Leaf Spring Angle Control Fastening, Axle Laser Alignment | Heavy-Duty Cart + Press | 40~70 min/unit
After frame assembly, the chassis moves to the marriage section. Front and rear axle installation is the most time-consuming step: aligning leaf springs to the axle housing, inserting U-bolts through the springs and housing, tightening. Two U-bolts per axle. How tightly each is torqued directly affects whether the truck pulls to one side.
A leaf spring press uses a hydraulic head to simulate vehicle load, compressing the spring while the operator tightens the U-bolt. This ensures correct initial spring deflection. U-bolts are tightened using the angle method — tighten to a specified angle, not a torque value. The reason: thread friction coefficient varies, and torque-based tightening cannot guarantee final clamp load.
Axle housing alignment uses laser positioning. Left-to-right housing position deviation is kept within 1.5mm. Downstream stations install air tanks, fuel tank, battery tray, exhaust after-treatment, and cab tilt mechanism. 40 to 70 minutes per unit, 5,000 to 30,000 units per year.
Technical Specifications
Applicable Models: Medium and heavy-duty truck chassis — leaf spring suspension with U-bolt fastening; applicable to both single-rear-axle and tandem-axle configurations; annual capacity 5,000–30,000 units.
Line Layout: Cart-based layout positioned after frame assembly section; process sequence — leaf spring pressing and U-bolt tightening (angle method) for front and rear axles, laser axle alignment, followed by air tank, fuel tank, battery tray, exhaust after-treatment, and cab tilt mechanism installation.
Core Equipment: Leaf spring press with hydraulic head (simulates vehicle load to compress the spring during U-bolt tightening, ensuring correct initial spring deflection); angle-method U-bolt tightening (tighten to specified rotation angle, not torque — eliminates thread friction coefficient variability); laser axle housing alignment system (deviation ≤1.5mm left-to-right).
Key Technical Features: Leaf spring press simulates full vehicle load during U-bolt tightening — ensures correct initial spring deflection that torque-based methods cannot guarantee. Angle-method tightening is used instead of torque-method because thread friction coefficient varies between bolts; angle control achieves consistent clamp load regardless of friction variation. Axle housing laser positioning keeps left-to-right deviation ≤1.5mm, critical for straight-line driving.
Production Metrics: Cycle time 40–70 minutes per unit; annual capacity 5,000–30,000 units; axle housing alignment tolerance ≤1.5mm; U-bolt tightening by angle method (not torque method); two U-bolts per axle, each tightened under simulated load.
