Book excerpt: Becoming a professional driver requires a lot of knowledge of the transportation industry, commercial motor vehicles, and the federal regulations which govern the operation of commercial motor vehicles. CDL Digest has created this updated study guide in an effort to provide the most current knowledge required to successfully pass the written exams required to obtain a Class A Commercial Learner’s Permit (CLP). This Class A Commercial Learner’s Permit (CLP) Study Guide covers the following required knowledge areas: General Knowledge Air Brakes Combination Vehicles Practice Test Questions Using this study guide along with the CDL manual from your State Driver Licensing Agency will provide you with the best opportunity for success when you take the required exams needed to obtain a Class A Commercial Learner’s Permit (CLP). It will also provide you with a great knowledge-based advantage that will be critical when you go through Entry Level Driver Training. Our study guides have already helped thousands of people just like you to easily pass their written exams. Our study guides are used by many of the leading driver training facilities across the country and have been praised by people just like you, who have used our study guides to successfully pass their written exams.