（よ）うとするTry to; be about to
（よ）うとする presents someone making an effort or moving toward the start of an action. With certain developing events, it can also mean that something is just about to happen.
The focus is the attempt
With an action a person can control, the construction focuses on the effort or movement toward starting. It does not by itself tell you whether the action was completed, so the result must come from the surrounding sentence.
箱を持ち上げようとして何度も力を入れ、最後には一人で持ち上げた。
I repeatedly strained to lift the box, and in the end I lifted it by myself.
AnalyzeThe target describes the effort. The final clause separately states that the attempt succeeded.
An attempt can be unsuccessful
ドアを開けようとしたが、鍵がかかっていて開かなかった。
I tried to open the door, but it was locked and would not open.
AnalyzeFailure is stated by the second half of the sentence; it is not a fixed part of the target’s meaning.
An effort in progress
ようとしている often shows that someone is currently making an effort or is at the point of beginning. The action itself may not yet be fully underway.
転んだ子どもは、泣かずに立ち上がろうとしている。
The child who fell is trying to stand up without crying.
AnalyzeThe moment just before an action
The past form commonly appears before expressions meaning “when” or “just as.” It places another event at the moment the person was moving to begin the intended action.
声をかけようとしたとき、彼女の電話が鳴った。
Just as I was about to speak to her, her phone rang.
AnalyzeThe phone call interrupts the movement toward speaking; the sentence does not say that the speaker actually spoke.
An event on the verge of happening
With natural changes and developing events such as beginning, ending, becoming, or the sun setting, the same pattern can mean “be just about to.” This use does not imply conscious effort and should not be freely extended to every uncontrollable verb.
駅に着いたとき、電車がちょうど出ようとしていた。
When I reached the station, the train was just about to leave.
AnalyzeChoosing among similar patterns
ようと思う states an intention or thought about acting, without showing that an attempt has begun. てみる means deliberately doing something as a trial to see what happens or what it is like. By contrast, ようとする can describe an effort that is interrupted before the action truly gets underway. るところだ neutrally says that someone is just about to act, while the target more strongly presents an attempt or movement toward the action.
More examples
弟は自分で靴ひもを結ぼうとしている。
My younger brother is trying to tie his shoelaces by himself.
Analyze窓を閉めようとしたら、猫が外から戻ってきた。
Just as I was about to close the window, the cat came back from outside.
Analyze私は謝ろうとしたが、緊張して声が出なかった。
I tried to apologize, but I was so nervous that I could not speak.
Analyze重い机を動かそうとしたが、二人でも動かなかった。
We tried to move the heavy desk, but it would not move even with two people.
Analyzeパスワードを入力しようとしましたが、画面が固まりました。
I tried to enter the password, but the screen froze.
Analyze赤ちゃんが自分でスプーンを使おうとしている。
The baby is trying to use a spoon without help.
Analyze