What is the correct procedure to stop quickly without ABS?

When stopping quickly in a vehicle that does not have Anti-lock Braking System (ABS), the proper technique involves applying the brakes firmly but not so hard that they lock up. Locking the brakes can cause the wheels to stop rotating, leading to a loss of steering control and potentially resulting in a skid. By applying the brakes as hard as possible without locking them, you maximize braking force while maintaining traction and control. This technique allows the driver to steer the vehicle while slowing down, which is crucial in emergency situations.

In contrast, immediately pulling the parking brake can lead to loss of control, especially at higher speeds, as it is not designed for rapid stopping in driving conditions. Maintaining a constant speed until stopped is not practical for quickly reducing speed in an emergency. Shifting gears up does not effectively reduce speed; instead, it's more effective to downshift, but this is not a standard method for quick stopping and can complicate the situation if not done correctly. Thus, applying the brakes properly is the most effective and safest way to stop quickly without ABS.