Suspension transfers force and torsion between the frame. It cushions the impact from the road. It reduces the vibration. This keeps the flatbed trailer running smoothly. This shows the importance of choosing the right suspension system for flatbed semi-trailers. Currently, the common suspensions are leaf spring suspension, air suspension, and single-point suspension. These suspensions have different effects on the ride and cargo security. This post will give you more details about the differences.
Table of Contents
Different Suspension
Rigid suspension: The body chassis has a rigid suspension between the wheels. There are no springs. It relies on the balance beam to handle bumps. It keeps the front and rear axles in balance. This suspension kind is rare now. It has poor damping. It is mainly used for slow delivery of goods on flatbed semi-trailers.
Leaf spring suspension: It is also called tandem steel plate spring balanced suspension. This name is a synonym for steel plate spring suspension. It is mainly made of steel plate springs, suspension support, connecting rods, U-bolt, and so on. The biggest advantages of this kind of trailer suspension are low cost, reliable work, and easy maintenance. Because of this, steel plate suspension is currently used in the largest proportion of semi-trailers, about 70-80%.
Air suspension: The most obvious feature of air suspension is its airbag-type air spring. The spring is lighter and has less friction. It makes almost no noise. Its life span is 2-3 times that of the steel plate spring. But the use of air springs must transmit only up and downforce. They must not transmit other types of forces and moments. So, the suspension structure is complex. In addition, air springs have strict sealing requirements and are also costly.
Single-point suspension: This is the usual steel plate spring front and rear braces. They are reduced to a single bracket attached to the vehicle body. It can be split into different axles. So, the load capacity is greater. They are usually used in heavy flatbed trailers.
Comparing Suspension Types and Considerations
Choosing the right suspension for a flatbed semi-trailer requires considering ride comfort, load capacity, maintenance, and cost. Each suspension system has unique pros and cons. Truckman Automobile recommends selecting the right suspension for your specific needs.
Coil Spring Suspension
These systems use helical springs. They absorb shock and keep the vehicle stable. These springs are made of coiled, strong wire. They compress and expand to absorb road shocks. They give a smoother ride than leaf springs because they absorb shocks better. Coil springs are lighter and can be customized for different load capacities and ride heights. They offer a comfy ride and good handling. This makes them ideal for light and medium-duty trailers. Maintenance involves regular inspection for spring fatigue and potential breakage. But, coil springs typically need less maintenance than leaf springs. In comparison, coil springs offer a better ride. They are generally lighter and pricier at first. But, they have better long-term performance and comfort.
Air Spring Suspension
Air spring suspension systems use airbags filled with compressed air to support the load and absorb shocks. These systems have airbags, a compressor, and sensors and valves. They maintain the best air pressure to provide adjustable ride height and a great ride. Air springs reduce tire wear and fuel consumption due to their lighter weight and better shock absorption. They can be customized for specific loads. They offer varying stiffness and ride heights. However, air springs are more complex and expensive to maintain, requiring a reliable air supply and regular maintenance. Compared to leaf springs, air springs offer smoother rides and better cargo protection but are more expensive and complex.To ensure the safety of flatbed trailers, it is also important to use advanced braking systems.
Torsion Bar Suspension
Torsion bar suspension systems use a bar that twists to absorb road shocks and support the load. One end of the torsion bar is fixed to the trailer frame and the other to the axle, twisting to absorb impacts. Torsion bars provide a compact and durable solution. They have good ride quality and can be adjusted for different load conditions. This makes them ideal for medium to heavy-duty trailers. However, they can be more complex to adjust and maintain, with limited flexibility in ride height adjustment compared to air springs. Torsion bars are more durable and require less frequent maintenance than leaf springs but are generally more expensive and offer better load handling.
Rubber Suspension
Rubber suspension systems use rubber blocks or components to absorb shocks and vibrations. These systems offer excellent shock absorption and noise reduction, being maintenance-free and highly durable. Rubber suspensions are good for light to medium-duty trailers. They are especially useful where maintenance access is limited. However, they have a limited load capacity and may not perform well in extreme conditions. Rubber suspensions need almost no maintenance. They offer great ride comfort and vibration isolation. They are generally cheaper in the long term than leaf springs due to low maintenance.
Factors Affecting Flatbed Trailer Suspension Selection
Depend on the self-weight: For higher cargo damage requirements or more sensitivity to vehicle weight, standard transport can choose air suspension. It is light and dampens vibration well.
Depend on the loading capacity: For some heavy transport semi-trailers, the choice of single-point suspension is very appropriate. Single-point suspension is strong and lowers the flatbed trailer’s center of gravity. This improves the trailer’s stability.
Depend on road conditions: You often run heavy loads or run poor road conditions. You transport goods with low requirements for cargo damage. So, ordinary leaf spring suspension is enough, and it is still cheap.
Depend on the cargoes: Leaf spring suspension is good for coal, sand, gravel, timber, and steel coils. Air suspension has clear advantages for hazardous chemicals, flowers, fruits, and vegetables. It is also good for cold chain goods, electronic instruments, express delivery, and fragile items.
Leaf Spring and Air Suspension Cost Analysis
We see leaf spring suspensions most often. They are common due to their simplicity, low cost, and reliability. Compared with traditional steel plate suspension, the biggest advantage of air suspension is its lightweight. The direct benefit of air suspension to freight users is that they can load more cargo and burn less fuel. Lifting can be reflected in two aspects, one is that the air suspension can lift the axle, and help to reduce tire wear, and fuel saving. Also, air suspension can lower the vehicle loading platform a bit. This is useful for loading and unloading goods. Of course, air suspension has great advantages. But, its disadvantages are high price and strict tonnage requirements.
An important factor influencing the type of suspension chosen for a flatbed semi-trailer is cost. While air suspensions offer many benefits, their higher price may influence purchasing decisions. Understanding these price factors can help freight users make more informed decisions when making their choices.
Summary
Choosing the right suspension for a flatbed semi-trailer is crucial. It can achieve twice as much with half the effort. When choosing the suspension system, focus on the payload weight, cargo distribution, road conditions, safety, and cost. Use these factors to pick the right flatbed trailer’s suspension system. TRUCKMAN has mature R&D and production experience in the field of semi trailer and spare parts. TRUCKMAN has reliable quality, pro service, and fair prices. We have worked with customers all over Asia, Europe, Latin America, the Middle East, Australia, and Africa. We have worked with customers from more than 80 countries. We can recommend the right suspension for you according to your transport goods, road conditions, etc. Please feel free to contact us!
FAQ
Yes, you can upgrade from a leaf spring to an air suspension. This upgrade provides smoother transport, reduces tire wear, and improves fuel efficiency. It involves installing airbags, a compressor, and sensors.
Air suspension systems typically last 2-3 times longer than leaf spring systems due to reduced internal friction and wear. Regular maintenance ensures optimal performance and longevity.
Air suspension is more fuel-efficient due to its lighter weight and ability to maintain a consistent ride height. This reduces air resistance and tire wear, leading to better fuel consumption.
Air suspension is great for fragile cargo. It offers better shock absorption and smoother rides. It is best for transporting chemicals, flowers, electronics, and other delicate items.
Consider cargo weight, loading capacity, road conditions, and cargo type. Maintenance requirements and costs also play a crucial role. Air suspension offers better ride quality, while leaf springs are more cost-effective.