What does ガッコンガッコンと mean in this sentence?


The sentence is describing a giant robot, with its giant drill stored in its
chest started to rotating, thrusting in and out violently (?)

But I don't understand what does this sfx means here, please help me to
understand its meaning. Much thanks o/

> 胸部に格納してあった巨大ドリルを回転させながら、 **ガッコンガッコンと** 前後に激しくピストン運動させる。




The basic form of this onomatopoeia is ガコン. Many people would say exactly that
it's the metallic noise a giant robot makes when it walks or moves its joints.
Others may say it's the noise of a half-broken washing machine, or the trunk
of an old car being closed violently.

You can hear many audio clips tagged with ガコン here:
<https://pixta.jp/audio/tags/%E3%82%AC%E3%82%B3%E3%83%B3>

[ガタン](https://pixta.jp/audio/tags/%E3%82%AC%E3%82%BF%E3%83%B3) refers to
almost the same type of sound, but for some reason I feel ガコン is more commonly
associated with giant robots.




The basic form of this onomatopoeia is ガコン. Many people would say exactly that
it's the metallic noise a giant robot makes when it walks or moves its joints.
Others may say it's the noise of a half-broken washing machine, or the trunk
of an old car being closed violently.

You can hear many audio clips tagged with ガコン here:
<https://pixta.jp/audio/tags/%E3%82%AC%E3%82%B3%E3%83%B3>

[ガタン](https://pixta.jp/audio/tags/%E3%82%AC%E3%82%BF%E3%83%B3) refers to
almost the same type of sound, but for some reason I feel ガコン is more commonly
associated with giant robots.

