Anti-Lock Brake Control System (ABS)
The Anti-Lock Brake Control is featured on an autonomous mining truck that has the capability of monitoring all four-wheel speeds. The ABS also activates the primary service brake pressure to the front and rear brakes separately. The intent of this feature is to maintain stability of the truck during deceleration by preventing wheel lock and slippage.
The ABS feature looks to see if one or both wheels of a given axle are approaching lock-up. When lock-up occurs, ABS releases and reapplies the brakes. That action is intended to minimize braking distance during slippery conditions and maintain machine stability. Wheel slip is computed by looking at wheel speed as well as an estimate of how fast that point on the machine is moving. That estimate is generated by looking at machine motion measurements taken by an onboard accelerometer.
When any associated diagnostic codes or event codes are active, the ABS system will be disabled. Refer to the Troubleshooting section of this manual for more information about the active codes.
Note: Due to the implementation for autonomous trucks, this feature will only be functional while the autonomous control system is applying brakes. The feature will not be functional while an actual operator is applying the brakes.
The Brake ECM monitors the status of switches and sensors that are related with the brake system. The following specific parameters are monitored by the Brake ECM:
The Brake ECM determines the status of the accumulator pressure for the service brake by monitoring the "Service Brake Accumulator Pressure" Sensor. This sensor changes states when the pressure is low and the ECM outputs this low-pressure status to the monitoring system for display.
Secondary Brake Accumulator Pressure
The Brake ECM determines the status of the accumulator pressure for the secondary brake by monitoring the "Secondary Brake Accumulator Pressure" Sensor. This sensor changes states when the pressure is low and the ECM outputs this low-pressure status to the monitoring system for display.
The Brake ECM determines the status of the service brake pressure by monitoring the "Service Brake Pressure" Switch. This pressure switch changes states when the service brake is active and the brake lights are driven accordingly.
The Brake ECM detects the clogging of the filter for the brake actuation fluid by reading Brake Filter Bypass Switch Status. If the filter detects too high of pressure at the filter, fluid will be routed through the bypass portion of the filter. This will actuate the bypass switch input to the Brake ECM. The Brake ECM will send the status of this switch to the monitoring system for display.
The Brake ECM receives information from temperature sensors that are located at the left and right front wheels and left and right rear wheels of the truck. The Brake ECM outputs this temperature status to the monitoring system for display. The Brake ECM will alert the operator if the temperature falls outside a predetermined range.