From:
http://www.dmv.org/il-illinois/apply-cdl.php#New-Federal-Requirements
Although the page is supposed to be pertinent to Illinois, this section appears to be generic as it mentions "many states" in the last paragraph.
Minimum Training Requirements
There are no federal standards in place for on-the-road commercial driver training. The government only requires that you take and pass your CDL knowledge (written) and skills (driving) tests. Longer-combination-vehicle (LCV) drivers must receive training in driver wellness, driver qualifications, hours of service, and whistleblower protection.
Your state's
commercial driver's manual is a good place to learn basic information, but you
will need to be professionally trained to drive a commercial motor vehicle.
In order to pass your driving skills tests, you will need to learn how to inspect vehicles before driving, learn how to couple and uncouple tractors and trailers, and have plenty of practice driving. This includes driving in different conditions and on different road surfaces, turning, parking, backing up, and braking.
Many motor carriers train their employees, while other drivers take courses at private driving schools, vocational or technical schools, and community colleges. Individual states often approve or certify training courses. The
Professional Truck Driver Institute (PTDI) has set minimum standards for training curriculums and certifies driver training courses that meet industry and
Federal Highway Administration (FHA) guidelines. Many employers require their drivers to take PTDI-approved training.
Some states may specify minimum training guidelines. Check with your state's motor vehicles department to see if there are minimum training requirements to get your CDL.