Line lock

A line lock is a device that allows the front brakes to lock independently of the rear brakes via a switch. The device is an electric solenoid that controls a valve which is placed on the front brake line, and is controlled by a switch. Simpler systems consist of a manually operated valve which directly opens and closes the brake line, usually with a lever or tap inside the cabin of the vehicle. Normally, the valve is open and allows fluid to pass through to the front brakes. However, when the brakes are applied and the solenoid is activated, the valve closes to trap the brake fluid, keeping the front brakes applied until the switch is released.