What type of braking systems are permissible on trailers with a GVW over 15000 lbs?

The correct answer is that surge or inertia braking systems are permissible on trailers with a Gross Vehicle Weight (GVW) over 15,000 lbs. Surge braking systems operate based on the forward momentum of the trailer, which activates the brakes when the trailer pushes against the towing vehicle. These systems are particularly beneficial because they eliminate the need for additional wiring to connect to the vehicle's braking system.

Inertia braking systems, meanwhile, rely on the trailer's weight and motion to activate the brakes. These types of braking systems are designed for heavy trailers, providing adequate stopping power when traveling at speed. Regulations often require that trailers of certain sizes be equipped with a system that can handle the weight and stopping distance necessary for safe operation, making surge and inertia systems ideal choices.

Other options, such as only hydraulic systems or only electric systems, do not accommodate the required braking capabilities for heavier trailers, which is why they are not acceptable choices. While both hydraulic and electric braking systems can be effective, the regulations specifically address the necessity for systems designed to manage the demands of trailers over 15,000 lbs, which is fulfilled by surge or inertia braking systems.