A mechanism for opening and closing a tent or awning is disclosed. A plurality of poles are pivotally attached to a hub at upper engagement points. A plurality of braces are pivotally coupled to the poles at lower engagement points at one end and pivotally coupled to a base at another end. The base has a shaft slidable in the hub and the shaft houses a biasing member which generates an upward force on the shaft which is transmitted to the braces and the poles. The upward force urges the poles to pivot toward the open position when the lower engagement point is radially outward of the upper engagement point, and the upward force urges the poles to pivot toward the closed position when the lower engagement point is radially inward of the upper engagement point.