A BRAKE ASSEMBLY

Abstract: Improved brake assembly which may be utilized to automatically brake a driven shaft or the like. The brake assembly (18) includes a rotatable brake disc (26) about which a fixed brake pad (27) on one side of the disc and a movable brake pad (28) on the opposite side of the disc are automatically actuated to engage and disengage the disc. The actuating means includes a hydraulic ram assembly (40) incorporating a piston (41) biassed by a coil spring (43) towards the engaged position. An actuating lever (37), connected to the ram, rotates the movable brake pad, which, by means of complementary mating ramp faces or helical inserts (34) received within the complementary annular recesses (32, 33) urges the brake pad into engagement with the rotatable brake disc.

Description: ABRAKEASSEMBLY This invention relates to an improved brake assembly and in particular it relates to a brake assembly applicable to hydraulic motors although it is not exclusively for use with such motors. The present invention has wide application as braking means for a power plant and in particular in relation to power plants coupled to winches. Such winches may be relatively small types, such as those attachable to vehicles or, alternatively, they may be of the large industrial type used on building sites and the like to elevate building materials. At present, the braking arrangements associated with such winch and drive assemblies are generally of the contracting band type in which a brake drum is provided with an external band which may be tightened about the drum either manually or automatically if desired. A disadvantage of such arrangements is that the complete brake assembly is relatively cumbersome since the brake drum has to be sufficiently wide tp provide the necessary frictional area. Additionally, such brakes are generally exposed and this can create a working condition in which the life of the brake is extremely short and it may also provide exposed moving machinery which can be hazardous to operators. Furthermore, the brake assemblies are generally mounted on the appliance which is being driven as they are custom manufactured to suit the particular application It is an object of the present invention to provide in one aspect an improved brake assembly which will alleviate the abovementioned disadvantages. It is also an object of the present invention to provide an improved brake assembly which may be easily fitted to drive motors such as hydraulic motors to provide a unit comprising a motor and brake assembly which will be easily attachable to apparatus to be driven. In a further aspect, the present invention aims to provide an improved winch assembly which will alleviate the disadvantages of the prior art devices described above and which will prove reliable and efficient in operation. Other objects and advantages of the present invention will hereinafter become apparent. With the foregoing and other objects in view, this invention in one aspect resides broadly in an improved brake assembly including:- support means; a rotatable brake plate assembly having a braking surface; a brake pad assembly supported by said support means for selective engagement with said braking surface and there being provided actuating means to urge said brake pad assembly and said brake plate into engagement. Preferably the actuating means is biassed towards the braking position and there are provided releasing means operable to hold the actuating means in an inoperative position. Suitably, the actuating means is spring biassed towards the braking position and the releasing means includes a fluid actuated ram assembly. It is also preferred that when the brake assembly is adapted for use with a hydraulic motor the fluid actuated ram assembly is operatively connected to the fluid supply for the motor whereby during operation of the motor the releasing means will move the actuating means to the inoperative position until fluid supply to the hydraulic motor is stopped whereupon the biassing means will move the actuating means to the engaged position. Preferably the braking plate is engageable at opposite sides by a pair of brake pads one of which is a fixed pad and one a movable pad pivotable about the axis of rotation of the braking plate and operatively associated with ramp means such that upon pivoting the brake pad is moved axially towards or away from the braking plate. Suitably, the ramp means comprises co-operating helical form faces on the movable brake plate and the support structure respectively and preferably the helical faces are provided on co-operating inserts spaced around said brake pad. In a further aspect, the present invention resides broadly in a brake assembly adapted to be mounted on a motor whereby the motor and brake assembly may be easily affixed to a utility to be driven, the braking assembly being of the type described above and said braking plate being supported on an adaptor having a first mounting portion securable to the drive shaft of the motor and a second mounting portion adapted to be connected to the utility to be driven. Preferably the arrangement is such that the second mounting portion is substantially identical to the drive shaft of the motor and its relationship with the mounting arrangement provided on the brake assembly is substantially identical to the mounting arrangement on the motor to which the brake assembly is coupled whereby the motor with the brake assembly attached thereto can be mounted directly to a utility to be driven provided with mountings for securing the motor. In a further aspect the present invention resides in a winch assembly including a winch drum mounted for rotation within a support frame and there being provided a motor and brake assembly substantially as described above coupled to said drum to rotate same. Preferably the winch drum is provided with mounting means on each end thereof whereby a motor and brake assembly can be supported at either end of the drum. It is also preferred that the braking plate be secured to a splined adaptor whereby it may move axially for engagement between the respective brake pads. For this purpose, the braking plate may have a splined connection or the like to the adaptor which alternatively may be provided with spline connectors or the like for connection to the output shaft of the motor and the winch drum. It is also preferred that the brake assembly be encased within a housing to exclude grit and other foreign matter from entering into the brake assembly. Of course the latter may be a single plate brake assembly or a multiple plate brake assembly as desired. In order that the invention may more readily be understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention illustrated in the form of a winch assembly wherei :- FIG. 1 is a part cross sectional view of one end portion of a winch assembly made in accordance with the present invention; FIG. 2 is a cross sectional view of the brake assembly through the line 2-2 of FIG. 1 in the disengaged position; FIG. 3 is a view similar to FIG. 2 but illustrating the brake assembly in the engaged position; FIG. 4 collectively illustrates in side elevational view and in plan view, the co-operation of the helical inserts of the brake assembly in the disengaged position; FIG. 5 illustrates the helical inserts in the engaged position; and FIG. 6 collectively illustrates in plan; side elevation; inverted plan and in end view an insert made in accordance with one aspect of the present invention. The winch assembly 10 in FIG. 1 includes a winch drum 11 supported between end flanges 12 (only one of which is shown) on a central shaft 13 by bearings 14 for rotation about a central axis 15 within the fixed support housing 16. The latter at each end thereof is provided with a plurality of tapped apertures 17 to enable the brake assembly 18 to be bolted thereto which in turn is provided with a plurality of tapped apertures 19 to enable the hydraulic motor 20 to be mounted. A splined coupling member 21 is provided with an internal spline 22 for connection to the output shaft 23 of the motor 20 and an external spline 24 adapted to be engaged in a corresponding internal spline 25 provided in both ends of the central shaft 13. The brake plate 26 is a disc-like member fixed concentrically about or to the splined coupling member 21 for rotation therewith and it is supported between a fixed brake pad assembly 27 on one side of the disc and a movable brake pad assembly 28 at the opposite side of the disc. Each brake pad is provided with facings 29 as illustrated. The movable brake pad assembly 28 is in the form of an annular disc rotatable about a hub portion 30 provided on the fixed housing 31 of the brake assembly 18 and complementary annular recesses 32 and 33 are formed in the mating faces of the brake pad 28 and a fixed housing 31 to receive a plurality of pairs of helical inserts 34 as best illustrated in FIG. 2. Each insert is identical and is received neatly in the respective recesses 32 and 33 and each insert 34 is provided with a locking boss 35 adapted to be located in counter bores machines into the recesses 32 and 33 so as to locate the inserts in their operative position. Furthermore, the brake pad 28 is provided with a recess 36 to accommodate an actuating lever 37 which projects radially therefrom for connection to the actuating shaft 38 of the actuating means 39 supported on the fixed housing 31 as illustrated. The actuating means 39 includes a hydraulic ram assembly 40 incorporating piston 41 which is biassed by the coil spring 42 towards the engaged position as shown in FIG. 3. The actuating assembly 39 is further provided with an inlet aperture 43 whereby the cylinder 44 is placed in fluid communication with the fluid supply to the hydraulic motor and the piston and spring are so designed that the normal working fluid pressure of the hydraulic motor applied to the cylinder 44 will force the piston 41 to a disengaged position as illustrated in FIG. 2 against the pressure of spring 42. In this position, the co-operating inserts 34 are pivoted about the axis 15 such that their respective helical ramp surfaces 45 are moved to a position in which the braking pad 28 abuts the fixed housing 31. An adjustable stop assembly 50 is provided to limit the travel of the piston 41 to the disengaged position and the arrangement is such that the piston 41 will move to this position under the influence of a fluid pressure considerably less than the normal working fluid pressure of the motor 20. The stop assembly 50 has an abutment portion 51 disposed inwardly of the coil spring 42 whereby the latter cannot be compressed to a bottomed position. However, when the fluid supply to the hydraulic motor 20 is stopped the fluid ■ pressure in the cylinder 44 is relieved and the spring 42 immediately urges the shaft 38 through the cylinder causing the actuating lever 37 to move to its engaged position carrying the braking pad 28 with it pivotally about the axis 15. This causes the respective ramp surfaces 45 to move across one another and forces the braking pad 28 away from the housing 31 towards the braking plate 26. The latter initially moves axially as it is supported on the splined coupling member 21 until it is clamped firmly between the braking pad 28 and the fixed pad 26. This will immediately brake the winch drum 11 and the output shaft 23 of the motor to a stop and the braking effort will be maintained until the motor 20 is again actuated whereupon the hydraulic pressure applied to the cylinder 44 will release the braking means. The surface of the helical inserts are machined to the same helical form as a screw thread such that as the braking pad 28 pivots, full surface to surface contact is maintained between the opposing inserts irrespective of their operative relative positions. This will ensure efficient actuation of the brake and against accidental locking through say jamming which could result if straight ramped members were utilized. Since the accuracy of machining and surface finish and nature of the helical surfaces 35 is extremely important, the inserts 34 can be manufactured accurately to ensure correctness of operation. Alternatively, if inserts are not used larger components would have to be manufactured and heat treated and this would result in a much more costly construction. However, in certain instances, it could be beneficial to provide such an arrangement. It will be seen that the fixed brake pad 27 is secured to the housing' 31 and the winch assembly by the through bolts engaging the threaded apertures 17 and that the movable pad 28 is in close relationship to the - face of the housing 31. Thus heat generated during the braking operations is quickly dissipated by conduction through the heavy metal housing to both the brake drum and the motor 20. It will also be seen that the housing 31 is recessed at 46 for location about a boss on the motor 20 and that the overall axial length of the brake assembly is relatively short. This is advantageous in maintaining the overall length of the winch assembly as short as possible. However, in a particular installation if the winch is not so mounted to provide adequate clearance at one end, the motor and brake assembly may be simply moved for mounting on the opposite end of the winch without making further alterations to the apparatus, it being understood that the end portion of the winch drum assembly 10 which is not shown is identical to the end portion illustrated whereby the shaft 13 is supported by the support housing 16 at each end and does not rely on the motor for location or support. Also if desired, the winching capacity of the winch assembly may be doubled by mounting a motor and/or a brake assembly at each end thereof. Alternate means may be utilised to actuate the brake assembly. For example, a peripheral worm drive may be used to pivot the movable brake pad, the brake assembly may be used with electric motors or with internal combustion engines or the like, however in such cases an auxilliary oil pressure supply would be required to operate the actuating means 39. However, mechanical or electrical means could be utilised as desired to move the actuating means to the inoperative position against the biassing means. For instance, if automatic actuation is not required, a simple manual override or actuating means may be provided. The arrangements of inserts 34 as illustrated for the actuation of the brake pad 28 could be varied to suit the application. For example one full circular or two semi-circular inserts could be provided in lieu of the three inserts 34 as illustrated and of course the angle of the helical ramp surface can be varied as desired. When referring to a hydraulic motor herein this reference is to be taken as a reference to any fluid actuated motor such as a pneumatic motor. The brake assembly of the present invention will be found to be particularly useful as a safety brake on winches and personnel lifts and the like where fail-safe operation is necessary. However, it may be used successfully in other applications such as in application in which the surrounding conditions are harsh due to the presence of abrasive material which would normally foreshorten life expectancy of braking systems having exposed wearing surfaces. All such and other modifications and variations to the present invention as would be apparent to persons skilled in the art and deemed to fall within the broad scope and ambit of the present invention as is defined in the appended claims

Claims: CLAIMS : 1. An improved brake assembly including: support means; a rotatable brake plate assembly having a braking surface; a brake pad assembly supported by said support means for selective engagement with said braking surface and there being provided actuating means to urge said brake pad assembly and said brake plate into engagement. 2. A brake assembly according to claim 1, wherein said brake pad assembly is movable towards or away from said brake plate assembly and said actuating means includes complementary mating ramp faces arranged on said movable brake pad assembly and said support means respectively and there being provided drive means to urge said brake pad assembly relative to said support means so as to cause relative operational movement between said complementary mating ramp faces. 3. A brake assembly accordingto claim 2, wherein each said complementary ramp face has a substantially helical form. 4. A locking assembly according to claim 2 or claim 3, wherein said ramp faces are formed on inserts disengageable from said movable brake pad assembly and said support means. 5. A brake assembly according to claim 4, wherein said inserts are each located in a respective annular groove extending concentrically around said movable braking pad assembly and said support means and there being provided connector means to secure said inserts into the respective said groove. 6. A brake assembly according to claim 5, wherein said groove in said movable brake pad assembly is formed at the side thereof remote from said brake plate assembly. 7. A brake assembly according to anyone of the preceding claims, wherein said brake plate assembly is support between said movable brake pad assembly and a fixed brake pad assembly. 8. A brake assembly according to claim 7, wherein said brake plate assembly is adapted to be supported on a rotatable member to be braked whereby the brake plate assembly may move along the axis of rotation of said rotatable member. 9. A brake assembly according to anyone of claims 2-8, wherein said actuating means includes drive means to actuate said movable brake pad assembly, said drive means including biassing means, biassing said brake pad assembly to an engaged position and override means adapted to be actuated to override said biassing means and move said movable brake pad assembly to a disengaged position. 10. A brake assembly according to claim 9, wherein said biassing means is in the form of a spring and said override means is in the form of a fluid actuated ram assembly. 11. A brake assembly according to claim 10, wherein said fluid actuated ram assembly is a hydraulic ram assembly adapted to be arranged in fluid communication with a hydraulic motor to be braked by said brake assembly, the arrangement being such that during actuation of said hydraulic motor, said fluid actuated ram will override said biassing means to release said brake assembly. 12. A brake assembly according to any one of the preceding claims, wherein said support means is in the form of a housing encasing said rotatable brake plate assembly, the latter being supported for rotation about axle means engageable with a rotatable member to be braked. 13. A winch assembly including a winch drum mounted for rotation on a support frame; drive means for rotating said winch drum and a brake assembly as defined in any one of the preceding claims operatively supported on said support frame whereby said rotatable brake plate assembly is supported for rotation with said winch drum. 14. A winch assembly according to claim 13, wherein said support frame provides alternate mountings for said brake assembly at opposite ends of said winch drum. 15. A winch assembly according to claim 13 or claim 14, wherein said drive means is supported spaced from said support frame by said brake assembly and said brake plate assembly is carried on a coupling member operatively interconnecting the output shaft of said drive means to said winch drum. 16. A winch assembly according to any one of claims 13 to 15, wherein said drive means is a hydraulic motor. 17. A winch assembly according to any one of claims 13 to 16, wherein said winch drum is supported at respective opposite ends by rolling element bearings carried by said support frame. 18. A winch assembly substantially as hereinbefore described with reference to the accompanying drawings. 19. A brake assembly substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: DANKS HECTOR REDMOND
Applicants: DANKS HECTOR REDMOND, REDMOND GARY PTY LTD
Application year: 1982
Main classification: F16D59
IPC codes: B66D5, F16D55, F16D59, F16D65