1980 - A New Auto Chassis
||8860 Auto Chassis
A specialized differential gear was introduced. The ring gear, which has 28 teeth, can act as either a spur gear or a crown gear due to the tooth profile (like the crown gear). This part is made to be used in conjunction with 3 of the new 14 tooth bevel gears. One bevel gear goes on each side attached to an axle, and a third acts as a planet gear and rides on a pin in the cage. The assembly acts like a real differential in every way: wheels can turn at different speeds or together, wheels turn opposite directions if the ring gear is fixed, and one wheel drives at double speed if the other is held.
The new 14 tooth bevel gears were the first gears LEGO® made which were purpose-designed to work on perpendicular axes. The gear is only 1/2 stud thick and the teeth do not have any back iron (webbing between the teeth), so it is a bit weak, but future iterations would correct this.
The shock absorber was an important step. Finally, models could have real suspension. This part was eventually used for other purposes, including holding mechanisms over center.
The shock absorber consists of a telescoping mechanism inset with a helical compression spring. The spring is quite stiff compared with the weight of parts it typically supports. The shock bottoms before the spring reaches solid height.
The new pulley is smaller than the previous, and has a nice round groove for driving belts or rubber bands. It is also only 1/2 stud thick, so it fits in smaller spaces.
The new 3x2 plate with a centered hole on one end can be used to support axles or pins, and is a way to align studded construction with Technic beam holes, which are located halfway between the studs.