Quality Inspection for BPW W Series Tandem Axle Leaf Spring - TRA-2740 Trailer part leaf spring parabolic leaf springr – Jiachuang

This spring assy are widely used in American for trailer .

Spring Measurements Specs

Totally 3 blades , 3pcs middle pads , End to End Measurement 1159 mm (Free Length Measurement), Tolerance range ±6mm ,A side Free Arch Measurement 146mm，Tolerance range ±6mm ,B side Free Arch Measurement 132mm,Tolerance range +6mm, Middle straight 203mm .

All datas are obtained by measuring the new produce product .

Parabolic Tra2740 Leaf Spring Are Made As Follows

Multi-leaf springs are made as follows:

1.   Shearing of flatbar

2.   Center holepunching / Drilling

3.   End Heatingprocess forming (hot & cold process)

1.  Eye Forming /Wrapper Forming

2.  Diamond cutting/ end trimming / width cutting / end tapering

3.  End punching /end grooving / end bending / end forging / eye grinding / end rolling

4.  Center holepunching / Drilling / nibbing

4.   Heat Treatment

1.  Heating

2.  Hardening

3.  Cambering

4.  Quenching

5.  Tempering

5.   Surfacepreparation

1.  Shot peening /stress peening

2.  Primary painting

6.   Eye bushpreparation process

1.  Eye reaming /eye boring

2.  Bush insertion

3.  Bush reaming

7.   Assemble

1.  Presetting &load testing

2.  Finish painting

3.  Marking &packing

TRA Leaf Spring Characteristics

1. The TRA LEAF SPRING acts as a linkage for holding the axle in position and thus separate linkages are not

necessary. It makes the construction of the suspension simple and strong.

2. Because the positioning of the axle is carried out by the leaf springs, it is disadvantageous to use soft springs

i.e. springs with low spring constant.

3. Therefore, this type of suspension does not provide good riding comfort. The inter-leaf friction between the leaf

springs affects the riding comfort.

4. Acceleration and braking torque cause wind-up and vibration. Also wind-up causes rear-end squat and nose-

diving.

5. The inter-leaf friction damps the spring’s motion and reduces rebound, which until shock absorbers were widely

adopted was a great advantage over helical springs.

Key Points Keep The High Quality

Production Process

1.Material Cutting

4.Edge Cutting

7.Stress Peening

2.Punching

5.Quenching

8.Assembling

3.Eye Rolling

6.Tempering

9.Painting

FAQ

Q1: What type of leaf spring could you produce ?

A: We can produce most kinds of springs in the market. especially on the parabolic springs.

Q2: What material could you supply for leaf spring?

A: Our material grade should be SUP9/SUP9A /SUP11A/51CrV4 /52CrMoV4/ even 55Cr3 and  SAE5160H as well .

Q3: How long will be your delivery time?

A: 20-40days. If material stock enough around 20days. if not,would be 40days

Q4: What payment terms are acceptable?

A: TT and LC at sight

Q5: What is the packing?

A: No fumigation wooden pallet . we also can pack according to whatever you request if reasonable.

Q6:How about the surface finishing ?

A : electrophoresis coating (black,red,gray,or as customer’s requests )