"4 poster" redirects here. For the bed type, see Four poster bed

Four poster bed

A four-poster bed is a bed with four vertical columns, one in each corner, that support a tester, or upper panel. There are a number of antique four-poster beds extant dating to the 16th century and earlier; many of these early beds are highly ornate and are made from oak...

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A 4-poster or four poster automotive test system is specifically designed for the testing of vehicles (cars, trucks). These test systems consist of 4 hydraulic actuators on top of which the wheels of the vehicle are placed. Movements of the actuator

Actuator

An actuator is a type of motor for moving or controlling a mechanism or system. It is operated by a source of energy, usually in the form of an electric current, hydraulic fluid pressure or pneumatic pressure, and converts that energy into some kind of motion. An actuator is the mechanism by which...

s simulate the road surface and forces exerted by the road on the wheels. The movements of the system are tightly controlled by a digital test controller. During the research phase of a vehicle a 4-poster system is used to test newly designed suspension systems and their durability. In production 4-poster systems are usually used to test every vehicle at the end of the production line on squeak and rattle, which is a check to make sure the vehicle doesn't have any loose parts.