In this article, we’ll take a closer look at how the power is distributed. We’ll explain how the parts which contribute to its operation work together so you’ll have an appreciation for the system.
Differentials And Locking Hubs
A four-wheel drive has three basic units: the differentials, transfer case, and locking hubs. The differentials are assemblies that take the torque from the transmission and route it to the tires. In addition, differentials allow the wheels to spin independently of one another when turning.
Locking hubs are devices used to preserve the front wheels. In every car, each tire is bolted to a hub, but in a 4WD vehicle when the front wheels are not receiving power, the differential and half-shafts are still spinning. With locking hubs, the front tires are disconnected so they avoid causing undue wear and tear on the drive shaft, differential, and half-shafts. A sliding collar is employed that connects the hub to the half-shaft and is moved depending upon whether the car is in two-wheel drive or not.
Many years ago, locking hubs were manually operated. If you wanted to switch to 2WD mode, you needed to exit your vehicle and manipulate a knob on the front tires to lock and disengage them. Today, the mechanism is completely automatic and can be activated when the car is moving.
The Transfer Case
The transfer case is responsible for splitting the power between the front and rear tires. These can vary depending upon whether your car is all-wheel drive (which means all wheels are permanently activated) or part-time. In a part-time vehicle, the transfer case binds both the front and rear axles together so everything spins at the same speed. However, this is not usually recommended on dry concrete or otherwise stable road surfaces as it will cause your tires to slip, needlessly wearing them down.
In some transfer case systems, the mechanism contains a set of gears known as a low range. The low range transfers large amounts of torque while operating at a very low speed. This is especially useful when driving in very slippery conditions or on steep roads.
Most motorists enjoy driving their 4WD vehicles without realizing how they operate. Long-time readers know that I always recommend learning as much as you can about the parts under your car’s hood. When the time comes to visit a mechanic, you’ll have a deeper understanding about your vehicle.
When your vehicle is experiencing problems, taking it to a mechanic is often inconvenient and costly. Plus, there’s always a nagging feeling that an auto technician will suggest more work than is truly necessary. In a spurt of inspiration, you might be motivated to lift the hood of your car and fix the problem yourself.
If you have experience working under the hood, you’re probably (hopefully) taking the proper safety measures. However, many of you may have little to no experience performing auto repairs. As a result, you could be neglecting safety precautions that are meant to protect you from injury. Whether you’re replacing your vehicle’s fuel filter, rotating the tires, or pulling out the cylinder head, you need to take the proper steps in order to remain safe.
In this article, I’ll provide an overview of safety precautions that will protect you from harm. Observing them can make the difference between an easy, safe auto repair job and a potential nightmare.
Wear Protective Eye Goggles
Depending on the type of work you’re performing, your eyes can be extremely vulnerable to damage. For example, if you’re grinding something, the tools you’re using can throw debris into the air. Or, if you’re working underneath your vehicle, debris can easily fall directly into your eyes. Air conditioning refrigerant, battery acid, and other items can cause severe harm. Wear goggles to protect your eyes.
Disconnect Your Car’s Battery
If you’re doing any work on any of the parts that make up your vehicle’s electrical system, disconnect the battery. Even a task as simple as replacing the alternator can be dangerous if a charge is sent unexpectedly through the system. Whether you’re fixing your car’s starter, replacing the switch, or repairing wires, unhook one of the terminals from the posts on your battery. That way, there’s no chance of accidentally starting a fire in the electrical system.
Relieve Pressure From The Fuel Injection System
When your vehicle is running, pressure builds within the fuel injection system. If you open a fuel line while it’s running, you can cause significant injury to yourself from the spray. Even if your car’s engine has been turned off for a few hours, some of the pressure can still remain. If you’re planning to open a line, use a thick towel or rag and snugly wrap it around before you loosen it. Then, take it off slowly to relieve some of the residual pressure.
Being Safe Under The Hood
There are a lot of things that can go wrong when you’re working on your vehicle. Even minor repair work can result in a fire or injury. Your first priority is to protect yourself and anyone around you. If you don’t have experience repairing cars, either work with an experienced friend or take it to a trained mechanic. Protecting your safety is worth the investment.
Without a muffler, the modern automobile would be much louder. What may seem like a nondescript metal cylinder is actually a device that reduces engine noise by partially canceling out sound waves. In this article, I’ll describe the nature of sound in the context of how it is controlled under the hood.
What Is Sound And How Is It Controlled?
Sound is a form of mechanical energy, a vibration formed by alternating phases of compression and rarefaction (high and low pressure) in frequencies able to be detected by the ear. An internal combustion engine creates sound by the opening of exhaust valves, sending pulses of high-pressure gas into the exhaust system in rapid succession. The spaces between these pulses, in combination with the low-pressure environment in the exhaust pipe, create the distinct hum (or roar) of an engine.
If the engine is running faster, then the space between the pulses is shorter and the frequency rises, leading to a higher-pitched noise. If the gas pedal is depressed, then the pressure of the individual pulse rises, increasing the amplitude of the sound waves and volume.
Understanding Its Operation
A muffler operates on the principle of sound known as destructive interference. Destructive interference is the effect by which two opposing waves cancel each other out. As a muffler is tuned to cancel out a majority of the frequencies produced by the common engine, the noise level is partially reduced.
Originating at the inlet, the exhaust fumes and noise pass through a tube into the resonating chamber. The sound waves then reflect off the back wall of the resonating chamber and pass through a hole into the main chamber. From this point, the gases then travel through the outlet pipe and exit the vehicle.
The resonating chamber is designed to a specific length to match the majority of sound frequencies produced by the engine. When the they reflect off the back wall, they are inverted; when passing through the hole of the main chamber, the inverted waves collide with incoming waves and cancel each other out.
In addition to the resonator chamber, the shell of the muffler is made of three layers: a thicker layer sandwiched between two thin layers of metal. Secondly, the pipes entering and exiting the muffler are wrapped in thousands of tiny holes that serve to reflect and cancel a portion of the sound. In certain luxury automobiles, the muffler is supplemented by a resonator, a cylinder very similar to the resonator chamber that serves to cancel additional noise.