When moving ACS-64 units dead in tow, which electrical connections must be made between units?

• A. 27-point MU cable and 480V cables must be connected between units; brake pipe, main reservoir and all MU hoses connected; HEP control switch set to HEP line; emergency magnet valve cut out.
• B. No electrical connections are required.
• C. Only the 120V control cable is required.
• D. Only the HEP line is required.

Answer: (A)

When moving ACS-64 units dead in tow, you must interconnect both electrical and pneumatic systems so the lead unit can control and power the trailing unit as needed. The 27-point MU cable provides the full control and signaling link between units, allowing coordinated throttle, brake, and system commands to pass from the lead locomotive to the trailing one. In addition, 480-volt cables supply essential electrical power between units, so cab equipment and other systems on the towed unit stay powered while being towed.

The air brake system also has to be linked: the brake pipe and main reservoir connections ensure the lead unit can apply or release the brakes on the trailing unit in sync with its own braking, and all MU hoses carry the necessary brake control signals. Setting the HEP control switch to the HEP line ensures head-end power can be supplied to the trailing unit’s systems, keeping critical equipment energized during the tow. Finally, cutting out the emergency magnet valve on the trailing unit prevents unintended brake activation from emergency signals during movement, allowing safe, controlled towing.

These connections together provide proper control, power, and braking coordination, which is why this option is the correct approach.