Here’s how Simplicity’s Smart Coil and Tandem Load-Sharing Suspensions revolutionised Caravan Suspension
Caravan off-road suspension manufacturer Simplicity understands remote area travel. We see it in their designs and their approach to customer servicing. The Aussie fabricator has the serial number and vital statistics on every axle sold since the early 80s ensuring easy maintenance for years to come. And with so many of the components engineered in-house–including the drums and hubs–combined with many locally acquired parts like bushes, turnaround on service times is reassuring.
Engineering Firsts
Those engineering smarts have sparked their share of innovations, notably with the Simplicity Smart Coil in 2015, followed by the gravity smart Tandem Load-Sharing systems in 2017.
These solutions work beautifully together in Simplicity’s signature Tandem Load-Sharing Coil (LSC) suspension, tailored for medium to heavy vans with high payload capacities. Let’s see how the technologies meet vanners’ needs starting with the Smart Coil.
Same Van, Different Day
While your camper or van’s dimensions may change little in its lifetime, how you load it and where you take it places different demands on your suspension.
The breadth of change is increasing as more of us carry and consume water and food in bush settings off-the-grid. A van’s weight may fluctuate 10 per cent on the same trip depending on its water tank capacities.
Soft vs Stiff Springs
Traditionally, a stiff or heavy duty suspension will protect heavier caravans on rough tracks. But they are less comfortable on the highway because the springs need more impact to respond. Choosing a softer suspension that responds to roughly patched tarmac can improve towing comfort. But, if you load up that van and take it too far off the tarmac, the springs can fully compress when they hit a rough bump– shaking your gear.
One Spring, More Conditions
Simplicity addresses these opposing needs with its progressive rate Smart Coil spring, which is sympathetic to load variation.
The wider spirals respond to less pressure for a smoother ride, even if you are carrying less gear. The tighter coils remain ready for harsher impacts caused by rough tracks or a heavier load. Simplicity uses these Variable Rate Springs in two systems: the Single Coil axle suspension (1400kg-2600kg) and the Tandem Load-Sharing Coil suspension (2500-4400kg), which we explain in greater detail below.
Sharing the Load
Many of us consider our van to be a home. A tandem axle setup can help support one that’s loaded with daily comforts, with all four wheels carrying their share. This works well on a flat track. But what happens to that weight when you travel over a bump or up on a curb? Does it tilt the van? And if so, where does that weight go?
Thankfully, the Simplicity Tandem Load-Sharing Coil suspension (also avail. with leaf springs) has a few cards up its sleeve to keep that weight on each wheel.
Vertical Travel
Simplicity Tandem LoadSharing suspensions maintain their balance while towing heavy loads on uneven surfaces using a nifty trick called vertical travel. This measures how far your wheels move up and down before tilting the caravan and shifting that weight. To achieve this, two things need to happen. First, the wheels need to move up and down independent of each other. Secondly, the weight and shock affecting one wheel must transfer onto the other wheels without transferring to the van.
The Vital Link
Simplicity achieves this by attaching the wheels and their control arms that articulate freely, to a central cross beam. These control arms are coupled front to rear via a pivoting Link Arm and Coil springs. This freely transfers load between the leading and trailing control arms giving equal load and shock load. As a result, the four control arms on the Simplicity Load.
Sharing suspension will let your wheels move 20cm+ vertically as you tow over rocks and potholes without tilting the axle. Is it gravity defying? No, it’s gravity in action!
Less Resistance
While other independent trailing arm suspensions use vertical travel to a degree–the trailing arms on equivalent-rated Simplicity Load-Sharing designs face fewer forces on the tracks. It does a great job at keeping that axle straight. That’s because Simplicity radically rethought the role of springs (and shock absorbers on the LSC) in its Load-Sharing designs. The springs aren’t connected to the chassis to soften the entire control arm motion; instead, they move with the arms–only activating when it matters.
Inherently Efficient
Because the system maintains equal loads on all four wheels, components in the Aussie made Simplicity Tandem Load-Sharing suspensions experience less wear and tear. The system is so efficient that the coil springs on the LSC only require one shock absorber per wheel to stop them from vibrating after an impact. And the leaf-spring version requires no shock absorbers at all.