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62 Masterpiece 2 • The Learning Brick Sorter

Arm Step 9

The dual perpendicular joiner is
used to guide the pneumatic
tubes that transfer air to the
small piston.

The Valve

The Valve sub-assembly is a motorized valve switch.As the RCX can control only elec-
tric devices (like motors and lamps), we need an interface to make it able to control the
pneumatic pistons of the Arm sub-assembly.This Valve sub-assembly couples an electric
motor with a pneumatic switch, thus allowing the program to transform the airflow into
short electric impulses to the motor.You will need to create two of these sub-assemblies,
one to control the small pneumatic piston that operates the hand, and another to control
the large pneumatic pistons that raise and lower the arm.