I’m not sure what you’re referring to. Could you please provide more context or clarify your question? If you’re referring to the block operation of the EHB system, I found a manual for the BrakeRite Electric Hydraulic Brake Actuation System by Titan Brakes & Actuators . It provides installation, instruction, and service manuals for the system. The manual explains that the BrakeRite systems use electric power from the towing vehicle to drive hydraulic power source. The system is actuated one of three ways: by brake pedal of tow vehicle being depressed, manual over-ride switch on in-cab brake controller, or during breakaway situation when breakaway switch is activated. Both manual over-ride and breakaway systems are required by Federal Law .
I also found a block diagram of the EHB system on BizDiagram’s Facebook page . However, I couldn’t find any other information about it. If this isn’t what you’re looking for, please provide more details and I’ll do my best to help.