Category: Leaf Springs

The multi leaf spring design is based on the use of a flat trapezoid geometry, with cut leaves stacked one on top of the other. This leads to a multi leaf design with different lengths of each leaf. When a multi leaf spring deflects the leaves move relative each other. The contact between the leaves produces a friction between them, which leads to a difference in load between compression and decompression. The longest leaf has two eyes for assembling to the vehicle body. The strength of this leaf and the eyes are critical and sometimes the second leaf will have safety loops which hook around the main eye as a back up in case of failure. The centre of the spring is normally fixed to the vehicle axle with U-bolts.

The parabolic spring is designed for low internal friction and lowest possible weight and consequently has fewer leaves. The leaves are partly given a parabolic shape from the centre to the end of the leaf, which gives an equal bending stress level along the parabolic part. This ensures efficient use of material and minimum weight. The shape of the leaves are such that contact between the leaves only exists at the centre and the ends. And since the centre of the leaf spring is fixed to the axle with U-bolts, the only friction comes from the end contacts. Rubber pads are also sometimes used to lower the friction. As with multi-leaf springs, the strength of the eyes is a critical safety factor.

Leaf springs can be divided in to three broad areas:

– Preparing leaves

– Bending – heat treatment – shot peening

– Assembling – presetting – surface treatment

Leaves for multi-leaf springs are prepared by cutting and stamping whilst parabolic leaves are hot rolled in a purpose-made rolling machine. The ends of the main leaf are heated and the eyes are then hot rolled. The leaves are heated and individually bent to the correct arc radius and, whilst still clamped between the bending tool, each leaf is quenched in oil to receive high strength and the correct shape. Parabolic leaves also have an arc radius but are however normally straight in the thicker central section. The leaves are finally tempered for high material toughness and strength.

After cooling, the shot peening process is necessary for all parabolic leaves. For multi-leaf springs however, it is normally only the two safety-critical leaves that require shot peening. The bushes are pressed into the eyes and the stack of leaves is assembled. Positive stresses are then introduced in to the spring by a pre-stressing process.

The multi leaf surfaces are protected against corrosion by painting of the outer surfaces and by lubrication between each leaf. Parabolic leaves are individually painted on all surfaces.

The advantages of leaf spring:

in the structure of leaf spring composition is relatively simple, relatively low cost of manufacture, and easy maintenance, it not only played the role of shock absorption buffer, as well as the effectiveness of guidance agencies; so the use of leaf springs more widely , Trucks, buses, sport utility vehicles, vans and pickups are very useful.

The shortcomings of the leaf spring:

The structure is only applicable to non-independent suspension, the use of certain limitations; leaf spring by the name suggests is a combination of steel, the overall quality and stiffness are great, resulting in relatively poor comfort , The vertical size is too long, is not conducive to shortening the car before the overhang and rear suspension, in addition to the framework of the steel leaf spring connection is also very easy to wear.

With more than 10 years’ development, we can supply a full range of spare parts for full trailers, semi-trailers, heavy & light duty trucks agricultural machines and engineering machines. Our main Products are Leaf Spring, Coil Spring, Wheel Rim,Landing Gear,Trailer Jack,Jockey Wheel, Axle, Mechanical Suspension, Air Suspension, Agricultural Suspension, Bogie Suspension,Turntable, Fifth Wheel, King Pin, Brake Chamber, Container Lock, Coupling, Towing Eye, Drum, Hub, Mudguard, Lamp, Excavator Bucket, Bucket Teeth, Track Link, and other Chassis Parts.

We could design and produce any type truck & Trailer & Car leaf spring as per customers’ drawings and samples. Tell us what you need or were expecting to find. Don’t forget to include your email address if you’d like a reply from us.—Mail To: info@tinmyautoparts.com

Ever have a leaf spring crack, become fatigued or break and wonder what the cause is? We will take a look at a few common reasons why leaf springs fail.

Loose U-Bolts

 
The image below shows center bolt failure due to a truck spring not having tight enough u-bolts. U-bolts, especially on newly installed truck springs should be checked periodically to verify they are tight. Even if you have a professional installer install springs on your truck, you should stop by after 500 miles and have your u-bolts inspected to make sure they didn’t come loose.

Corrosion and Fatigue

Corrosion and fatigue are typically caused by a combination of time and the elements. Numerous variables will weigh on how long your leaf spring will last before it suffers from corrosion or fatigue. How much weight you haul, what part of the country you live in, etc. will play a role in the life of your springs. Making sure salt and other corrosive materials are washed off and not overloading your truck will help prevent corrosion and early spring fatigue.

Overloading Your Truck Springs

Everyone says they never do it , but we see it all the time. Overloading is pretty self-explanatory. You have more weight in the back of your truck or you are towing a load heavier than what your truck is rated at. We all love to do it, but the negative effect on your truck springs is unavoidable. On the left image below you can see the radial shear marks from an overloaded spring. The image on the right shows distortion of the spring eye from overloading

How do you prevent overloading your truck springs? Obviously you could carry less weight or purchase a truck with a higher weight rating. If buying a new truck or hauling less weight is not an option, you could add an overload kit like a Firestone Air Spring kit, Hellwig Helper springs or a Air Lift Air Spring kit. Overload kits are designed to take some of the weight off the leaf springs and place it onto the overload kit.

Another option that is more popular with commercial vehicles it to add another piece of steel to the spring pack. This may cause the ride to be stiffer, but if you are always hauling heavier loads in a commercial setting this may be your best bet.

We do not recommend adding a new piece of steel to leaf springs that already suffer from fatigue. You are better off replacing both of your truck springs with new ones with a higher weight rating. It’s very common that we will have someone only want to replace one busted leaf in a spring pack and a few months later a different leaf breaks. If one has cracked, the others are probably in the same condition and will not last much longer.

Weld Splatter

Weld splatter is more common in commercial trucks and vans that come from the factory without a bed or on motorhome leaf springs . This is caused by welding a body or accessories to your truck in the same area as your leaf springs. Just a small amount of weld spatter can be disastrous to the life of your spring. About the only way to prevent this is to inspect your springs after and make sure no one was careless with the welder.

Above are a few common reasons why leaf springs fail. There are other manufacturing reasons such as quench cracks, tight eyes, notches, incorrect temperatures, etc. that can cause failure. With today’s modern, high-tech manufacturing processes and quality control, they are not nearly as commons as they were in the past.

If you need have any questions about your leaf springs or need replacement leaf springs, call Michigan Truck Spring at info@tinmyautoparts.com. They carry OEM replacment leaf springs for everything from old corvettes to semi trucks and trailers.