Caravan shock absorption – An easy guide for novices

Within this third piece of writing in our Introduction to Shock Absorption for Beginners series, Robert Pepper explores the variances between caravan and towcar suspension, as well as the kinds of shock absorption systems evident in caravans and trailers.

Just as critical as your vehicle, your caravan necessitates proper shock absorption for a secure and effective tow. Much like the towcar, the caravan comprises a body and wheels. The wheels traverse bumps, the caravan maneuvers corners, and decelerates. All these activities necessitate shock absorption.

The basic principles of caravan shock absorption mirror those of the towcar; a spring absorbs the jolt, while a damper (shock absorber) curtails the ensuing bouncing. The springs and dampers are also quite similar. Caravans commonly feature coil, leaf, or air springs. The dampers perform a similar function and adopt a parallel design; twin-tube, monotube, foam, and so forth.

Distinctions amid caravan and towcar shock absorption

Certainly, there exist substantial disparities between caravan and towcar shock absorption. A driver will detect poor shock absorption more acutely in a towcar in comparison to a trailer, and generally speaking, shock absorption configurations in trailers pale in sophistication when juxtaposed with those in towcars. You can readily witness this phenomenon when trailing a combination over uneven tarmac; the trailer will bounce, while the car remains stable.

This divergence in shock absorption structure and caliber elucidates why towcars typically benefit from meticulous engineering related to suspension geometry, alignment, and spring and damper calibration. Aftermarket enhancements build upon this well-engineered foundation and subsequently fine-tune it for a specific purpose.

Conversely, trailers are often based on readily available chassis equipped with off-the-shelf suspension systems, coupled with additions according to the trailer manufacturer’s preference. Despite inquiries, evidence of substantial engineering efforts geared towards enhancing the dynamic attributes of caravan shock absorption systems seems scanty – most manufacturers seem content with incorporating shiny independent suspension systems without much custom design, save for a select few who craft bespoke chassis and suspension setups tailored to their trailers.

This discrepancy does not imply a disparity in quality, for there indeed exist robust, well-crafted shock absorption mechanisms. Rather, the key lies in aligning the shock absorption system with the trailer itself.

Diverse shock absorption systems in caravans

Caravan shock absorption systems typically feature a beam axle, where both wheels connect to a single axle, or independent suspension, where each wheel enjoys a separate, shorter axle. While independent suspension enhances handling and ride quality in cars, its advantages in trailers are less definitive. The optimization of independent suspension necessitates substantial engineering work and thorough testing.

Independent suspension does offer superior offroad ground clearance (as depicted in images above and below); nevertheless, even a beam axle is anticipated to provide more ground clearance than the towcar due to its axle’s lack of a differential or driveshaft. In theory, independent suspension ought to deliver better towing performance, provided it’s precisely tailored for the target trailer’s specifications.

Numerous caravans utilize twin dampers …. why?

Several caravans deploy twin dampers instead of singles. Why? Heavy-duty trucks operate efficiently with single dampers, suggesting that load might not be the decisive factor. Even in cases where leaf springs offer some damping, numerous heavy-duty trucks and 4x4s featuring coil springs utilize single dampers. Additionally, the argument for redundancy is feeble; well-engineered dampers seldom malfunction, and in the rare event of a failure, towing is still viable albeit with increased bouncing – each damper is designed to shoulder a portion of the load, leading to a scenario where a failed damper places undue strain on its counterpart, hastening its potential failure.

The assertion that caravan suspension performs twofold the work of towcars is unsubstantiated. The load is unlikely to be twice as significant, and in a single-axle configuration, both wheels maintain more substantial ground contact as they function as a tripod, unlike the four wheels of a towcar.

This isn’t to imply that twin-damper configurations never yield positive performance outcomes; I possess a trailer equipped with such a design, towing impeccably. Industry insights suggest cost considerations play a significant role. Acquiring two compact dampers proves more economical than procuring a single larger damper, and aesthetically, dual dampers exude a robust impression.

From a consumer standpoint, do not automatically perceive dual dampers as superior to singles; the overarching engineering design and component quality take precedence. Nonetheless, human psychology often associates “more” with “better” or “sturdier.” This trend is also evident in the surging popularity of larger shock tube sizes, remote-reservoir shocks, all marketed at a premium, along with the prevalent promotion of 12,000lb winches despite 9500lb ratings sufficing in most scenarios. Returning to caravan shock absorption considerations.

Caravan springs

Caravan shock absorption springs may encompass coil, leaf, or air variants. Air springs offer the perk of self-leveling when stationed at a campsite, facilitating trailer hookup, and enabling adjustments for offroad expeditions and on-road travel. Despite being pricier and less dependable than conventional steel springs, air springs prove reliable for the vast majority.

Leaf springs often endure criticism for subpar handling in cars; however, in trailers, this drawback is less pronounced. I contend that leaf-sprung, live-axle trailers present no inherent flaws and function admirably during towing operations. Yet, the prevailing marketing biases advocate independent suspension systems with flashy components for caravans. Consequently, trailers incorporating leaf springs are relatively rare; nevertheless, should you encounter one, avoid hastily deeming it subpar or ill-suited for towing – the key lies in the quality of components and engineering.

Loadsharing shock absorption

Certain caravans boast four wheels instead of two, known as tandems. Dynamics diverge significantly between single and tandem axles; the former operate akin to a tripod, ensuring constant wheel-ground contact. In contrast, tandems may exhibit diagonal wheels suspended in mid-air or unloaded. Tandem wheels also necessitate coordinated operation; when one front-wheel rises over an obstacle, the corresponding rear-wheel should maintain contact with the ground to sustain traction and curtail bouncing. This explains the rationale behind loadsharing shock absorption systems, characterized by cooperative functionality between wheel pairs.

If you plan to haul a caravan or trailer through rugged terrain, it’s advisable to utilize loadshare suspension to enhance control and grip. When towing on smooth roads, this may be less crucial, but ensure the trailer remains level.

Adjustments to caravan suspension are infrequent compared to tow vehicles, as caravan suspensions are typically tailored for their intended purpose. Weight distribution can significantly affect towing abilities; excessive weight at the extremities can compromise even the best-designed trailer’s performance, while centralized and lower weight can greatly improve towing experiences.

In conclusion…

In conclusion, while your caravan does have suspension necessities, it may not be as finely tuned as your tow car’s suspension. Flashy independent dual-shock suspensions may not be as critical as they appear; modifying your caravan’s suspension is likely unnecessary. If you encounter towing instability, first check the weight distribution before considering worn suspension components or exceeding the manufacturer’s weight guidelines.