http://www.utexas.edu/cola/centers/lrc/eieol/gotol-6-X.html#Got06_GP26

The third strong conjugation comprises verbs whose present system generally shows the vowel i followed by a resonant (l,r,m,n) and one other consonant. The historical evolution of these verbs is shown in the chart at the link at the top of the page.

Class III Ablaut Pattern

The difference in ablaut patterns is conditioned by the consonant following the vowel. In the present, the e generally changes to i, except when followed by a non-nasal resonant. Likewise in the past plural and past participle, u generally appears, except when replaced by au [QV] before a non-nasal resonant.

The verb binda 'bind', with prinicpal parts binda -- band -- bundum -- bundans, serves to illustrate the forms of the third conjugation. The forms are as follows.

For consonant changes before the second person singular past indicative ending, see

http://www.utexas.edu/cola/centers/lrc/eieol/gotol-2-X.html#Got02_GP06_03

Sound Rules