The Antikythera mechanism is more valuable than Mona Lisa!
says professor Michael Edmunds from Cardiff University, who led a 2006 study of the mechanism!
Honestly, this is one of the most mysterious, extraordinary, fascinating & interesting machines I’ve ever seen in my life! The Antikythera mechanism is one of the most remarkable inventions of the ancient world that came to light in 1900 when a Greek Sponge diver discovered the wreck of an ancient Greek or Roman cargo ship that had sunk off the Greek island of Antikythera around 80 B.C.E!
In my previous article, we learned how 4 stroke engines work ! This time we will learn about the second type of engine i.e 2 stroke engine. The 2 stroke engine is a type of Internal combustion engine where one power cycle is completed with two strokes of the piston during only one rotation of crankshaft. The first commercial two-stroke engine involving in-cylinder compression is attributed to Scottish engineer Dugald Clerk.
The 2 stroke engine performs all the same steps which are performed by 4 stroke engine – suction, compression, expansion & exhaust; but the 2 stroke engine performs these all steps in only 2 stroke unlike the 4 stroke engine which completes one power cycle in 4 strokes. more “How does a 2 stroke engine work ?”
Seriously, what would have happen if there were no elevators & if people were to walk up & down a 50 or 100 storey building everyday in cities like NY ! I can’t even imagine the fatigue.
The name itself gives us an idea that it is invented by Archimedes. Now this man – Archimedes, was an Ancient Greek mathematician, engineer, inventor, physicist, & an astronomer(such a smartass). We are living in 21st century & still we are not able to think stuff like this on our own & this man did it in the 3rd century BC !!!!!
We already discussed one of his works – buoyancy & we sawhow do ships float ? So the Archimedean screw OR screw pump is just a simple machine consisting a cylinder & a helical surface on the inside part of cylinder. Basically, it was designed to work like a pump & it worked without any of our presently available motors which we use to run todays pumps. The screw was used mostly for draining water out of mines or other areas of low lying water.
Animation of the Archimedean screw. Let us assume that the ball is a water molecule.
Construction :- The screw pump consists of a screw or a helical structure inside a hollow pipe. The screw is turned through a handle which is outside the cylinder. As the shaft turns, the bottom end scoops up a volume of water. The water then gets pushed out up by the rotating helicoid until it pours out from the top of the tube & done just so simple.
Applications OR Uses :- Why it was made ? – the first purpose was to transfer the water from low lying region to other parts of the city. Along with transferring water to irrigation ditches, the device was also used for draining land that was underneath the sea in the Netherlands and other places in the creation of polders.
A screw conveyor :- It is an Archimedean screw contained in a tube & turned by a motor so as to deliver material from one end to other end. It is particularly used for transporting granular materials such as plastic granules used in injection molding and cereal grains.
Conveyor Screw (source :- ibis-int.co.uk)
Screw turbine :- If water is poured into the top of Archimedes’s screw, it forces the screw to rotate. The rotating shaft can then be used to drive an electric generator.
Worm gear :-
This is actually not an application of the Archimedean screw but yea it might be an inspiration to the one who designed & invented the worm-gear mechanism.It is awesome & I really love it. Remove the outer cylinder of the Archimedes’s screw, mesh a gear of proper tooth thickness with the screw & we are done. Here the screw thing is called worm. Now the reason I love it is because the worm will definitely drive the gear but the gear may or may not drive the worm depending on the design of worm.
(It’s like if you close your door/gate of your house with help of worm gear mechanism, only you would be able to open & close it from inside because only you would be able to rotate the worm. Don’t ever worry about burglars unless & until the gate/door is big enough & not made of wood ! 😛 )
The Geneva drive or Maltese cross is a gear mechanism that translates a continuous rotation into an intermittent rotary motion. The rotating drive wheel has a pin that reaches into a slot of the driven wheel advancing it by one step. The drive wheel also has a raised circular blocking disc that locks the driven wheel in position between steps. Because the mechanism needs to be well lubricated, it is often enclosed in an oil capsule.
The Geneva drive
Internal Geneva drive :- An internal Geneva drive is a variant on the design. The axis of the drive wheel of the internal drive can have a bearing only on one side. The switch time is greater than the time the driven wheel stands still. This is also a main difference between them.
Internal Geneva drive
Applications :-
What is Switzerland known for ? for its beautiful sceneries, yea… but also for its mechanical watches- Rolex, Omega, Rado. The name derives from the device’s earliest application in mechanical watches.
Also one of the application of Geneva drive is the movie projectors. These were used earlier as the film doesn’t run continuously, instead the film was advanced frame by frame, each frame standing still in front of the lens for a very short period of time. In modern projectors, stepper motors are used.
Other applications of this mechanism include automated sampling devices, banknote counting machines, CNC machines, turret lathes & turret drills.
The external form is the more common, as it can be built smaller and can withstand higher mechanical stresses.
