How do I use the transbrake

how do I use it? When I press the keys nothing happens

 

The transbrake should first be bound in the control settings menu, and then you need to use a gearbox that actually supports it. The Drag transmissions of the Burnside, Barstow, and Moonhawk all have this.

 

i know this is old but i have the 2 speed drag trans in the h series van if i add the heavy duty locking torque converter does this give me a transbrake sorry im new to all this