GB2079879A - Internal-shoe drum brake - Google Patents

Internal-shoe drum brake Download PDF

Info

Publication number
GB2079879A
GB2079879A GB8120980A GB8120980A GB2079879A GB 2079879 A GB2079879 A GB 2079879A GB 8120980 A GB8120980 A GB 8120980A GB 8120980 A GB8120980 A GB 8120980A GB 2079879 A GB2079879 A GB 2079879A
Authority
GB
United Kingdom
Prior art keywords
brake
wedge
plungers
expansion
shoe
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.)
Granted
Application number
GB8120980A
Other versions
GB2079879B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Deutsche Perrot Bremse GmbH
Original Assignee
Deutsche Perrot Bremse GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Deutsche Perrot Bremse GmbH filed Critical Deutsche Perrot Bremse GmbH
Publication of GB2079879A publication Critical patent/GB2079879A/en
Application granted granted Critical
Publication of GB2079879B publication Critical patent/GB2079879B/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
    • F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
    • F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
    • F16D51/20—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots
    • 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
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
    • F16D65/08—Bands, shoes or pads; Pivots or supporting members therefor for internally-engaging brakes
    • 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
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
    • F16D65/08—Bands, shoes or pads; Pivots or supporting members therefor for internally-engaging brakes
    • F16D65/09—Pivots or supporting members therefor
    • F16D65/091—Pivots or supporting members therefor for axially holding the segments
    • 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
    • F16D65/22—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for pressing members apart, e.g. for drum brakes
    • 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
    • F16D65/38—Slack adjusters
    • F16D65/40—Slack adjusters mechanical
    • F16D65/42—Slack adjusters mechanical non-automatic
    • F16D65/48—Slack adjusters mechanical non-automatic with eccentric or helical body
    • 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
    • F16D2125/58—Mechanical mechanisms transmitting linear movement
    • F16D2125/66—Wedges

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Braking Arrangements (AREA)

Abstract

The brake has shoes (11, 11') actuated at one pair of ends by a floating hydraulic cylinder (12) for service braking but actuated at their other pair of ends by a mechanical wedge expansion device (1) for parking. The device (1) has a wedge (17) acting between plungers (7, 7') which engage respectively the ends of the brake shoes (11, 11') through pressure pads (3) having hemicylindrical bracing projections (4), projecting from shoe boss (2). An adjusting device (13) with an eccentrically arranged stud (16) is provided (see Fig. 3, for details). <IMAGE>

Description

SPECIFICATION Internal-shoe drum brake The invention relates to an internal-shoe drum brake with a hydraulic expansion device arranged floating between one pair of ends of the two brake shoes and combined with an automatic take-up device for the service brake which is designed as a simplex brake, and with a mechanical expansion device arranged between the other pair of ends of the brake shoes for the parking brake which is designed as a servo brake.
In an internal-shoe drum brake of this category described in German Patent Specification 14 75 310, the mechanical expansion device consists of a floating expansion cam which the brake shoes abut by means of pressure pads provided at their ends. The expansion cam is arranged on a radial fillet of a head of a brake shaft, which is mounted rotatably in the brake plate. An actuating lever is arranged on the brake shaft to rotate with it and is connected by a linkage to an actuating element, e.g., a spring accumulator cylinder. Any rotation of the expansion cam caused through the actuating element results in an expansion of the brake shoes.However, since the actuating region of the expansion cam lies above the rotary bracing of the brake shoes, it is unavoidable that with increasing wear of the brake linings, in this region also the distance between the brake shoe installation and expansion cam increases. This in turn increases the length required in the work stroke of the spring accumulator cylinder. However the work strokes of such spring accumulator cylinders are very short and the point at which the stroke force diminishes is reached comparatively rapidly. This then means ultimately that the retaining force necessary to supply the brake moment for the parking brake ceases to be attained.
The underlying aim of the invention is to produce an internal-shoe drum brake of this category, in which the actuating stroke of the mechanical expansion device for the parking brake remains the same irrespective of the wear of the brake linings.
Accordingly the invention provides such an internal-shoe drum brake in which the mechanical expansion device is constructed as a wedge expansion device. The actuating element, e.g., a spring accumulator cylinder, can be attached directly to this wedge expansion device.
Embodiments of the invention may be easier to accommodate in the brake and may produce a cost saving.
In an advantageous embodiment of the invention, the wedge expansion device consists of an expansion wedge and of two coaxial plungers loaded by the latter and abutting terminal pressure pads of the brake shoes, whilst the expansion wedge and the plungers are mounted slidably in mutually perpendicular planes in a rotationally fixed brake support.
In order to reduce the friction losses, it is provided that the plungers are braced against the expansion wedge through rollers.
In an embodiment of the invention which is advantageous from the standpoint of bracing the brake shoes, it is provided that each terminal pressure pad of both brake shoes is provided with a hemicylindrical bracing projection extending in the tangential direction with an axis oriented parallel to the axis of the brake, and that the brake support is provided with a hemicylindrical bracing recess accommodating the bracing projection.
In order that linear contact exists between the bracing projection of the pressure pads and the associated plunger, it is provided that the end face of the plungers abutting the bracing projection of the pressure pads is plane.
As a precaution against any axial displacement of the brake shoes, it is provided as a further development of the invention that the plungers have a projecting bar at the end face and that the bracing projections of the pressure pads have a groove accommodating the bar of the associated plunger.
In order to ensure that, taking into consideration the installation position of the brake, no obstruction of the free mobility between the brake shoes and the brake drum occurs, the brake according to the invention is preferably provided with an adjusting device. In an embodiment of the invention it is provided that the adjusting device is mounted on the brake support so that it can rotate but is restrained from doing so by friction, and has an eccentrically arranged stud which engages into a cavity of the associated brake shoe with a play corresponding to the lifting play of the brake shoe, and that the brake shoe is engaged by a spring loading it towards the disengaged position. The spring is preferably constructed as an annular spring which is attached to the adjusting device and engages with its free end into the cavity of the associated brake shoe.
An embodiment of the invention given by way of example only will now be described with reference to the accompanying drawings, to which express reference is made for the disclosure of any particulars not described in the text. In the drawings: Fig. 1 shows an elevation of an exemplary embodiment of an internal-shoe drum brake associated with a left-hand vehicle wheel, this illustration being rotated 900 counter-clockwise with reference to the actual installation position, Fig. 2 shows a section made along the line Il-lI in Fig. 1, Fig. 3, shows a section made along the line Ill-Ill in Fig. 1, and Fig. 4 shows a section made along the line lV-lVinFig. 1.
The vehicle brake illustrated in Fig. 1 is an internal-shoe drum brake with hydrauiic actuation as a so-called simplex brake for the service brake, and with mechanical actuation as a so-called servo brake for the parking brake. A hydraulically actuated wheel cylinder 12 is mounted floating between the one end of the two brake shoes 11, 11 ' and is combined with an automatic take-up device. An exemplary embodiment of such a wheel cylinder is described in the above mentioned German Patent Specification 14 75 310, so that any further explanation is superfluous. The two brake shoes 11, 11' are braced at the other end against a stationary brake support 6.The bracing of the brake shoes 11, 11' is such that, in each case, a pressure pad 3 projecting from the brake shoe bar 2 is provided with a bracing projection 4 extending in the tangential direction and having the form of a hemicylinderwith an axis oriented parallel to the axis of the brake, and with which a corresponding hemicylindrical bracing recess 5 of the brake support 6 is associated.
A wedge expansion device 1 is provided for actuating the parking brake. This device consists of an expansion wedge 1 7 and of two coaxial plungers 7, 7', loaded by the latter, and abutting terminal pressure pads 3 of the brake shoes 11, 1 1'. The expansion wedge 1 7 and the plungers 7, 7' are mounted slidably in mutually perpendicular planes in the brake support 6, whilst the plungers are braced agains the expansion wedge through rollers 1 8. The actuating element (not shown), e.g., a spring accumulator cylinder, may be attached directly to the expansion wedge 1 7. The plungers 7, 7' are constructed so that, as a result of two milled portions 8, a bifurcate abutment with linear contact exists with reference to the hemicylindrical bracing projection 4 of the brake shoes 11, 11'.
A bar 9 of the plunger 7 or 7', formed between the milled portions 8, engages into a groove 10 of the bracing projection 4 of the brake shoe 11 or 11' and thus serves to secure the latter against axial sliding. The bar 9 further serves as a rotational securing means for the plunger 7 or 7'.
When the parking brake is actuated the plungers 7, 7' are moved axially outwards by means of the rollers 1 8 due to the axial displacement of the expansion wedge 1 7, so that they expand the brake shoes 11, 1 1', which are braced at their ends against the wheel cylinder 12.
A linear contact then exists between the end faces of the plungers 7, 7' and the envelope surface of the hemicylindrical bracing projection 4 of the associated pressure pad 3 of the brake shoes 11, 11'. Because the distance from the centre of rotation M to the envelope surface of the bracing projection 4 does not vary, the actuating stroke always remains the same regardless of the rest position of the brake shoes 11, 11'.
The brake shoes undergo their wear take-up at their far ends, on the wheel cylinder 12, and no take-up is necessary at the wedge expansion device 1.
In order to ensure that, taking into consideration the installation position of the brake, no obstruction of the free mobility between the brake shoes and the brake drum occurs, a separate adjusting device 1 3 is provided. The adjusting device 1 3 is mounted on the brake support 6 so that it can rotate, but is restrained from doing so by friction (see Fig. 4). The adjusting device 13 has an eccentrically arranged stud 1 6.
As may be seen from Fig. 1, the stud 16 of the adjusting device 1 3 engages into a cavity 1 5 of the brake shoe 11' with a play L corresponding to the lifting play of the brake shoe. A coil spring 14 is attached to the adjusting device 1 3 and engages with its free end into the cavity 1 5 of the brake shoe 11' and loads the latter towards the disengaged position. When the prescribed lifting play L is exceeded due to the wear of the brake shoe 11' the adjusting device 1 3 is turned. In the rest position, the annular spring 14 arranged on the adjusting device 13 ensures that both the brake shoes 11, 11' with the wheel cylinder 12 arranged floating between them hold the required position free of the brake drum, because the brake shoe 11' comes into abutment with the stud 1 6 of the adjusting device 13 in the region of the cavity 1 5.
In the case of the brake associated with a right hand vehicle wheel, the adjusting device is provided analogously on the brake shoe 11.

Claims (10)

1. Internal-shoe drum brake with a first expansion device between first ends of the brake shoes and a second, mechanical, expansion device arranged between the second ends of the brake shoes for the parking brake, the second, mechanical, expansion device being a wedge expansion device.
2. A brake according to Claim 1, in which the wedge expansion device has an expansion wedge and two coaxial plungers loaded by the wedge and abutting terminal pressure pads at the second ends of the brake shoes, and in which the expansion wedge and the plungers are mounted slidably in mutually perpendicular planes in a brake support.
3. A brake according to Claim 2, in which the plungers are braced against the expansion wedge through rollers.
4. A brake according to Claim 2 or Claim 3, in which the pressure pads have hemicylindrical bracing projections which are accommodated in hemicylindrical recesses in the brake support, the axes of the hemicylinders being parallel to the axis of the brake.
5. A brake according to any one of Claims 1 to 4 in which the end faces of the plungers abutting the pressure pads is flat.
6. A brake according to Claim 4, in which the plungers each have a projecting bar on their end face and the pressure pads each have a groove accommodating the bar of the associated plunger.
7. A brake according to any of Claims 1 to 6 in which there is an adjusting device.
8. A brake according to Claim 7, in which the adjusting device is mounted on the brake support so that it can rotate but is restrained from rotation by friction, and has an eccentrically arranged stud which engages a cavity in one of the brake shoes with a play corresponding to the lifting play of the brake shoe, and in which the brake shoe is engaged by a spring loading it towards the non braking position.
9. A brake according to Claim 8, in which the spring is a coil spring which is attached to the adjusting device and engages with its free end the cavity of the brake shoe.
10. A brake substantially as herein described with reference to and as illustrated in the accompanying drawings.
GB8120980A 1980-07-16 1981-07-07 Internal-shoe drum brake Expired GB2079879B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19803026938 DE3026938A1 (en) 1980-07-16 1980-07-16 INNER JAW DRUM BRAKE

Publications (2)

Publication Number Publication Date
GB2079879A true GB2079879A (en) 1982-01-27
GB2079879B GB2079879B (en) 1983-11-23

Family

ID=6107332

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8120980A Expired GB2079879B (en) 1980-07-16 1981-07-07 Internal-shoe drum brake

Country Status (5)

Country Link
AT (1) AT384660B (en)
DE (1) DE3026938A1 (en)
FR (1) FR2493442A1 (en)
GB (1) GB2079879B (en)
IT (1) IT1147383B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112897132A (en) * 2021-01-29 2021-06-04 苏州比阳特服装设备有限公司 Cloth roll frame structure for cloth spreading machine

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110159673A (en) * 2019-04-23 2019-08-23 高邮市顺达动力机电有限公司 A kind of adjustable braking drum brake

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1253586A (en) * 1969-08-12 1971-11-17 Girling Ltd Improvements relating to internal shoe-drum brakes for vehicles
GB1290784A (en) * 1970-01-16 1972-09-27
GB1418628A (en) * 1971-12-16 1975-12-24 Automotive Prod Co Ltd Internal shoe drum brakes
GB1419115A (en) * 1972-03-23 1975-12-24 Girling Ltd Shoe drum brakes provided with automatic adjusters
GB1427521A (en) * 1972-05-04 1976-03-10 Girling Ltd Shoe drum brakes for vehicles
IT1025491B (en) * 1974-11-07 1978-08-10 Cremonese Ind CARDBOARD CONTAINER PARTICULARLY FOR LOOSE CLEANING PRODUCTS
GB1476798A (en) * 1974-11-15 1977-06-16 Girling Ltd Actuator assemblies for vehicle brakes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112897132A (en) * 2021-01-29 2021-06-04 苏州比阳特服装设备有限公司 Cloth roll frame structure for cloth spreading machine
CN112897132B (en) * 2021-01-29 2024-02-02 苏州比阳特服装设备有限公司 Cloth roll rack structure for cloth spreading machine

Also Published As

Publication number Publication date
FR2493442A1 (en) 1982-05-07
IT1147383B (en) 1986-11-19
IT8112582A0 (en) 1981-07-14
AT384660B (en) 1987-12-28
GB2079879B (en) 1983-11-23
FR2493442B1 (en) 1984-12-28
ATA301681A (en) 1987-05-15
DE3026938A1 (en) 1982-02-04

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee