Mechanical Engineering

Would you entrust the translation of a machine—whose design cost millions of euros—to someone with no engineering background? Would you risk a mistranslation causing injuries during the operation of your machinery?

The mechanical field is vast, and without the proper experience and knowledge, even the simplest mechanisms can be difficult to understand.

Consulting a dictionary, even a good one such as Routledge or Beigbeder, is of no help if you don’t know how to interpret it. Take, for example, just one word: bolt. It is a very common word, yet translating it can be quite challenging.

The entry for bolt in the Routledge English-Spanish technical dictionary contains no fewer than 11 possible Spanish translations: perno, abrazadera, pasador, cerrojo, bulón, tarugo, tornillo, pestillo, falleba, and canto doblado. In addition to this entry, there are 61 compound terms throughout the dictionary that include the word bolt—for example, hollow bolt, flexible stay bolt, coach bolt, etc.

How can one distinguish among all these options? Although the dictionary includes very useful additional information such as the applicable field (construction, automotive, mechanics, etc.), choosing the correct term requires knowing the precise meaning and nuances of each word in Spanish.

Let’s examine the main translations of the word bolt:

• Tornillo (Screw): Cylindrical threaded element with a head, usually metallic, used to fasten parts together. 

Perno (Bolt): Similar to a screw. Typically, the end of the perno is blunt (not pointed) and used with a nut. In general, perno refers to a stronger and larger fastening element than a screw. 

Still, the distinction between tornillo and perno is far from clear, and there is no consensus on their usage. An inexperienced person will always struggle to know which one to use. 

Bulón (Pin/Bolt): Rarely used in Spain (more common in Latin America). Refers to large bolts threaded only at the end. 

Abrazadera (U-bolt/Clamp): Part used to secure cylindrical elements.

Cerrojo (Bolt): Metal cylinder containing the firing and cartridge ejection components of certain light firearms.

Pestillo (Latch/Bolt): Sliding bar that locks a door.

As an industrial engineer and technical translator with 18 years of experience, I have advanced knowledge of mechanical engineering, essential for translation in this field.

© 2025 Alejandro Moreno Ramos, www.ingenierotraductor.com