Commercial Driver's License

Answer: D - On commercial vehicles that use hydraulic brakes (which are NOT the same as air brake systems), brake failure usually occurs because of poor maintenance, loss of hydraulic pressure or brake fade during downgrade driving. All of these conditions are preventable. Hydraulic brakes require periodic maintenance and drivers should ensure that this maintenance is being performed. Maintenance will often reveal potential problems with the pressure system that can be corrected before they become serious. Avoid "riding" the brakes on downgrades to prevent brake fade.