Importance

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Abstract

A mid-power spring brake actuator includes first, second, and third actuator housing portions, with the first actuator housing portion interposed between the second and third housing portions. A parking brake release actuator is received within the third housing portion, and a connecting shaft is attached at a first end to the parking brake release actuator and extends through a dividing wall defined by the first housing portion. A service brake apply actuator is received within at least one of the first and second housing portions. Between the dividing wall defined by the first housing portion and a second end of the connecting shaft, a brake actuator spring is provided, and a service brake actuation chamber is interposed between the brake actuator spring and the service brake apply actuator. A parking or emergency brake de-actuation chamber is defined between the parking brake release actuator and the first housing portion. Travel of the connecting shaft as a result of force applied by the brake actuator spring upon failure of an interconnection between the connecting shaft and the parking brake release actuator is limited so as to avoid undesired or unsafe power spring expansion or release beyond the rated power spring stroke.

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First Claim