Mi padre trajo un alicate pequeño porque la tuerca del somier no encajaba bien.

Trajo is the preterite form of traer (to bring) for él/ella/usted.

• Mi padre trajo... = My father brought...

The preterite is used here because it describes a completed action in the past: he brought the tool at a particular moment.

Compare:

• trajo = he brought it, a finished event
• traía = he was bringing / used to bring, more ongoing or habitual
• ha traído = he has brought, a present-perfect form; in Spain this is often used for recent past connected to the present, but here the sentence is simply narrating a past event

Also, traer is irregular in the preterite:

• yo traje
• tú trajiste
• él/ella trajo
• nosotros trajimos
• vosotros trajisteis
• ellos trajeron

Encajaba is the imperfect of encajar. Here it describes the background problem that was going on:

• la tuerca del somier no encajaba bien = the bed-frame nut wasn’t fitting properly

This sounds like an ongoing situation that explains why the father brought the tool.

If you said no encajó bien, that would sound more like a single completed attempt:

• no encajaba bien = it wasn’t fitting well / it didn’t fit properly
• no encajó bien = it didn’t fit well on that particular occasion

So the contrast is:

• trajo = main completed action
• encajaba = background situation or problem

That mix of preterite + imperfect is very common in Spanish storytelling.

Here encajar means something like:

• to fit
• to slot into place
• to line up properly

So la tuerca no encajaba bien means the nut was not fitting correctly with the part it was supposed to go onto.

Be careful: encajar can have different meanings depending on context, such as:

• to fit physically
• to make sense
• to suit
• to accept/deal with something

But in this sentence it is clearly the physical/mechanical meaning.

Because this is because, not why.

• porque = because
• por qué = why

So:

• Mi padre trajo un alicate pequeño porque... = My father brought a small pair of pliers because...

If it were a question, you would use por qué:

• ¿Por qué trajo mi padre un alicate pequeño? = Why did my father bring a small pair of pliers?

A useful quick guide:

• porque = because
• por qué = why
• el porqué = the reason
• por que = rarer combination in specific structures

Del is the contraction of de + el.

• de el somier → del somier

This contraction is mandatory in normal Spanish, except with proper names or titles in some cases.

So:

• la tuerca del somier = the nut of the bed base / bed frame

Compare:

• de la mesa = of the table
• del coche = of the car

Also note that somier is masculine, so it takes el:

• el somier

In Spain, somier usually refers to the bed base, especially the structure under the mattress. Depending on context, English translations could include:

• bed base
• bed frame
• slatted base

So la tuerca del somier is the nut belonging to that part of the bed.

This is a very Spain-specific household word, so learners often notice it because it is less common in basic textbook Spanish.

Spanish normally uses a possessive adjective directly before close family nouns:

• mi padre = my father
• mi madre = my mother
• mi hermano = my brother

You do not say el mi padre in standard modern Spanish.

Could you say el padre? Yes, but that usually means the father, not specifically my father, unless context makes it obvious.

So here mi padre is the normal and natural choice.

In Spanish, adjectives often come after the noun:

• un alicate pequeño = a small pair of pliers / a small tool
• una casa grande = a big house
• un coche rojo = a red car

That is the default position for many descriptive adjectives.

If an adjective goes before the noun, it often adds a more subjective, stylistic, or emphatic nuance. For plain physical description, after the noun is the most natural choice.

So un alicate pequeño is exactly what you would expect for a straightforward description of size.

That is a very good question. In real usage, many speakers—especially in Spain—very often say alicates in the plural when referring to the tool as a whole, much like English pliers.

So you may hear:

• unos alicates pequeños

However, alicate in the singular also exists and is understood. In a learning sentence, un alicate pequeño is grammatically possible, even if unos alicates pequeños may sound more idiomatic to many native speakers in everyday speech.

So the key point is:

• alicate = possible singular form
• alicates = very common everyday way to refer to the tool

If you want to sound especially natural in many Spain contexts, unos alicates is often a safe choice.

Because tuerca is a feminine noun:

• la tuerca = the nut

Its grammatical gender is something you generally have to learn with the word. There is no guarantee from the meaning alone.

In hardware vocabulary, compare:

• la tuerca = the nut
• el tornillo = the screw
• el perno = the bolt/pin
• la arandela = the washer

So the article la is simply the correct article for tuerca.

No negates the verb:

• encajaba bien = it was fitting well
• no encajaba bien = it was not fitting well

In Spanish, the basic negation pattern is very simple:

• no + verb

Examples:

• No funciona = It doesn’t work
• No vino = He didn’t come
• No encajaba bien = It wasn’t fitting properly

So here no is directly attached to the verb phrase.

Bien means well here, but in this context a more natural English sense is:

• properly
• correctly

So:

• encajaba = was fitting
• encajaba bien = was fitting properly
• no encajaba bien = was not fitting properly

Without bien, the sentence would still work:

• la tuerca del somier no encajaba

But bien makes the problem more specific: it was not fitting correctly, not just failing in some vague way.

Yes, but the original order is the most neutral and natural.

Original:

• Mi padre trajo un alicate pequeño porque la tuerca del somier no encajaba bien.

You could change the order for emphasis:

• Porque la tuerca del somier no encajaba bien, mi padre trajo un alicate pequeño.

This is still correct, but it sounds a bit more deliberate or written.

Spanish word order is flexible, but not random. The original sentence follows a very common pattern:

1. subject: Mi padre
2. verb: trajo
3. object: un alicate pequeño
4. reason clause: porque...

That makes it easy and natural to process.