An auxiliary power unit (APU) on a truck is a self-contained system that provides electrical power and climate control to the vehicle’s cab when the main engine is turned off. It typically consists of a small diesel engine or battery pack connected to a generator and air conditioning compressor. This system allows the driver to maintain a comfortable temperature and operate appliances inside the cab without idling the primary engine.
The importance of these systems lies in their ability to significantly reduce fuel consumption and emissions. Extended idling of the main engine to power climate control and electrical devices can consume considerable fuel. Use of an APU provides a more efficient alternative, contributing to cost savings for fleet operators and a reduction in environmental impact. Historically, idling was the only option for maintaining cab comfort, making APUs a relatively recent innovation addressing both economic and environmental concerns.
