Name: 你一定看過！為什麼有些卡車輪胎根本不落地？(Why Do Some Truck Tires Don't Touch The Ground?)
Uploaded: 2026-01-23T21:01:30.000Z
Duration: 4 min 49 s

現在完成進行式

Have you ever been driving down the highway,

你有沒有在高速公路上開車時，

looked over at a massive dump truck or a cement mixer and noticed something wrong?

看向一輛巨大的砂石車或水泥攪拌車，然後發現哪裡怪怪的？

You see the massive wheels spinning, the heavy frame rattling.

你看到巨大的輪子飛快轉動，沉重的車身不停震動。

One entire row of them isn't even touching the ground.

其中整整一排輪胎，居然完全沒有碰到地面。

They're just hovering there, spinning in the air, ghosting along the pavement.

它們就那樣懸在空中轉動，彷彿幽靈般沿著路面滑行。

At first glance, it looks like a mechanical failure,

乍看之下，這就像是機械故障，

又或者是電玩遊戲裡的畫面錯誤。

但那個懸空的輪胎，其實不是錯誤。

It is actually a brilliant piece of engineering that saves billions of dollars in road repairs,

它其實是一項極為聰明的工程設計，每年為道路維修省下數十億美元，

saves the trucking company a fortune in fuel,

為運輸公司節省大量燃料成本，

and stops the truck from destroying itself during a turn.

也防止卡車在轉彎時把自己搞壞。

Today, we're looking at the surprising reason why some truck tires are designed not to touch the ground.

今天，我們就要來看看，為什麼有些卡車的輪胎，會被設計成不接觸地面。

Right here in Simple Things: Surprising Histories.

就在《簡單事物：驚人歷史》。

To understand the floating wheel, we first have to look at the road beneath it.

要理解這個「懸浮輪胎」，我們得先看看它下面的道路。

Concrete and asphalt are strong, but they have a breaking point.

混凝土和瀝青很堅固，但它們也有承受極限。

If you put too much weight on a single point,

如果你把太多重量集中在單一點上，

you don't just drive over the road - you crush it.

你不只是開過馬路，而是直接把它壓碎。

This is why governments enforce strict act axle weight limits.

這就是為什麼政府會嚴格限制「單軸承重」。

It's not just about how heavy the entire truck is.

這不只是整台卡車有多重的問題。

It's about how that weight is distributed.

把它想像成在厚厚的雪地上走路。

If you walk in high heels, you sink immediately.

如果你穿高跟鞋，一踩下去就會陷進去。

But if you wear snowshoes, your weight is spread out over a larger area,

但如果你穿雪鞋，重量被分散到更大的面積，

This is exactly what that extra set of wheels, technically called a lift axle, is for.

這正是那組額外輪胎——技術上稱為「升降軸」——的用途。

When a dump truck is fully loaded with 20 tons of gravel,

當一輛砂石車滿載 20 噸碎石時，

that weight is too much for just two or three standard axles to handle legally.

光靠兩到三個標準車軸，在法律上是承受不了這個重量的。

於是駕駛在駕駛室裡按下一個開關，

huge airbags inflate, pushing that hovering axle down until it hits the pavement.

巨大的氣囊充氣，把那組懸空的車軸推下來，直到接觸路面。

The weight is distributed across more tires, the pressure on the road drops,

重量被分散到更多輪胎上，道路承受的壓力降低，

and the truck becomes legal to drive without destroying the asphalt.

卡車也能合法行駛，而不會摧毀瀝青路面。

So if more wheels mean better weight distribution and safer roads,

既然輪胎越多，重量分配越好、道路也越安全，

那為什麼不一直讓它們接觸地面呢？

The answer, as is often the case in history, comes down to money.

答案就像歷史上許多事情一樣，歸根究柢是錢的問題。

Big rig tires can cost hundreds of dollars each, and they wear out quickly.

大型卡車的輪胎，一條就要好幾百美元，而且磨損得很快。

Every mile a tire rolls against the pavement creates friction.

每一公里輪胎在路面上滾動，都會產生摩擦。

The more tires you have touching the ground,

the harder the engine has to work to push the truck forward,

引擎就得更賣力地推動卡車前進，

Imagine a truck has just dropped off its load.

If the driver leaves those extra axles down,

如果駕駛還讓那些額外車軸接觸地面，

they are just burning fuel and wearing down expensive rubber for no reason.

那就只是白白燒油、磨損昂貴的橡膠。

By lifting them up, they instantly reduce rolling resistance.

把它們升起來，就能立刻降低滾動阻力。

這就像是重型機械的「省油模式」。

Many highways and bridges charge trucks based on the number of axles touching the ground.

許多高速公路和橋樑，會依照接觸地面的車軸數量收費。

a driver can legally classify the truck as a smaller vehicle,

駕駛就能合法把卡車歸類為較小型的車輛，

There is one final crucial reason for the lift.

還有最後一個至關重要的原因。

When a truck with multiple fixed axles tries to turn a tight corner,

當一輛有多個固定車軸的卡車要轉急彎時，

They get dragged sideways across the pavement.

它們會被硬生生拖著側向滑過路面。

這種現象稱為「輪胎磨擦拖行」。

It screams, it shreds the tires, and it puts massive stress on the truck's frame and suspension.

它會發出刺耳聲響、撕裂輪胎，並對車架與懸吊造成巨大壓力。

If a truck has too many wheels on the ground,

如果一輛卡車有太多輪胎接觸地面，

it essentially wants to drive in a straight line forever.

By lifting that extra axle, the driver effectively shortens the truck's wheelbase.

把那組額外車軸升起來，等於縮短了卡車的軸距。

It allows the truck to pivot smoothly around corners,

navigating tight construction sites or city streets without ripping the tread off the tires

在狹窄的工地或城市街道中穿梭，而不會把輪胎胎紋撕裂，

So, the next time you see a truck with a ghost wheel hovering in the air,

所以，下次你看到卡車有一顆「幽靈輪胎」懸在空中，

balancing the laws of physics with the laws of the road and the cost of doing business.

在物理定律、道路法規與營運成本之間取得平衡。

I hope you enjoyed this slice of engineering history.

希望你喜歡這段工程史的小故事。

and subscribe to Simple Things: Surprising Histories for more stories about the everyday world around us.

並訂閱《簡單事物：驚人歷史》，了解更多日常世界中的故事。

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