The Latin term tractĭo came to our language as traction. It is the act and consequence of pulling something to move it or make it move. In this sense, we speak of animal traction or blood traction due to the use of an animal to drag a cart, plow or other device.
Oxen, horses and donkeys are the species most used in animal traction. It is noteworthy that, in urban areas, the extraction of blood is usually prohibited because it is considered cruel to the animal. Although every day more people open their eyes to the need to respect all species equally, animal exploitation continues to be a reality throughout the world, in all large cities and rural areas. It is enough to buy a product of animal origin to participate in abuse and, as there is no country or city where only vegetable products are consumed, the solution to this great problem is far away in the chronology of our evolution.
Drawing blood is a brutal practice for many and a lack of consideration that goes beyond the limits of our tolerance: would we put our parents, brothers or friends to pull a very heavy cart? No. So why do we use animals, even those we say “love”? The answer is as simple as it is alarming: because we do not consider them equal. But can we love and despise the same being at the same time? Perhaps in this strange capacity lies the secret of our supposed superiority. For mechanics and engineering, traction is the effort to which an object is subjected when two opposing forces intervene that tend, due to their application, to lengthen or stretch it. Said stress falls within the group of internal or sectional forces, a physical quantity used to calculate prismatic parts (such as columns and beams), sheets and plates. Every force that tries to stretch a body is complemented by a normal force, that is, that force opposite to the first and whose tension, which is applied to the sections perpendicular to the parts affected by the traction, is also necessary for the phenomenon to occur. . Taking this into account, it is possible to understand that all elongation is complemented by a shrinkage: while traction causes a positive deformation in one axis, transverse ones usually compensate this change with an opposite one. In the case of a solid body, the deformation can be permanent if it exceeds its elastic limit and exhibits plastic behavior. The body is elastic if, after traction, it returns to its original length.
In the field of orthopedics, traction is a procedure that is performed with the aim of minimizing the pressure exerted on the skeleton or achieving alignment of the bones after a fracture. If we focus on motor vehicles, the mechanism that transmits the force of the movement made by an engine to the wheels is called traction. Depending on how the mechanism works, we can talk about rear-wheel drive, front-wheel drive, 4×4 drive or double-wheel drive. In rear-wheel drive, the power from the engine is transmitted to the rear axle of the vehicle. If the power is transmitted to the front axle, instead, we speak of front-wheel drive. 4×4 drive, meanwhile, affects all wheels, while two-wheel drive affects two rear axles simultaneously.
