Braking, Steering and Suspension Systems
Braking
Hydraulic braking relies on Pascal's principle: pressure is transmitted equally, so force = pressure x piston area. A larger master cylinder piston increases fluid volume but reduces pressure for a given pedal force; larger wheel cylinders increase braking force. Disc brakes resist fade better than drums. Components include master cylinder, proportioning valve, ABS modulator, calipers, pads and shoes. Air in the system causes a spongy pedal; a sinking pedal suggests internal leakage. Brake fluid is hygroscopic and must be replaced periodically.
Steering
Recirculating-ball and rack-and-pinion systems convert rotary input to linear movement. Correct wheel alignment covers camber, caster, toe and steering axis inclination. Incorrect toe causes rapid tyre wear; incorrect camber causes uneven shoulder wear. Power steering faults include pump noise and fluid leaks.
Suspension
MacPherson struts, double wishbones and leaf springs locate the wheel and absorb road input. Shock absorbers damp oscillation; worn dampers cause bounce and poor tyre contact. Ball joints, bushes and wheel bearings must be checked for play.
Worked example: master cylinder area 4 cm2, wheel cylinder area 16 cm2, pedal force 200 N. Pressure = 200/4 = 50 N/cm2; wheel force = 50 x 16 = 800 N, a fourfold multiplication. Rule of thumb: check tyre pressures and alignment before condemning suspension parts.