For Class 7 and Class 8 trucks which are registered farm use vehicles, most states require the operator have a current DOT medical card.
If you have a CDL, you're required to have a current and valid medical card, period.
All classes of CDL require a DOT medical card - A, B, and C. Additionally, anyone operating a commercial vehicle with a GVWR in excess of 10,000 lbs. is required to have one, even if the vehicle doesn't require a CDL.
A medical card is required for the operation of commercial vehicles with a Gross Vehicle Weight Rating of more than 10,000 lbs. If your state requires registration of DOT medical cards, then you must do this if your job involves operating a vehicle for which a medical card must be carried by the driver, even if a CDL is not required.
You're required to have a current medical card on your person at all time when you're driving a vehicle which requires a CDL. In any state. That's federal law.
If the commercial vehicle requires a CDL to drive it, you do.
If it requires a CDL, then yes - that's federal law.
Whether it has air brakes or not has absolutely zero impact as to whether the vehicle requires a CDL. None, whatsoever. Now the Gross Vehicle Weight Rating of the vehicle will make a difference. If it's under 26,000 lbs. GVWR, a CDL is not required (if it's over 10,000 lbs. GVWR, however, a valid and current DOT medical card will be required). If it's a single vehicle over 26,000 lbs. GVWR, and is not pulling a trailer rated at more than 10,000 lbs. GVWR, a Class B CDL will be required.
You will not have your CDL revoked, but the moment your medical card expires, you're prohibited from operating a CMV (or any commercial vehicle with a GVWR of more than 10,000 lbs., for that matter) until you get a new medical card. Additionally, you won't be able to renew your CDL without a valid and current medical card.
If the vehicle doesn't require a CDL and the vehicle is registered in that state, no. If the vehicle requires a CDL, yes. Vehicles falling under exemptions such as the farm truck exemption or emergency vehicle exemption vary by state.
If used in interstate commerce, any vehicle with a Gross Vehicle Weight Rating or Gross Combination Weight Rating in excess of 10,000 lbs. requires a DOT medical card.
Yes
No.