Previous Versions:

Servo Actuated Brake Lever - V.1

Built June 2006, decommissioned soon thereafter...

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This airbrake system had only 4 positions. An electrical motor moves the lever when needed. Separation of gearbox and lever (for manual operation) is done with an electromagnetic clutch.

The brake system contains 4 micro switches. These are actuated by a spring loaded steel ball, taken from a ball bearing. The steel ball moves inside a casing that is attached to the lever. The state of each micro switch is monitored by the EPIC card.

The red circle in the drawing represents the electric motor. It came with an integrated 148:1 reduction gearbox. With the different gear wheels a further RPM reduction is achieved, so that the lever - when driven by the servo - travels at roughly 30 degrees per second.

The parts used to make the lever housing. They have openings for 4 micro switches. I used sandwiched 3mm acrylic sheets, joined with 2-component glue. Same procedure for the spring housing on the lever.

All pieces joined, and the micro switches glued in.

The spring was supposed to be strong enough to produce audible clicks and tactile feedback for each lever position. What happened in reality is that it got stuck after just a few days of use. I think that I has simply underestimted the friction the steel ball would produce while being draged over the wave-shaped surface between the micro switches.

After some hard thinking I came up with Version 2. It uses a Hall sensor for analogue output and generally has a much improved design.