Hydraulic System: Testing and Inspection

Hydraulic Brake Actuation - Escape Hybrid

Principles of Operation

WARNING: Use of any other than approved DOT 3 motor vehicle brake fluid will cause permanent damage to brake components and will render the brakes inoperative. Failure to follow these instructions may result in personal injury.

WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes with running water for 15 minutes. Get medical attention if irritation persists. If taken internally, drink water and induce vomiting. Get medical attention immediately. Failure to follow these instructions may result in personal injury.

CAUTION: Brake fluid is harmful to painted and plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.

CAUTION: Blistering or swelling of rubber brake components may indicate contamination of the brake fluid by a petroleum based substance. New rubber components must be installed in the hydraulic system if contaminated and the entire hydraulic brake system must be flushed with clean brake fluid to prevent recontamination.

CAUTION: Never use copper tubing. It is subject to fatigue, cracking and corrosion, which could result in brake tube failure.

Regenerative Braking System
Instead of just using the brakes to stop the vehicle, the electric motor that drives the Escape Hybrid can also slow the vehicle. In this mode, the electric motor acts as a generator and charges the batteries while the car is slowing down. To achieve this, the anti-lock brake system (ABS) module calculates the amount of speed reduction requested by the driver through the accelerator pedal position and brake pedal travel sensor. The ABS module measures the inertia of the vehicle through the longitudinal accelerometer and determines if the required deceleration has been achieved. During deceleration/braking, the powertrain control module (PCM) partially engages the electronically controlled continuously variable transaxle (ECVT) to be turned by the vehicle wheels and slow it down. The ABS module requests the amount of powertrain braking more or less dependant upon the driver request through the pedals. If the desired deceleration is not achieved through regenerative braking, the ABS module applies the friction brake pads to accommodate the driver request. The driver does not, under normal circumstances, have direct control over the amount of brake pressure that is applied to the rotors. In the event that the ABS module detects a fault which requires the deactivation of this system, the ABS module relinquishes control of braking and the driver still has the use of the manual hydraulic brakes.

Since the regenerative braking uses the electric motor to slow the vehicle front wheels, front brake pad wear is reduced. The rear brake pads, because of the regenerative braking, will wear at approximately twice the rate of the front brake pads.