Under which conditions should the parking brake not be set?

The parking brake should not be set under conditions of hot brakes and freezing temperatures due to the potential risks associated with each scenario.

When brakes are hot, typically caused by extended use or heavy braking, setting the parking brake can lead to the brake components becoming fused or damaged. This is because the heat can cause the brake materials to warp or create hot spots, which may compromise the braking system's integrity and effectiveness.

In freezing temperatures, moisture can freeze around the brake components. If the parking brake is engaged in these conditions, the brake may freeze in the engaged position, preventing it from being released when needed. This can lead to difficulties in operating the vehicle safely and effectively.

Thus, it is advisable to avoid setting the parking brake when either of these conditions is present to ensure both the safety of operation and the maintenance of the vehicle's braking system.