Disclaimer: The tools and calculators on this site are built on standard engineering textbook principles and are meant for baseline estimation and educational use only. Always seek independent professional validation before taking anything into production. Epiphany Drives doesn't assume any liability for discrepancies, mechanical issues, or accidents resulting from the use of these tools.
The tool helps evaluate/size mechanical and hydro-mechanical brakes for 2-wheel and 4-wheel drive.
Below is the theory driving these calculations.
1. Vehicle Dynamics and Load Transfer
When a vehicle decelerates, its mass resists the change in velocity due to inertia, creating a forward weight shift. Calculating this dynamic load transfer is important, as it dictates the maximum traction available at each axle before wheel lockup occurs.
The dynamic weight on the front and rear axles is calculated using the vehicle's center of gravity, wheelbase, and the required Mean Fully Developed Deceleration (MFDD). The dynamic load transfer is determined by: (Vehicle Mass * Deaccl. Rate * CG Height)/Wheelbase
For equipment pulling trailers, the static drawbar load is compounded by the trailer’s kinetic energy pushing against the towing vehicle, altering the traction limit and required brake shaft torque.
2. Actuation Kinematics and Mechanical Advantage
The total mechanical advantage of a braking system dictates the operator effort required to achieve target deceleration. The system evaluates the linkage pathway from the pedal to the brake friction surfaces.
The calculator also evaluates Actuation Build Time and Kinematic Jerk. A safe system must reach peak clamping force rapidly without inducing a jerk rate that destabilizes the vehicle.
3. Brake Torque and Sprag Risk Analysis
The core of the mechanical brake calculation relies on the dynamic actuator ratio. In self-energizing brakes (like ball-and-ramp configurations), the friction between the pads and the disc physically assists the actuation mechanism.
The required brake torque is a function of the clamping force, the effective radius, the friction coefficient, and the number of friction faces.
The Sprag Condition:
If the ramp angle is too shallow relative to the friction coefficient, the brake becomes self-locking—a catastrophic condition known as "Sprag." The calculator dynamically evaluates this to determine if the geometry is stable, grabby, unstable, or completely locked (Sprag), ensuring the denominator in the mechanical advantage equation never drops to or below zero.
4. Thermal Dynamics and Energy Dissipation
Brakes are energy conversion devices, transforming kinetic and potential energy into thermal energy. If the heat flux exceeds the material limits of the friction linings, brake fade occurs.
The total energy absorbed by the brakes includes the translational kinetic energy, rotational kinetic energy and the potential energy from gradient descents.
This energy is converted into heat over the duration of the stop. The tool outputs the Heat Flux distributed across the friction faces and the Bulk Temperature Rise, assuming a specific heat capacity and mass for the brake components. This helps evaluating if the brake housing can physically absorb and reject the thermal load of a worst-case scenario panic stop.