如轆轤之聲 A Sound Like A Windlass
不多時，腹中作響，如轆轤之聲不絕。即取淨桶，連行了三五次。服了些米飲，攲倒在龍床之上。不多时，腹中作响，如辘轳之声不绝。即取净桶，连行了三五次。服了些米饮，攲倒在龙床之上。
逐句解 Line by line
Before long there was a noise in his belly, unceasing, like the sound of a well-windlass.
轆轤 is the windlass over a well, and the comparison is exact: a rope running out over a wooden drum, on and on. It is the sound of something being hauled up from a great depth, which is precisely what is happening. 中 is zhōng, within.
He called at once for the close-stool and went three or four times running.
The prescription has done exactly what Sha the monk warned it would. 行 is xíng in its medical sense, to pass through — one of the few places in this chapter where the character is not part of 行者.
He took a little rice gruel and sank down on the dragon couch.
倒 is dǎo here, to fall or collapse, not the dào of "after all" that the same character took when Pilgrim conceded the king was a worthy man.
The medicine works, and the narrator reports it with one exact comparison: a noise in the belly like a well-windlass, unceasing. A rope running out over a wooden drum, on and on. It is the sound of something being hauled up from a great depth, which is precisely what is happening.
Then the close-stool, three or four times running, a little rice gruel, and collapse onto the dragon couch. Sha the monk objected to this prescription on exactly these grounds — vomiting above and purging below — and he was right about the effect and wrong about whether it was a mistake.