The Gated Wye valve is a hose extension valve that can also split a single truck output to two separate attack lines (same pressure requirements)
Retrieve the Gated Y from the trucks equipment menu and wear it. Enter mouselook (m) and click on the pump of the truck.
Confirm the output is connected then walk to where you want to place the Wye.
Click in mouselook to place the wye. Attack lines can be connected to it by clicking connect while near the wye.
To remove the wye, click on its connector (on the truck) and hit "REMOVE".