The Collaborative International Dictionary of English v.0.48:
Truckle \Truc"kle\, v. t. [imp. & p. p. Truckled; p. pr. & vb. n. Truckling.] To roll or move upon truckles, or casters; to trundle. [1913 Webster]WordNet (r) 3.0 (2006):
truckling n 1: the act of obeying meanly (especially obeying in a humble manner or for unworthy reasons)