Final answer:
The proper method for braking on long or steep grades is to use 'engine braking' and controlled brake application, slowing down around 5 mph below the 'safe' speed before releasing the brakes to allow for cooling. The specified speeds such as 10, 20, 30, or 40 mph are not as important as the technique and the situation's specifics.
Step-by-step explanation:
When descending long and/or steep grades, the recommended method of braking after selecting the appropriate gear is not about reaching a specific speed such as 10, 20, 30, or 40 mph, but rather involves a technique known as 'engine braking' combined with controlled use of the brakes. This technique entails using the engine's resistance to help slow the vehicle down, thus preventing the brakes from overheating. If braking is necessary, it's advised to reduce speed by approximately 5 mph below the 'safe' speed and then release the brakes. This allows them to cool down and reduces the risk of brake fade. The proper method varies depending on various factors such as the vehicle's weight, the steepness of the grade, road conditions, and the vehicle's braking system.
For example, if the safe speed is 35 mph, you would slow down to 30 mph and then allow your vehicle to coast back up to 35 mph before repeating the braking sequence. This is known as the 'snub braking' method. It's essential to always remain in control of the vehicle and adjust the braking technique as needed for safety.