Sentence:  While Kitto chatted to William, Jessamy looked with interest at the dog cart. It had a pair of high wooden wheels with two seats back to back above. Between the <WSD>shafts</WSD> the bay mare tossed her head and fidgeted on the cobbles. 
Meaning of the word marked with <WSD> tags:  Any long thin object, such as the handle of a tool, one of the poles between which an animal is harnessed to a vehicle, the driveshaft of a motorized vehicle with rear-wheel drive, an axle, etc.