2024-01-03 Meeting Notes

Owned by Jonathan Xie
Last updated: Jan 07, 2024
4 min read

Things to talk about

  • samson’s brake pedal

    • potentiometer adding

    • design review

    • (dwg)

  • RSU sims

  • RSU caliper mount dwg

    • no dwg needed, can export dxf

  • FSU caliper mount design review

    • (dwg)

  • parking brake mount design review

    • (dwg)

 

 

Fasteners Discussion

 

ASC says:

  • mismatch in bolt and nut grade does not batter as long as both individually meet requirement (Grade 5, Class 8.8)

  • must have two FULL threads protruding out the end of the nut

    • iusually last 1 or 2 threads are tapered a bit, so those don’t count

    • (so add extra leeway for bolt length)

  • OTS parts (e.g. caliper) CAN be modified (shaved, etc) so long as structural integrity is maintained

  • factory-installed bolts on calipers are allowed to be taken apart, if properly re-installed with a flexloc nut

  • No shaving nuts

  • Shaving bolts ????

  • Caliper mounting bolts:  do not need to be secured

Flexlocs:

  • low profile flexlocs exist, datasheet here

  • jon sent email, no response yet, will ask for quote

  • FOR ALL shoulder bolts, use low-profile flex-loc

  • for static connections, use regular or low-profile (depending on price)

Questions to ask maybe still:

  • Can you shave/cut/modify bolts

    • front-most clevises on chassis might require it

  • Matt check regs, if not jon email

Action items:

  • parking caliper: take apart factory bolts, align slots, and replace with M10 locknut + bolt pairing

Brake Design Review

How to read input:

  • rotary potentiometer

  • limit switch

  • brake fluid pressure sensor

  • rotary encoder w spring ('tape measure')

 

Problem with displacement-based sensors is distance from rotating axis:

  • (sensor travel range) = (sensor distance to pivot point) * 30mm/4mm

Potentiometer

  • no space doesnt work with design

 

Limit Switch

  • limit switch is much simpler mechanically & electrically, would be preferred

for example, this is a good limit switch

 

 

 

‘Tape Measure’

Force-variable resistor

Hydraulic Sensor

Design Concerns

 

To-do: @Samson Wong

  • find a limit switch that works within mechanical parameters defined, which are:

    • Limit switch actuator must displace 2.5mm in order to count as ‘unactivated’

    • ^^ actuation must occur after around 4mm cylinder travel

    • screw mounting if possible, no hot glue pls

    • look thru the limit switches on digikey

  • make the pedal arbitrarily 10 degrees forward (or such that it doesn’t look stupid to press)

    • check the “Pedal Behaviour Nodal” sketch uploaded to the Github, or make ur own, to define the geometry appropriately

    • look up what a normal resting position and angular travel for a car brake pedal is

    • find the ‘absolute limit' of pedal depression using sketches in the assembly ('what is the furthest the pedal can be tilted forward such that the heel is still on the floor, but the mounting bracket at the bottom does not interfere?')

 

 

 

 

 

 

 

 

 

Parking Caliper - Pull Cable

Lokar Floor Mount Emergency Brake Cables

 

Caliper Mounts

Jens was tired so he will look at details later, but no glaring issues

@Ahnaf Shahriar will do the drawings :))))

 

Misc:

  • high strength

    • send sponsorship package

    • this could mean

      • you do another part

      • you give a grant

      • you re-consider costs a little bit

  • accelerometer pedal cad?

    • might exist somewhere, but dont hope on it

  • what is the max gauge the ESMS can bend?

    • must be at least 10 gauge or else it’ll fail sims

 

Questions for ASC: (Jon will ask….)

  • modifying bolts?

  • parking tow cable not nyloc?