Spring brake actuator and brake release mechanism therefor

1. A brake release mechanism ( 24 , 124 , 224 ) for a spring brake actuator ( 2 ), in particular a parking or emergency spring brake actuator ( 2 ) for use in a commercial vehicle, the brake release mechanism ( 24 , 124 , 224 ) comprising:

a brake release bolt ( 30 , 130 , 230 ) having a threaded portion ( 34 , 134 , 234 ),

a running nut ( 12 , 112 , 212 ) engaging the threaded portion ( 34 , 134 , 234 ), the running nut ( 12 , 112 , 212 ) being adapted to axially travel along the threaded portion ( 34 , 134 , 234 ) in order to move a spring brake actuator piston ( 8 ) against a force of an actuator power spring ( 6 ),

an indicator device ( 32 , 132 , 232 ) having an indicator pin ( 26 , 226 ) at least partially accommodated in a receiving space ( 40 ) of the release bolt ( 30 , 130 , 230 ),

wherein the indicator device ( 32 , 132 , 232 ) includes a pin actuator ( 16 , 116 , 216 ) for axially moving the indicator pin ( 26 , 226 ) relative to the receiving space ( 40 ), wherein the pin actuator ( 16 , 116 , 216 ) includes an indicator cap ( 36 , 136 , 236 ) attached to the indicator pin ( 26 , 226 ), the indicator cap ( 36 , 136 , 236 ) having a basic body ( 42 , 142 , 242 ) and at least one spacing element ( 38 , 138 , 238 ) attached to the basic body ( 42 , 142 , 242 ), the at least one spacing element being ( 38 , 138 , 238 ) abutting the running nut ( 12 , 112 , 212 ); and

wherein the at least one spacing element is at least two and at most seven spacing elements ( 38 , 138 ).

2. The release mechanism ( 24 , 124 ) according to claim 1 , wherein the spacing elements ( 38 , 138 ) are equally spaced around the circumference of the basic body ( 42 , 142 ).

3. The release mechanism ( 24 , 124 , 224 ) according to claim 1 , wherein the brake release bolt ( 30 , 130 , 230 ) comprises a spring element ( 20 ) biasing the indicator pin ( 26 , 226 ) in a first direction ( 50 ), and a locking piece ( 18 , 118 , 218 ) attached to the release bolt ( 30 , 130 , 230 ), the pin actuator ( 16 , 116 , 216 ) being configured to abut against the locking piece ( 18 , 118 , 218 ) to limit a motion distance (d) of the indicator pin ( 26 , 226 ) in the first direction ( 50 ).

4. The release mechanism ( 24 , 124 , 224 ) according to claim 3 , wherein the motion distance (d) of the pin ( 26 , 226 ) in the first direction ( 50 ) is limited to at least 3 mm and at most 7 mm.

5. The release mechanism ( 24 , 124 ) according to claim 3 , wherein at least one of the basic body ( 42 , 142 ) and the locking piece ( 18 , 118 ) comprises guiding means ( 44 , 144 ) to guide the indicator cap ( 36 , 136 ) relative to the locking piece ( 18 , 118 ) in at least one of an axial or radial direction.

6. The release mechanism ( 124 ) according to claim 1 , wherein a locking piece ( 118 ) attached to the release bolt comprises centering protrusions ( 152 ) configured to extend into gaps ( 154 ) between the at least one spacing element ( 138 ), for guiding and centering the indicator cap ( 136 ).

7. The release mechanism according to claim 6 , wherein the brake release bolt ( 30 , 130 , 230 ) comprises a spring element ( 20 ) biasing the indicator pin ( 26 , 226 ) in a first direction ( 50 ), the pin actuator ( 16 , 116 , 216 ) being configured to abut against the locking piece ( 18 , 118 , 218 ) to limit a motion distance (d) of the indicator pin ( 26 , 226 ) in the first direction ( 50 ).

8. The release mechanism ( 224 ) according to claim 1 , wherein the at least one spacing element ( 238 ) is formed as a sleeve ( 256 ).

9. The release mechanism ( 224 ) according to claim 1 , wherein the indicator pin ( 226 ) and the indicator cap ( 236 ) are press-fittingly attached to one another.

10. The release mechanism ( 224 ) according to claim 9 , wherein the basic body ( 242 ) of the indicator cap ( 236 ) comprises an internal hexagonal recess ( 258 ) while the pin ( 226 ) comprises a coupling section having an external hexagonal cross section ( 262 ).

11. The release mechanism ( 24 , 124 , 224 ) according to claim 1 , wherein the indicator pin ( 26 , 226 ) is located at an operating area ( 28 ) of the brake release bolt ( 30 ) being accessible or visible from outside a housing ( 4 ) of the actuator ( 2 ).

12. The release mechanism ( 24 ) according to claim 1 , wherein the indicator pin ( 26 ) is at least partially retracted into the brake release bolt ( 30 ) when the running nut ( 12 ) forces the indicator cap ( 36 ) against a spring force of the spring element ( 20 ).

13. A spring brake actuator ( 2 ) comprising:

a brake release mechanism according to claim 1 ,

an actuator housing ( 4 ) having an actuator housing base ( 5 ),

a spring brake actuator piston ( 8 ) located in the actuator housing ( 4 ) for applying a braking force, and

an actuator power spring ( 6 ) located between the actuator housing base ( 5 ) and the spring brake actuator piston ( 8 ), the actuator power spring ( 8 ) being effective to push the spring brake actuator piston ( 8 ) away from the actuator housing base ( 5 ).

14. The release mechanism according to claim 1 , wherein a locking piece is attached to the release bolt, wherein the locking piece ( 18 ) comprises at least one aperture ( 46 ) for accommodating and guiding the at least one spacing element ( 38 ) of the indicator cap ( 36 ).

15. A brake release mechanism ( 24 , 124 , 224 ) for a spring brake actuator ( 2 ), in particular a parking or emergency spring brake actuator ( 2 ) for use in a commercial vehicle, the brake release mechanism ( 24 , 124 , 224 ) comprising:

a brake release bolt ( 30 , 130 , 230 ) having a threaded portion ( 34 , 134 , 234 ),

a running nut ( 12 , 112 , 212 ) engaging the threaded portion ( 34 , 134 , 234 ), the running nut ( 12 , 112 , 212 ) being adapted to axially travel along the threaded portion ( 34 , 134 , 234 ) in order to move a spring brake actuator piston ( 8 ) against a force of an actuator power spring ( 6 ),

an indicator device ( 32 , 132 , 232 ) having an indicator pin ( 26 , 226 ) at least partially accommodated in a receiving space ( 40 ) of the release bolt ( 30 , 130 , 230 ),

wherein the indicator device ( 32 , 132 , 232 ) includes a pin actuator ( 16 , 116 , 216 ) for axially moving the indicator pin ( 26 , 226 ) relative to the receiving space ( 40 ), wherein the pin actuator ( 16 , 116 , 216 ) includes an indicator cap ( 36 , 136 , 236 ) attached to the indicator pin ( 26 , 226 ), the indicator cap ( 36 , 136 , 236 ) having a basic body ( 42 , 142 , 242 ) and at least one spacing element ( 38 , 138 , 238 ) attached to the basic body ( 42 , 142 , 242 ), the at least one spacing element being ( 38 , 138 , 238 ) abutting the running nut ( 12 , 112 , 212 );

wherein the brake release bolt ( 30 , 130 , 230 ) comprises a spring element ( 20 ) biasing the indicator pin ( 26 , 226 ) in a first direction ( 50 ), and a locking piece ( 18 , 118 , 218 ) attached to the release bolt ( 30 , 130 , 230 ), the pin actuator ( 16 , 116 , 216 ) being configured to abut against the locking piece ( 18 , 118 , 218 ) to limit a motion distance (d) of the indicator pin ( 26 , 226 ) in the first direction ( 50 ); and

wherein the locking piece ( 18 ) comprises at least one aperture ( 46 ) for accommodating and guiding the at least one spacing element ( 38 ) of the indicator cap ( 36 ).

16. The release mechanism according to claim 15 , wherein the at least one spacing element is at least two spacing elements ( 38 , 138 ).

17. The release mechanism ( 124 ) according to claim 15 , wherein the locking piece ( 118 ) comprises centering protrusions ( 152 ) configured to extend into gaps ( 154 ) between the at least one spacing element ( 138 ), for guiding and centering the indicator cap ( 136 ).

18. A brake release mechanism ( 24 , 124 , 224 ) for a spring brake actuator ( 2 ), in particular a parking or emergency spring brake actuator ( 2 ) for use in a commercial vehicle, the brake release mechanism ( 24 , 124 , 224 ) comprising:

a brake release bolt ( 30 , 130 , 230 ) having a threaded portion ( 34 , 134 , 234 ),

a running nut ( 12 , 112 , 212 ) engaging the threaded portion ( 34 , 134 , 234 ), the running nut ( 12 , 112 , 212 ) being adapted to axially travel along the threaded portion ( 34 , 134 , 234 ) in order to move a spring brake actuator piston ( 8 ) against a force of an actuator power spring ( 6 ),

an indicator device ( 32 , 132 , 232 ) having an indicator pin ( 26 , 226 ) at least partially accommodated in a receiving space ( 40 ) of the release bolt ( 30 , 130 , 230 ),

wherein the indicator device ( 32 , 132 , 232 ) includes a pin actuator ( 16 , 116 , 216 ) for axially moving the indicator pin ( 26 , 226 ) relative to the receiving space ( 40 ), wherein the pin actuator ( 16 , 116 , 216 ) includes an indicator cap ( 36 , 136 , 236 ) attached to the indicator pin ( 26 , 226 ), the indicator cap ( 36 , 136 , 236 ) having a basic body ( 42 , 142 , 242 ) and at least one spacing element ( 38 , 138 , 238 ) attached to the basic body ( 42 , 142 , 242 ), the at least one spacing element being ( 38 , 138 , 238 ) abutting the running nut ( 12 , 112 , 212 );

wherein a locking piece ( 18 , 118 , 218 ) is attached to the release bolt ( 30 , 130 , 230 ), the locking piece ( 18 ) comprising at least one aperture ( 46 ) for accommodating and guiding the at least one spacing element ( 38 ) of the indicator cap ( 36 ).

19. The release mechanism according to claim 18 , wherein the at least one spacing element is at least two spacing elements ( 38 , 138 ).

20. The release mechanism according to claim 18 , wherein the locking piece ( 118 ) comprises centering protrusions ( 152 ) configured to extend into gaps ( 154 ) between the at least one spacing element ( 138 ), for guiding and centering the indicator cap ( 136 ).