【化】 蒸汽往复泵(锅炉进水泵)

[ noun ]
a supplementary pump available if needed
<noun.artifact>

Donkey \Don"key\ (d[o^][ng]"k[y^]), n.; pl. {Donkeys}
(d[o^][ng]"k[i^]z). [Prob. dun, in allusion to the color of
the animal + a dim. termination.]
1. An ass; or (less frequently) a mule.

2. A stupid or obstinate fellow; an ass.

{Donkey engine}, a small auxiliary engine not used for
propelling, but for pumping water into the boilers,
raising heavy weights, and like purposes.

{Donkey pump}, a steam pump for feeding boilers,
extinguishing fire, etc.; -- usually an auxiliary.

{Donkey's eye} (Bot.), the large round seed of the {Mucuna
pruriens}, a tropical leguminous plant.