The day I was standing on a street corner in downtown Chicago. I saw a demolition crew taking apart a parking garage. This was rough work. There was a machine it was yellow, like the machines you see at construction sites. This machine was breaking through concrete like it was nothing. The engine was very loud. Making a lot of smoke.. That was not what got my attention. The demolition crew and the machine were doing something that looked very intense. The machine it was an excavator was tearing through the parking garage.
I was watching the steel tubes on the machine. They were really shiny and made of chrome-plated steel. These tubes were going in and out, along the arm of the machine. The steel tubes moved without making any sound. The steel tubes moved really smoothly too.. What the steel tubes were doing was amazing. They were strong enough to break the rebar into two pieces.
The hydraulic cylinder is really something. This thing is like the worker that does a lot of heavy lifting, in our daily lives. The hydraulic cylinder is what makes a lot of machines move and work properly.
We really like to focus on the brain of our machines things like microchips and artificial intelligence and sensors.. We do not pay much attention to the muscle that makes them work. The hydraulic cylinder is an important part of our machines. Without it our whole civilization would come to a standstill. We would have to go to using ropes and pulleys and a lot of people would have to haul heavy stone blocks. The microchip is like the brain that helps our machines think. The hydraulic cylinder is, like the muscle that helps our machines act. If we did not have the cylinder the microchip would not be very useful. The hydraulic cylinder and the microchip work together to make our machines work properly.
The Liquid Lever
What is a hydraulic cylinder? If we forget about the talk a hydraulic cylinder is something that makes things move in a straight line. It takes the energy from a fluid. Turns it into motion that goes up and down or back and forth. A hydraulic cylinder is a simple thing. It is a linear actuator that helps things move in a straight line.
But that definition is boring.
Here is a better way to think about the syringe: Imagine a syringe. The syringe is the kind that a doctor uses. The syringe has a barrel, which’s the tube and the syringe has a plunger, which is the piston. The syringe also has a liquid inside the syringe. When you push down on the plunger of the syringe with your thumb the liquid, inside the syringe shoots out of the needle of the syringe.
Now, reverse that process.
Imagine you are pumping liquid into the needle end of a machine. The pressure from the liquid would make the plunger slide back out of the barrel. This is what a hydraulic cylinder is like. It is basically a syringe that is very strong because it is made with steel. The hydraulic cylinder is, like a steel syringe.
This is where things get really cool. The idea is called Pascals Principle. It is the reason why a person who weighs 150 pounds can actually lift a car that weighs two tons using a jack. Pascals Principle is what makes this possible.
Liquids really do not like being squished. They are much impossible to compress. If you put oil in a space and try to push on it the pressure is felt the same in every direction.
If you use a pump to push oil through a thin hose, which has a small surface area into a big fat cylinder, which has a large surface area the oil gets a lot of extra force. This is because the pressure of the oil is spread out over an area in the cylinder. Liquids like oil are very good, at transferring pressure, which’s why this works so well with the oil.
Think of it like this: when you are riding a bike and you shift gears it is of like that. You pedal fast and it is easy this is like the pump that moves the oil. But then the back wheel of the bike turns slow and it has a lot of power this is like the cylinder extending. So you are giving up speed to get power from the bike or, in this case from the cylinder.
Anatomy of a Brute
I visited a factory in the Rust Belt where they make these machines for mining trucks. It was really something to see. The mining trucks they were making were very impressive. What surprised me the most was how precise everything was. We usually think that heavy machinery is of rough around the edges.. The inside of a hydraulic cylinder for the mining trucks needs to be very smooth. It needs to be as smooth, as a mirror for the mining trucks to work properly. The hydraulic cylinder is an important part of the mining trucks.
Here is the setup:
The Barrel is the part that surrounds everything. This is the tube that holds all the pressure, inside The Barrel. The Barrel is very important because it keeps everything together and safe.
The Piston is a metal disc that’s inside the thing. It divides the barrel into two parts, which’s a pretty important job for the Piston. The Piston is really a simple metal disc but it does a big job, in the barrel.
The Rod is a stick that is made of chrome. It is connected to the piston. The Rod pokes out to do the work. The Rod is really important because it helps the piston do its job. The piston and The Rod work together to get things done.
The Fluid is usually oil. This is because oil does not rust the metal and the fluid handles heat well. The fluid, which is usually oil is a choice, for this.
This is a push-pull dance. When the rod needs to be extended a pump pushes pressurized oil behind the piston. The rod then comes out fast. To make the rod go in the valves switch. Oil is pumped into the front of the piston. This pushes the piston back down. The rod goes in because of this.
The whole thing works like a dance, between the pump and the valves and the piston and the rod. The pump pushes the oil and the valves switch and the piston moves and the rod comes out or goes in. This is what makes the rod extend and retract. The rod extends when the pump pushes the oil behind the piston. The rod retracts when the valves switch and the oil is pumped into the front of the piston.
Simple. Elegant. Absurdly powerful.
The Muscle Everywhere
When you figure out what to look for you will always notice the things you are looking for. The things you are looking for will be right, in front of you. You will see them everywhere. You can not ignore the things you are looking for once you know what they are.
Hydraulic cylinders are everywhere. Look at that dump truck tipping its load. It has a cylinder. The flaps on the wing of the 737 you flew in on those are hydraulics too. The big rudder on a container ship that is battling the Atlantic that is hydraulics well. Even your office chair has a hydraulic cylinder that is filled with gas, which lets you adjust the height of the chair. Hydraulic cylinders are really around us even in things, like your office chair.
These machines are the reason we can build tall buildings and dig tunnels for subways. Electric motors are good, for making things spin around like car wheels or ceiling fans. When you need to move something that weighs a lot like a million pounds, just a little bit then pressurized oil is the best way to do it. Pressurized oil is the best because it can push hard.
The Leak in the System
These machines are not perfect though. I have interviewed operators who really hate these machines. Why do they hate these machines? These machines leak. The seals on these machines wear out. The hoses on these machines burst.. When a hydraulic line on one of these machines blows on a hot engine it is like a flamethrower.. These machines are very heavy and they require a lot of other things, like pumps and reservoirs and filters.
The tech world is trying to get rid of the cylinder. We are seeing actuators, which are basically fancy electric screws trying to replace the hydraulic cylinder. Elon Musk wants his robots and his cars to be fully electric without any messy fluids, like the cylinder has. The hydraulic cylinder is being pushed out by these electromechanical actuators.
The thing is the physics are being really stubborn now. When you use actuators they can really mess up the gears if something hits them hard. What about hydraulics? The fluid in hydraulics is, like a cushion. It helps take the hit.
The Smart Muscle
The future is not about doing with cylinders it is about making cylinders smarter. I have seen the cylinders at trade shows and they are really smart. These cylinders have sensors inside the steel that tell the computer the exact position of the piston, which is very precise. The sensors can also feel the load on the cylinders. The cylinders can even predict when a seal is going to fail. This happens before any oil leaks out. The future of cylinders is, about making them smarter and these smart cylinders are a big part of that.
We are taking muscles and turning them into precision instruments. This is a change, for the muscles they are becoming very precise. The muscles are now precision instruments, which’s really something.
Time you walk by a construction site do not pay attention to the loud noise and the dirty smoke from the diesel machines. Look for the shiny metal part of the cylinder rod instead. Watch how it moves out. That is the power of the age making the world a better place, one small step at a time, with the cylinder rod the cylinder rod is really making it happen.
Will we ever find something stronger? Maybe. But until we rewrite the laws of physics, fluid wins.
