"Attacking a city with a battering ram (or siege tower designed for upward assault, though 'battering ram' is the more conventional term in this context)" can be a translation for "攻城用仰冲车".
Here, “仰冲车” is a somewhat specialized and less commonly encountered term in modern usage. In ancient Chinese siege warfare, “仰冲车” likely referred to a type of siege engine used for upward assault on city walls. “Battering ram” is a well-known term in English for a heavy beam or structure used for breaking down doors or walls in sieges, and while it doesn't perfectly capture the "upward assault" aspect of “仰冲车”, it's the closest conventional term. If you want to emphasize the upward-moving nature more specifically, you could add a descriptive phrase like "designed for upward assault" as shown above, though this makes the translation a bit longer.
In a more concise and commonly understood translation, especially if the upward-moving detail isn't crucial to the overall meaning, you could simply say "Attacking a city with a battering ram".