravan owners choose to use hooks, they will often attach them to the towbar with hammerlocks (permanent coupling links) to optimise connection convenience. Again, this is another component in the system that must be adequately rated.
D-shackles are the conventional way to attach safety chains
Safety chain hooks permanently attached with hammer locks
Breakaway devices
Mandated for caravans exceeding 2000kg GTM, breakaway devices are your second line of defence in the event that your van detaches from the tow vehicle. If the worst happens the electric brakes are automatically activated to prevent the van from careering down the road without the tow vehicle. They come into play if the coupling and safety chains fail or if the entire towbar assembly detaches from the car.
The breakaway system typically includes a dedicated battery, a switch with a pull-pin and wiring integrated with the caravan’s braking system. When the pull-pin is dislodged (due to disconnection), the switch activates the brakes and must hold them for a minimum of 15 minutes.
BMPRO TrailSafe breakaway system
The breakaway cable must be attached directly to the tow vehicle (not the towbar or safety chains), ideally to a fixed loop or anchor point on the vehicle’s structure. The cable should be slightly shorter than the safety chains to ensure it activates before the chains are fully tensioned.
Proper maintenance includes regular testing of the battery, verifying the charge level and ensuring the pin is securely inserted before every journey.
Weight distribution hitches
All of the above components would be considered imperatives, whereas the weight distribution hitch (WDH) is a matter of choice, with some people loving them and others loathing them. When a heavy caravan is hitched to a tow vehicle, the rear car suspension compresses, and the car chassis tilts slightly around the rear axle. This ‘see-saw’ effect decompresses the front suspension and shifts weight off the front axle. In turn, this reduces the downward force on the front axle/front tyres, compromising steering and braking.
It is not easy to visualise, but a WDH uses levers to put upward force on the towbar, which redistributes some of the towball load off the car rear axle back to the car front axle. The levers are the spring bars, which are connected to the car towbar and the caravan A-frame. Chains are used to hold the levers in the correct position and effectively ‘hang’ some of the load lifted off the rear of the car onto the A-frame.
Lovers of the system point to the improved handling and braking safety. Loathers believe they are a band-aid for a poorly setup tow rig. WDHs must be compatible with the tow vehicle and caravan. Some vehicle manufacturers, particularly those with monocoque construction, explicitly disallow their use. Misuse can result in frame or towbar damage. Also, offroad travel generally requires the inconvenience of removing the WDH, as uneven terrain can place significant stress on the spring bars and A-frame brackets.
Weight distribution hitches can improve vehicle handling and braking
Summary
Connecting a caravan to a tow vehicle involves multiple interrelated components that each play a critical role. All components must be rated, fitted, regularly inspected and used correctly to ensure safe towing and legal compliance.
Before every trip, conduct a full check of all towing components. Confirm your towbar and tongue are correctly fitted and torqued, the coupling is securely latched, the safety chains are crossed and connected with rated hardware, and the breakaway system is operational. Your safety and that of others depend on it.
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