What does "trailing" mean?

Trailing: a. & vb. n. from Trail. Trailing arbutus. (Bot.) See under Arbutus. -- Trailing spring, a spring fixed in the axle box of the trailing wheels of a locomotive engine, and so placed as to assist in deadening any shock which may occur. Weale. -- Trailing wheel, a hind wheel of a locomotive when it is not a driving wheel; also, one of the hind wheels of a carriage.