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ความคิดเห็นที่ 21 |
ค้นมาให้ จากหนังสือ The Automotive Chassis: Engineering Principles
คานแข็ง
ข้อเสีย
Rigid axles (Fig. 1.20) can have a whole series of disadvantages that are a
consideration in passenger cars, but which can be accepted in commercial
vehicles:
Mutual wheel influence (Fig. 1.21).
The space requirement above the beam corresponding to the spring bump
travel.
Limited potential for kinematic and elastokinematic fine-tuning.
Weight if the differential is located in the axle casing (Fig. 1.20), it produces
a tendency for wheel hop to occur on bumpy roads.
The wheel load changes during traction (Fig. 1.22) and (particularly on twin
tyres) there is a poor support base bSp for the body, which can only be
improved following costly design work (Fig. 1.42).
ข้อดี
In contrast to standard-design vehicles, the use of the rigid rear axle in frontwheel
drive vehicles has advantages rather than disadvantages (Fig. 1.24). As
Section 6.1.3 explains, the rigid rear axle weighs no more than a comparable
independent wheel suspension and also gives the option of raising the body roll
centre (which is better for this type of drive, see Fig. 3.42). Further advantages,
including those for driven axles, are:
they are simple and economical to manufacture;
there are no changes to track width, toe-in and camber on full bump/reboundtravel,
thus giving
low tyre wear and sure-footed road holding;
there is no change to wheel camber when the body rolls during cornering (Figs
1.6 and 3.54), therefore there is constant lateral force transmission of tyres;
the absorption of lateral force moment MY = FT,X hRo,r by a transverse link,
which can be placed at almost any height (e.g. Panhard rod, Fig. 1.25);
optimal force transfer due to large spring track width bsp
the lateral force compliance steering can be tuned towards under- or oversteering
(Figs 3.81 and 1.29).
เรื่องcamberในทางโค้งเป็นข้อดี คือถึงแม้ว่าช่วงล่างจะเทออกด้านนอกโค้ง ยางยังตั้งฉากกับถนนคงที่ตลอด ซึ่งดีกว่าcamber gain ของช่วงล่างอื่นๆซึ่งเมื่อช่วงล่างเทcamberของยางเทียบกับถนนจะเป็นบวกเพิ่มขึ้นคือcamber gainของช่วงล่างน้อยกว่ามุมเอียงของรถเทียบกับถนน
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