Caravans would be difficult to control without an effective suspension system to smooth out the forces from bumps and holes in the road. John Hughes takes a look at the pros and cons of various types of caravan suspension systems.
The suspension system in your caravan plays a vital role in how it handles various road conditions. Suspension smooths out the forces imparted on the caravan by bumps and holes in the road.
This is achieved with two critical components – springs and dampers (usually referred to as shock absorbers). Springs compress to soak up forces. Caravan suspension springs generally come in three different types. Coil springs, leaf springs and airbags – more detail later.
Dampers slow down the spring as it returns from its compressed state. This is a critical function otherwise your caravan would bounce up and down uncontrollably. Little box trailers with leaf springs usually don’t have shock absorbers and it is not unusual to feel and hear them bounce significantly, particularly when empty. Dampers vary less in their construction compared to springs.
The vast majority of shock absorbers involve some form of cylinder with valving containing compressible fluid to control the rebound of the spring.
Good suspension is essential when travelling on rough, corrugated roads, especially when towing a caravan
Another way of looking at is to say the suspension system works to keep the wheels moving up and down in response to variations in the road while minimising how much the van body moves up and down. Without an effective suspension system, a caravan would be difficult to control, leading to instability and increased wear on the structure and internal components.
The suspension directly affects the safety and longevity of both the caravan and its internal components. A well-designed suspension system reduces impacts and vibrations, preventing excessive stress on the chassis and fixtures inside the caravan. Without adequate suspension, rough roads can lead to structural fatigue, causing cracks in cabinetry, appliances and even the caravan’s frame over time. This is why selecting the correct suspension system is critical for different styles of travel, from highway cruising to extreme off-road adventures.
A variety of suspension types have been developed over time. Each type offers different advantages depending on the intended use of the caravan. Some systems are simple and robust, designed for on-road travel, while others provide greater articulation and flexibility for off-road adventures. The right suspension system improves towing dynamics and reduces sway which is essential for maintaining control at higher speeds and in adverse weather conditions.
Below we provide an overview of the most commonly used suspension types used in caravans today along with some of the lesser-known systems too.
Leaf spring suspension
Leaf spring suspension is one of the oldest and traditionally most widely used suspension systems for caravans. It consists of several layers of steel strips (leaves) stacked together and mounted to the chassis using fixed hangers at one end and shackles at the other. The caravan’s axle is attached to the centre of the leaf pack. As the wheels encounter bumps, the leaf springs flex and absorb the impact, and then return to their original shape.
AL-KO leaf spring suspension on a Condor caravan
Leaf spring suspension is a solid axle system, where the axle runs the full width of the caravan with a wheel attached on each side. This means when a wheel on one side of the axle encounters a bump, the force is partially transferred to the other wheel. This means the system copes with loads but less well with uneven ground.
Leaf springs are known for their simplicity, durability, cost-effectiveness and relatively lightweight compared to other systems. However, they do have limitations. The ride can be harsh, especially on rough terrain, because the multiple layers of steel create friction as they move. As the axle spans the full width of the caravan it reduces ground clearance, compared to independent suspension systems. However, in many tow rigs, the lowest point still could be the rear differential of the tow vehicle.
Leaf spring suspensions offer less refined wheel alignment adjustment than other systems as the axle is bolted into place with U clamps. Unlike independent suspension systems, there is no straightforward way to adjust toe or camber angles.
Some variations, like Simplicity suspension, improve upon traditional leaf springs by using load-sharing rocker arms that distribute weight between tandem axles more effectively. These systems enhance ride quality and reduce stress on individual components, making them a more refined option within the leaf spring category.
Trailing arm independent suspension
Trailing arm independent suspension has been the golden child of the caravan industry for the past decade or so. It offers greater control and comfort by allowing each wheel to move independently.
The system consists of trailing arms that extend backward from a chassis-mounted pivot point. A coil spring or airbag supports the weight, while a shock absorber controls movement. As each wheel moves independently, one side of the caravan can absorb bumps without directly affecting the other, resulting in a smoother ride and better traction on uneven terrain.
Independent suspension provides several advantages over leaf spring systems. By eliminating the solid axle, it improves ground clearance and reduces unsprung weight, allowing the caravan to handle rough tracks more effectively. Wheel alignment is more sophisticated where some systems are designed to allow simple toe and camber adjustment.
Even though unsprung weight is reduced, the overall weight of trailing arm systems is usually heavier than equivalent leaf spring systems increasing the tare weight of the van. The increased number of moving parts makes them more complex, expensive and require more maintenance over time.
AL-KO IRS with coil spring
Coil springs are the default lower-cost solution while airbags are the golden child when it comes to independent suspension. Airbags allow for dynamic ride height adjustments based on load and terrain conditions. This means caravan owners can raise or lower the suspension to suit specific environments - lowering for improved aerodynamics and fuel efficiency on highways or increasing ride height for extra ground clearance when tackling rough tracks. Another benefit of airbags is the ability to raise or lower airbags independently to level the van when parked at camp.
Cruisemaster and AL-KO are among the well-known trailing arm independent suspension providers to the RV industry with both players offering different levels of performance suited to various travel needs.
Cruisemaster XT suspension with coil springs
The Cruisemaster CRS (Country Road Suspension) is specifically engineered for touring caravans that primarily travel on sealed roads and light gravel tracks. It provides a significant improvement over leaf spring suspension in terms of comfort and control, thanks to its coil springs and tuned shock absorbers. It is the lightest weight and most cost-effective solution in the Cruisemaster lineup.
For those requiring more rugged capabilities, the Cruisemaster XT offers reinforced trailing arms, heavy-duty coil springs, and upgraded dampers to handle more challenging conditions. Designed for serious off-roaders, the XT provides increased suspension travel and shock absorption, allowing caravans to maintain traction and stability over corrugated roads, rocky trails, and sand tracks. It is heavier and more costly than the CRS system, however. It has proven its durability for more than a decade and has been under countless vans that Caravan World has taken to remote places. It is undoubtedly the most well-known of the Cruisemaster systems.
Cruisemaster ATX suspension for extreme offroad
At the top of the Cruisemaster lineup, the ATX is designed for extreme conditions. It features the most robust components and the longest wheel travel. The remote reservoir shocks which provide more shock oil and greater cooling capacity differentiate it from the XT making it best equipped for extended corrugated road travel.
The AL-KO offer is known as the Enduro series. The Enduro Cross Country is designed for semi-off-road use, making it a suitable option for travellers who frequently encounter unsealed roads but do not need extreme articulation. With coil springs and tuned dampers, the Enduro Cross Country provides a balance of comfort and resilience, absorbing shocks effectively while maintaining a straightforward design for easy maintenance.
For off-road enthusiasts who seek maximum durability, the Enduro X delivers high performance on rough terrain. Engineered with heavy-duty components and extended suspension travel, this system is designed to remain stable and controlled on rocky tracks, deep ruts, and washouts. The Enduro X is differentiated from other players by its ‘clamshell’ trailing arm. It is constructed from two pressed steel sections welded together to make it significantly lighter than traditional trailing arms while maintaining strength. Another key attribute is the forged bolt-on stub axles. Forging optimises strength and bolt-on makes it easy to replace if it breaks.
Semi-trailing arm independent suspension
Semi-trailing arm suspension is a variation of independent suspension where the arms that connect the wheels to the chassis extend diagonally rather than straight back. It is designed to improve wheel geometry, helping to maintain proper tyre alignment and reducing excessive wear. It provides a balance between ride comfort and off-road capability, arguably offering better stability and control than traditional trailing arm setups.
Terraglide suspension by Premcar (Image John Ford)
The Terraglide suspension by Premcar is an advancement of semi-trailing arm suspension in the caravan industry. This system is designed to provide improved handling, particularly in off-road conditions where greater articulation is necessary. The diagonal positioning of the arms provides a balance between the suspension responding smoothly to undulations in the terrain while maintaining strong lateral stability. Coil spring and airbag options are available.
Proponents of semi-trailing arm suspension espouse its ability to maintain more consistent tyre contact with the road surface, reducing excessive camber changes that can lead to uneven tyre wear. Additionally, it is claimed to offer improved load-sharing capabilities compared to traditional trailing arm designs, distributing forces more evenly across both axles in dual-axle setups. Semi-trailing arm setups are similar to trailing arm suspension systems in a number of ways. They are wheel alignment friendly, and they are generally heavier, more expensive and complex than leaf spring systems.
Wishbone suspension
Wishbone suspension is similar to that used in many performance cars. It uses wishbone-shaped arms to connect the wheels to the chassis, allowing for independent wheel movement. The arms pivot out to the sides of the caravan rather than to the rear or on an angle as described in the systems above. This design is claimed to allow for precise control over camber angles, improving tyre contact with the road and enhancing handling characteristics. Wishbone suspension also enjoys the benefits of good wheel alignment adjustability.
Wishbone suspension with airbags on an On The Move caravan
Users of wishbone suspension include On The Move Caravans which has adopted a very robust iteration for its vans.
As with other independent suspension systems airbags are a high-end choice to raise and lower the system and adjust for varying loads. Wishbone systems are also more complex and higher maintenance compared to simpler systems like leaf springs or torsion axles.
Torsion suspension
Torsion suspension is a unique system that eliminates the need for external springs by using rubber inserts within a tubular axle. When the wheel moves up, the internal bar twists against the rubber elements, absorbing the impact from forces imparted by road variation.
The AL-KO Independent Rubber Suspension (IRS) system is one of the most widely used torsion suspension systems. It provides a smooth and controlled ride on sealed and light gravel roads while requiring minimal maintenance due to its sealed design. Unlike coil springs and trailing arm suspensions, torsion suspension does not have multiple moving parts. It is a lightweight, cost-effective, simple and durable solution in many cases.
AL-KO Independent Rubber Suspension
One of the primary advantages of torsion suspension is its progressive spring rate, meaning that as the suspension compresses, it becomes stiffer. This provides a smoother ride over minor bumps while also allowing the system to handle larger impacts effectively. However, one downside is that torsion axles have limited wheel articulation, making them less suitable for extreme off-road conditions where independent wheel movement is required.
AL-KO torsion IRS keeps the van low to the ground while still providing moderate articulation
Torsion suspension does not allow for easy wheel alignment adjustments. As the axle is fixed to the chassis, any misalignment must be corrected through external modifications, such as shims or adjustable mounting brackets. This makes it a low-maintenance, but less flexible option compared to adjustable trailing arm and wishbone systems.
Despite these limitations, torsion suspension is an excellent choice for touring caravans that primarily travel on highways and well-maintained gravel roads. It provides a stable, predictable ride with minimal maintenance requirements, making it particularly appealing to caravan owners who prioritise reliability and simplicity.
Suspension and shock specialists
We have seen suspension systems rely heavily on quality springs and shock absorbers to perform optimally, and Tough Dog 4WD Suspension has become a well-known name in this space. Originally a 4WD suspension specialist, Tough Dog has expanded into the caravan market, developing tailored shock absorbers and spring solutions for various types of caravan suspensions.
Tough Dog 4WD Suspension has branched out into caravan-specific suspension setups
It works with Australian caravan manufacturers to develop shock and spring configurations to suit Australian conditions. Its coil springs are engineered to handle heavy loads while maintaining flexibility, which is crucial for maintaining ride comfort and wheel articulation in independent suspension systems. Its shock absorbers are exposed to extensive field and lab testing to prove their suitability for a given application.
The wrap
Choosing the right suspension system for a caravan depends on the intended use and travel conditions. There are a variety of independent suspensions using pivoting systems to enable individual wheel articulation. These independent systems are generally higher performance, more complex and expensive than other systems.
Torsion suspension provides a simple, low-maintenance solution for highway and light off-road travel. And leaf spring suspension is the reliable grandfather of the caravan industry. Each has its place, and it is worth understanding the differences to make an informed decision for your next caravan.
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