How Do Hydraulic Lifts Work?

If you work in the industrial field, odds are you’ve handled more elevators and lifts than you can count. But have you ever wondered how exactly a hydraulic lift works? Or what’s the difference between a hydraulic elevator and a regular elevator? Don’t worry, it’s not too complicated. Read on to learn the secrets behind hydraulic lifting systems.

Hydraulic Lifts vs Roped Elevators

Technically speaking, anything that lifts an object or person is an elevator. You don’t need buttons or a carpet or terrible background music—just tie a rope around a box. Congratulations! That’s an elevator. There are only two major lifting systems in use today: hydraulic elevators and roped elevators. Both types of lifting systems have their pros and cons. A hydraulic elevator is any device that uses Pascal’s Principle to do some serious heavy lifting with not much effort from the operator. Without sounding too much like an 8th-grade physics professor, here’s the gist of hydraulic lift physics: Fluid trapped in a container can transfer enormous amounts of force. By applying force to a small amount of trapped liquid, that force can be transferred to a much larger surface area on the other side of the container. Hydraulic lifts are a great option for moving enormous objects that otherwise couldn’t be lifted by any reasonable rope elevator.

Easy as Tank, Pump, and Valve

All hydraulic lifts use the same basic components, though they can come in any number of shapes and sizes. Whether lifting the arms of a construction crane or lifting trucks with a car elevator, hydraulic lifting systems need the same three things:

1. A fluid reservoir (a tank full of incompressible fluid)
2. A pump (to apply small amounts of force)
3. A valve (to control the amount of liquid to which the pump has access)

What’s an incompressible fluid? In brief, that’s a term used for any liquid able to maintain the same density and consistency despite changes in temperature and pressure. Most industrial hydraulic lift systems will use an oil as their incompressible fluid. To operate a hydraulic lift, the operator needs to open the valve and let small amounts of fluid out of the tank. The pump will apply small but repetitive force and push fluid against the lift compartment. As long as the valve is open and the pump is on, the fluid pushed against the lift compartment will be trapped and unable to flow back into the tank. To stop the elevator rising, the lift operator can close the valve and turn the pump off. The trapped fluid will keep the lift compartment where it is until that fluid is allowed to slowly return to the fluid reservoir through another controlled valve. Not so hard, right?

Ready, Set, Lift

Hydraulic lifts are an essential part of any warehouse or material handling business. To recap what we’ve learned so far:

• Any elevator or lift system that doesn’t involve a rope is probably a hydraulic elevator. They’re more common than most people realize.
• Hydraulic lifting systems all use the same basic tank, pump, and valve system. They just use them in different sizes.
• Because most liquids can’t be compressed and can’t flow backward against pressure, hydraulic lifts are safe to use while lifting an incredible amount of weight, unlike some other systems.

Return to the Blog main page.