Sim. Racing Pedal Project #2

Introduction

After more than 2 years, my original pedals needed some maintenance work.  I wanted to replace the potentiometers with Hall effect sensors, but the pedals had developed enough mechanical "slop" in them that just adding Hall sensors wouldn't work.  So I decided to build a new set of pedals with bearings and Hall sensors for smoother operation and longer
life.

Assembly with bearing.  1 is a bolt with threads only on the end so the bearing isn't on threads. 3 and 9 are the frame rails that don't move. 8 is the pedal. 4 is a washer the size of the inner bearing (5).  6 is a washer the size of the outer part of the bearing (5)..  7 makes sure 6 is centered when assembled.   These don't move 1,2,3,4, inner 5, 9.  These move, outer 5, 6 and 8.  7 may or may not move, I don't know.

The white nylon piece and the washer are in place so the washer lines up with the outside of the bearing.

3 and 9 are the frame rails, 8 is the pedal.  The assembly between 3 and 8 (shown 2 pictures above) is duplicated between 8 and 9.

The pedal assembled with the Hall sensor and pedal stop (adjusted by the flat metal pieces) in place.  The return springs are not in place.  The pedal is in the at rest position.

The pedal is pressed down.  Note how the magnet has moved so that  it has passed its entire length by the Hall sensor.

Design

I stuck closely to my original design because there were things I liked about it and I could reuse a few parts.  Especially valuable was not having to redesign the way the pedals were mounted.  The pedals could however be mounted on a metal frame for a cleaner look.

The old pedals with their mechanical connections to the potentiometers.

Old pedals removed, Base plate holes need to be enlarged for the new pedals.

New pedals in place.  Note at top, the accelerator was moved forward for better pedal alignment with the other pedals.

The new pedals are individual units that can be removed separately and intact from the frame.  The old ones required the base plate to hold their form.  Therefore they could not be easily taken out for making repairs/changes.  The new pedals still use a back plate (on the race frame) to stop their travel when fully pressed (just like the old design) and that is also where the brake feel comes from. 

The return springs A,B and C. Note the spring size and placement for setting the feel and accounting for (but not setting) pedal travel.

The pedal travel is stopped by a very robust back plate.  The dirty white pad behind the clutch pedal is to avoid a hard hit against the wood yet to give a firm stop.  The black padding under the brake gives it a very stiff feel with not a lot of travel.  All pedal dimensions were approximated from my real car.

Main Parts

I used these Hall sensors (Allied #642-2257, Mfr #SS495A), these magnets (D6XO form K&J Magnetics, Inc.) and these bearings (R4 ZZ 1/4" x 5/8" x 0.1960" from VXB Bearings).   I do not recommend smaller magnets.  I could not get acceptable results with smaller magnets.

Flexible Design

As usual, I tried to make a design with a lot of flexibility so I could easily adjust things as they came together.  To adjust how far the pedal comes up, I adjusted the triangle formed by the top bars and the bottom frame.  To adjust how far the pedal goes down, I added blocks to the frame behind the pedals.  Pedal spacing (side to side) and forward/back
placement are set based on where the pedals are mounted on the base plate.

In order to be able to move the magnet mounting point to an ideal spot after setting pedal travel, I glued (clear) plastic tubing to (black) plastic and slid the magnet inside the plastic tubing.  If a change was needed, I could easily remake the plastic holder or drill new holes in the plastic rather than drilling multiple holes in the metal pedal shaft. To make the Hall sensors adjustable I mounted them on a long screws allowing them to be adjusted for height and closeness to the Hall sensor.

The bottom picture is the pedal at rest, the top when fully pressed.

Upcoming:

1. I need to keep my eye on these bearings. I don't know if they are robust enough for this application. Time will tell.

2. The sensor and magnet on the brake need to be moved up higher to get more travel through the full magnetic field.  I originally planned for more brake pedal travel but after trying it, I realized I liked a shorter travel.  So for now the full magnetic range isn't being covered by the Hall sensor but it still works well and translates to full range electrically when calibrated.  

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