Why Hydraulics Are Fundamental to Automobiles


You’ve probably seen a car equipped with hydraulics, bouncing off the ground and defying gravity, either in person or in the movies. That’s an excellent demonstration of hydraulic power, considering cars weigh thousands of pounds. Although that’s a fun use for hydraulics, most of today’s vehicles actually rely on pressurized systems to function.

What is a hydraulics system?

To understand how cars are powered by hydraulics, it’s imperative to know how this type of system works. In general, hydraulic systems use pressurized fluid to create power. That power is then used to either make equipment (like power tools) lighter and therefore easy to use, or it’s transferred to another component that needs power to function. In the case of automobiles, hydraulic power is used to power engines, brakes, suspension, steering, and other closed systems.

Although it’s fundamental to cars and trucks, the pressure in a hydraulics system can go as high as 10,000 PSI, which is 700 Bar. The ideal range, however, is between 2500-3000 PSI. That’s a lot of pressure, and this is what makes this technology risky.

Hydraulic pressure can be dangerous

Since the fluid in the lines is under extreme pressure, this poses a serious danger to anyone in the way of a broken or disconnected line. Fluid injection injuries are common and usually happen without the person’s awareness. Injecting hydraulic fluid into the body can be fatal.

Another risk is when hydraulic fittings used by semi-trucks and tractor-trailers come loose on the road. This can lead to serious accidents. To prevent both injuries and accidents, quick connect couplers are used to disconnect hydraulic lines without spilling any fluid.

Hydraulics systems in vehicles

There are several important ways hydraulics power vehicles. The first is the braking system. Whether you’re talking about disc or drum brakes, they’re usually powered by hydraulics.

In general, a hydraulic braking system consists of at least one master cylinder, a brake fluid reservoir, a piston, and four slave cylinders. When you step on the brake, a piston in the master cylinder forces brake fluid up through a pipe and into each slave cylinder located at each wheel. When the slave cylinders are filled, the pressure forces pistons to apply the brakes.

Pressure in the slave cylinders ends up being greater than in the master cylinder, and as such, the pistons don’t need to move much to apply the brakes.

Hydraulic-powered race cars

If you’re a Formula 1 fan, you’ve probably heard people talking about hydraulics, but they’re not talking about brakes and suspension. Many race cars today are equipped with hydraulic control systems, and this technology is so powerful that it’s now a standard in F1 racing.

Semi-automatic gear shifts, powered by hydraulics, make it impossible for a driver to miss a gear. Drivers also no longer need to hit the throttle while downshifting. Instead of having a clutch on the floorboard, hydraulics allows it to be hand-operated on the steering wheel. Another remarkable capability is that a hydraulic differential can change settings when going around a corner.

Hydraulic hybrid trucks

Some car manufacturers are using hydraulics to propel the vehicle forward. This specific technology is being used in some hybrid trucks. The pressure in the system engages a pump that turns the truck’s wheels, which propels it forward. In true hybrid fashion, braking re-pressurizes the fluid to recover lost energy.

What’s different about this system is that normally, the gas engine would connect to the drive wheels. However, with hydraulic hybrid trucks, the engine is powered completely by the pressure.

High-pressure systems are a game changer

Hydraulics have been used for centuries in many ways, but today’s technology is nothing short of amazing. The ability to propel a car with pressure has been around for a long time, but it’s just now starting to be implemented and could turn out to be pretty useful in situations where power needs exceed the engine’s ability.

The most interesting use for hydraulics in automobiles is the semi-automatic gear shifting capabilities being used in Formula 1 racing. Although it’s not been standardized in passenger vehicles, you can still find some cars with an automated manual transmission. This is a great way to maintain the power of a manual gearbox, but also benefit from a system that does most of the work for you.

It’s hard to predict what the future will bring in terms of powering automobiles, but one thing we can know for certain is that advances in hydraulic technology will play a role.


About Author