FSGP 2017 Regulations

7.6 Parking Brake

Solar cars must be equipped with a parking brake.

7.6.A

The parking brake shall be able to hold the car in place without wheel chocks on dry pavement under either a forward or rearward force equal to 10% of the cars weight in driving configuration with properly ballasted driver.

7.6.B

This brake must operate completely independently from the main braking system and may not be used in the performance tests specified in Reg. 7.9.D.

7.6.C

It must be able to be locked into the “ON” position, such that the driver does not have to continue to hold it to maintain position. The driver shall be able to lock the parking brake while seated in the normal driving position and seat belted in.

7.6.D

The parking brake shall not be of a tire or wheel contact style (i.e. pad on tire or pad on rim styles are not considered as acceptable designs).

Parking Brake Specs

Assumptions

-5/32" disc thickness (3.9mm)

-8" rotor diameter

550kg total car mass (including ballasted driver & passenger)

Requirements

ASC:

Hold 10% of cars weight in fully loaded position on dry pavement

WSC:

Hold car on a 20% incline or decline (approx. 11.3 degrees)

Calculations

ASC

Braking Force = Pulling Force - Friction Force

= (0.1)(9.81N/kg)(550kg)

= 539.55N

WSC

Braking Force = mgsin(θ)

=(9.81N/kg)(550kg)sin(11.3)

=1057.22N

Required braking force is driven by WSC requirements.

Performance data for Tolomatic Mechanical Brakes. Static torque data is to be used.

Braking radius for an 8" disc = 3.376" = 0.08575m

Braking Torque = (Braking radius + wheel radius)(Braking Force) = (0.18738m)(1057.22N) = 198.1Nm

Since there are two parking brakes, torque required per brake = (198.1Nm)/2 = 99.05Nm

Maximum static torque for ME10 is 226Nm. If we order a 3.5" lever, will need between 75-100lbs of lever force.

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