Classification of Automobile Leaf Springs

A leaf spring is the most widely used elastic element of automobile suspensions. It is an approximate equal strength steel beam composed of several alloy spring sheets of equal width and unequal length. There are many kinds of leaf springs, which can be classified according to the following classification methods:

1. Classified by raw material sizes 

1) Small size leaf springs

It mainly refers to the leaf springs with material width range of 44.5 ~ 50mm and material thickness of 6 ~ 9mm.

There are mainly the following leaf springs:

Boat Trailer leaf springs, livestock Trailer leaf springs, RV leaf springs, station wagon leaf springs, utility trailer leaf springs, etc.

 2) Light duty leaf springs

It mainly refers to the leaf spring with material width of 60 ~ 70mm and material thickness of 6 ~ 16mm.

There are mainly the following leaf springs:

Pickup leaf spring, van leaf spring, agricultural trailer leaf spring, minibus leaf spring, etc.

3) Heavy duty leaf springs 

It mainly refers to the material width of 75 ~ 120mm and the material thickness of 12 ~ 56mm. 

There are four main categories:

 

A. Semi trailer leaf springs, such as BPW / FUWA / YTE / TRAseries trailer leaf springs, with material sizes involving 75x13 / 76x14 / 90x11 / 90x13 / 90x16 / 100x12 / 100x14 / 100x16, etc.

 B. Bogie(Single point suspension) leaf springs, involving 24t / 28T / 32t leaf springs for a boogie single point suspension, with material sizes of 90x13 / 16 / 18 and 120x14/16/18.

C. Bus leaf springs, involving Toyota / Ford / Fuso / Hino and other brands. Most products are parabolic leaf springs.

D. Heavy duty truck leaf springs, including Benz / Volvo / Scania / Hino / Isuzu and other models. The main products are parabolic leaf springs.

 

E. Agricultural leaf springs, which are mainly used on off-road transport trailers.

F. Air linkers(Trailing arm), mainly used for air suspensions.

2. Classified according to the section of flat bar

1) Conventional leaf springs:  they are composed of multiple leaf springs with equal width and thickness and different lengths. The product manufacturing process is relatively simple and the manufacturing cost is low.

2) Parabolic leaf springs:  they are composed of one or more leaf springs with thin ends, thick middle, equal width and unequal lengths. Compared with the conventional equal thickness leaf springs, they have many advantages: light weight; longer fatigue life; lower working noise; better ride comfortability and stability.

3. Classified according to leaf spring structure

 

A leaf spring is a relatively complex industrial product, involving tens of thousands of products models. Through the product process structure, we can make the following classification:

1) Double-eye leaf spring

2) Single-eye leaf spring

3) Sliding plate leaf spring(Semi trailer springs, TRA springs series, etc.)

4) Main and help spring combined leaf springs

(Upper help spring type)

 

(Lowerhelp spring type)

5) Air linker

Straight plate type air linker

Z-type air linker

 

6) Other leaf springs, such as sprung drawbar etc.

4. According to the raw material grade classification of leaf spring(spring steel flat bar), the following table for reference:

GB	ISO	ASTM	JIS	DIN	NF	BS	OCT	H Applied	Usage
65Mn		1066				080A67	65Γ		Low-end aftermarket
60Si2Mn	61SiCr7	9260	SUP7	60SiCr7	60Si7	Z51A60	60C2	6~16	Small, light-duty, truck/pickup,   heavy-duty springs etc.
55CrMnA	55Cr3	5155	SUP9	55Cr3	55Cr3	525A58		16~25	Medium/heavy duty springs, parabolic spring, etc.
60CrMnA		51605	SUP9A			525A60
50CrVA	51CrV4	6150	SUP10A	50CrV4	51CrV4	735A51	50CrΦA	25~35	Medium/heavy duty springs, parabolic spring, etc.
51CrV4								35≤H≤45	Air linkers
52CrMoV4								H＞45	Air linkers

 

Remarks:

Various spring end processes: 

There are many kinds of end treatments for leaf springs, such as eye rolling, eye wrapping, edge trimming, corner cutting, rib and groove pressing, bending, tapering, etc. Various processes are briefly described as follows:

 

1. Eye rolling

The eye rolling is divided into upper eye rolling, central eye rolling and lower eye rolling. As shown in the following diagram:

 

2. Eye wrapping

The eye wrapping is divided into 3 / 4 eye wrapping, 1 / 2 eye wrapping and 1 / 4 eye wrapping. As shown in the following diagram:

3. End treatment

End treatment includes edge trimming, corner cutting, bending, groove pressing, hole punching, edge pressing. As shown in the following diagram:

 

  From: Wondee Autoparts