As we all know, shock absorber is an important device o […]
As we all know, shock absorber is an important device of motorcycle. The function of motorcycle shock absorber is to alleviate and attenuate the impact and vibration of motorcycle during driving, and ensure the smoothness and comfort of driving, which is beneficial to improve the motorcycle. The service life and handling stability of the motorcycle are equipped with shock absorber devices. The following article analyzes the classification and selection of motorcycle shock absorbers for the reference of the majority of motorcycle users and fans.
Classification of shock absorbers:
There are many types of Mo Ruochen shock absorbers. The vast majority of motorcycles use cylindrical shock absorbers. Only a few of them use leaf spring structure. There are many types and varieties of cylindrical shock absorbers. Generally speaking, they are classified according to the installation position. Shock absorber and rear shock absorber.
(1) According to the direction of attenuation force: there are single-acting shock absorbers and two-way acting shock absorbers.
(2) According to the load adjustment type: there are spring initial pressure adjustment type, gas spring type, installation angle adjustment type.
(3) According to the structure: there are telescopic tube type front* hydraulic shock absorber (this is the most used front shock absorber in motorcycles), rocker type shock absorber, rocker lever vertical center shock absorber , Rocker lever tilt type central shock absorber.
(4) According to the working position of the cylinder: there are inverted shock absorbers (that is, the cylinder position is above, the piston rod is below), and the upright shock absorber (the cylinder position is below, and the piston rod is above).
(5) According to the working medium: there are spring-type shock absorbers, spring-air damping shock absorbers (because the damping force of air is limited, the damping effect is not ideal, and it is generally only used for mopeds with low speed. Used as rear shock absorber), hydraulic damping shock absorber, oil-gas combined front* shock absorber, nitrogen filled hydraulic shock absorber.
Telescopic tube type front* hydraulic shock absorber:
(1) The telescopic front* is connected to the front wheel and the frame. It not only serves as a part of the frame support, but also acts as a shock absorber. With the mutual expansion and contraction between the handle tube and the casing, the oil in the front tube flows through the small holes provided in the partition wall.
(2) When the handle tube is compressed, with the movement of the handle tube, the oil in the B chamber flows to the C chamber 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 the oil flows, the resistance attenuates the compressive force.
(4) When the compression stroke is approaching the limit, the tapered oil seal at the end of the handle tube will be inserted, thereby closing the oil passage in the B chamber.
(5) At this time, the oil pressure in chamber B rises sharply, making it in a closed state, which limits the stroke of the handle tube and effectively prevents instantaneous mechanical collisions between the movable parts on the front *.
(6) When the handle tube stretches (that is, rebounds), the oil in the A chamber flows to the C chamber through the small hole located on the upper part of the front piston (near the piston ring).
(7) At this time, the resistance to the oil flow attenuates the tension.
(8) When the extension stroke is approaching the limit, the extension of the rebound spring absorbs the vibration energy, and in this process, the oil is replenished to the B chamber through the small hole in the lower part of the front * piston, ready for the next work ready.
Hydraulic damping rear shock absorber
(1) Hydraulic shock absorber is currently the most common shock absorber used in motorcycles. 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. There are small holes in the valve.
(2) When the rear wheel encounters a convex road surface and is impacted, the cylinder moves upward, and the piston relatively moves downward in the inner cylinder. At this time, the piston valve is flushed upward, and the oil on the lower side of the piston in the inner cylinder cavity 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 cavity between the inner and outer cylinders through the small holes on the bottom valve.
(4) This effectively attenuates the impact load of the bumpy road on the vehicle.
(5) When the wheel falls over the raised ground, the cylinder will also move downward, and the piston will move upward relative to the cylinder.
(6) When the piston moves upward, the oil rushes through the valve at the bottom and flows to the inner cylinder. At the same time, the oil on the upper side of the piston of the inner cylinder flows to the lower side through the small hole on the piston valve.
(7) At this time, when the oil flows through the small hole, it will receive a lot of resistance, which will produce a better damping effect and play the purpose of damping.
In the competition with each other, motorcycle manufacturers from all over the world have invested heavily in the design of the front suspension and rear suspension of motorcycles. They have adopted more novel variable-diameter and variable-pitch elastic elements, such as hydraulic damping. Advanced structures such as oil-gas regulating device, load regulating device, rocker lever type central shock absorber.
The popularization of these new technologies can quickly attenuate the impact and vibration caused by changes in vehicle speed, load and various road conditions, automatically adjust the vibration resistance to the best technical state, and greatly improve the shock absorption performance of motorcycles. The adaptability, comfort, stability and safety of motorcycle riding have been improved to varying degrees.
Performance and selection of shock absorber oil
The length of time the motorcycle is used, the ambient temperature during use, etc. are different. Therefore, in order to adapt to the various climatic conditions in the area where motorcycles operate, most shock absorbers absorb impact and vibration energy through the flow damping force of oil, and convert it into oil heat to dissipate. Therefore, the damping force is closely related to the viscosity of the oil, and the viscosity of the oil changes with temperature. The following technical requirements are put forward for shock absorber oil:
(1) The shock absorber oil must have good anti-rust and anti-wear effects;
(2) The shock absorber oil should have as little vaporization loss as possible in the motorcycle's use range (including special conditions such as high speed, full load and overload driving), which is the so-called low vaporization performance;
(3) When shock absorber oil is in contact with air, it must have anti-oxidation stability and anti-oil-gas mixing stability, which is the so-called good working stability;
(4) The freezing point of shock absorber oil used in my country shall not be lower than -40°C. That is to say, when the temperature drops to 0℃～-40℃ in the severe cold winter, the oil should not lose its fluidity;
(5) The shock absorber oil containing impurities will quickly scratch the piston rod or cause the oil seal blade to be incomplete during the motorcycle driving process, resulting in oil leakage. Therefore, the shock absorber fluid must be kept absolutely clean;
(6) Shock absorber oil should not only have good viscosity-temperature performance and high viscosity index, but also have a low freezing point. When the ambient temperature changes or as the working time increases, the temperature of the shock absorber oil itself changes, the viscosity of the oil should change very little.
Selection of shock absorber oil and precautions for use
To sum up, the viscosity of the shock absorber oil has a great influence on the performance of the shock absorber. If the oil is too viscous, it will make the soft shock absorber hard, and the oil that is too thin will make the shock absorber hard. The device becomes soft. 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. Due to my country's motorcycle petroleum products stores and motorcycle monopoly points and maintenance markets, there is currently no special shock absorber oil for sale, and it can only be solved by self-allocation. Several methods of blending shock absorber oil are now recommended for reference.
(1) In order to avoid the intrusion of moisture and impurities as much as possible, when replacing the shock absorber oil, you should choose a fine weather with higher temperature, lower humidity, and less sandy dust. It is best to operate in a relatively clean environment. The used shock absorber oil must not be used again. After the shock absorber oil is prepared, it should be used in time, and should not be stored for too long, so as not to oxidize and deteriorate the shock absorber oil and affect its performance.
(2) For motorcycles with low speed and low load (referring to vehicles below 50ml), you can directly purchase L-EOC grade gasoline engine oil with the brand name of 5W/30;
(3) In order to improve 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, and the amount of oil added must be accurate. For this reason, it is recommended to use a measuring cup for filling. If the conditions are not available, you can also use a 50ml medical syringe (with the ml scale on it as the unit of measurement) to absorb the oil and inject it. It is worth pointing out that the amount of oil in the two front shock absorbers must be the same. Otherwise, it will cause inconvenience to the normal operation of the motorcycle, please pay special attention.
(4) When changing the shock absorber oil, you can remove the steering handle, front wheel, mud plate, and brake caliper in order, loosen the fixing screws of the upper link plate, the fixing screws of the steering column, and turn the handle tube back and forth from left to right. Slowly pull out the handle tube etc. For motorcycles equipped with a front dust shield, the dust shield and front cover bolts should be removed first (the front cover bolts may pop out under the action of the spring, so be careful). If it is an air-pressurized type, before loosening the bolt, press the valve core to exhaust air. Remove the spring washer, spring guide tube, and front spring in order, move the handle tube, and pour out the shock absorber oil in the front tube. Then, inject the recommended front shock absorber oil according to the specified amount of oil, and then slowly pull the handle tube two or three times to remove the mixed air, and finally install it in order. Now briefly introduce the oil volume of the front shock absorber of some motorcycles (referring to a single):
(5) Choose mixed oil to prepare, usually according to the following three ratios:
a. Use 22# turbine oil and transformer oil to mix 50% each;
b. Mix 40% 22# turbine oil and 60% transformer oil;
c. Mix 60% of No. 22 turbine oil and 40% of transformer oil.
It is worth noting that after the formulation of the national standard "GB2357. Steam Turbine Oil", the trade name of turbine oil was replaced by steam turbine oil. As the steam turbine oil has a variety of different performance, according to the current appearance of several steam turbine oils, the viscosity grade is 32 grades of L-TSA steam turbine oil (this oil is similar to the original "GB2537. Steam Turbine Oil" No. 30, "SYB1656. Turbine Oil" No. 22) is the most suitable to replace the original No. 22 turbine oil.