汽车底盘构造和四大体系详解
车轮与轮胎
功用是支承汽车车体重量，缓和由于路角不平引起的冲击力，接受和传递制动力和驱动力，轮胎具有抵抗侧滑的能力，轮胎具有自动回下正的能力，使汽车正常转向，保持汽车直线驶。
一、车轮
1、组成通常车轮由轮毂、轮辋以及这两件元件之间的连接部分称为轮辐的元件所组成
2、分类
按照轮辐的结构车轮可分为辐板式和辐条式。
根据轮辋形式不同又可分为组装轮辋式，可调式车轮，对开式，可反装式车轮。
根据车轮材质不同又有铝合金、镁合金、钢车轮之分。
辐板式车轮由档圈，辐板，轮辋和气门嘴伸出口组成（如上图）。辐板为钢质圆板，它将轮毂和轮辋连接为一体，大多是冲压制成的，少数是与轮毂铸成一体。后者多用于重型汽车上。辐板与轮辋是铆接或焊接在一起的，对于采用无内胎轮胎的车轮，宜采用焊接法可提高轮辋的密闭性。
轿车的辐板采用材料较薄，常冲压成起伏各样形状，以提高刚度。辐板上开有若干孔，用以减轻质量，有利于制动器散热，安装时可作把手。
货车后轴负荷大多比前轴大很多，为使后轮胎不致过载，后桥车轮一般安装双式车轮，在同一轮毂上安装两副相同的辐板和轮辋，为方便互换，辐板的螺栓也两端面做成锥形，便于安装。
辐条式车轮这种车轮的轮辐是钢丝辐条或者是用轮毂铸成一体的铸造辐条。钢丝辐条车轮(如右图a所示)由于价格昂贵、维修安装不便，故仅用于赛车和某些轿车上。铸造辐条式车轮（如右图b所示）用于重型货车上。在这种结构的车轮上，轮辋是用螺栓了和特殊形状的衬块固定在辐条上，为使轮辋与辐条对中好，在轮辋和辐条上都加工出配合锥面。
轮辋结构及规格代号
轮辋按其断面结构形式分为深式轮辋、平式轮辋和可拆式轮辋。
深槽式轮辋，代号（DC），这种轮辋多用于小轿车及越野车上。易于装卸，它的轮辋一般都采用钢板冲压成形的整体结构。
平底轮辋如图，代号（WFB），主要用于中、重型载货汽车，自卸汽车和大客车。
对开式轮辋（对拆平底式轮辋）代号（DT）。它由左右可分的两半轮辋组成。两部分轮辋可以是等宽度，也可以不等宽，它们之间用螺栓固紧在一起形成用以安装轮胎的轮车内。
二、轮胎
轮胎作为汽车与道路之间力的支承和传递部分，它的性能对汽车行驶性能影响很大。轮胎的性能与其结构，材料、气压、花纹等因素有关。
轮胎总成是安装在轮辋上的，直接与路面接触。它的作用是：承受汽车的重力；当汽车行驶中，路面不平引起冲击和振动要求轮胎与悬架一齐起缓和冲击的作用；保证车轮和路面接触具有良好的附着性，传递驱动力和制动力，保持汽车行驶稳定性。
结构轮胎主要由胎冠、胎肩，胎侧，胎体和胎圈等部分组成。
1、胎冠是指外胎两胎肩夹的中间部位。包括胎面，缓冲层（或带束层）和帘布层等。
胎面是指胎冠Zui外层与路面接触带有花纹的外胎胶层。作用是保护胎体，防止其早期磨损和损伤。
缓冲层是指斜交轮胎胎面和胎体之间的胶布层。作用是缓和并部分吸收路面对轮胎的冲击。
带束层是指在子午线轮胎和带束斜交轮胎的胎面基部下，沿胎面中心线圆周方向箍紧胎体的材料层。作用是增强轮胎的周向刚度和倾向刚度，并承受大部分胎面的应力。
帘布层是指胎体中由覆胶平行帘线组成的布层，它是胎体的骨架，支撑外胎各部分。
2、胎侧是指胎肩到胎圈之间的胎体侧壁部位上的橡胶层，作用是保护胎体，承受侧向力。
3、胎体是由一层或数层帘布与胎圈组成整体的充气轮胎的受力结构。斜交轮胎的胎体帘布线彼此交叉排列，子午线的胎体帘线互相平行。
4、胎圈是指轮胎安装在轮辋上的部分。由胎圈芯和胎圈包布等组成。作用是防止轮胎脱离轮辋。
轮胎
轮胎种类
汽车轮胎按胎体结构不同可分为充气轮胎和实心轮胎。汽车上常用的汽车轮胎是充气轮胎。实心轮胎目前仅用于在沥青混凝土路面的干线道路上行驶的低压汽车或重型挂车上。
充气轮胎按结构不同可以分为有内胎和无内胎两种。
按帘布材料可分为棉帘布轮胎、人造线轮胎、尼龙轮胎、钢丝轮胎、聚酯轮胎，玻璃纤维轮胎、无帘布轮胎。
按胎面花纹可分为普通花纹轮胎、越野花纹轮胎，混合花纹轮胎。
按气压可分为高压轮胎、低压轮胎、超低压轮胎。
按帘布层结构可分为斜交轮胎、带束斜交轮胎和子午线轮胎。
1、有内胎的充气轮胎主要由外胎、内胎、垫带组成。内胎中充满压缩空气，外胎用来保护内胎不受损伤且具有一定弹性；垫带放在内胎下面，防止内胎与轮辋硬性接触受损伤。
2、普通斜交轮胎
它的特点是帘布层和缓冲层各相邻层帘线交叉排列，各帘布层与胎冠中心线成35o~40o的交角，叫斜交轮胎。
3、子午线轮胎
这种轮胎的胎体帘布层与胎面中心线呈90度或接近90o角排列，帘线分布如地球的子午线，称为子午线轮胎。子午线轮胎帘线强度得到充分利用，它的帘布层数小于普通斜交轮胎帘布层数，使轮胎重量可以减轻，胎体较柔软。子午线胎采用了与胎面中心线夹角较小（10o~20o）的多层缓冲层，用强力较高，伸张力小的结构帘布或钢丝帘布制造，可以承担行驶时产生的较大的切向力。带束层象钢带一样，紧紧箱在胎体上，极大地提高胎面的刚性和驱动性以及耐磨性。
子午线轮胎本身结构原因，使其高速旋转时，变形轮，生温低，产生驻波的临界速度比斜交胎高，提高了行驶中的安全性。
4、无内胎轮胎
在外观上与普通轮胎相似。所不同的是无内胎轮胎的外胎内壁上附加了一层厚约2~3mm的专门用来封气的橡胶密封层，它是用硫化的方法粘附上去的，密封层正对着的胎面下面，贴着一层未硫化橡胶的特殊混合物制成的自粘层。当轮胎穿孔时，自粘层能自行将刺穿的孔粘合，又有叫有自粘层的无内胎轮胎。
无内胎轮胎在穿孔时，压力不会急剧下降，有利于安全行驶，无内胎轮胎不存在内外胎之间的摩损和卡住，它的气密性好，可直接通过轮辋散热，温升低，使用寿命长，结构简单，重量轻。其缺点是途中坏了修理困难。
轮胎的气压
充气轮胎按胎内空气压力大小可分为高压胎，低压胎和超低压胎三种。高压胎（气压0.49~0.69MPa），低压胎（气压0.147~0.49MPa），超低压胎气压0.147Mpa以下）。
现今，载重车、轿车大都采用低压胎，因为低压胎弹性好，断面宽，与路面接触面积大，胎壁薄散热性好。这些性能使轮胎寿命延长。
Wheels and tires
The function is to support the weight of the car body, relievethe impact force caused by the uneven road angle, accept andtransfer the braking force and driving force. The tire has theability to resist sideslip, and the tire has the ability toautomatically return to the bottom, so as to make the car turnnormally and keep the car straight.
Wheel
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1. A wheel is usually composed of a hub, a rim, and elementscalled spokes that connect the two elements
2, classification
According to the structure of the spokes, the wheels can bedivided into the spoke plate type and the spoke type.
According to the different rim forms, it can be divided intoassembled rim type, adjustable wheel, split type and reverse typewheel.
According to different wheel materials, there are aluminumalloy, magnesium alloy and steel wheels.
The spoke wheel is composed of retainer, spoke, rim and valveoutlet (as shown in the above figure). The spoke plate is a steelround plate, which connects the hub and the rim as a whole, most ofwhich are made by stamping, and a few of which are cast as a wholewith the hub. The latter is mostly used in heavy vehicles. Thespokes and rims are riveted or welded together. For wheels withtubeless tires, the welding method should be used to improve thetightness of rims.
The spokes of cars are made of thin materials, which are oftenstamped into various shapes to improve the rigidity. The spokeplate is provided with a number of holes to reduce the mass andfacilitate the heat dissipation of the brake. It can be used as ahandle during installation.
The rear axle load of freight cars is much larger than that ofthe front axle. In order to prevent the rear tires fromoverloading, the rear axle wheels are generally equipped with dualwheels. Two pairs of identical spokes and rims are installed on thesame wheel hub. In order to facilitate interchange, the bolts ofspokes are also tapered on both ends for easy installation.
Spoke wheel the spokes of this kind of wheel are either steelspokes or cast spokes made of hub. The steel spoke wheel (as shownin figure a on the right) is only used in racing cars and someluxury cars due to its high price and inconvenient maintenance andinstallation. Cast spoke wheels (as shown in Figure B on the right)are used on heavy trucks. On the wheel with this structure, the rimis fixed on the spokes with bolts and special shaped lining blocks.In order to align the rim and spokes well, a matching cone ismachined on the rim and spokes.
Rim structure and specification code
Rim can be divided into deep rim, flat rim and detachable rimaccording to its section structure.
Deep groove rim, code (DC), which is mostly used in cars andoff-road vehicles. It is easy to load and unload, so its rims aregenerally made of steel sheet stamping.
Flat rims as shown in the figure, code (WFB), mainly used formedium and heavy trucks, dump trucks and buses.
Split rim (split flat bottom rim) code (DT). It is composed oftwo halves of rims which can be divided left and right. Thetwo-part rims can be of equal or unequal width, and they are boltedtogether to form a wheel car for mounting tires.