Parking piston direct connection to APR rod
In a brake actuator including a plurality of actuator housing portions, a diaphragm seal, partially delimiting a parking brake de-actuation chamber, is retained between adjacent actuator housing portions, and an elastic element disposed between the diaphragm seal and one of the housing portions opposes expansion of the parking brake de-actuation chamber. A push rod extends into and out of a service brake actuation chamber upon respective release of fluid pressure from the parking brake de-actuation chamber and supply of fluid pressure to the parking brake de-actuation chamber. In order to constrain a central portion of the diaphragm seal for movement together with both the push rod and a piston, a clamping arrangement is used to axially clamp the central diaphragm seal portion between an end of the push rod and a surface of the piston.
1. A brake actuator comprising:
a plurality of actuator housing portions,
a service brake diaphragm seal that, together with one of the actuator housing portions, partially delimits a service brake actuation chamber to be expanded and contracted by fluid supply and relief,
a parking brake diaphragm seal, partially delimiting a parking brake de-actuation chamber that is separate from the service brake actuation chamber and is also to be expanded and contracted by fluid supply and relief, retained between another of the actuator housing portions adjacent to said one of the actuator housing portions,
an elastic element disposed between the parking brake diaphragm seal and the other of the housing portions to oppose expansion of the parking brake de-actuation chamber,
a push rod operable to produce brake actuation upon depressurization of the parking brake de-actuation chamber, the push rod extending through the parking brake de-actuation chamber,
a piston, secured to and movable together with the push rod, secured to and movable with the parking brake diaphragm seal, and acting as a seat for the elastic element, and
a clamping arrangement including a threaded member passing through a central hole in the parking brake diaphragm seal to axially clamp the parking brake diaphragm seal to the push rod and against a surface of the piston and constrain the parking brake diaphragm seal for movement with both the push rod and the piston.
2. The brake actuator of claim 1 , wherein the threaded member is received within a bore.
3. The brake actuator of claim 2 , wherein the bore extends axially into the push rod.
4. The brake actuator of claim 2 , wherein the clamping arrangement further includes a washer within said parking brake de-actuation chamber pressing against the central portion of the parking brake diaphragm seal.
5. The brake actuator of claim 4 , wherein the washer is moved into a matching recess in the piston as the threaded member is tightened in the bore.
6. The brake actuator of claim 1 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.
7. The brake actuator of claim 1 , wherein the clamping arrangement further includes a washer pressing against the central portion of the diaphragm seal.
8. The brake actuator of claim 7 , wherein the washer is moved into a matching recess in the piston as the threaded member is tightened.
9. The brake actuator of claim 2 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.
10. The brake actuator of claim 4 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.
11. A safety brake arrangement and a service brake arrangement together defining a brake actuator, comprising:
a plurality of actuator housing portions,
a service brake diaphragm seal that, together with one of the actuator housing portions, partially delimits a service brake actuation chamber to be expanded and contracted by fluid supply and relief,
a parking brake diaphragm seal, partially delimiting a parking brake de-actuation chamber that is separate from the service brake actuation chamber and is also to be expanded and contracted by fluid supply and relief, retained between another of the actuator housing portions adjacent to said one of the actuator housing portions,
an elastic element disposed between the parking brake diaphragm seal and the other of the housing portions to oppose expansion of the parking brake de-actuation chamber,
a push rod operable to produce brake actuation upon depressurization of the parking brake de-actuation chamber, the push rod extending through the parking brake de-actuation chamber,
a piston, secured to and movable together with the push rod, secured to and movable with the parking brake diaphragm seal, and acting as a seat for the elastic element, and
a clamping arrangement including a threaded member passing through a central hole in the parking brake diaphragm seal to axially clamp the parking brake diaphragm seal to the push rod and against a surface of the piston and constrain the parking brake diaphragm seal for movement with both the push rod and the piston.
12. The safety brake and service brake arrangements of claim 11 , wherein the threaded member is received within a bore.
13. The safety brake and service brake arrangements of claim 12 , wherein the bore extends axially into the push rod.
14. The safety brake and service brake arrangements of claim 12 , wherein the clamping arrangement further includes a washer within said parking brake de-actuation chamber pressing against the central portion of the parking brake diaphragm seal.
15. The safety brake and service brake arrangements of claim 14 , wherein the washer is moved into a matching recess in the piston as the threaded member is tightened in the bore.
16. The safety brake and service brake arrangements of claim 11 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.
17. The safety brake and service brake arrangements of claim 11 , wherein the clamping arrangement further includes a washer pressing against the central portion of the diaphragm seal.
18. The safety brake and service brake arrangements of claim 17 , wherein the washer is moved into a matching recess in the piston as the threaded member is tightened.
19. The safety brake and service brake arrangements of claim 12 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.
20. The safety brake and service brake arrangements of claim 14 , wherein the push rod extends into and out of said service brake actuation chamber upon release of fluid pressure from said parking brake de-actuation chamber and supply of fluid pressure to said parking brake de-actuation chamber, respectively.