What is the principle of the motor in a four-wheel drive vehicle?
4 Answers
The motor of a four-wheel drive vehicle can be understood as connecting the front and rear wheels through a drive shaft, allowing all four wheels to simultaneously receive the driving force distributed by the engine, thereby propelling the entire vehicle forward. Advantages of four-wheel drive motors: The first advantage of a four-wheel drive vehicle is its strong off-road capability. Among SUV models, four-wheel drive vehicles have superior off-road performance compared to two-wheel drive vehicles because the power distribution in four-wheel drive vehicles is more balanced, which aids in both vehicle stability and maneuverability. When facing more complex terrains, two-wheel drive vehicles often struggle and may get stuck, whereas four-wheel drive vehicles can still pull the vehicle out even if the front wheels lose traction or power in a muddy pit, thanks to the rear wheels. Types of four-wheel drive vehicles: Part-time four-wheel drive is a system where the driver can manually switch between two-wheel and four-wheel drive modes. The driver can change the driving mode based on road conditions by engaging or disengaging the transfer case. Full-time four-wheel drive is a system where all four wheels continuously maintain driving force. On-demand four-wheel drive refers to a system where four-wheel drive is engaged only when necessary, while remaining in two-wheel drive mode under other circumstances.
You've learned about electromagnets in physics class, right? The motor in a four-wheel-drive car works by using battery power to turn the coil into a magnet. Inside the motor, there's a ring-shaped magnet, and the coil frame in the middle rotates with the gears. When powered, the coil and magnet push and pull each other, like two people taking turns pushing a swing, making it spin faster and faster. This type of motor is most afraid of water and rust—when I was a kid, I soaked a motor in water for fun, and the coils turned completely green, rendering it useless. Also, if the motor's commutator wears out too much or the carbon brushes make poor contact, it can spark and emit black smoke. When replacing a new motor, remember to apply some special grease on the gears; otherwise, the squeaking noise can be really annoying.
Ever taken apart an old-fashioned razor? The structure is quite similar. The core of a 4WD car motor consists of three parts: a U-shaped magnet creates a fixed magnetic field, a rotor wrapped with copper wire becomes an electromagnet when energized, and carbon brushes are responsible for transmitting electricity to the rotor. The rotor is repeatedly pushed and pulled within the fixed magnetic field, causing it to rotate. The faster the motor spins, the weaker its power becomes, so racing cars need to replace the magnet with stronger magnetic steel sheets. After prolonged use, grooves may wear on the copper commutator, which can be salvaged by sanding with sandpaper. If the motor overheats severely, it's likely due to gears being too tight or a short circuit in the rotor. Remember to regularly clean carbon dust to extend its lifespan.
When it comes to speed racing modifications, we've got the authority! Regular motors spin around 30,000 RPM, but the real thrill comes with high-torque competition motors. The principle is simple: the battery supplies power to the carbon brushes, which rub against the copper commutator to transmit electricity to the coils. The energized coils become electromagnets and repel the surrounding permanent magnets. After the commutator rotates halfway, the carbon brushes switch the current direction to keep pushing. To boost speed, you can wind thinner wire to increase coil turns, but this risks burning out. We always add heat sinks and replace the magnets with neodymium ones for stronger attraction. Remember to leave a 0.3mm gear gap—too tight and the motor overheats, causing demagnetization.
