2 new models, a large motorcycle and a bulldozer, as well as 6 small boxed supplementary sets and a 12 V stationary motor were released. The 12V motor, released only in Europe, was powered by the 741 transformer originally designed for the 12V Lego trains.
New elements in 1979 included the now common connector peg with axle, tread links, and the 12 V motor. The tread links were essentially a modified chain link and have appeared in only a handful of sets.
1979 US ad: 125K
Construction equipment has always been a common Technic theme and the 856 bulldozer was an good early example. The bulldozer included realistic treads running on 40t gears and a front scoop that could be raised and lowered as well as tipped forward and back via an interesting rack and gear mechanism. Although still largely based on regular bricks and plates this model signaled the beginning of more complex designs that were possible with Technic elements, particularly the use of cross axles.
874 Yellow Beams and Connector Pegs
875 Red Beams and Connector Pegs
876 Blue Beams and Connector Pegs
877 Steering Gear Parts
878 Piston Parts
879 Gear Wheels and Chain Links
880 12 V Technical Electric Motor