With each passing year, trucks and cars gain new features that enhance comfort and enjoyment for both the drivers and passengers. These improvements over the past decades have become so commonplace that we rarely give them a second thought. If you are anything like me, as long as the vehicle steers easy and goes straight without veering off the road or into the next lane, I don’t stop to wonder how it steers, I just drive.
The same mindset holds true for the air conditioning, transmission, brakes, and truth be told, the entire vehicle! As long as everything is going well, why bother thinking about it? However, it’s important to understand how various vehicle systems work together, as they may not always function as expected. Knowing how these systems work can make identifying and resolving potential problems so much easier.
Throughout my career, I have read a good number of technical manuals, attended classes, and worked on countless vehicles. Of course, technical theory is important to understand in order to know a system’s inner-workings. While those technical theories are often presented in an accurate manner, they may not be so easy to grasp. Sometimes a simple and practical explanation goes a long way in providing a foundational understanding for a system that will ultimately make diagnosing issues easier.
Here are a couple of examples from my experience:
Air conditioning: More than just cold air
When the AC system works properly, it makes life bearable in hot weather. The AC vent blows cold air in my face, and that’s how it works. Well, yes and no. While it is true that I feel cold air from the vent, that cold air is actually the result of hot air being removed from the cabin.
The air gets cold because heat dissipates to whatever is cooler, and this principle is similar to what happens when using an aerosol can. If you recall, the longer you held down the spray nozzle, the colder your finger got, as heat was drawn away from your finger.
In the air conditioning system, the liquid refrigerant passes through a small orifice, similar to the aerosol can spray nozzle, and gets cold. The cold refrigerant then enters the evaporator, resembling a radiator. Hot air from inside or outside the cabin is then drawn through the condenser and cooled. Finally, a fan blows this cooled air into your face.
Steering castor: Understanding steering geometry
To better grasp steering geometry, particularly caster, everyday objects like a shopping cart, can be incredibly helpful. Consider a shopping cart’s front wheels, which are set back at an angle from the point where the forks attach to the cart frame.
Those assemblies are typically called casters, which, no big surprise, also reflect the concept of caster in steering geometry. This caster design helps the cart move straight in the direction it’s pushed with minimal effort.
Similarly, bicycles utilize caster in their front forks. If the forks pointed straight down, the bike would change direction easily but would require the rider to make constant steering corrections. By adding caster to the fork angle, the bike is more likely to travel straight with less effort from the rider. If the caster is angled too far forward, the bike stays going straight but is harder to turn.
Thus, in a truck, too much caster – also known as positive castor – can slow down steering and require more turning of the steering wheel. Too little, or negative castor, can make steering slow and require constant turning of the steering wheel to correct direction.
So, the next time you embark on a smooth and enjoyable ride in your truck, take a moment to appreciate the complex systems at work. If you take a look around, you’ll likely gain an understanding of how different vehicle systems work together through simple, everyday objects. Understanding the mechanics behind the operations of your vehicle will make it so much easier to identify potential issues and find appropriate solutions.
