Nowadays, electric vehicle is the main means of transportation in family, peopleare generally concerned about electric vehicle batteries. In case the battery can not work, they will replace the battery in time. But the attention to the tires of the electric vehicle is very low, It is considered that tire just make sure they can ride, unless the tires can not be filled, or the tires wear out, they will think about changing a tire.
In fact, the quality of the tire is also one of the important factors in the safety of cycling electric vehicles, such as the electric vehicles tire aging, rupture of tire tendon leads to "bite inner tube", tire wear thin, tire damage, skin bumps, etc.
Tires are the ‘shoes’ of a car, and it’s condition is directly related to the safety of the vehicle. Tires are made of rubber, and always in contact with the ground, so inevitably become consumables, since it is consumables, we naturally can not ignore the extent of its wear, when necessary, we need to replace in time.
Ø The signal that the tire needs replacing
1) Tire wear to wear limit mark. Any brand of tire has a wear mark at the bottom of the tread groove. The normal wear mark height for tires is 1.6 mm (which is also the legal minimum groove depth for tires) and 2.4 mm for truck tires. So in order to facilitate the owner to check the tire wear, usually wear marks corresponding to the tire shoulder will have "△" and other marks. This method can be used to check whether the tread depth of the tire is OK.
Some owners think that as long as the tire is not broken, even if the tire pattern quickly polished, it still continue to be used, such an old tire is actually very dangerous. Really to this extent, the tire grip and drainage performance will be greatly reduced, safety will become poor. Therefore, tread marks should be kept at a depth of more than 3 mm.
2) Tire cracks or bulging and other damage. Cracks on the surface of tires can also be a safety hazard. In the daily use of the process, The tire may be punctured by a foreign body, the damaged condition of the tire includes tread crack, tread bulge, tread rubber absence, serious tire side wear, etc.
Especially the bulge, the tire will burst at any time the danger. This usually happens after the internal cord tissue is strongly impacted or squeezed, and because of the lack of cord restraint, high pressure air in the tire pushes the rubber out of the bag. This is also likely to happen at any time the risk of a flat tire, responsible for the small life, or as early as possible to change the tire better.
Cord is the warp material for weaving the cord. It is also used as the reinforcing material for tire, transport belt, transmission belt and other rubber products. It is mainly used in tire. Tyre side appears a bulge, the surface of this part of the cord has been broken, at any time there will be the danger of puncture.
3) Tire life expires. Tires used for a long time, also will gradually aging. The life of the tire is usually about 5 years, beyond this life, the tire will begin to age. The main manifestation of tire aging is surface hardening, followed by turtle cracks. Aging tires can lose their elasticity, which can lead to deformation of the tread and the risk of a flat tire.
The disc brake is that disc pushes the brake caliper through the hydraulic pump, and grasps the brake disc. Different from the hub brake, more linear and It doesn't stop all of a sudden.
The advantages of the disc brake:
Ø Disc brakes have better heat dissipation than drum brakes, and they are less likely to cause brake degradation and brake failure when continuously stepping on the brakes.
Ø The change in size of the brake disc after heating does not increase the stroke of the brake pedal.
Ø The disc brake system responds quickly and can do high-frequency braking actions, which is more in line with the needs of the ABS system.
Ø Because the brake disc has better drainage, it can reduce the situation of poor braking due to water or mud.
Ø Compared with drum brakes, disc brakes are simple in structure and easy to repair.
The disadvantage of disc brake:
Ø Because there is no automatic braking effect of the drum brake, the braking force of the disc brake is lower than that of the drum brake.
Ø The friction area between the brake pad and the brake disc of a disc brake is smaller than that of a drum brake, so that the braking force is also smaller.
Ø The hand brake device is not easy to install. Some models with disc brakes on the rear wheels have specially added a set of hand brake mechanisms with drum brakes.
The brake principle of the hub brake is to pull or push the brake hub in the brakehub so that the shoes on both sides are close to the inner wall of the wheel to achieve the braking effect.
The wheel is rolling forward, and the forward rolling force acts against the brake hub. As the brake hub and the wheel are in full contact, the braking force will increase instantaneously and the braking effect will be obvious.
Advantages of the drum brake:
Ø The brake force is large and can be stopped in time. We can often see that large trucks are generally hub brakes
Ø The cost of the hub brakes is lower than that of disc brakes.
Ø The parking brake mechanism is easy to install.
Disadvantages of the drum brake：
Ø 1. The diameter of the brake drum of the drum brake will increase after being heated, which will increase the stroke of stepping on the brake pedal, and it is easy to happen that the brake response is not as expected.
Ø The brake system reacts slowly, and the pedaling force of the brake is not easy to control, which is not conducive to high-frequency braking actions.
Ø There are many parts with complex structure, and the brake clearance must be adjusted, making maintenance difficult.
According to the national standard "speedometer for automobiles" (GB15082-2008), the speedometer indicates that the speed of the vehicle must not be lower than the actual speed.
Considering the tolerance errors on the speedometer, in order to prevent speeding, we manufacturers usually make the displayed speed higher than actual speed.
But meanwhile, the following relationship should be satisfied between the displayed speed and the actual speed:
1. Displayed speed ≥ Actual speed
2. Displayed speed ≤ Actual sped + Actual speed/10 + 4km/h