Why are tractor heads (big trailer heads) all manual gears? Do you have an automatic transmission?

There is no automatic gear, because the tractor needs low speed and high torque when starting, and only manual gear can realize this function.

The car with driving ability in front is called tractor, and the car without driving ability in the back is called trailer, which is towed away by tractor. There are two ways to connect the tractor and trailer: the first way is that the first half of the trailer rides on the traction saddle at the back of the tractor, and the bridge behind the tractor bears part of the weight of the trailer, which is the semi-trailer; The second is that the front end of the trailer is connected with the rear end of the tractor, which only provides forward pulling force and drags the trailer without bearing the downward weight of the trailer. This is full suspension.

In order to ensure the stability and safety of vehicle starting and driving, the whole vehicle is required to output different speeds and torques and the maximum power utilization rate under different conditions, so the manual transmission is adopted.