Pedal Box

As the driver’s Controls lead for the Ryerson Formula Racing team, my responsibilities included designing and producing a pedal box system to controls functions such as throttle, braking. The regulations for the pedal box are set by the SAE to ensure driver safety.

Crucial rules to follow: the brake pedal must be able to withstand a force of 2000N. Pedals are sometimes tested by judges sitting in the driver’s seat and kicking the pedal to ensure it will not break under a real world stress.

Considering the pedal box was for a race car, two important factors are form factor and weight, as you want the front of the car to be narrow for aerodynamics and you want the vehicle to be light for faster acceleration and less inertia in corners.

The car is also meant to fit 95% of drivers out there, and adjustability to tailor to driver’s need is an advantage. So we ensures the pedals were going to be large enough to allow most drivers to use them, while ensuring accidental contact to the undesired pedal does not occur.

I chose to only have 2 pedal for throttle and brake, because we moved the clutch to be hand operated with the shifter. This would shorten cable length for the clutch, declutter the pedal box area, and allow the driver to keep one foot per pedal, a standard design choice in performance race cars such as F1.

I then designed the brake pedals, ensuring it could withstand the 2000N force while being as light as possible. Few design principles I followed was proper triangulation to avoid buckling. Hand calculations and FEA was simulated through Solidworks. The biggest challenge was ensuring proper constraints, and proper loading, as an incorrect input will yield incorrect results, voiding the complete simulation.

FOS on the main frame of the pedal box.

10 tabs, which are welded to the frame, are used to secure the pedal box to the car via 5 bolts. Majority of the stress is on the left side, as the brake pedal is on the left side.

For the simulation the tabs were fixed rigidly at points of weld.

The applied force components were calculated in the three primary vectors and applied at the points of contact.

Max displacement of the brake pedal with two different conditions of fixtures.

On the left with the bias bar and pivoting point (hinge) as a sliding surface fixture, which represents realistic working conditions.

On the right with no fixture in the bias bar and a rigid fixture at the pivot, which represents a worst case scenario.

Force was applied evenly at the top half, as that is through which the driver will apply force into the pedal.

Max displacement on the left is 8.025e-2 mm.

Max displacement on the right is 2.859e0 mm.

Minimum Factor of Safety of the brake pedal with two different conditions of fixtures.

On the left with the bias bar and pivoting point (hinge) as a sliding surface fixture, which represents realistic working conditions.

On the right with no fixture in the bias bar and a rigid fixture at the pivot, which represents a worst case scenario.

Force was applied evenly at the top half, as that is through which the driver will apply force into the pedal.

Minimum FOS on the left is 1.172e1.

Minimum FOS on the right is 1.508e0.

thin