Yes all semi trucks have speed governors on them that are set through the computer.
The speed governors or speed limiters prevent the semi truck from going above a set speed for safety.
Most semi trucks have a speed governor that is set to either 65 MPH or 67 MPH depending on the company that owns the trucks.
The speed governor is also used to save fuel because speeding is not only dangerous but also can increase the fuel consumption.
A semi truck driver that works for a company gets paid by the mile so they have to drive a certain amount of miles in a day so they can make the money.
However the semi truck driver is also limited to the amount of hours the semi driver can stay on the road and they have a mandatory break.
A semi truck driver is limited to 11 hours of driving on the road and then they have to take a 14 hour break before they can get back on the road again.