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Meccanismi composti
_2xx Macchine da guerra
In Codex Madrid I, Leonardo has drawn and studied a very large number of mechanisms to produce various kind of motion, often without any specific purpose in mind, simply to explore the possibilities of mechanical science.These are composites or developments of simple machines, or different ways of obtaining the same result. There are over a hundred in just the first 12 pages.
 
"Unequal" motion ~ Codex Madrid I, f. 0v
 

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    Leonardo starts the codex with this mechanism, whose purpose is to achieve non-linear, “dis-equal” motion along the axis. The motion is obtained by using the handle to turn the main wheel, which is connected to the rod. The end of the rod engages the irregular outer rim of the wheel and slides around it, following the shape. Since it is fixed at three points so that it can only move horizontally, it follows that the horizontal motion is programmed by the irregular shape of the wheel.


Rod transmission ~ Codex Madrid I, f.1r

 

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      When he used a straight “connector” between two discs to transmit motion, Leonardo met with a transmission problem: the mechanism gets caught when the disc is turned. So he added two small rollers in the center connecting with the center of the rod and improve transmission of the movement it creates, resulting in contrary motion. In the last system, with three in-line discs, motion is transmitted in the same direction to all three discs without any problem (except for a slight pause in the straight position, which is overcome by the lack of movement).

Alternating motion using a handle ~ Codex Madrid I, f. 2r

 

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Leonardo called the effect of these two machines “contrary friction”. The first, operated by the handle, makes use of the movement of a large toothed wheel with pegs arranged in groups on the flat surface. These groups of pegs engage alternately with, first, the small cylinder at the top and then with the one at the bottom. The two cylinders then transmit the reciprocating motion to the toothed, 3-sided curved part (lunula), which makes the notched bar slide first one way, then the other.

The second idea is simpler: the handle turns two toothed semi-circles and these engage alternately with the pegs on the two adjacent bars. The two bars are linked by a cord passed around the cylinder, which returns them to their original position, at the same time receiving reciprocating motion from them.


Spring with helical transmission ~ Codex Madrid I, f. 4r
 

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  On the fourth page of the manuscript we find the first spring-driven motor. Leonardo writes that the spring is inside the bottom drum and that from now on we are to assume the spring is there each time it is needed. This mechanism is based on the assumption that a wound spring releases maximum energy at the beginning, which becomes gradually weaker as the spring runs down. The aim is therefore to turn this diminishing energy into a constant, linear force. The fully wound spring is connected to the central pin and pushes the drum in a clockwise direction. At the same time, the small cylinder sets off from point and is obliged to follow the line of the helical (spiral) gear. However, as the cylinder is fixed to the axis, it only moves in one direction as it travels toward the center and turns the axle with the square profile. Leonardo is aware of the geometrical and mechanical problems the cylinder will meet as it nears the center and he also suggests that the teeth at the end of the spiral should be further apart than those at the beginning. The axle then transmits motion to the large vertical wheel at the side.

Polishing motion ~ Codex Madrid I, f. 2v
 

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      This mechanism gives rise to two composite movements. Moving the handle rotates the two rods. The upper rod, which passes through the hole, transmits anti-clockwise rotary motion over the base. At the same time, the lower rod transmits rotary motion to the second rod, which converts it into direct reciprocating motion by means of the joint and the pulley beneath the base. The result is the complex movement of the end of the rod, which could be used, for example, to polish flat mirrors.

Alternating rotary motion~ Codex Madrid I, f. 11v
 

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      This mechanism is powered by a handle, which puts the large toothed wheel into rotary motion via a cage transmission. The large wheel shows 16 teeth arranged around only one half of the circumference. This makes the system engage first with the cylinder on the right and then the one on the left. The cylinders on the outside are linked to two discs or upper gears which thus receive alternating rotary motion. Given the number of teeth Leonardo indicates (8-16), one disc should stay still while the other completes two rotations; then the first disc will rotate while the other stays still, and so on.

Reciprocating motion with blades and split lever ~ Codex Madrid I, f. 7r

 

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On page 7r, Leonardo sets out the rule on the number of teeth in a gear. He also portrays two machines to create reciprocating motion. The first, moved by the handle, turns a wheel with 5 pegs or teeth that move alternately above and below two blades connected to a vertical rod. The rod with the blades moves alternately, moving the horizontal rod by reciprocating motion. The second machine shows two large wheels moved by a handle. Each wheel has 9 long pegs staggered against those on the opposite wheel so that they engage and push the split lever alternately, making it move from side to side. Finally, the mechanism pushes the upper rod with reciprocating direct motion.


Pre-programmed motion along a track ~ Codex Madrid I, f. 8r
 
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These two systems include a remarkable innovation: a wavy line is carved into a large wheel, making a track that can be “programmed” as desired. One or more pointed rods fixed to a pivot are inserted into the groove so that the pivot has to follow the track when the wheel is turned. In this way, oscillating motion is produced which can also be programmed by altering how the wheel turns. In the first example, the symmetrical twin tracks could be used to operate a pair of shears held in position by a block above the wheel. In the second, the mechanism is a blade like the ones used in clocks, but Leonardo says it is quieter.


Gravitational gyroscope ~ Codex Madrid I, f. 13v

 

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This system of rings enables the inner hemisphere to keep its original position independently of its rotation. Two ring pivots fix the three outer rings to each other as they rotate, with a 90° displacement between each pair of rings. In this way, the inner system can move freely on three axes (X, Y, Z). The weight beneath the rotational axis keeps the inner hemisphere horizontal. The same system had always been used on ships to hold oil lamps steady in spite of the pitching caused by waves.


Self-blocking spring ~ Codex Madrid I, f. 13v
 

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Inside the cylinder there is a spring that moves the toothed wheel below. On top, there is a metal arch with a castor that runs and rests on the upper surface of the cylinder, which has a step in it. The metal arch keeps the castor under pressure. In this way, the mechanism can only turn in one direction, because if it turned the other way it would be blocked by the castor bumping into the step.


Progressive spring-loading ~ Codex Madrid I, f. 14r
 

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This complex gear system makes maximum use of the energy produced by a spring. The tightened spring is hidden inside the container. When the stop lever is released, the spring begins to turn the helical (spiral) gear, which makes use of the initial strong energy from the spring to rotate briefly. As the gear rotates, it automatically moves down the screw, increasing its pace as it descends. In this way, full use is made of even the spring’s slight residual energy. The helical gear turns the cylinder and thus the upper wheel. At the same time, the lower mechanism enables the spring-blocking device to move slowly and gradually to the right. The handle is used to rewind the spring by hand.


Out of phase spring-powered motor ~ Codex Madrid I, f. 16r
 

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The tightened spring is hidden inside the container; its center of rotation is the axle. Winding is therefore decentralized and will cause the drum to move in an odd, but useful, way. In fact, a toothed spiral is placed on the drum which rises as it becomes further away from the axle. As it rotates, this spiral gear engages the upper conical cylinder which is fixed between points n and h. The cylinder is a conical cage-wheel gear. The narrow radius makes use of the initial energy from the spring, while the wide radius at the end exploits the residual energy. The cylinder is connected directly to the final wheel.


Segmented reciprocating motion ~ Codex Madrid I, f. 21r
 

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Leonardo tried to improve the system of reciprocating motion because it had gear problems. Here he suggests making the main mechanism by using a quarter-circle (45° segment). The handle turns the wheel which has 32 teeth arranged on only half its circumference. The teeth engage alternately first segment, which makes disc rotate, completing four turns. At the next stage, wheel, which continues turning in the same direction, engages segment which, in the same way as above, makes disc rotate four times. Interestingly, Leonardo uses a bell which is shaken when segment reaches the end of its course and rings while segment is turning.


Belt transmission ~ Codex Madrid I, f. 23r
 

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In this system, transmission of the manually driven reciprocating motion to a bell that rings is made by means of cloth or leather belts. Leonardo suggests using belt transmission to avoid the noise of the gears. In the second mechanism the reciprocating motion is supplied by the double-headed toothed “axe” which engages alternately with the cylinders. The “axe” is operated manually by the rod.


Movement along a pre-programmed course ~ Codex Madrid I, f. 24r
 

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By turning wheel, the cogwheel moves the little disc, which can only move along the straight groove. If it is fixed or the assembly is stood on end, gravity will make it follow the same pre-programmed path back and forth. On wheel there is a groove in the shape of a double spiral. In this case, a spool is inserted in the groove. When the wheel turns, the spool is fixed so that it can only move in one direction, thus it has to follow the pre-programmed course; because it is lens-shaped it can even negotiate the points where the tracks cross. By altering the shape of the groove, it is possible to program the movement in the desired direction.


Reciprocating direct motion with belt transmission ~ Codex Madrid I, f. 30v
 

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The system is operated by the handle which transmits motion to the wheel via an endless screw. The wheel always turns counterclockwise. Wheel R1 has 12 teeth arranged only at the front, with the result that the sequence is divided into two movements. First the wheel engages the bottom cylinder, which pushes the belt and makes it move clockwise. Then, alternately at each turn of wheel R1, the top cylinder is also engaged and this makes the belt move counterclockwise. So the belt moves forward and backward alternately, carrying along the iron rod attached to it. Leonardo suggests that the handle should not be turned too quickly, otherwise the gears jump out of place.


Spring-powered helical motor~ Codex Madrid I, f. 45r
 

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This spring-powered motor is a development of two motors on pages 4r and 16r. The spring, which this time Leonardo states must be of tempered steel, supplies rotary movement to the whole of the central block. In this way, the cylinder, which is fixed to run only vertically between the central axle and the lateral axle, is pushed and made to rotate over the toothed “spiral staircase”. The teeth of the cage gear support and engage the teeth on the outside of the spiral, whereas point C rests on the smooth inner part of the spiral. In two and a half turns this system makes (the others only allowed one turn), the cylinder which is connected to a large wheel with a ring gear not only to rotate, but move upwards, engaging the top disc. The gear turns and slides on the grooved cylinder. To illustrate the mechanism clearly, Leonardo has also shown a section through the central motor.


Examination of the connecting rod ~ Codex Madrid I, f. 86r
 

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Very often Leonardo examines the mechanisms and suggests various experiments with minor modifications in order to find better solutions. In this case, for example, he analyzes the efficiency of the rod-and-handle system, suggesting two types of connecting rods (which he calls “la mezana”), one short and one long. He then suggests using an extremely long rod, which has a smoother movement, instead of a short one that may even hamper it.


Flywheels with handles~ Codex Madrid I, f. 86r
 

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To operate a flywheel, an inverse rod-and-handle system is used, and this later became the principal mechanism of the steam engine. In this case, to increase speed, Leonardo suggests doubling, tripling and quadrupling the handle assemblies. In the system with four handles set around the flywheel, he adds two rotating discs that indicate a use for the extra energy obtained. The system with four rods is mechanically similar to modern engines with 4-pistons connected to four rods that turn the axle.


Multiple pulleys ~ Codex Madrid I, f. 87 e 88r


 

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A pulley can also be used to move gears, not just to lift weights. In addition, there are countless possible ways of combining different types of motion and the length of the rope allows the movement to be transmitted over a very long distance. The friction and noise produced by gears are also eliminated. It is possible to obtain rotation in any direction, depending on the way the rope is arranged and the inclination of the pulley. What is essential is that the rope must be turned around at least half of the pulley wheel so that the friction will engage it. These systems are the basis for the robot soldier.


“Wheels with no teeth” ~ Codex Madrid I, f. 97v


 

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In experimenting with the use of pulleys, Leonardo also suggests methods to test his theories. In this case, there are five pairs of weights, each pair connected by a rope and pulleys. The rope for each pair (A, B, C, D and E) passes by way of the central, rotating pillar and, in descending order, each rope is given one more half-turn around the pillar than the previous one. The aim is to understand how far the friction from the pulleys can move the weights as the rope is pulled. In fact, the Codex Madrid is also full of ideas on statics and geometry explained by means of mechanical experiments.


Diamond tipped drill ~ Codex Madrid I, f. 119v


 

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Leonardo also studied tools for making his machines. In this case, he suggests a drill with a diamond-tipped bit, which could be used to make holes in any kind of material. The power comes from a large, handle-operated flywheel whose inertia keeps the system turning. The flywheel makes the drill cylinder rotate. A large ball of lead sits on top of the drill to exert pressure on the piece being drilled. The diamond tip must be cooled with water - exactly the same process used in today’s industry.


Polishing mechanism ~ Codex Madrid I, f. 119v


 

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This is one of the many mechanisms which can be considered a machine in itself, because we can see its use. In fact, other than the simple machines and composite mechanisms, Madrid I includes suggestions for several machines that are almost complete and ready to work. In this case, Leonardo studies a mechanism for polishing stone or mirrors. In the first system, the handle engages the axle underneath, rotating the plate which holds the mirror to be polished. At the same time, the handle moves a system of connecting rods which supplies rectilinear reciprocating motion to the polishing stone. The stone rests directly on the mirror and runs between four vertical rollers. In the second system, the handle engages the wheel directly and at the same time makes the system of three rods joined at point X move backwards and forwards.

             
_Leonardo's machines
 
- Page of simple machines
- Page of meccanismi composti

- Page of flying machines and studies on flight
- Page of war machines
- Page of machines for use with and on water
- Page of industrial and building machines
- Page of theatrical machines
- Page of musical machines
- Page of miscellaneous machines
- Page of geometrical studies

- Page of machines designed by other Renaissance engineers
 
   
 
 

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