Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
harness [ˈhɑːnɪs] n (for horse) у́пряжь f (for child) постро́мки*fpl (safety harness) привязны́е ремни́ mpl
vt (horse, dog) запряга́ть (запря́чь*perf) (resources, energy etc) обу́здывать (обузда́ть perf)
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.