Teves Mark IV System Description

The Teves Mark IV antilock brake system has several unique design features. It functions as an antilock and traction control system combined. It contains two separate fluid reservoirs, each with its own fluid level sensor.

The traction control feature is designed to operate at speeds below 25 mph (40 km/h), and can be deactivated via the traction control switch located on the instrument panel. An electronic control module is used to monitor wheel speeds and to modulate (control) hydraulic pressure in each brake channel. The hydraulic pressure is used to prevent wheel lock-up during braking, and to maintain traction at the driven wheels by reducing wheel spin.

The Teves Mark IV and Mark IVG system use a diagonal split hydraulic brake system. In the standard brake mode the master cylinder primary circuit supplies pressure to the right and left rear wheel brakes, and the secondary master cylinder circuit supplies pressure to the left front and right rear wheel brakes.

During an antilock stop the Mark IV system uses four-channel operation. This means that during antilock operation each wheel brake is independently controlled. By using separate hydraulic channels for each wheel, the system is able to retain directional stability and steering control while applying maximum braking. The system provides maximum braking even when road conditions vary.

During an antilock stop, "wheel lock-up" does not necessarily mean that the wheel has locked, it means only that the wheel is turning slower than the vehicle speed. This is called "wheel slip" and is indicated in percent. 0% slip means that the wheel is rolling free and 100% slip means that the wheel is locked. The antilock system maintains an average of approximately 20% wheel slip.

It is important to remember that the antilock brake system does not shorten the vehicle stopping distance under all driving conditions, but provides improved control of the vehicle while stopping. Vehicle stopping distance is still dependent on vehicle speed, weight, tires, road surface, and other factors.