USB hubs are to expand a single port from a PC so you can use multiple devices. It will not connect a single device to multiple computers.
If you want to share a single HDD between multiple computers at the same time you will have to share the drive over a network. If you have the HDD plugged into a Windows PC you can right click (context menu click) on the drive and select "Sharing and Security" and then select the option to share the folder. From another Windows PC on the same network you can type in \\computer-name\folder and access the folder.
Be extremely careful if you use a USB drive with a switch! Before switching the drive from the first machine to the second, you MUST use "Safely Eject Hardware" to close out the drive (flush cache and tell the machine that the drive is no longer available). Otherwise, you are vulnerable to the same corruption that you would get if you simply unplugged the drive without stopping it.