Whats are the functions and technical demands of piston rods in shock absorber?
The piston rod is the transmission and guiding rod of the shock absorber. When we drive on a bumpy road, the wheels are impacted and the force is first transmitted to the piston of the shock absorber. One end of the piston rod is connected to the piston and the other end to the vehicle body. There is a top rubber on the shock absorber, and the piston rod is connected to the top rubber. Below the top rubber is a spring, and the top rubber is directly connected to the vehicle body, which can smoothly transmit the impact force and guide the piston to move back and forth in the shock absorber cylinder without deviation. When the piston moves, the hydraulic oil in the shock absorber flows through the small holes on the piston to generate damping force to counteract the vibration. The sealing performance of the piston rod directly affects the leakage of the hydraulic oil. If the sealing at the connection between the piston rod and the shock absorber system is not good and the hydraulic oil leaks, there will be no damping force, and the shock absorber will become an empty shell. Driving will feel extremely bumpy and the vehicle body will shake significantly. Therefore, sealing performance is also a key factor for the piston rod. In addition, the piston rod has the functions of load-bearing and fatigue resistance. Part of the vehicle's weight is transmitted to the lower end of the shock absorber through the piston rod, and during vehicle operation, the piston rod repeatedly withstands tensile and compressive forces. Over time, the forces it experiences are complex. If the strength of the piston rod is insufficient, it is prone to bending, deformation, or even fracture, which could lead to serious consequences such as vehicle body loss of control.
From the perspective of actual driving experience, how does the quality of the piston rod directly affect the driving experience?
The most obvious aspects are comfort and handling. A piston rod with high precision and a smooth surface ensures smooth movement of the piston and stable damping force. When driving over speed bumps or uneven roads, the shock can be smoothly absorbed. Conversely, if the piston rod is severely worn and has scratches on its surface, causing unstable damping force, the vehicle may experience bouncing and unstable steering when driving, and even the body may deviate when braking, affecting safety. Therefore, the piston rod not only affects comfort but also driving safety. Many people only focus on the piston seal when repairing shock absorbers, but they overlook the piston rod. In fact, the wear and deformation of the piston rod are the root cause of many shock absorber failures. For example, if there are scratches on the surface of the piston rod, it will wear out the seal during reciprocating motion, leading to oil leakage.
How to determine if the piston rod is normal?
We can regularly inspect the piston rod of the shock absorber. If there is oil, rust on the surface or a distinct scratchy and uneven feeling when touched by hand, it indicates that there might be a problem. Additionally, if while driving, you notice a significant deterioration in the shock absorber's performance and increased body jolts, you should also check the piston rod for any bending or deformation.
The performance of shock absorbers largely depends on the quality of the piston rod. We hope everyone can pay more attention to the key components inside the shock absorbers. By being more observant during daily driving, we can make the shock absorption system more durable and drive with greater peace of mind.
The following introduces some requirements for the selection of materials and technical processing of piston rods:
Generally, 45# steel is chosen. For some welded ones, 35# steel is selected. According to technical requirements, more than ten different processes are involved in the production process, and each process has strict technical and process requirements. For instance, quenching and tempering, and electroplating are included. The electroplating is hard chromium plating. Additionally, the dimensional tolerance requirements are extremely high because it needs to closely cooperate with oil seals, shock absorber oil, valve systems, etc. The straightness, ellipticity, roughness, and other aspects of the electroplating layer on the surface of the piston rod have extremely high requirements.
