US20050252737A1 - Parking brake assembly - Google Patents
Parking brake assembly Download PDFInfo
- Publication number
- US20050252737A1 US20050252737A1 US11/127,773 US12777305A US2005252737A1 US 20050252737 A1 US20050252737 A1 US 20050252737A1 US 12777305 A US12777305 A US 12777305A US 2005252737 A1 US2005252737 A1 US 2005252737A1
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- US
- United States
- Prior art keywords
- parking brake
- push rod
- clamp
- brake assembly
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000000712 assembly Effects 0.000 description 5
- 238000000429 assembly Methods 0.000 description 5
- 239000002783 friction material Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
- F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
- F16D65/18—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for drawing members together, e.g. for disc brakes
- F16D65/183—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for drawing members together, e.g. for disc brakes with force-transmitting members arranged side by side acting on a spot type force-applying member
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/02—Fluid pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2125/00—Components of actuators
- F16D2125/18—Mechanical mechanisms
- F16D2125/20—Mechanical mechanisms converting rotation to linear movement or vice versa
- F16D2125/22—Mechanical mechanisms converting rotation to linear movement or vice versa acting transversely to the axis of rotation
- F16D2125/28—Cams; Levers with cams
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2127/00—Auxiliary mechanisms
- F16D2127/06—Locking mechanisms, e.g. acting on actuators, on release mechanisms or on force transmission mechanisms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2129/00—Type of operation source for auxiliary mechanisms
- F16D2129/02—Fluid-pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2129/00—Type of operation source for auxiliary mechanisms
- F16D2129/06—Electric or magnetic
- F16D2129/10—Motors
Definitions
- the present invention relates generally to a parking brake assembly. More particularly, the present invention relates to a parking brake assembly for an air actuated disc brake.
- Air actuated disc brakes are typically used in heavy vehicle applications, such as for braking trucks or buses. Such brakes typically operate as follows. Pressurized air is introduced behind a diaphragm of an air chamber, which generates a load in a push rod. The push rod in turn applies a force to a pivotably mounted operating shaft, causing it to rotate. By means of an eccentric action, an amplified force is applied to one or more adjustable tappet assemblies that advance a brake pad towards a brake rotor. This causes a clamping effect on the brake rotor, thereby retarding rotation of the brake rotor due to friction generated between the brake pad in contact with the tappet assembly and a further brake pad mounted on an opposite face of the brake rotor.
- the parking brake function is achieved by the addition of a large spring to the rear of the air chamber that generates a load on the push rod when no pressurized air is present.
- the present invention seeks to overcome, or at least mitigate, the problems of the prior art.
- the present invention provides a parking brake assembly for an air actuated disc brake including a pneumatic actuator including a push rod for applying a brake force to brake pads.
- the push rod is generally translatable between a rest position at which the brake force is not applied and an actuated position at which a brake force is applied.
- the parking brake assembly includes a clamp assembly operable to retain the push rod in the actuated position and thereby apply the parking brake.
- the clamp assembly is configured for fitment within a caliper housing of the brake.
- FIG. 1 shows a cross section of a vehicle brake according to the present invention in an unactuated, or brakes off, position
- FIG. 2 shows vehicle brake of FIG. 1 with the parking brake applied
- FIG. 3 shows an isometric view of certain parts of the vehicle brake of FIG. 1 ;
- FIG. 4 shows a view of FIG. 3 taken in the direction of arrow A;
- FIG. 5 shows an enlarged cross section view of a collet of FIG. 2 in isolation
- FIG. 6 shows an enlarged view of part of FIG. 1 ;
- FIG. 7 shows a second embodiment of a clamp arrangement for a parking brake according to the present invention.
- FIG. 8 shows a third embodiment of a clamp arrangement for a parking brake according to the present invention.
- FIG. 9 is a further isometric view of certain parts of the vehicle brake of FIG. 1 ;
- FIG. 10 is a further isometric view of certain parts of the vehicle brake of FIG. 1 .
- FIGS. 1 to 6 show parts of a brake 8 which is operable in a service mode, i.e., is operable to retard an associated vehicle when the vehicle is being used on public highways, etc.
- the brake 8 can also be operated as a parking brake, i.e., the parking brake can be applied, and the vehicle operator can then leave the vehicle.
- the brake 8 is of the type including a caliper housing that straddles a disc or rotor (not shown).
- the caliper is typically mounted on an axle of the vehicle to be braked (not shown) and is slideable longitudinally relative to the axle.
- the rotor is mounted for rotation together with a wheel of the vehicle.
- the brake 8 is actuated by the introduction of pressurized air (represented by arrows B 1 ) behind a diaphragm 9 of an air chamber 15 (only shown in FIG. 2 ).
- the diaphragm 9 includes sealing features (not shown) sealing between the diaphragm 9 and the air chamber 15 and is connected to a push rod 11 that cooperates with a socket 17 at a radially outer end of an operating shaft or “op-shaft” 14 of the brake 8 .
- the op-shaft 14 is generally “T” shaped.
- the lower end (when viewing FIG. 1 ) of the op-shaft 14 has at its opposite ends arcuate bearing surfaces 42 seated in bearing seats 43 arranged at the lower end of an inner housing part 16 of the caliper to permit the op-shaft 14 to rotate about an axis.
- the lower end of the op-shaft 14 is further provided with pockets (not shown) positioned eccentric to the op-shaft axis of rotation which, upon rotation, cause a force to be transmitted to a pair of spaced adjustable tappet assemblies.
- the tappet assemblies apply the input load from the actuator to a rear face of an inner brake pad (not shown), thus pressing the friction material of the brake pad into frictional engagement with the rotor.
- a reaction force is generated through the frictional engagement between the rotor and the inner brake pad that is fed back through the tappet assemblies and the op-shaft 14 that is supported by the inner housing part 16 .
- the inner housing part 16 is secured to an outer housing part (not shown).
- the applied force generated by movement of the op-shaft 14 is ultimately transmitted by reaction means to the outer housing part, which in turn presses an outer brake pad (not shown) into frictional engagement with the rotor. Therefore, upon movement of the op-shaft 14 in an application direction APP (see FIG. 1 ), the rotor is clamped between the inner and outer brake pads to generate a braking force for service braking the vehicle under control of the applied input movement from the push rod 11 . Release of air pressure from the air chamber 15 causes the push rod 11 to move in a release direction RLS (see FIG. 1 ) under the action of a return spring (not shown).
- the tappet assemblies are adjustable to compensate for wear of the friction material of the brake pads.
- the reader is referred to U.S. Pat. No. 6,435,319 which shows a similar brake and the service operation thereof.
- FIGS. 3 and 9 show the major components of the parking brake assembly. Except for the push rod 11 and the diaphragm 9 , all other components shown in FIG. 3 are primarily aimed at providing a parking brake function. These components include a collet 20 (also known as a wedgeable element), a clamp housing 22 , a clamp housing mount 24 and 26 , a release lever 28 , a release actuator 30 , a release lever pivot mount 32 and a spring 34 (best seen in FIG. 1 ).
- a collet 20 also known as a wedgeable element
- the collet 20 (best seen in FIG. 5 ) includes a generally cylindrical body portion 46 .
- Projections 48 (in this case six in total) depend from the cylindrical body portion 46 .
- the cylindrical body portion 46 and the projections 48 have a common internal diameter 47 .
- Each projection 48 is separated from the adjacent projection by a slit 49 .
- Each projection 48 includes a radially outer wedge surface 50 which is orientated at an angle B (in this case approximately 6 degrees) relative to an axis C of the cylindrical body portion 46 .
- the slits 49 allow each projection 48 to move radially inwardly to frictionally engage the push rod 11 , as will be further described below.
- a stepped flange 50 A projects generally radially from an end of the cylindrical body portion 46 remote from the projections 48 .
- the stepped flange 50 A includes a recess 51 and a release surface 52 .
- the collet 20 is slideably mounted on the push rod 11 such that the axis C is substantially coincide
- the clamp housing 22 includes a generally cylindrical body 54 having four “flats” 56 , as shown in FIG. 4 . Cylindrical bosses 58 project from two opposing flats 56 , also known as lugs.
- An inner bore 59 of the generally cylindrical body 54 is machined with a profile that compliments the radially outer profile of the cylindrical body portion 46 and the wedge surface 50 of the collet 20 .
- a region 60 of the inner bore 59 is conical and is, angled relative to an axis of the inner bore 59 at an angle equivalent to angle B. As is best seen in FIG. 6 , when assembled, the region 60 faces the wedge surface 50 .
- a spring 34 is mounted in the recess 51 which acts on and biases the collet 20 to the left when viewing FIG. 6 and reacts against the clamp housing 22 .
- the spring force is sufficient to move the collet 20 to the left relative to the clamp housing 22 , thereby wedging the projections 48 between the region 60 of the clamp housing 22 and the push rod 11 when the parking brake is applied, as will be further described below.
- the collet 20 and the clamp housing 22 together provide a clamp assembly.
- the clamp housing mounts 24 and 26 are secured to the inner housing part 16 and each includes a slot 62 within which a corresponding cylindrical boss 58 sits.
- the slots 62 allow vertical movement (when considering FIG. 3 i .e., movement in a lateral direction of the push rod 11 ) of the cylindrical bosses 58 , and hence the clamp housing 22 , but prevent axial movement (when considering the axis of the push rod 11 ) of the clamp housing 22 .
- FIG. 4 two flats 56 sit snugly between the clamp housing mounts 24 and 26 .
- the interaction between the flats 56 and the inner surfaces of the clamp housing mounts 24 and 26 prevent rotation of the clamp housing 22 in a clockwise or counter-clockwise direction when viewing FIG. 4 .
- the cylindrical bosses 58 have an axis E, and thus the clamp housing 22 can rotate about the axis E during operation of the brake.
- a socket 17 moves in an arc as the op-shaft 14 rotates during brake operation.
- the diaphragm 9 moves substantially in a straight line.
- the collet 20 is initially raised and then lowered and furthermore is caused to tip about the axis E.
- This raising and lowering is accommodated by the slot 62 (as mentioned above), and the tipping is accommodated by the slight rotation of the clamp housing 22 about the external surface of the cylindrical bosses 58 .
- the release lever 28 is pivotally mounted via a pin 64 about a pivot axis F. Opposing ends of the pin 64 are secured in corresponding release lever pivot mounts 32 .
- the upper end of the release lever 28 is forked and includes fork tines 66 (only one of which is shown in FIG. 3 ) on either side of the push rod 11 . The ends of the fork tines 66 engage an adjacent region of the release surface 52 .
- the lower portion of the release lever 28 is connected to the release actuator 30 .
- the release actuator 30 is an air operable actuator in which air is supplied to power the actuator to an actuated condition. To return the air actuator to a rest condition, air is vented and an internal return spring (not shown) returns the actuator to the rest condition.
- Alternative actuators could be used, such as air motors, electric motors or linear electric actuators.
- Operation of the release actuator 30 causes the lower end of the release lever 28 to move in the direction of arrow G (see FIGS. 1, 3 and 9 ), thereby causing the fork tines 66 to move the collet 20 to the right when viewing FIG. 1 .
- the release actuator 30 is located near a rear face 70 and base walls 72 of the inner housing part 16 substantially in alignment with a vertical centerline of the caliper and directly beneath push rod 11 .
- a projection 74 is provided in a lower portion of the rear face 70 where it does not interfere with the positioning of the air chamber 15 above the projection on the rear face 70 .
- the positioning of the release actuator 30 enables it to extend under the op-shaft 14 in a recess 76 between arcuate bearing surfaces 42 , thereby optimizing the packaging of the release actuator 30 within the brake 8 .
- the brake 8 can be operated in a service mode or in a parking brake mode.
- the release actuator 30 is powered to an actuated condition to move the lower end of the release lever 28 to the left when viewing FIG. 1 .
- This causes the fork tines 66 to move the collet 20 to the right when viewing FIG. 1 , thereby ensuring that there is no wedging action between the collet 20 , the push rod 11 and the clamp housing 22 .
- the push rod 11 is free to slide within the collet 20 .
- the release actuator 30 is deactivated when required to apply the parking brake, i.e., air is vented from the actuator, thereby allowing the lower portion of the release lever 28 to move to the right when viewing FIG. 2 and hence the fork tines 66 will move to the left when viewing FIG. 2 .
- This in turn allows the spring 34 to force the collet 20 to the left when viewing FIG. 2 .
- such leftward movement of the collet 20 is limited as the projections 48 are progressively wedged between the region 60 and the push rod 11 , thereby clamping the push rod 11 .
- one method of applying the parking brake is to initially apply the service brake to pressurize the air chamber 15 such that the op-shaft 14 rotates and the brake 8 is applied.
- the release actuator can then be deactivated, causing the collet 20 to wedge between the clamp housing 22 and the push rod 11 .
- air pressure B 1 will be released, but the push rod 11 will remain in the position shown in FIG. 2 by virtue of it being clamped by the collet 20 and clamp housing 22 .
- the wedging action of the collet 20 prevents the push rod 11 moving to the left (in the release direction RLS) as shown in FIG. 2 , but does not prevent the push rod 11 from moving to the right (in the application direction APP) as shown in FIG. 2 .
- an alternative way of applying the parking brake is to initially deactivate the release actuator 30 , thereby causing the collet 20 to wedge onto the push rod 11 with the brakes in the off condition.
- Subsequent application of the service brake causes the push rod 11 to move to the right (in the application direction APP) since the wedging action will be ineffective when the push rod 11 moves in this direction.
- the push rod 11 will not move to the left (in the release direction RLS) when the service brake is released since it will be held in position by the clamp arrangement because the wedging action is effective when the push rod 11 attempts to move to the left.
- the release actuator 30 has been deactivated, the clamp arrangement is self engaging and self clamps the push rod 11 to apply the parking brake.
- the collet 20 has a radially outer wedge surface 50 (a wedgeable element wedge surface) which engages with a region 60 (a clamp housing wedge surface) of the clamp housing 22 .
- a wedgeable element wedge surface a wedgeable element wedge surface
- FIG. 7 shows a part cross section view of a clamp arrangement including a wedgeable element 120 with a wedge surface 150 similar to the wedge surface 50 .
- the clamp housing 122 does not include a wedge surface equivalent to the region 60 of the clamp housing 22 .
- FIG. 8 which is a part cross section view of a clamp arrangement having a clamp housing 222 with a wedged surface 260 equivalent to the region 60 , but which has a wedgeable element 220 which does not include a wedge surface equivalent to wedge surface 50 of the collet 20 .
- the term wedgeable element as used in the present application is not restricted to an element having a wedge surface, but rather it refers to the ability of the element to be wedged. Therefore, the wedgeable element 220 does not have to include a wedge shaped surface.
Abstract
A parking brake assembly for an air actuated disc brake includes a pneumatic actuator having a push rod for applying a brake force to brake pads. The push rod is generally translatable between a rest position at which the brake force is not applied and an actuated position at which a brake force is applied. The parking brake assembly includes a clamp assembly operable to retain the push rod in the actuated position and thereby apply the parking brake. The clamp assembly is configured for fitment within a caliper housing of the brake.
Description
- This application claims priority to United Kingdom Patent Application 0410838.7 filed on May 14, 2004.
- The present invention relates generally to a parking brake assembly. More particularly, the present invention relates to a parking brake assembly for an air actuated disc brake.
- Air actuated disc brakes are typically used in heavy vehicle applications, such as for braking trucks or buses. Such brakes typically operate as follows. Pressurized air is introduced behind a diaphragm of an air chamber, which generates a load in a push rod. The push rod in turn applies a force to a pivotably mounted operating shaft, causing it to rotate. By means of an eccentric action, an amplified force is applied to one or more adjustable tappet assemblies that advance a brake pad towards a brake rotor. This causes a clamping effect on the brake rotor, thereby retarding rotation of the brake rotor due to friction generated between the brake pad in contact with the tappet assembly and a further brake pad mounted on an opposite face of the brake rotor.
- To comply with safety legislation, when a vehicle fitted with air actuated brakes is parked, the brakes must be applied mechanically without reliance on the pressurized air to overcome the risk of the brake force being removed due to accidental leakage of the air, with obvious consequences.
- Conventionally, in air actuated brakes of the type described above, the parking brake function is achieved by the addition of a large spring to the rear of the air chamber that generates a load on the push rod when no pressurized air is present.
- The addition of the spring, together with an additional air chamber required to release the parking brake that is mounted behind the air chamber for the application of service brakes, adds to the bulk, weight and expense of the vehicle braking system.
- The present invention seeks to overcome, or at least mitigate, the problems of the prior art.
- The present invention provides a parking brake assembly for an air actuated disc brake including a pneumatic actuator including a push rod for applying a brake force to brake pads. The push rod is generally translatable between a rest position at which the brake force is not applied and an actuated position at which a brake force is applied. The parking brake assembly includes a clamp assembly operable to retain the push rod in the actuated position and thereby apply the parking brake. The clamp assembly is configured for fitment within a caliper housing of the brake.
- These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
- The invention will now be described, by way of example only, with reference to the accompanying drawings in which:
-
FIG. 1 shows a cross section of a vehicle brake according to the present invention in an unactuated, or brakes off, position; -
FIG. 2 shows vehicle brake ofFIG. 1 with the parking brake applied; -
FIG. 3 shows an isometric view of certain parts of the vehicle brake ofFIG. 1 ; -
FIG. 4 shows a view ofFIG. 3 taken in the direction of arrow A; -
FIG. 5 shows an enlarged cross section view of a collet ofFIG. 2 in isolation; -
FIG. 6 shows an enlarged view of part ofFIG. 1 ; -
FIG. 7 shows a second embodiment of a clamp arrangement for a parking brake according to the present invention; -
FIG. 8 shows a third embodiment of a clamp arrangement for a parking brake according to the present invention; and -
FIG. 9 is a further isometric view of certain parts of the vehicle brake ofFIG. 1 ; and -
FIG. 10 is a further isometric view of certain parts of the vehicle brake ofFIG. 1 . - FIGS. 1 to 6 show parts of a
brake 8 which is operable in a service mode, i.e., is operable to retard an associated vehicle when the vehicle is being used on public highways, etc. Thebrake 8 can also be operated as a parking brake, i.e., the parking brake can be applied, and the vehicle operator can then leave the vehicle. - Service operation of the
brake 8 is conventional and well known. However, in summary, thebrake 8 is of the type including a caliper housing that straddles a disc or rotor (not shown). The caliper is typically mounted on an axle of the vehicle to be braked (not shown) and is slideable longitudinally relative to the axle. The rotor is mounted for rotation together with a wheel of the vehicle. Thebrake 8 is actuated by the introduction of pressurized air (represented by arrows B1) behind adiaphragm 9 of an air chamber 15 (only shown inFIG. 2 ). Thediaphragm 9 includes sealing features (not shown) sealing between thediaphragm 9 and theair chamber 15 and is connected to apush rod 11 that cooperates with asocket 17 at a radially outer end of an operating shaft or “op-shaft” 14 of thebrake 8. The op-shaft 14 is generally “T” shaped. The lower end (when viewingFIG. 1 ) of the op-shaft 14 has at its opposite ends arcuate bearingsurfaces 42 seated inbearing seats 43 arranged at the lower end of aninner housing part 16 of the caliper to permit the op-shaft 14 to rotate about an axis. The lower end of the op-shaft 14 is further provided with pockets (not shown) positioned eccentric to the op-shaft axis of rotation which, upon rotation, cause a force to be transmitted to a pair of spaced adjustable tappet assemblies. The tappet assemblies apply the input load from the actuator to a rear face of an inner brake pad (not shown), thus pressing the friction material of the brake pad into frictional engagement with the rotor. - A reaction force is generated through the frictional engagement between the rotor and the inner brake pad that is fed back through the tappet assemblies and the op-
shaft 14 that is supported by theinner housing part 16. Theinner housing part 16 is secured to an outer housing part (not shown). Thus, the applied force generated by movement of the op-shaft 14 is ultimately transmitted by reaction means to the outer housing part, which in turn presses an outer brake pad (not shown) into frictional engagement with the rotor. Therefore, upon movement of the op-shaft 14 in an application direction APP (seeFIG. 1 ), the rotor is clamped between the inner and outer brake pads to generate a braking force for service braking the vehicle under control of the applied input movement from thepush rod 11. Release of air pressure from theair chamber 15 causes thepush rod 11 to move in a release direction RLS (seeFIG. 1 ) under the action of a return spring (not shown). - The tappet assemblies are adjustable to compensate for wear of the friction material of the brake pads. For a further explanation of the service operation of the
brake 8, the reader is referred to U.S. Pat. No. 6,435,319 which shows a similar brake and the service operation thereof. - As mentioned above, the
brake 8 can also be used as a parking brake, andFIGS. 3 and 9 show the major components of the parking brake assembly. Except for thepush rod 11 and thediaphragm 9, all other components shown inFIG. 3 are primarily aimed at providing a parking brake function. These components include a collet 20 (also known as a wedgeable element), aclamp housing 22, aclamp housing mount release lever 28, arelease actuator 30, a releaselever pivot mount 32 and a spring 34 (best seen inFIG. 1 ). - The collet 20 (best seen in
FIG. 5 ) includes a generallycylindrical body portion 46. Projections 48 (in this case six in total) depend from thecylindrical body portion 46. Thecylindrical body portion 46 and theprojections 48 have a commoninternal diameter 47. Eachprojection 48 is separated from the adjacent projection by aslit 49. Eachprojection 48 includes a radiallyouter wedge surface 50 which is orientated at an angle B (in this case approximately 6 degrees) relative to an axis C of thecylindrical body portion 46. Theslits 49 allow eachprojection 48 to move radially inwardly to frictionally engage thepush rod 11, as will be further described below. Astepped flange 50A projects generally radially from an end of thecylindrical body portion 46 remote from theprojections 48. Thestepped flange 50A includes arecess 51 and arelease surface 52. Thecollet 20 is slideably mounted on thepush rod 11 such that the axis C is substantially coincident with an axis D of thepush rod 11. - The
clamp housing 22 includes a generallycylindrical body 54 having four “flats” 56, as shown inFIG. 4 .Cylindrical bosses 58 project from two opposingflats 56, also known as lugs. Aninner bore 59 of the generallycylindrical body 54 is machined with a profile that compliments the radially outer profile of thecylindrical body portion 46 and thewedge surface 50 of thecollet 20. In particular, aregion 60 of theinner bore 59 is conical and is, angled relative to an axis of theinner bore 59 at an angle equivalent to angle B. As is best seen inFIG. 6 , when assembled, theregion 60 faces thewedge surface 50. - A
spring 34 is mounted in therecess 51 which acts on and biases thecollet 20 to the left when viewingFIG. 6 and reacts against theclamp housing 22. - The spring force is sufficient to move the
collet 20 to the left relative to theclamp housing 22, thereby wedging theprojections 48 between theregion 60 of theclamp housing 22 and thepush rod 11 when the parking brake is applied, as will be further described below. Thus, it will be appreciated that thecollet 20 and theclamp housing 22 together provide a clamp assembly. - The clamp housing mounts 24 and 26 are secured to the
inner housing part 16 and each includes aslot 62 within which a correspondingcylindrical boss 58 sits. Theslots 62 allow vertical movement (when consideringFIG. 3 i .e., movement in a lateral direction of the push rod 11) of thecylindrical bosses 58, and hence theclamp housing 22, but prevent axial movement (when considering the axis of the push rod 11) of theclamp housing 22. - As is best seen in
FIG. 4 , twoflats 56 sit snugly between the clamp housing mounts 24 and 26. The interaction between theflats 56 and the inner surfaces of the clamp housing mounts 24 and 26 prevent rotation of theclamp housing 22 in a clockwise or counter-clockwise direction when viewingFIG. 4 . Thecylindrical bosses 58 have an axis E, and thus theclamp housing 22 can rotate about the axis E during operation of the brake. As will be appreciated fromFIGS. 1 and 2 , asocket 17 moves in an arc as the op-shaft 14 rotates during brake operation. However, thediaphragm 9 moves substantially in a straight line. Thus, as the brake moves from the position shown inFIG. 1 to the position shown inFIG. 2 , thecollet 20 is initially raised and then lowered and furthermore is caused to tip about the axis E. This raising and lowering is accommodated by the slot 62 (as mentioned above), and the tipping is accommodated by the slight rotation of theclamp housing 22 about the external surface of thecylindrical bosses 58. - The
release lever 28 is pivotally mounted via apin 64 about a pivot axis F. Opposing ends of thepin 64 are secured in corresponding release lever pivot mounts 32. The upper end of therelease lever 28 is forked and includes fork tines 66 (only one of which is shown inFIG. 3 ) on either side of thepush rod 11. The ends of thefork tines 66 engage an adjacent region of therelease surface 52. The lower portion of therelease lever 28 is connected to therelease actuator 30. In this case, therelease actuator 30 is an air operable actuator in which air is supplied to power the actuator to an actuated condition. To return the air actuator to a rest condition, air is vented and an internal return spring (not shown) returns the actuator to the rest condition. Alternative actuators could be used, such as air motors, electric motors or linear electric actuators. - Operation of the
release actuator 30 causes the lower end of therelease lever 28 to move in the direction of arrow G (seeFIGS. 1, 3 and 9), thereby causing thefork tines 66 to move thecollet 20 to the right when viewingFIG. 1 . - As can be seen from
FIGS. 1, 2 , 9 and 10, therelease actuator 30 is located near arear face 70 andbase walls 72 of theinner housing part 16 substantially in alignment with a vertical centerline of the caliper and directly beneathpush rod 11. To accommodate therelease actuator 30 within theinner housing part 16, aprojection 74 is provided in a lower portion of therear face 70 where it does not interfere with the positioning of theair chamber 15 above the projection on therear face 70. - Furthermore, as is most apparent from
FIGS. 1, 2 and 9, the positioning of therelease actuator 30 enables it to extend under the op-shaft 14 in arecess 76 between arcuate bearing surfaces 42, thereby optimizing the packaging of therelease actuator 30 within thebrake 8. - As previously mentioned, the
brake 8 can be operated in a service mode or in a parking brake mode. When operated in a service mode, clearly the parking brake is not applied. Under these circumstances, therelease actuator 30 is powered to an actuated condition to move the lower end of therelease lever 28 to the left when viewingFIG. 1 . This in turn causes thefork tines 66 to move thecollet 20 to the right when viewingFIG. 1 , thereby ensuring that there is no wedging action between thecollet 20, thepush rod 11 and theclamp housing 22. As such, thepush rod 11 is free to slide within thecollet 20. Thus, when it is required to apply the service brake, air is admitted into theair chamber 15, thereby forcing thediaphragm 9 and thepush rod 11 to the right in an application direction APP, causing the op-shaft 14 to rotate and apply the brake. When the air is released from theair chamber 15, thebrake 8 is free to return to the position shown inFIG. 1 . In particular, the clamp arrangement does not restrict movement of thepush rod 11 in the release direction RLS. - The
release actuator 30 is deactivated when required to apply the parking brake, i.e., air is vented from the actuator, thereby allowing the lower portion of therelease lever 28 to move to the right when viewingFIG. 2 and hence thefork tines 66 will move to the left when viewingFIG. 2 . This in turn allows thespring 34 to force thecollet 20 to the left when viewingFIG. 2 . However, such leftward movement of thecollet 20 is limited as theprojections 48 are progressively wedged between theregion 60 and thepush rod 11, thereby clamping thepush rod 11. - The wedging action prevents the
push rod 11 from moving to the left when viewingFIG. 2 . Thus, one method of applying the parking brake is to initially apply the service brake to pressurize theair chamber 15 such that the op-shaft 14 rotates and thebrake 8 is applied. The release actuator can then be deactivated, causing thecollet 20 to wedge between theclamp housing 22 and thepush rod 11. Upon subsequent release of the service brake, air pressure B1 will be released, but thepush rod 11 will remain in the position shown inFIG. 2 by virtue of it being clamped by thecollet 20 and clamphousing 22. - The wedging action of the
collet 20 prevents thepush rod 11 moving to the left (in the release direction RLS) as shown inFIG. 2 , but does not prevent thepush rod 11 from moving to the right (in the application direction APP) as shown inFIG. 2 . - Thus, starting from a position shown in
FIG. 1 , an alternative way of applying the parking brake is to initially deactivate therelease actuator 30, thereby causing thecollet 20 to wedge onto thepush rod 11 with the brakes in the off condition. Subsequent application of the service brake causes thepush rod 11 to move to the right (in the application direction APP) since the wedging action will be ineffective when thepush rod 11 moves in this direction. However, once the service brake has been applied to apply thebrakes 8, thepush rod 11 will not move to the left (in the release direction RLS) when the service brake is released since it will be held in position by the clamp arrangement because the wedging action is effective when thepush rod 11 attempts to move to the left. Once therelease actuator 30 has been deactivated, the clamp arrangement is self engaging and self clamps thepush rod 11 to apply the parking brake. - As mentioned above, the
collet 20 has a radially outer wedge surface 50 (a wedgeable element wedge surface) which engages with a region 60 (a clamp housing wedge surface) of theclamp housing 22. In further embodiments, it is possible to provide a wedging action by providing a wedge surface on just thecollet 20 and without having a wedge surface on theclamp housing 22. -
FIG. 7 shows a part cross section view of a clamp arrangement including awedgeable element 120 with awedge surface 150 similar to thewedge surface 50. Theclamp housing 122 does not include a wedge surface equivalent to theregion 60 of theclamp housing 22. In a yet further alternative embodiment, it is also possible to apply a wedging action by having a wedging surface on just the clamp housing without having a wedging surface on thecollet 20. See in particularFIG. 8 , which is a part cross section view of a clamp arrangement having aclamp housing 222 with a wedgedsurface 260 equivalent to theregion 60, but which has awedgeable element 220 which does not include a wedge surface equivalent to wedgesurface 50 of thecollet 20. For this reason, the term wedgeable element as used in the present application is not restricted to an element having a wedge surface, but rather it refers to the ability of the element to be wedged. Therefore, thewedgeable element 220 does not have to include a wedge shaped surface. - The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.
Claims (20)
1. A parking brake assembly for an air actuated disc brake comprising:
a pneumatic actuator including a push rod for applying a brake force to brake pads, wherein the push rod is generally translatable between a rest position at which the brake force is not applied and an actuated position at which the brake force is applied; and
a clamp assembly to retain the push rod in the actuated position and thereby apply a parking brake, wherein the clamp assembly is configured for fitment within a caliper housing of the parking brake assembly.
2. The parking brake assembly as defined in claim 1 wherein the clamp assembly self clamps the push rod when the push rod is moved to the actuated position to apply the brake force.
3. The parking brake assembly as defined in claim 1 wherein the clamp assembly includes a clamp housing substantially fixed in an axial direction of the push rod relative to the parking brake assembly and a wedgeable element to retain the push rod in the actuated position by a wedging action between the clamp housing and the push rod.
4. The parking brake assembly as defined in claim 3 wherein the clamp housing includes a clamp housing wedge surface engageable by the wedgeable element to create the wedging action.
5. The parking brake assembly as defined in claim 3 wherein the clamp housing includes a bearing surface that allows the clamp housing to move generally in a lateral direction as the push rod moves in the lateral direction during operation.
6. The parking brake assembly as defined in claim 5 wherein the clamp housing includes lugs that provide the bearing surface.
7. The parking brake assembly as defined in claim 3 wherein the clamp housing includes a pivot arrangement that allows the clamp housing to pivot as the push rod pivots during operation.
8. The parking brake assembly as defined in claim 7 wherein the clamp housing includes lugs that provide a bearing surface of the clamp housing and the lugs provide the pivot arrangement.
9. The parking brake assembly as defined in claim 3 wherein the wedgeable element includes a wedgeable element wedge surface engageable by the clamp housing to create the wedging action.
10. The parking brake assembly as defined in claim 9 wherein the wedgeable element includes a plurality of resiliently mounted projections, and the wedgeable element wedge surface is provided on the plurality of resiliently mounted projections.
11. The parking brake assembly as defined in claim 1 further including a power actuator to release the clamp assembly and release the parking brake, wherein the clamp assembly includes a clamp housing substantially fixed in an axial direction of the push rod relative to the parking brake assembly and a wedgeable element to retain the push rod in the actuated position by a wedging action between the clamp housing and the push rod, and the power actuator moves the wedgeable element to a non-wedging position to release the parking brake.
12. The parking brake assembly as defined in claim 11 wherein the power actuator moves the wedgeable element in an application direction of the push rod to the non-wedging position.
13. The parking brake assembly as defined in claim 11 further including a pivotable lever, wherein the power actuator acts via the pivotable lever to release the parking brake.
14. The parking brake assembly according to claim 1 , wherein the clamp assembly is located within the caliper housing.
15. The parking brake assembly according to claim 14 wherein the caliper housing includes a wall and a portion of the clamp assembly is located within the wall of the caliper housing.
16. The parking brake assembly according to claim 15 wherein the caliper housing includes an opening and the portion of the clamp assembly is located near the opening in the caliper housing to receive the push rod.
17. The parking brake assembly according to claim 14 further including a power actuator to release the clamp assembly and release the parking brake, wherein the power actuator is located within the caliper housing.
18. The parking brake assembly according to claim 17 wherein the caliper housing includes a rear wall and a base wall and the power actuator is located near the rear wall and the base wall of the caliper housing.
19. The parking brake assembly according to claim 17 wherein the power actuator is located substantially along a centerline of the caliper housing in alignment with a line of action of the push rod.
20. The parking brake assembly according to claim 18 wherein the rear wall of the caliper housing includes a projection extending rearwardly to accommodate the power actuator.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GBGB0410838.7A GB0410838D0 (en) | 2004-05-14 | 2004-05-14 | Parking brake assembly |
GB0410838.7 | 2004-05-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050252737A1 true US20050252737A1 (en) | 2005-11-17 |
Family
ID=32527091
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/127,773 Abandoned US20050252737A1 (en) | 2004-05-14 | 2005-05-12 | Parking brake assembly |
Country Status (6)
Country | Link |
---|---|
US (1) | US20050252737A1 (en) |
EP (1) | EP1596090A1 (en) |
JP (1) | JP2005326012A (en) |
CN (1) | CN1696529A (en) |
BR (1) | BRPI0503269A (en) |
GB (1) | GB0410838D0 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080202870A1 (en) * | 2005-07-07 | 2008-08-28 | Damiano Molfetta | Holding Brake Device |
US20080217117A1 (en) * | 2007-03-05 | 2008-09-11 | Lars Severinsson | Disc Brake and an Additional Brake Actuator Therefore |
US10821955B2 (en) * | 2018-09-05 | 2020-11-03 | Zhicong Zhou | Railway car brake lock |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB0802212D0 (en) | 2008-02-06 | 2008-03-12 | Meritor Heavy Vehicle Braking | A brake system and method |
GB0817230D0 (en) | 2008-09-19 | 2008-10-29 | Meritor Heavy Vehicle Braking | A parking brake mechanism |
GB0817229D0 (en) | 2008-09-19 | 2008-10-29 | Meritor Heavy Vehicle Braking | A control system and method for a parking brake mechanism |
DE102009042856A1 (en) * | 2009-09-24 | 2011-03-31 | Pfenning Elektroanlagen Gmbh | Straddle carriers for use in container terminals and for general transport purposes |
GB201014181D0 (en) | 2010-08-25 | 2010-10-06 | Meritor Heavy Vehicle Braking | A parking brake mechanism |
CN105882679B (en) * | 2014-12-31 | 2019-03-01 | 法维莱运输亚眠公司 | For the railway brake system of rolling stock and the braking method of the rolling stock with this system |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3874747A (en) * | 1973-10-03 | 1975-04-01 | Walter Case | Fluid actuated brake locking mechanism |
US4589704A (en) * | 1984-08-07 | 1986-05-20 | Graham John M | Air brake with collet locked push rod and air supply system |
US5954162A (en) * | 1995-01-31 | 1999-09-21 | Itt Manufacturing Enterprises Inc. | Combined service and parking brake |
US20020171285A1 (en) * | 1999-10-18 | 2002-11-21 | Ake Nelander | Lock actuator |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB9806542D0 (en) | 1998-03-26 | 1998-05-27 | Lucas Ind Plc | Disc brake actuator |
SE0100842D0 (en) * | 2001-03-13 | 2001-03-13 | Haldex Brake Prod Ab | A Parking Lock |
SE523553C2 (en) * | 2002-07-04 | 2004-04-27 | Haldex Brake Prod Ab | Fluid-activated parking brake |
-
2004
- 2004-05-14 GB GBGB0410838.7A patent/GB0410838D0/en not_active Ceased
-
2005
- 2005-05-11 BR BR0503269-5A patent/BRPI0503269A/en not_active Application Discontinuation
- 2005-05-12 US US11/127,773 patent/US20050252737A1/en not_active Abandoned
- 2005-05-13 JP JP2005140786A patent/JP2005326012A/en active Pending
- 2005-05-13 EP EP05252973A patent/EP1596090A1/en not_active Withdrawn
- 2005-05-16 CN CN200510069384.3A patent/CN1696529A/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3874747A (en) * | 1973-10-03 | 1975-04-01 | Walter Case | Fluid actuated brake locking mechanism |
US4589704A (en) * | 1984-08-07 | 1986-05-20 | Graham John M | Air brake with collet locked push rod and air supply system |
US5954162A (en) * | 1995-01-31 | 1999-09-21 | Itt Manufacturing Enterprises Inc. | Combined service and parking brake |
US20020171285A1 (en) * | 1999-10-18 | 2002-11-21 | Ake Nelander | Lock actuator |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080202870A1 (en) * | 2005-07-07 | 2008-08-28 | Damiano Molfetta | Holding Brake Device |
US20080217117A1 (en) * | 2007-03-05 | 2008-09-11 | Lars Severinsson | Disc Brake and an Additional Brake Actuator Therefore |
DE102008009161B4 (en) * | 2007-03-05 | 2017-05-11 | Haldex Brake Products Ab | Disc brake and additional brake actuator for this |
US10821955B2 (en) * | 2018-09-05 | 2020-11-03 | Zhicong Zhou | Railway car brake lock |
Also Published As
Publication number | Publication date |
---|---|
CN1696529A (en) | 2005-11-16 |
GB0410838D0 (en) | 2004-06-16 |
EP1596090A1 (en) | 2005-11-16 |
BRPI0503269A (en) | 2006-01-10 |
JP2005326012A (en) | 2005-11-24 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: MERITOR HEAVY VEHICLE BRAKING SYSTEMS (UK) LIMITED Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MORRIS, ROYSTON LEONARD;TAYLOR, MARTIN PORS;CLARKE, LESTER;AND OTHERS;REEL/FRAME:016254/0004;SIGNING DATES FROM 20050519 TO 20050520 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |