Gear Functionality with PLAY Systems
Although the current PLAY systems do not have actual “gear” parts, but we can use the Large and Small Pulley Wheels and the Large Rubber Tires to build a Gear Train as shown below.
The Rubber Tire plays a very important role by its being "squeezed" at the contact points between adjacent Pulley Wheels, as this creates "friction" between the wheels which allows rotation motions on one wheel to be transmitted to the other wheel (but in the reverse direction).
This "Gear" functionality can be used in the construction of selected robots shown below:
4-Wheel Drive Transmission System.
Rough Terrain Vehicle.
Please see this video for more details and robot demonstrations.