Restriction
A limitation placed on a CDL that restricts the types of vehicles or equipment the holder may legally operate. Common restrictions include L (no air brakes) and E (no manual transmission).
Restrictions are applied when the CDL skills test was conducted in a vehicle that did not include certain features. Restrictions can often be removed by passing the appropriate additional test.
Common restrictions and what they mean
L (No air brakes): applied when the CDL skills test was conducted in a vehicle without air brakes. The driver cannot legally operate a vehicle with air brakes unless this restriction is removed. E (No manual transmission): applied when the test vehicle had an automatic transmission. Z (No full air brakes): less common, applies to specific air over hydraulic brake configurations. K (Intrastate only): limits the CDL to intrastate operations, typically applied under state-specific medical or age exemptions for drivers not meeting the federal standard.
Removing a restriction
Most restrictions are removed by retesting in a vehicle equipped with the relevant system. For the air brake restriction (L), the driver passes the air brake portion of the knowledge test and completes a skills test in an air-brake vehicle. For the manual transmission restriction (E), the skills test is repeated in a manual vehicle. Carriers regularly hire drivers specifically to help them remove the air brake restriction, which opens up most Class A trucking jobs. The process takes a single testing appointment at a state licensing office.
Last updated: June 4, 2026
When this definition matters
This term usually matters when a driver, owner-operator, or small carrier is deciding whether a federal rule applies, preparing a compliance file, or checking a state CDL step. Use this definition as a starting point, then confirm the controlling requirement in the official source listed below before making a licensing, hiring, dispatch, or recordkeeping decision.
The related terms above are included because they often appear in the same compliance workflow. Reviewing them together can prevent common mix-ups, such as treating a state licensing step as a federal carrier obligation or confusing a driver record with a separate employer record.