Patent ID: 8631913

Claim:
A braking system for a final drive for a wheel assembly, the braking system comprising: a brake housing having a bore with at least one uniform diameter section; a service brake actuator disposed within the bore of the brake housing, the service brake actuator being an annular element configured to be axially displaced under fluid pressure to retard rotation of the wheel assembly by engaging one or more brake discs contained within the brake housing; a park brake actuator disposed within the bore of the brake housing adjacent to the service brake actuator, the park brake actuator being an annular element configured to be displaced axially under fluid pressure independent of the service brake actuator and positioned in physically abutting relation with the service brake actuator to displace the service brake actuator to retard rotation of the wheel assembly; and a first seal and a second seal disposed axially between the service brake actuator and the park brake actuator in engagement with the brake housing at the uniform diameter section to effect seals between the brake housing and at least one of the service brake actuator and the park brake actuator; wherein the park brake actuator and at least a portion of the service brake actuator are disposed within the brake housing bore at the uniform diameter section such that a fluid chamber is formed between the first seal, the second seal, the brake housing and at least one of the service brake actuator and the park brake actuator in which is received pressurized fluid to displace the park brake actuator in an axial direction away from the service brake actuator; wherein a third seal is disposed axially between the service brake actuator and the park brake actuator in sealing engagement with the brake housing; wherein the first seal and the second seal engage the brake housing at the uniform diameter section, wherein the second seal is disposed centrally between the first seal and the third seal; wherein the first seal and the second seal in part form the fluid chamber that receives pressurized fluid to displace the park brake actuator in the axial direction away from the service brake actuator, and wherein the second seal and the third seal in part form a second fluid chamber that receives pressurized fluid to displace the service brake actuator in a second axial direction toward the one or more brake discs.