Before unlocking the inter-axle differential lock, what speed must an operator reduce to?

Answer: C — 25 mph or less

To safely engage the inter-axle differential lock, it is crucial for the operator to reduce the vehicle’s speed to 25 mph or less. This speed requirement exists to ensure that the driveline components are not under excessive strain when the differential lock engages. Engaging the lock at higher speeds can lead to potential mechanical failure or driveability issues, as the wheels may not be able to align properly due to differences in wheel speed. Maintaining the correct speed helps prevent binding or damage within the drivetrain, thereby promoting longevity and reliable operation of the vehicle.