Sentence:  we covered the rutted, rattling, dusty pot-holed roads of coastal Victoria, six big Walers in front, the cannon at the rear, and that unsprung cart they called a ‘<WSD>limber</WSD>' in the middle. 
Meaning of the word marked with <WSD> tags:  (en)  The detachable fore part of a gun carriage, consisting of two wheels, an axle, and a shaft to which the horses are attached. On top is an ammunition box upon which the cannoneers sit.