I am not sure about the first example. I agree with patinba that "tacos" seems like a better fit there, as here, for example:

"Rampa móvil [...] se constituye a partir de una plancha de fibra de carbono de escaso espesor, dotada inferiormente y en proximidad a su borde posterior de unos tacos o elementos de apoyo sobre el propio suelo"
http://patentados.com/patente/rampa-movil.1/

However, even if "tacto" is a typo in that case it doesn't seem likely that it's a typo in all cases, and in the second and third the standard meaning of "tacto" in automobile manufacturing seems to fit. That meaning is explained here:

"La línea de montaje se divide en tramos iguales (tactos) en los que deben concluirse las tareas encomendadas por uno o varios operarios asignados a dichos tactos."
http://www.minetur.gob.es/industria/observatorios/SectorAuto...

Here's a business studies dissertation on automobile production which makes it pretty clear:

"El montaje de las ruedas se realiza al inicio del cuarto tramo. Hay tres tactos reservados para el montaje de las ruedas, el 157, 158 y 159."
There's an illustration to go with this (Fig. 2.2, p. 9, p. 17 of file) showing the "tactos", which are sections of the production line.
"En el primer tacto, 157, dos operarios, uno por cada lado del vehículo, tienen que colocar la rueda en su posición con ayuda de un manipulador [...] En el siguiente tacto, 158, el tercer operario coloca los tornillos restantes en todas las ruedas."
See also p. 16 (p. 24 of file) for another illustration of the "tactos".
http://invenio2.unizar.es/record/5738/files/TAZ-PFC-2011-170...

Another reference, compatible with these:

"Es cierto que se van rotando los tactos, pero no deja de ser un trabajo super monótono"
http://m.forocoches.com/foro/showthread.php?t=3611910&page=2

These are called "stations" in English:

"Equally spaced surface sections, which are travelled per cycle, can be calculated for uniform cycle lengths. These are called stations. The length of a station depends on cycle and cycle speed. The depth of a station depends on the product to be produced (engine, axle, passenger car body, etc.). The arrangement into stations has organizational reasons in that it facilitates the assignment of human resources, materials, resources, etc. on the line into sections."
Advanced Manufacturing and Sustainable Logistics, 411
https://books.google.es/books?id=eEJuCQAAQBAJ&pg=PA411&lpg=P...

"Stock control is operated on a ‘pull’ system (where stock control is based on production needs) and there is a 45-minute takt time – the cycle time before each unit moves to the next station. Two idle stations allow for an increase in production numbers at short notice.
13 assembly stations
The cylinder heads are assembled and set up on a discrete six-point line to one side of the hall, while the main line of 10 stations is positioned in the centre of the hall. There are also two sub-assembly stations, making a total of 13 in all."
http://mp4-12c.over-blog.com/article-new-engine-new-assembly...