The Unknown Provider of Heavy Lifting: The Hydraulic Lift 

An excellent example of a hydraulic system is the hydraulic lift, commonly used in auto repair shops or for moving heavy goods.

The Unknown Provider of Heavy Lifting: The Hydraulic Lift 

Have you ever thought about how a mechanic can easily lift a multi-ton vehicle high into the air, or how large building materials are lifted on a construction site? The answer is that mechanics and construction workers are utilizing a fascinating application of fluid physics called a hydraulic system; the hydraulic lift is one of the best examples.

What is a hydraulic lift? 

The simplest view of a hydraulic lift is that it is a machine that uses a non-compressible fluid to generate force, which usually is some type of oil. It works based on Pascal's Law, which states that any pressure that is applied to an enclosed fluid will be transmitted equally throughout the entire fluid and to the walls of the vessel.

How does it work? The magic of Pascal's law 

The mechanism is simple and very powerful:

1. Input Force: A small force is applied to a fluid, like oil, that is in a small cylinder (or piston). 
2. Pressure transmission: This small force produces pressure (P=F/A). With Pascal's law, the pressure will be transmitted undiminished in every part of the hydraulic fluid.
3. Output force (The lift): The pressure of the hydraulic fluid exerts force through a large cylinder (or piston) that is supporting the load (the car, for example).

Since the pressure (P) in both cylinders is the same, and also the output piston area (A out) is well above the input piston area (A in), the force (F out) on the output, large piston is substantially greater:

Pressure(P)=​Fin​​ = Fout​​
                      Ain   Aout​
 
It is possible to exert a relatively small effort while lifting a vastly larger weight, which is the essence of a hydraulic lift being an actual force multiplier.

Key Components

• Reservoir: The hydraulic fluid is stored here.
• Pump: The pump provides the fluid flow.
• Valve: The valving directs the fluid flow (to raise, lower, or hold the lift)
• Cylinders/Pistons: The cylinders/pistons are where the pressure acts to perform the work (lift the load).
• Hydraulic fluid: The hydraulic fluid, typically oil, is the medium that transmits the force. The non-compressibility of the fluid is key.

Applications of Hydraulic Lifts

There are many applications for this technology:

• Vehicle Lifts: Possibly the most common use found in garages and repair shops.
• Forklifts: Used in warehouses to raise and lower heavy pallets.
• Dump Trucks: The hydraulic lifts provide the tilting for the truck bed.
• Elevators (some types): Smaller elevators can use hydraulic systems to move up and down vertically.
• Jacks: The simple car jack you might keep in your trunk operates on the same hydraulic principle.

The next time you see a heavy vehicle being lifted with ease, remember the clever physics at play! The hydraulic lift is a perfect demonstration of how a basic scientific principle can be engineered to solve some of the world's heaviest challenges.