How to Make Very Powerful Nine DC Motor are Connected Circular Arrangement

I am show about powerful nine dc motor are connected circular formation. the arrangement was fixed rotate in dc motor pulley in connected are parallel.

1).https://youtu.be/XSzpBO45X-c

2).https://youtu.be/6Py7r9zqFCU

3).https://youtu.be/CYkNY9ZLRyo