Tips on Using Leaf Springs

As shown in Figure 1 below. The leaf spring is installed between the chassis and the axle, connecting the vehicle body and the walking system. It plays the role of shock absorption and cushioning. In order to realize the use function of leaf spring, we should know the following common sense in the use of leaf springs.

(Figure 1. Leaf springs)

(1) Regularly check the U-bolts

After the new vehicle has been driven for more than1000 kilometers, the U-bolts shall be tightened under the full load state, so as to avoid the dislocation of the leaf spring caused by the loosening of the U-bolts, resulting in the deviation of the vehicle or the fracture at the center section of the leaf spring.

As shown in Figure 2 below. The fracture at the central hole of the leaf spring assembly is usually caused by the untimely tightening of the U-bolts. Because the weakest section at the central hole of the leaf spring is protected after being clamped by the U-bolts, it is considered to be a rigid whole in theory. The relatively weak sections of the leaf spring would be the ones outside of the two u-bolts after the u-bolts are tightened appropriately.

(Figure 2. The fracture at the central hole of the leaf spring)

(2) Regularly check the wear of leaf spring bushings and pins

As shown in Figure 3 below. After the vehicle has been driven a certain mileage, check the wear of leaf spring bushings and pins in time and lubricate them. If the bushing is found to be seriously worn, it shall be replaced with a new bushing in time to avoid pin fracture, leaf spring distortion, deviation during vehicle driving and serious traffic accidents caused by uneven wear of the bushings. At the same time, it can also avoid large noise from bumps of the rolling eye and the pin.

(Figure 3. Leaf spring eyes and pins inspection)

(3) Replace the left and right leaf springs at the same time

As shown in Figure 4 below. When the leaf spring assembly needs to be replaced after the vehicle has been driven for a certain mileage, the leaf springs on the left and right sides should be replaced at the same time to avoid the vehicle tilting caused by the inconsistent arc height on both sides of the leaf springs and reduce the possibility of overturning in the process of fast turning.

(Figure 4. Replace leaf springs simultaneously)

(4) Clean the leaf springs regularly

As shown in Figure 5 below. Cleaning the leaf spring regularly can reduce the intrusion of dust and sand into the leaf spring and improve the service life of the leaf spring. When cleaning the leaf spring, pay attention not to scratch as much as possible, and avoid using washing liquid containing abrasive, steel ball and grinding tools, which are easy to damage its surface.

(Figure 5. Cleaning the leaf springs)

(5) Lubricate the leaf spring regularly

When the leaf spring works normally, there is relative friction between the spring leaves.

Regular lubrication of leaf springs has the following benefits:

1) Reduce the friction and disperse stress of each leaf of the leaf spring to prevent the leaf surface from surface strain.

2) Reduce the intrusion of dust, soil and water between the leaves to prevent the leaf spring from rusting.

3) Reduce the friction coefficient between the leaves, cool the leaf spring, and prevent the elastic strength of the leaf spring from decreasing.

Adding grease is usually carried out at the end of the running in period of new vehicles and at the beginning of summer and winter use. During lubrication, firstly remove the leaf spring from the vehicle, secondly remove the central bolt to spread the spring leaves and clean them, thirdly evenly apply lithium base grease or graphite grease on both sides of the leaves, at last assemble the leaf spring and install it on the vehicle.

(6) Good driving habits

Good driving habits of drivers can not only improve driving safety, but also extend the life of your vehicle. Generally, the following two points should be paid attention to during driving:

1) On potholes with poor road conditions, try to avoid excessive vehicle speed. The deformation of the leaf springs will increase when the vehicle passes through the potholes at high speed. Such operation for a long time will accelerate the fatigue of the leaf springs and damage them.

2) Try to use engine traction braking during vehicle driving to reduce urgent braking. Under the emergency braking of the vehicle, the inertia force makes the leaf springs bear excessive bending stress and tensile stress. When the allowable stress is exceeded, the leaf springs will be broken.

(7) Precautions for disassembly and assembly of leaf spring

1) Professional tools shall be used to disassemble the leaf spring, and iron tools shall not be used to hammer the side and surface of the spring leaf.

2) After the leaf spring is disassembled, the fracture and crack of each leaf shall be checked, and the leaf with problems shall be replaced in time.

3) Before assembling the leaf spring, the rust of each piece must be removed and coated with graphite grease.

4) Before tightening the central bolt, the middle of each piece of the leaf spring shall be pressed tightly, and then tighten the central bolt.

5) The U-bolts shall be tightened evenly and crosswise, and the tightening torque shall be determined according to the technical requirements.

Compiled by  WONDEE Autoparts

2022-2-25