What are the classifications of motorcycle shock absorbers, and how to choose them correctly?

As we all know, shock absorber is an important device of motorcycle. The function of shock absorber is to mitigate and attenuate the impact and vibration of motorcycle in the course of driving, and to ensure the ride comfort and smoothness of motorcycle, which is conducive to improving the service life of motorcycle and the stability of motorcycle operation. There are shock absorber devices on motorcycle. Here, the classification and selection of shock absorber for motorcycle are analyzed. Used for the reference of motorcycle users and fans.

Classification of shock absorbers:

There are many kinds of shock absorbers in Morochen. Most motorcycles use cylindrical shock absorbers. Only a few use leaf spring structure. There are many types and varieties of cylindrical shock absorbers. Generally, according to the installation location, there are front shock absorbers and rear shock absorbers.

（1）According to the direction of attenuation force, there are one-way shock absorbers and two-way shock absorbers.

（2）According to the load adjustment type: spring initial pressure adjustment type, air spring type, installation angle adjustment type.

（3）According to the structural form, there are telescopic tube front * hydraulic shock absorber (which is the most used front shock absorber in motorcycles at present), rocker shock absorber, rocker lever vertical central shock absorber, rocker lever inclined central shock absorber.

（4）According to the working position of the cylinder, there are inverted shock absorber (that is, the position of the cylinder is above, the piston rod is below), and the positive shock absorber (the position of the cylinder is below, the piston rod is above).

（5）According to the working medium, there are spring shock absorber, SPRING-AIR damper (due to the limited air damping force, the effect of shock absorption is not ideal, generally only used for mopeds with low speed as rear shock absorber), hydraulic shock absorber, oil-gas combination front shock absorber, nitrogen-filled gas hydraulic shock absorber.

Telescopic tube front * hydraulic shock absorber:

（1）The telescopic front * is connected with the front wheel and frame. It not only supports part of the skeleton, but also acts as a shock absorber. With the expansion between the handle tube and the casing, the oil in the front * flows through the small hole set in the next wall.

（2）When the handle tube is compressed, with the movement of the handle tube, the oil in chamber B flows to chamber C through the small hole on the handle tube after being compressed.

（3）At the same time, it flows to Room A through the free valve. When oil flows, the pressure is attenuated by the resistance.

（4）When the compression stroke is fast to the limit, the tapered oil seal at the end of the handle pipe will be inserted, thus closing the oil passage in B room.

（5）At this time, the oil pressure of chamber B rises sharply, making it in a closed state, which limits the travel of the handle tube and effectively prevents the instantaneous mechanical collision between movable parts on the front *.

（6）When the handle tube stretches (i.e. rebounds), the oil in the A chamber flows to the C chamber through a small hole in the upper part of the front piston (* near the piston ring).

（7）At this time, the resistance to oil flow attenuates the tension.

（8）When the stretching stroke reaches its limit, the springs absorb the vibration energy. In this process, the oil is added to room B through a small hole in the lower part of the front piston, which is ready for the next work.

Hydraulic damped rear shock absorber

（1）Hydraulic shock absorber is the most common shock absorber used in motorcycles at present. The structure of hydraulic shock absorber is basically similar to that of suction pump. The difference is that the upper end of the steel body of the hydraulic shock absorber is closed, and there are small holes in the valve.

（2）When the rear wheel is impacted on the convex road surface, the cylinder moves upward and the piston moves downward relatively in the inner cylinder. At this time, the piston valve is flushed upward, and the oil from the lower side of the piston in the inner cylinder chamber flows to the upper side of the piston without any resistance.

（3）At the same time, this part of the oil also flows into the oil chamber between the inner cylinder and the outer cylinder through the small hole on the bottom valve.

（4）In this way, the impact load of concave and convex pavement on vehicles is effectively attenuated.

（5）When the wheel falls over the raised ground, the cylinder will follow downward, and the piston will move upward relative to the cylinder.

（6）When the piston moves upward, the oil flushes the valve at the bottom to the inner cylinder, and the oil at the upper side of the inner cylinder piston flows downward through the orifice on the piston valve.

（7）At this time, when the oil flows through the small hole, it will be subject to great resistance, which produces a better damping effect and plays the purpose of shock absorption.

In the competition among motorcycle manufacturers all over the world, the design of front suspension and rear suspension of motorcycle has been invested heavily and carefully. More novel elastic elements with variable diameter and pitch have been adopted, such as hydraulic damper, oil-gas regulating device, load regulating device, rocker lever type central shock absorber and other advanced structures.

The popularization of these new technologies can rapidly attenuate the impact and vibration caused by the change of speed, load and various road conditions, automatically adjust the vibration resistance to the best technical state, greatly improve the shock absorption performance of motorcycles, and improve the adaptability, comfort, stability and safety of motorcycles to varying degrees.

Performance and Selection of Shock Absorber Oil

Motorcycle use time, the use of environmental temperature and so on are different. Therefore, in order to adapt to the various climatic conditions of motorcycle operating areas, most shock absorbers absorb shock and vibration energy through the flow damping force of oil, and convert it into the heat of oil to emit. Therefore, the damping force is closely related to the viscosity of oil, and the viscosity of oil varies with temperature. The following technical requirements are put forward for shock absorber oil:

（1）Shock absorber oil must have good anti-rust and anti-wear effect.

（2）Shock absorber oil should be used in all areas of motorcycle (including high-speed, full-load and overload driving, etc.) to minimize the loss of vaporization, that is, the so-called small vaporization performance.

（3）When the shock absorber oil contacts with air, it must have anti-oxidation stability and anti-oil-gas mixing stability, that is, the so-called good working stability.

（4）The condensation point of shock absorber oil used in China shall not be less than - 40 C. That is to say, when the temperature drops to 0 - 40, the oil should not lose its fluidity.

（5）Because the shock absorber oil containing impurities will scratch the piston rod or cause the oil seal edge to be incomplete in the course of motorcycle driving, which will lead to oil leakage. Therefore, the shock absorber oil must be kept absolutely clean;

（6）Shock absorber oil should not only have good viscosity-temperature performance and high viscosity index, but also have low solidification point. When the ambient temperature changes or when the working time prolongs, the temperature of the shock absorber oil itself changes, the change of its oil viscosity should be very small.

Selection and application of shock absorber oil

In summary, the viscosity of shock absorber oil has a great impact on the performance of shock absorber. The oil is too viscous, which will harden the soft shock absorber, and the thin oil will soften the hard shock absorber. In order to change the shock absorption performance of the shock absorber, the brand of shock absorber oil can be changed, but the amount of oil added must not be increased or decreased at will. As China's motorcycle petroleum products stores and motorcycle Monopoly points and maintenance market, there is no special shock absorber oil for sale at present, only through self-allocation to solve. Several formulation methods of shock absorber oil are recommended for reference.

（1）In order to avoid the immersion of water and impurities as far as possible, when replacing shock absorber oil, we should choose sunny weather with high temperature, low humidity and less dust, and operate in a relatively clean environment. The used shock absorber oil shall not be used again. After the shock absorber oil is prepared, it should be used in time and not stored for too long, so as to avoid the oxidative deterioration of the shock absorber oil and affect its performance.

（2）For motorcycles with low speed and low load (referring to vehicles less than 50ml), they can be purchased directly as L-EOC grade gasoline engine oil of 5W/30.

（3）In order to improve the shock absorption performance of shock absorber, the brand of shock absorber oil can be changed, but the amount of oil added must not be increased or decreased at will, and the amount of oil added must be accurate. For this reason, it is suggested to use the measuring cup to add more filling. If conditions are not available, 50 ml medical syringe (with ml scale as measuring unit) can be used to absorb oil and inject it. It is worth noting that the amount of oil in the two front * shock absorbers must be consistent. Otherwise, it will bring inconvenience to the normal operation of motorcycle, please pay special attention to it.

（4）When replacing the shock absorber oil, the front wheel, fender and brake clamp can be removed in sequence, the fixed screw of the upper connecting plate can be loosened, the fixed screw of the direction column can be fixed, and the handle tube can be rotated from left to right, and the handle tube can be slowly pulled out. For motorcycles equipped with front * dustproof shield, the front * cover bolt and front * cover bolt should be removed first (front * cover bolt may jump out under spring action, attention should be paid). If it is air pressurized, the valve core should be pressed before loosening the bolt to discharge air. Remove spring pad, spring guide tube and front spring in sequence, move handle tube and pour out shock absorber oil in front. Then according to the prescribed amount of oil, the recommended pre * shock absorber oil is injected, then the handle tube is slowly pumped for two or three times to eliminate the mixed air. Finally, the air is packed in sequence. This paper briefly introduces the oil quantity of front shock absorber of some motorcycles：

（5）Mixtures are usually prepared in three proportions:

a、Mix the No. 22 turbine oil with 50% transformer oil.

b、Mix 40% 22 turbine oil and 60% transformer oil.

c、Mix 60% turbine oil 22 with 40% transformer oil.

It is worth noting that after the formulation of the national standard "GB2357. Turbine oil", the commercial name of turbine oil has been replaced by turbine oil. As turbine oil has various performance, according to several kinds of turbine oil appearing at present, L-TSA turbine oil with 32 grade of viscosity (which is similar to No. 30 of original GB2537. turbine oil and No. 22 of SYB1656. turbine oil) is most suitable to replace the original No. 22 turbine oil.