Obviously one can do good research without teaching unless the teaching is a variable in the research. Likewise, excellent teachers may be from within the field and therefore are good at translating the outcomes of research into an understandable format but they would not necessarily need to be in the research team.
Seems that both ends of the academia mutually enrich each other. If a teacher (lecturer) has not been involved in the advanced (or even better, cutting edge) research he/she may have difficulties in explaining what he/she has read from the articles and monographs and some mistakes and misinterpretations may creep in. Thus, research improves teaching by making it more adequate and informed. (And better able to add that flavor what a textbook text's abstract words may mis or inadvertently invite misinterpretation.) On the other hand, because a techer has to explain things explicitly to students and also because they get feedback from the auditorium or the tutorial group, he/she may better formulate things also for him(her)self and, as a corollary, the written up research in articles becomes better understandable. The main problem seems to be that teaching may "steal" too much precious time from research (with research becoming possibly less deep and concentrated) as well as research may take too much time away from preparing each lecture thoroughly and constantly updating your lecture materials. So I think that the academic research community should include all three types of academics -- (1) those more involved in research, (2) the ones more engaged in teaching, (3) the "Buridan-donkey" academics oscillating bewteen the two poles with an equal share between them. Collectively, this is a win-win situation although personally it is quite often frustrating. (Kurt Lewin's school nicely described an approach-approach conflict in one's field of behavior :-).) But, and this is important, no teacher should be allowed to teach in university who has not had at least some minimally necessary amount of research experience and who keeps visiting the lab at least occasionally.
I am 100% agree with Prof. Bachmann. But problem is that availability of jobs in academic-less research institute or high profile academic universities is a very serious issue, specially in 3rd word countries. Most of researchers have to do jobs in undergraduate environment, where very little research facilities and non-research environment are available. I define 4th class as 4) Those who are heavily involve in teaching just to survive job and do little research with hope to get better job in future.
I also think combining combining research with teaching ii itself is tedious. In most Higher Education institution, there are dedicated researcher whose responsibility is to research. However, it has become a prerequisite that lecturers who teach must also research. With my experience, research gives you the knowledge and teaching what you've research gives you the experience.
Hence: Research + Teaching = Knowledge/Experience.
Both of these are complementary and supplementary to one another. Research should always be simple to communicate. The researcher should communicate the research in the form of teachings (Form can be any) .
On the other hand, if a teacher who is a researcher can enhance the impact of teaching manifold by including research as a pedagogy tool.