Engel subgroups of triangular matrices over local rings

We consider Engel subgroups of the group T(n,R) of upper triangular matrices over a local ring R which satisfies a weak commutativity condition. If, in addition, R is artinian then we give a complete description of the maximal Engel subgroups of T(n,R) up to conjugacy. These subgroups turn out to be nilpotent and we study their nilpotency class.