Why do some Trucks and Buses have Plastic Arrows on the wheels?

Why do some Trucks and Buses have Plastic Arrows on the wheels?

You’ve likely seen them whizzing by on the highway- trucks, and buses with small plastic arrows or mudguards attached to their wheels. At first glance, these tiny appendages might seem like mere decorations or afterthoughts, but they serve a crucial purpose that’s both practical and safety-driven.

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As we delve into the world of commercial vehicles, we’ll explore the fascinating reasons behind these humble plastic arrows, and how they play a vital role in protecting the vehicles themselves and the road they travel on.

Unlike the small cars and trucks we see on the road every day, semi’s and buses are very big vehicles that travel a lot. Most semi’s/trucks or buses spend an average of 110,000 miles on the road every year. And it’s no surprise that during the journey, they go through serious wear and tear.

Although transmission and engine failures would be the first thing someone would think of, more than common, tires endure a lot of wear and tear. A tire failure while traveling 70 mph can have serious consequences and can put a lot of lives at risk. That is why some commercial trucks or buses have those tiny plastics on the wheels.

What are those Arrows and what do they do?

Those little plastic arrows are called “loose wheel nut indicators”. When machines first put on the wheels, or balance the wheels, and tighten all the nuts properly, these little plastic arrow things are placed on them. There are several methods but the two popular to use loose wheel nut indicators are the “buddy system” and the “chain method”.

In the chain method, the arrows point at the center of the next nut. And so on, forming an unbroken, flowing chain-of-arrow effect. So if one of the wheel nuts comes loose, the arrow will move, breaking the following chain-of-arrow effect. This lets the driver know that they need to inspect the wheel immediately.

In the buddy system, the arrows point at one another.

plastic arrows

The buddy system only works on wheels with an even number of wheel bolt holes. Whatever method a mechanic prefers, they both provide easy, one-glance checking to see if any of the bolts have come loose. Before the driver starts his journey, he/she can do a quick walk around. This act is to  immediately tell if any critical wheel nuts are loose.

This cheap plastic indicator also helps reduce maintenance costs since it eliminates the need for expensive electronic types of equipment.

Once the driver notices that the loose nut indicator has moved, the nuts need to be retorqued by a qualified person using the proper tools. If a wheel has been replaced but not retorqued, a red indicator can be used. This is removed when the wheel is properly retorqued.

This step should always be performed by a qualified technician since over-torquing or under-torquing can have serious consequences.

For instance, some drivers think that over-torquing nuts is the best option since the tighter is better. Over-torquing actually stretches the studs or threads beyond their ability to respond, eventually causing them to fail. It can also result in cracked, seized, or cross-threaded nuts and cracked wheels.

Additionally, these plastic indicators also protect the nuts from dirt, rain, and other elements that could damge them or cause them to loosen.

Who Invented the Wheel?

No one individual, culture, or civilization can take sole credit for inventing the wheel. Although the consensus is that the ancient Sumerians had a hand in it. The wheel is, without a doubt, one of humanity’s most transformative innovations. Its invention marked a turning point in the development of tools and technology, and its influence transcended time and place.

But why is it so important to uncover the origins of the wheel? Understanding the inception of this remarkable invention allows us to appreciate its significance in the broader context of human progress. From early agricultural advancements to the modern industrial age, the wheel has been an enduring symbol of innovation. It enables us to conquer distances, transport goods, and shape the world as we know it.

When Was the First Wheel Invented?

The quest to pinpoint the exact moment of the wheel’s invention takes us back in time to ancient civilizations that laid the foundation for modern technology. While the invention of the wheel wasn’t a sudden, isolated event, it emerged through a gradual process of human innovation.

The earliest evidence of wheeled vehicles dates back to approximately 3500-3300 BCE in Mesopotamia. It’s a region that encompassed parts of modern-day Iraq, Syria, and Iran.

These early wheels were not solid disks as we commonly envision them today but rather wooden disks with a hole in the center for an axle. They were attached to carts used for transporting goods, primarily in agricultural and trade activities.

Beyond Mesopotamia, evidence of wheeled vehicles also emerges from other ancient cultures. In the Indus Valley, which is now part of India and Pakistan, wheeled toys dating back to 2000 BCE have been discovered. This is providing additional insight into the early uses of this technology.

The ancient Egyptians, known for their impressive engineering feats, are believed to have developed wheeled vehicles around 2000 BCE as well. These early wheels were used in chariots and helped enhance the military capabilities of this ancient civilization. Called a wrrt or a market, the chariots of ancient Egypt were essential to the military successes of the New Kingdom Period.

It’s difficult to attribute the invention of the wheel to a single individual or culture. However, these discoveries highlight the gradual evolution of the wheel across different regions of the ancient world. It underscores the fact that human innovation is often a collective effort, with various civilizations. This is contributing to the development of key technologies over long periods.

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