Wednesday, September 10, 2008

The Actual Load Cell

Finally we were able to assemble the actual load cell to the aluminum channel section part that I'm calling the pedal platform, and set all the load cell actuation pieces in place.

The right-hand end of the load cell in these photos is bolted to the pedal platform by two metric bolts that go through holes from the bottom side and into the load cell, which is tapped with metric threads from the factory.

To the other end of the load cell we've bolted a part we made. This is just a flat piece of steel bar stock that is slotted to accept the load cell actuator fulcrum.

The fulcrum projects upwards and the plastic knob, whose stud screws into the fulcrum, clamps the fulcrum to the horizontal section of the load cell actuator. So when you push on the pedal, the pushrod will move to the left (in these photos), rotating the actuator counter-clockwise, and putting upward pressure on the fulcrum.

This will lift the left end of the load cell, which will cry uncle and send a resistence change through its wires to the load cell controller (which has yet to make an appearance in this blog). The controller will notice this change and produce numbers which will, in turn, be sent via USB to the racing sim to let it know you are pressing on the brake - and precisely how hard.

We still need to drill the holes in the steel U-bracket that will accept the actuator's pivot bolt, and also we need to drill holes in the U-bracket and the aluminum channel that will allow us to bolt the two together.

We put these off till last because the size of the fulcrum and load cell and the actuator all dictate where the pivot holes have to be.

At the moment we're debating whether to cut down the top of the fulcrum a little, which will allow us to lower the actuator so the pushrod will end up being more nearly parallel to the top surface of the pedal platform. (See the top photo in this post for the actual position of the actuator and fulcrum once everything's assembled.)

This is just a question of aesthetics, but, hey, aesthetics are important, right?

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