The most innovative aspect of Leonardo's contribution to technology was his analysis of the components of machines, carried out from the beginning of the 1490s onwards. He regarded the machine as the result of assembling a series of elementary devices, and it is clear that he was not only familiar with simple mechanisms (namely, the winch, lever, pulley, wedge and screw) but that he developed their function and specificity in such a way as to be able to apply them to complex machines which allowed a series of operations to be carried out automatically, through the use of various systems of motion transmission. He made an accurate classification of screws by carefully measuring their strength and identifying the number of ways in which they could be used and designed two machines for cutting them.
He also studied the cogwheel closely, paying particular attention to the profile of the teeth and carefully classifying the different types of movement produced by various combinations of cogwheels, pinwheels and sprockets. He stressed the advantages to be had from the proper use of blocks and pulleys, in particular for lifting heavy loads. Closely connected to motion transmission was his study of friction, and his solution of using bearings still holds good today. Lubricating alone is not enough to prevent wear of machine parts and Leonardo first attempted to solve the problem by shaping the axles so as to reduce friction, then with bearings made of anti-friction metal (an alloy of copper and tin), and finally with various types of ball bearings that prefigure those used today. He also suggested the use of the piston for converting rotary motion into reciprocating motion, as in the coil of the automatic winder in Madrid Codex 1.
His reflections on the function of flywheels for facilitating and regulating the movement of rotating axles are also notable. He drew up what can be regarded as an illustrated catalogue of springs and suggested their use in locks and the workings of clocks, with carefully prepared solutions for regulating the movement. He also designed a machine for making springs. His interest in cams was connected to this desire to perfect and regulate clock movement, as can be seen in his studies of pendulum and balance escapements with sinusoidal cams. He produced an illustrated catalogue of different types of chains for lifting heavy loads, as well as suggesting the use of ropes and belts for transmitting circular motion. Finally, he designed shock absorbers for flying machines, to lessen the impact on landing.