Armoured personnel carriers (APCs) are light armoured fighting vehicles for the transport of infantry. They usually have only a machine gun although variants carry recoilless rifles, anti-tank guided missiles (ATGMs), or mortarss. They are not really designed to take part in a direct-fire battle, but to carry the troops to the battlefield safe from shrapnel and ambush. They may have wheels or tracks. Examples include the American M-113 (tracked) and the Russian BRD series (wheeled).
Most armoured personnel carriers use a diesel engine comparable to that used in a large truck or in a typical city bus. The M-113 for instance used the same engine as the standard General Motors urban bus. A single M-113 moving at top speed made about the same sound as a General Motors urban bus moving at top speed. However, the typical armoured personnel carrier contains only six or ten soldiers while a typical urban bus can carry thirty to fifty seated passengers and hundreds when standing passengers are included.
