Vehicle spring brakes having reduced length

A vehicle spring brake comprising:

• a parking brake housing that defines a parking brake chamber;
• a service brake housing that defines a service brake chamber;
• a flexible membrane between the parking brake chamber and the service brake chamber, wherein the flexible membrane is caused to flex into the parking brake chamber or the service brake chamber based on a pressure differential between air pressure in the parking brake chamber and air pressure in the service brake chamber;
• a pushrod in the service brake chamber that moves with the flexible membrane as the flexible membrane flexes;
• a control valve that controls the pressure differential to thereby control movement of the flexible membrane and the pushrod;
• a parking spring assembly in the parking brake chamber, wherein the parking spring assembly is movable into and between:
• an extended state in which the parking spring assembly pushes the flexible membrane such that the pushrod extends out of the service brake housing;
• and
• a retracted state in which the parking spring assembly does not push the flexible membrane or push the pushrod out of the service brake housing;
• and
• a return spring on the pushrod that has a natural resiliency that tends to cause the pushrod to retract into the service brake chamber.

A vehicle spring brake comprising:

• a parking brake housing that defines a parking brake chamber;
• a parking spring assembly in the parking brake chamber;
• a service brake housing that defines a service brake chamber;
• a flexible membrane between the parking brake chamber and the service brake chamber, wherein the flexible membrane is caused to flex into the parking brake chamber or the service brake chamber based on a pressure differential between air pressure in the parking brake chamber and air pressure in the service brake chamber;
• and
• a pushrod in the service brake chamber that moves with the flexible membrane as the flexible membrane flexes.

A method for operating a vehicle spring brake, the method comprising:

• defining a parking brake chamber with a parking brake housing and a service brake chamber with a service brake housing;
• positioning a flexible membrane between the parking brake chamber and the service brake chamber, wherein the flexible membrane is caused to flex into the parking brake chamber or the service brake chamber based on a pressure differential between air pressure in the parking brake chamber and air pressure in the service brake chamber;
• positioning a pushrod in the service brake chamber such that the pushrod moves with the flexible membrane as the flexible membrane flexes, wherein the pushrod extends from the service brake housing when the flexible membrane flexes into the service brake chamber such that the pushrod applies a braking force on a vehicle;
• and
• controlling, with a control valve that is coupled to a vehicle air system, the pressure differential to thereby control movement of the flexible membrane and the pushrod.