GB2172054A

GB2172054A - Brake actuator

Info

Publication number: GB2172054A
Application number: GB08602725A
Authority: GB
Inventors: Haasteren Christopher P Van
Original assignee: Montalvo Corp
Current assignee: Montalvo Corp
Priority date: 1985-03-05
Filing date: 1986-02-04
Publication date: 1986-09-10
Also published as: FR2578501A1; AU5263186A; GB8602725D0; DE3600155A1; NL8600568A; IT8647717A0; IT1208454B; JPS61201941A

Abstract

A safety device in the form of a spring applied actuator includes a two-part housing (10, 11), in which a pressurized fluid is applied to a diaphragm 12 to compresses a set of springs (23, 24) within the housing, in order to maintain a friction surface (4) in a retracted condition and apart from a rotating surface (R). A diminution of fluid pressure enables the previously compressed spring set (23, 24) to expand and to push the previously retracted friction surface (4) into contact with the rotating surface (R) with sufficient force to stop the rotation thereof. <IMAGE>

Description

SPECIFICATION A safety device The invention relates to the construction of a safety device for automatically controlling the movement of a rotating member.

Fluid actuated brakes and clutches having friction members driven outwardly by a pistoncylinder assembly, have been described in the Montalvo U.S. Patent No 4,366,884, in which coiled springs positioned around the external moulding studs of the piston-cylinder assembly cause the assembly to return to its original non-contacting, relaxed state when the air supply pressure is removed. Internally located within said assembly is flat, disc-like spring which is directly contacted by a pressurized fluid.

The present invention seeks to provide a safety device that is reliable, easy to manufacture, and is adaptable to a wide variety of uses. It can be used in many control situations, such as where mechanical apparatus is involved, particularly where a rotating member such as a wheel or a shaft is being utilised.

According to the invention, there is provided a safety device for- selectively controlling the movement of a moving surface, by a stationary surface, comprising means defining a first cavity defined a flexible member partially contacting a first rigid member, said flexible member being also partially spaced from said first rigid member, means for injecting a fluid under pressure into said first cavity, means defining a second cavity adjacent to said first cavity comprising said flexible member partially contacting a second rigid member, said flexible member being also partially spaced from said second rigid member, a third rigid member within said second cavity contacting said flexible member and spaced from said second rigid member, a resilient compressible means within said second cavity and positioned to simultaneously contact said second rigid member and said third rigid member, and means connecting said stationary surface to said flexible member, the arrangement of the device being such that whenever fluid under pressure is injected into said first cavity, said flexible member is moved away from said first rigid member so as to increase the size of said first cavity, and said flexible member is moved toward said second rigid member so as to decrease the size of said second cavity by compression of said resilient means therein, and so as to move said surfaces way from each other, and such that whenever said pressurized fluid is withdrawn from said first cavity, said flexible member is moved toward said first rigid member so as to decrease the size of said first cavity, and said flexible member is moved away from said second rigid member so as to increase the size of said second cavity by expansion of said resilient means therein, and so as to move said surfaces towards each other.

The safety device of the present invention includes a spring set friction module which is intended to be a safety feature suitable, for example, for installation on certain types of known brakes and clutches. It is preferably the same in appearance and the. same in phy sical size as the standard size brake, or clutch, friction module, or pod, assembly, to ensure that it can be retrofitted into an existing brake or clutch, if necessary or desirable, and can be completely interchangeable with any modu lar product in the corresponding product line.

The spring set friction module operates contrary to a standard pneumatic, or air brake which uses air pressure to actuate the brake cylinder to extend the brake cylinder piston.

The spring set friction module of the present invention does exactly the opposite, in that it utilises air pressure to retract the piston. If there is insufficient air pressure in the cylinder to retract the piston, the piston will remain in the extended position, so that the safety device will function as a brake to prevent movement of a rotatable surface to which the piston is adjacent.

The safety device of the present invention has the following advantages: Should anything happen to the air pressure supply to the safety device of the invention, such as an air supply line being blocked, or cut, resulting in loss of significant air pressure, or in loss of all the air pressure, the spring set friction module located in a brake, or clutch, would be mobilised into service as a safety device which would be extended into the braking position.

So, if for example, a safety device of the invention is installed onto a paper machine unwinding stand, and due to workman error, or accidental mishap, the paper machine loses all air pressure, the spring set safety device which requires no air pressure to operate, is mobilised into service automatically as a brake so as to force its non-rotating safety friction pad into contact with a rotating machine part for stopping the operation of the machinery.

This will prevent injury to people near the machinery and will also prevent damage to the product produced by the machinery.

Another advantage of the safety device of the present invention is as follows: Air pressure applied by a precision control device, in varying amounts, will also render the safety device useful as a continuous slip tension brake. By varying the amount of air pressure applied to the cylinder, a variabie torque range can be obtained, while still retaining the safety features of the spring set friction module.

The safety device has the advantage that it may be held in a fixed, stationary, non-rotating manner in order to stop the rotary movement of a member around which it is located, or near to which it is adjacent.

The spring set friction module consists of various parts including two sets of resilient compressible means, such as springs, located in the back end within the friction module.

There are several like springs of one set, and being of a larger diameter, than many like springs, of a second set, which are of a smal ler diameter.

The springs rest in a cavity machined into the stationary back end part of the safety device with more than one spring being placed in each cavity.

Preferably, one large spring is contained in the cavity and is gripped along its outside diameter, a small spring is preferably nested and held within the larger spring by a post within the cavity.

The embodiment of the invention consisting of a first spring, nested inside a second ,spring, has the further advantage of permitting a much greater amount of air pressure to be applied and counterbalanced in a limited compact area, than if only one solitary large spring were being utilised. This embodiment of a first spring within a second spring haS the further advantage that if one spring should become damaged or broken, the other spring can still function in a backup, or reserve, safety fashion.

The springs are held in place at one end by a circular groove in a small portion of the stationary back end of the safety device. The stationary back end serves to compress the spring sets when air pressure is introduced into a chamber on the front side of a flexible member of the piston cylinder assembly The flexible member is moved rearward causing the front end of the friction module to be moved rearward to compress the springs.

When the air pressure is removed, this allows the springs to decompress and expand outward to move a piston carrying the friction pad into the braking position.

The flexible member, which may be a diaphragm, therefore serves a dual purpose. Not only is it part of the working mechanism for the retraction and extension operation, but is also serves as a fluid-tight seal between the stationary back end and the movable front end of the module. The back end and the front end are joined together by suitable fastener means.

The front end of the module houses a fluid sealing means which provides a fluid-tight seal for the front end piston part to prevent loss of fluid pressure, such as air or hydraulic pressure, during and after the piston extension and retraction strokes. The front end also serves as a limitation on the length of travel by the piston to prevent the piston assembly, from retracting too far inwardly, or from extending too far outwardly, beyond the maximum length of its stroke. The front end also houses the fluid vents for introducing, or exhausting, pressurized fluid such as air via two or more orifice ports such as shaped fittings placed into holes in the front end.

The front end houses a piston which is one of the working members of the piston cylinder module assembly, because it is capable of extending and retracting the safety devices nonrotatable stationary friction pad against the brake, or clutch, rotary friction surface. The front end piston, usually made of a strong, tough solid material, houses means which fixedly hold the friction pad stationary and nonrotatably and which serves to retract the friction pad when the piston is retracted within the pneumatic or hydraulic cylinder.

The front end including the piston, and the back end, are fastened together by a suitable fastener means, sealing the flexible member between them. Thus, as an assembly, the front end and the back end can be transported as one unit or module, and can also be easily disassembled to inspect, or to replace, any worn out or damaged parts.

The module also contains two torque posts made of a strong solid material. These torque posts serve to stop and prevent any twisting motion of the friction pad when the brake is applied to a rotating surface. These posts keep the friction pad as stationary as possible and also keep the pad from falling out of the cylinder brake assembly, when in the retracted position. The torque posts also join torque arm retainer plates to the front end and the rear end of the brake module.

Torque posts are inserted into holes through the torque arm plates, and are peened over against the backside of assembly housing opposite the piston. The torque arm plates. serve to hold the module assembly to the brake mounting bracket by inserting suitable fastener means, through the torque arm plates and being fastened into the mounting bracket.

Generally speaking, the safety device of the present invention is directed to a spring set friction module, in which a pressurized fluid compresses a set of springs within the module, in order to maintain a friction surface retracted and apart from a rotating surface, and in which a diminution or loss of this fluid pressure enables the previously compressed spring set to expand and to push the previously retracted friction surface into contact with the rotating surface with sufficient force to stop the rotation thereof.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig 1 shows a top view of the safety device of the invention with a friction pad, Fig 2 shows a side view of the safety device of Fig f with the friction pad retracted, Fig 3 shows a bottom view of the safety device of Fig 1 Fig 4 shows a sectional view along the line 4-4 of Fig 1 with the friction pad extended, and with the view having been rotated through 90" clockwise, Fig 5 shows a section along the line 5-5 of Fig 1 with the friction pad retracted, and with the view having been rotated through 90" clockwise, Fig 6 shows a top view of a second embodiment of the safety device of the present invention mounted on a rotatable shaft, Fig 7 shows an axial end view of the safety device of Fig 6 as viewed along the rotatable shaft, Fig 8 shows an axial section of the safety device along the line 8-8 of Fig 7, with the friction pad extended Fig 9 shows a section of the safety device along the line 9-9 of Fig 7, with the friction pad retracted, Fig 10 shows the safety device of the invention utilised in combination with a rotatable wheel, Fig 11 shows a sectional view taken along the line Il-lI of Fig 10, Fig 12 shows the safety device of the invention utilised in combination with a rotatable disc, Fig 13 shows a side view of the arrangement Fig 12, Fig 14 shows the safety device of the invention utilised in combination with both a rotatable wheel and a rotatable disc, and Fig 15 shows a side view of the arrangement of Fig 14.

As can be seen from the drawings, Fig 1 shows a top view of a safety device 1 in accordance with this invention having a friction pad 2. The friction pad or shoe is stationary and immovable when in use. By 'stationary' it is intended to be understood rotatable, but yet is reciprocatable into and out of contact with a relatively rotating member. When in contact with the rotating member, pad 2 is held tightly in position as part of the safety device such that this friction pad will remain immovable, stationary, and non-rotatable while being in use. The friction pad or shoe 2 is usually formed from a carbon material with a graphite base material.

Fig 2 shows a side view of the safety device of Fig 1 with the friction pad 2 retracted, friction pad 2 resting snugly against upper retainer plate 3 of the safety device. The top or face surface 4 of friction pad 2 is parallel to plate 3, and the bottom or rear surface 5 (shown in Fig 4) of pad 2 is also parallel to plate 3.

As shown in Fig 1, the friction pad or shoe 2 has two sides substantially parallel to each other, and two sides which are convex in shape connecting the two parallel sides. Each of the convex sides of the friction pad has a slot 6 integrally formed therein.

Fitted within each slot 6 is a fastener means 7, such as. a metal torque post, comprised of brass. The torque post 7 can be more clearly seen from Fig 4. These torque posts 7 serve to stop any twisting motion of the friction pad 2 when the safety device is applied to a rotating surface the movement of which it is intended to stop. These torque posts keep the friction pad as stationary as possible, and also keep the friction pad from falling out of the safety device braking means when in the retracted position. As shown in Fig 4, these torque posts 7 also join the upper retaining plate 3 and the lower retaining plate 8 together in such a way as to contain therebetween all of the working elements that comprise the piston-cylinder assembly of the safety device.The torque posts 7 are inserted into holes through torque arm plates 3 and 8 and are flattened out, or peened over, onto the back face of the lower retaining plate 8 of the safety device 1.

As shown in Figs 4 and 5, a spacer 9 serves to cover the peened rivet head of the torque post, and mount the rear torque arm or lower retaining plate 8 flush with the surface of the rear portion of the safety device of the invention. This can readily be seen from Figs 3, 4 and 5.

The safety device 1 of the present invention includes a spring loaded module, which is intended to activate a friction surface and be utilised as a safety feature for installation on certain types of brakes and clutches. Figs 2, 4 and 5 show that the spring set friction module comprises a front end 10 and a back end 11.

The front end 10 is that part of the module which is adjacent to the friction pad 2. The back end 11 of the module is that part remote from the friction pad 2.

Fig 4 shows a section view along line 4-4 of Fig 1 with the friction pad 2 being extended away from the front surface of the upper plate, this view being rotated clockwise through 90".

Fig 5 shows a section view along line 5-5 of Fig 1 with the friction pad 2 being retracted and adjacent to front surface of upper plate 3, this view also being rotated clockwise through 90".

Separating front end 10 from back end 11 is a diaphragm 12, as shown in Figs 4 and 5.

As shown in Figs 4 and 5, the front end 10 includes a piston 13 which carries a magnetic ring 14. The graphite friction shoe 2 carries a steel ring 15 on its inner surface adjacent to magnetic ring 14, which serves to retain the friction pad 2 securely in position adjacent to the piston 13.

Fig 4 shows the friction pad 2 extended outwardly away from the upper retaining plate 3, and into contact with surface S of rotatable member R, which may be made of cast iron.

Fig 5 shows the friction pad 2 retracted toward and in contact with the upper retaining plate 3.

As shown in Figs 4 and 5, the safety device generally comprises a means comprising a first cavity 16 which is defined by a fluidimpervious rubber or fabric flexible diaphragm member 12 which partially contacts a first rigid member 17 which is a part of front end 10. The flexible member 12 is partially spaced from the first rigid member 17, to form the cavity 16 as shown in Figs 4 and 5. As shown in Fig 5, there is a means 18 for injecting a hydraulic or a pneumatic fluid, such as air, under pressure into the first cavity 16.

This fluid injection means 18 includes a conduit which is fastened to the front end 10 of the safety device and also includes nozzle 19 which opens into the first cavity 16. Means 18 is also used for withdrawing, and exhausting, fluid from within the safety device.

The safety device also includes means shown in Figs 4 and 5, comprising a second cavity 20 adjacent to the first cavity 16. This second cavity is defined by the flexible diaphragm member 12 which partially contacts a second rigid member 21 which is a part of the back end 11. The flexible member 12 is partially spaced from this second rigid member 21.

As also shown in Figs 4 and 5, there is a third rigid member 22 within the second cavity 20 and in contact with the flexible diaphragm member 12. The third member 22 is spaced from the second rigid member 21. Resilient compressible means 23 and 24 are located within the second cavity 20 and are positioned to contact the second rigid member 21 and the third rigid member 22 simultaneously. These resilient compressible means are a set of metallic springs composed, for example, of cadmium or zinc plated wire ('music' or 'piano' wire) compression springs. Usually there are six springs in each of the two sets. The six springs 23 of one set are alike, and are of a larger diameter, than are the six springs 24 of a second set, which are also alike and of a smaller diameter.

The two sets of springs reside in a cavity 25 machined into the stationary back end part of rigid member 21 of the metallic module, which is usually composed of steel, with the smaller diameter spring 24 nested within the larger diameter spring 23 and both being placed in each cavity 25.

One larger spring 23 is contained in the cavity and is gripped along its outside diameter. A smaller spring 24 is nested and held within the inside of the larger spring 23 by a post 26 created during the machining out of the cavity.

The embodiment having a first spring, nested inside a second spring, has the advantage of permitting a much greater amount of spring pressure to be applied and counteracted in a limited, compact area, than if only one of the larger springs were utilised. This embodiment of a first spring within a second spring has the further advantage that if one spring should become broken or damaged, the other spring can still function in a backup, or reserve, safety fashion.

The second rigid member 21 serves to compress the springs 23 and 24 when air pressure is introduced into the cavity 16 through nozzle 19 on the front side of the diaphragm 12 which is part of the piston cylinder assembly. Diaphragm 12 is moved rearward causing the front end of the module to be moved rearward in order to compress the springs between the second rigid member 21 and the third rigid member 22. When the air pressure is sufficiently reduced, this allows the springs to decompress, to expand and to move this piston 13 forwards.

Thus, whenever the pressurised fluid is injected into the first cavity, the flexible member 12 is moved away from the first rigid member 17 so as to increase the size of the first cavity 16. This increase in size can be seen by comparing the 'smaller size of cavity 16 in Fig 4 with the larger size of the cavity 16 in Fig 5. The flexible member 12 is moved toward the second rigid member 21 so as to decrease the size of the second cavity 20 from the larger size shown in Fig 4 to the smaller size shown in Fig 5. Decreasing the size of the second cavity 20 also causes compression of the springs 23 and 24 therein, so as to move this stationary surface friction pad 2 away from the moving surface S of a rotatable member R, such as the rotating disc shown in Figs 12 to 15.

Whenever the pressurized fluid is withdrawn from the first cavity 16, the flexible diaphragm member 12 is moved toward the first rigid member 17 by springs 23 and 24, so as to decrease the size of the first cavity 16. This can be seen by comparison of the larger size of the first cavity 16 shown in Fig 5, which is then shown in Fig 4 to be a cavity of much smaller size. While a decrease in the size of the first cavity 16 is occurring as the diaphragm 12 is moved away from the second rigid member 21, there is a simultaneous increase in the size of the second cavity 20.

This is shown by observing Fig 5 wherein the smaller size of the second cavity 20 is shown in comparison with Fig 4, wherein the larger size of the second cavity 20 is shown. Thus, an increase in the size of the second cavity occurs by expansion of the resilient springs 23 and 24 contained therein, so as to cause a movement of the stationary surface friction pad 2 toward the moving surface S, of rotatable member R, which member R is to have its rotary motion halted.

The safety device has a reciprocating means, piston 13, which connects the friction pad 2 to the flexible diaphragm 12, as shown in Figs 4 and 5. This connecting means, piston 13, is a Y-shaped fourth rigid member which has a wide central portion 27 with Lshaped arms 28 and 29 continuously attached thereto as shown in Figs 4 and 5. In actuality, the piston 13 includes this central portion 27 which is a cylindrical tube having a dish shaped flange integrally formed therewith, in such a manner that the outer ends are turned outward so as to form the right angular Lshaped arms 28 and 29. The central tube portion of the cylinder 27 is hollow and threaded so that attachment means 30 can be placed and held therein.

Thus, the connector means piston 13 comprises the fourth rigid member 27 having magnet 14 carried by L-shaped arms 28 and 29 for holding stationary the friction pad 2. The front surface 4 is to be maintained stationary.

The connecting means, piston 13, further comprises at the other end thereof, the means for attaching the diaphragm 12 thereto. This comprises the resilient compressible spring set 23 and 24 pressing upon the third rigid member 22, which in turn presses upon the flexible diaphragm 12, in order to hold the flexible diaphragm tightly against the fourth rigid member 13 along the central portion thereof 27.

The attachment means further comprises the means 30 for coupling the third rigid member 22 to the fourth rigid member 27 so as to fasten the flexible member 12 therebetween.

A comparison of Figs 4 and 5 shows that as the air pressure injected through nozzle 19 causes flexible diaphragm 12 to move to the left as shown in Figs 4 and 5 which is toward the back end wall 8, the coupling means 30 moves toward the back surface of second rigid member 21. The end of coupling means 30 rests in notched portion 31 thereof.

The third rigid member 22 has an outer lip 36 and an inner lip 37 for containing therebetween the nested spring sets 23 and 24.

Outer lip 36 has a smoothly curved portion in contact with the diaphragm 12.

As shown in Fig 4, between outer lip 36 and the smoothly curved portion 38 of member 21 is the cavity zone 16 within which a portion of diaphragm 12 is arcuately shaped into a curvi-linear, free-floating or rolling loop 39 such that it is not in contact with any of the rigid members of the safety device. This free floating or rolling loop 39 enables the cavity 16 to increase in size as the friction pad 2 is retracted by the piston 13 as shown in Fig 5; and it enables the cavity 16 to decrease in size as the friction pad 2 is extended outward by the piston 13 as shown in Fig 4. As shown in Fig 5 loop 39 will rest against shoulder 40 when the pad 2 is full retracted against upper retaining plate 3.

As the piston 13 moves to the left from its position as shown in Fig 4, to its position as shown in Fig 5, the maximum distance that the piston travels is shown in Fig 4 as length 32. This length of travel 32 is also equal to the maximum distance through which piston arms 28 and 29 travel as these arms move through the cylinder portion of the safety device as defined by the space between the upper retaining plate 3 and the front surface of first rigid member 17. This length of travel 32 is further equal to the maximum distance through which that central portion of diaphragm 12 connected to third rigid member 22 will move as cavity 16 is enlarged as shown in Fig. 5.

As shown in Fig 5, the front end part 10 and the back end part 11 are also connected together by auxiliary fastener means 33, such as metallic screw means.

As shown in Figs 1, 2 and 3, the safety device 1 is connected to a fixed structure, which may be, for example, a part of the frame of a machine for which the safety device, a brake cylinder assembly, is to be utilised. The safety device 1 can be connected to this fixed structure, for example, by external attachment means 34, which may be a bolt.

As shown in Figs 4 and 5, the diaphragm 12, generally speaking, separates the front end 10 from the back end 11 of the safety device. The front end 10 has a silicone O-ring seal 35 which is located within the central portion of the wall of first rigid member 17.

O-ring 35 provides a fluid tight seal for the front end part 10 around the piston 13 to prevent loss of fluid pressure, such as air pressure, during and after the extension and the retraction stroke of the piston 13. If a hydraulic fluid is to be employed, then a suitably known fluid sealing means can be used in place of silicone O-ring 35.

The front end of the safety device also serves as a travel limiter, to prevent the piston 13 from extending beyond its permitted stroke length 32. The front end 10 also serves as the air inlet portion for introducing and exhausting air via the two barbed hose fittings 18 which are screwed into the front end 10 within tapped holes therein. The piston 13 is the actual working member of the piston cylinder assembly, since it extends and retracts non-rotatable friction pad 2 against a brake, or a clutch, type of rotatable friction surface S.

Any component part of the safety device which is to be in contact with the flexible diaphragm will be rounded and/or smooth enough to prevent damaging or cutting the diaphragm.

The safety device 1 of the present invention may be used in order to selectably, frictionally engage a freely rotatable member such as one of the freely rotatable shafts and frictional surfaces as illustrated in Figs 6 to 15, in order to bring a rotating member to a complete stop.

Fig 6 shows a top view of another embodiment of the safety device of the present invention, mounted on a rotatable shaft. Fig 7 shows an axial end view of the safety device of Fig 6 along the rotatable shaft. Fig 8 shows a sectional view of the safety device along line 8-8 of Fig 7, with the friction pad extended. Fig 9 shows a section view of the safety device along line 9-9 of Fig 7, with the friction pad retracted.

Regarding Figs 6, 7, 8 and 9, the same reference numerals as used in Figs 1 to 5 are used whenever possible for the same features in Figs 6 to 9, except that in Figs 6 to 9, these reference numerals have a prefix of '200' for the same features shown therein.

Also, for the sake of brevity, a complete relisting and rediscussing of all of the features of Figs 6 to 9, which are the same as corresponding features in Figs 1 to 5, will not be repeated, except insofar as explaining the manner in which the embodiment of Figs 6 to 9 functions differently from that embodiment shown in Figs 1 to 5 is concerned.

Safety device 201 is shown in Figs 6 to 9.

Safety device 201 also incorporates the spring set safety features of Figs 1 to 5. Again, the objective of the device is to provide a failure proof mechanical means to stop a rotating mechanism. In the event of a situation which deprives the safety brake of the pneumatic pressure to keep the brake in the 'off' position, i.e. not actuated, the device would be mobilised into service, rendering enough pressure and torque, by means of the spring sets decompressing, to stop the rotating mechanism to which it has been mounted.

Safety device 201 consists of several individual parts, many of which are interchangeable with the safety device 1 discussed above.

This device has a cylindrical housing 50 mounted on a rotatable shaft 51. This housing 50 is located by a key 52 and set screw 53 fitted into shoulder 54 of friction disc 55, and by a set screw collar 56 fitted to the inner race 57 of a ball bearing first housing 58 at the back or rear end 211 of the safety device 201. Key 52 and set screw 53 are at the front end 210.

The front end 210 of the safety device also contains a second ball bearing housing 59 which is fitted around part 54. The combined functioning of the first and second ball bearing housings 58 and 59 is to keep the safety device 201 running concentrically to the shaft 51, by preventing any internal components from contacting the shaft. This can be seen in Figs 8 and 9, wherein the non-contact, tolerance spacing, or gap 60 is maintained between the rotatable shaft 51 and the nonrotatable, but yet reciprocatable, or else immovable, parts of the safety device. The nonrotatable, but reciprocatable friction pad 202, will be held immovable and stationary when pressed against brake disc 55.

While the friction disc 55 will rotate whenever the mounting shaft 51 is rotating, all the other components are fixed and stationary. As shown in Fig 9, this is accomplished by attaching a mounting bracket (not shown) between a solid stationary part of the machinery and the device 201. Tapped holes 61 are provided in housing 50 and holes 62 are in back end 211 for this purpose. This allows the friction brake disc 55 to rotate along with the shaft 51, while all the other components within the housing 50 remain non-rotational.

The stationary, non-rotatable friction pad 202 is positioned around the first movable surface, or shaft 51 and adjacent to the second movable surface, or disc brake 55, by at least one of, or by both of, the two sets of ball bearings in the two raceway housings 58 and 59.

As shown in Figs 8 and 9, there is a reciprocating means, or piston 213, which connects the friction pad 202 with the flexible diaphragm 212. Piston 213 has a central portion 227 with a concentric bore completely therethrough, which provides a clearance space around the rotating shaft 51, allowing the piston to reciprocate freely over the shaft.

Central portion 227 is threaded at both ends, such that the dish shaped threaded flange having right angular L-shaped arms 228 and 229 may be attached thereto at joint 63. At the other end of portion 227, the threaded third rigid member 222 is attached thereto at threaded joint 64.

As shown in Fig 8, the first rigid member is means 217; the second rigid member is means 221; the third rigid member is means 222; and the fourth rigid member is reciprocating piston 213. The threaded joint 64 is part of the central portion 227 and is part of the means at the back end of the fourth rigid member 213 for attaching the flexible diaphragm 212 thereto. This threaded joint 64 is thus part of the means for coupling the third rigid member 222 to the fourth rigid member 213 so as to fasten the flexible diaphragm therebetween.

The housing 50 which is metallic, may be made from aluminium, and serves to tie the safety device 201 together. The housing 50 slides axially over ail the components to be contained therewithin, and is internally supported by the first and second set of ball bearings within the housings 58 and 59. The housing 50 is held in the proper position by the fastener means, or metallic screws, 61, shown in Figs 6, 7 and 9.

When changing of the friction pad 202 becomes necessary, the amount of friction pad wear can be seen through the vent slots 65 spaced evenly around the exterior of the housing. These ports 65 also serve to allow heat built up by friction between the pad 202 and the disc 55 to escape into the atmosphere thus cooling the internal components. To change friction pads 202, the screws 61 are removed from the housing 50 and the set screw collar 56 on the back end of the shaft 60 is loosened. The two air hose fittings 218 and the inner assembly are slipped out from inside the housing, providing easy access to the friction pad 202.

In summary, safety device 201 functions in the same manner as the safety device 1, since both devices 1 and 201 contain a spring set friction module. However, the devices 1 and 201 differ in that the safety device 1 is intended to be used as a component of a brake or clutch, singly or in multiple units to achieve a desired safety range or torque factor. Safety device 201 is an integral unit, designed to be used alone in braking or clutch operations.

The safety device may be used in a continuous slip operation wherein the spring set friction module would rest in the retracted position with air pressure on the diaphragm to compress the springs. If for instance an operator of winding machinery prematurely turns off air pressure or significantly reduces the air supply so as to hinder proper operation of the standard pods, resulting in loss of tension on the would material, the spring set friction module would actuate and reinstate the tension requirements, or put enough pressure on the mechanism to stop it. This would prevent any damage to the product being wound, or wound prevent injuries to personnel, until such a time as the cause of the problem is found and corrected, or the machinery is shut down.

The spring set friction modules thus cause the safety device to compensate for the rest of the braking systems if it should become operational. In a purely safety orientated operation, a brake or clutch containing only spring set modules would rest, until the occasion when it is needed such as in an emergency. Then it would spring into operation, by controlled, or not controlled circumstances.

Fig 10 shows the safety device 1 utilised in combination with rotatable brake wheel 70.

While Fig 10 shows the possible use of three safety devices 1, only one such safety device is necessary. Fig 10 also indicates how safety device 1 can be pivotally swung outwardly (in phantom lines 1A) away from brake wheel 70 around external attachment means 34. This enables the safety device 1 to be inspected, repaired or replaced in a periodic fashion. This pivotal swing of the safety device 1 is also shown in Fig 12 (in the phantom lines IA).

Slotted channel 95 in Fig 14 also provides a means for this pivotal swing of device 1.

Fig 11 shows a sectional view of the combination of Fig 10 along line 11-11 of Fig 10.

The rotatable wheel 70 is composed of two parallel discs 71 and 72 aligned so as to have the same longitudinal axis, and each disc having the same diameter as the other disc.

These two parallel discs 71 and 72 are joined together at the central portion 73 of the wheel. A rotatable shaft 74 is fastended within a channel in the center of the central portion 73 of the wheel.

There are a plurality of coolings fins 75 equally arcuately spaced and extending radially outwardly to the periphery of each rotatable disc from a point approximately midway on each disc, as measured radially from the centreline of the shaft 74.

External attachment means 34, for the safety device 1 includes a bolt, or stud, which passes through a flange 76 which is connected to an immovable fixed structure (not shown) such as part of the frame of a machine, or part of a building structure, adjacent to the safety device 1. A coiled spring 77, which is optionally positioned around each bolt, serves to absorb vibrations and to minimise movement out of alignment by the safety device 1 during use.

The safety device 1 of Fig 11 is supplied with air under pressure through fluid supply line 78. This safety device comprises a tandem pair of back to back spring set friction modules and having dual friction pads 2 and 2A. These pads 2 and 2A are parallel to each other and are parallel to the inside surfaces of the discs 71 and 72 respectively.

Even though there are dule safety devices, and two friction pads, shown in Fig 11, only one single pad 2 is necessary to adequately serve to halt the rotation of wheel 70.

Whenever there is sufficient pressure in the fluid supply line 78, the dual friction pads 2 and 2A would be retracted away from, and be held out of contact with, the inside surfaces of rotatable discs 71 and 72. This would permit these discs to freely rotate, as wheel 70 spins abouts its rotating shaft 74. If there should be a significant decrease in the pressure in the fluid supply line 78, then the dual friction pads 2 and 2A would be extended outwardly and away from each other.

Eventually pads 2 and 2A would extend into non-rotatable contact with the spinning inside surfaces of rotating discs 71 and 72, with such force as to bring to a halt the rotating wheel 70 and the rotating shaft 74.

Figs 12 and 13 show the safety device 1 utilised in combination with a solitary disc brake 80. The safety device 1 is structured and positioned to be in the nature of a caiiper arrangement relative to the disc 80.

As shown in Fig 13, there are at least two safety devices 1, with each one being mounted parallel to disc 80 and to each other, on the opposite side of the disc 80. External attachment means 34 help to position and to maintain these safety devices 1 in this fixed relationship by attaching the safety devices to footmount L-shaped bracket 81. Bracket 81 is connected to an immovable fixed structure 82.

The safety devices of Fig 13 are supplied with air under pressure through fluid supply lines 78. The safety device comprises a pair of safety devices 1 positioned such that friction pads 2 and 2A are on opposite sides of disc 80 and are parallel to the rotatable surfaces of disc 80.

Even though there is a pair of safety devices, and two friction pads, shown in Fig 13, only one single pad 2 is necessary to adequately halt the rotation of disc 80.

Whenever there is sufficient air pressure in the fluid supply lines 78, the pair of friction pads 2 and 2A would be retracted away from, and be held out of contact with, the opposite sides of rotatable disc 80. This would permit the disc 80 to freely rotate about its spinning shaft 83. If there should be a significant decrease in the pressure in the fluid supply lines 78, then the pair of friction pads 2 and 2A would be extended outwardly from each's device 1, and towards each other. Eventually friction pads 2 and 2A would extend into non-rotatable contact with the spinning opposite sides of rotating disc 80, with such force as to bring to a halt the rotating disc 80 and the rotating shaft 83.

Figs 14 and 15 show the safety device 1 utilised in combination with both a rotatable wheel, similar to wheel 70 of Figs 10 and 11, and a rotatable disc, similar to disc 80 of Figs 12 and 13. Wheel 70 and disc 80 are attached together and rotate together about shaft 74 in such a manner as to be coaxial and concentric about shaft 74 which is a common axis of rotation. For the sake of brevity, the above-discussed description of the operation of these component parts 70 and 80 will not be repeated.

Figs 14 and 15 also show that the same fluid supply metering system 90 can be provided for controlling the air pressure and the volumetric flow rate simultaneously to the fluid supply lines 78 for the safety device that are placed adjacent to the wheel 70 and the disc 80.

The metering system 90 is to control the air pressure in the fluid supply transmission lines 91 and 92. This is done in such a manner as to coordinate the pressure in the transmission line 91 to the disc pressure distributor 93, with the pressure in the transmission line 92 to the wheel pressure distributor 94.

Air under sufficient pressure flows through supply line 91 into the disc pressure distributor 93, wherein it is redistributed through lines 78 into the safety devices 1 arranged in caliper fashion on the opposite surfaces of the disc 80. Air at the same sufficient pressure flows through supply line 92 into the wheel pressure distributor 94, wherein it is redistributed through lines 78 into the safety devices 1 arranged adjacent to the inside surfaces of wheel 70.

As long as the air pressure to the control system 90 is sufficient, the friction pads 2 and 2A will be retracted and held away from the rotating surface to which it is adjacent, thus permitting the rotation thereof to continue. If the air pressure should descrease significantly, the control system 90 would coordinate this drop in pressure so as to equalise the same throughout the transmission lines 91 and 92. This would equalise the pressure into the distributors 93 and 94, causing pressure equalization through all lines 78 into all of the safety devices 1. Hence all of the safety devices 1 would react to the pressure drop by simultaneously extending the friction pad outwardly into non-rotational contact with the rotating surfaces. Thus the rotational movement of the'disc brake 80, the wheel brake 70 and the shaft 74 will be halted simultaneously.

The combination of the safety device 1 with a rotatable wheel brake 70 adjacent thereto and/or with a rotatable disc brake 80 adjacent thereto is a safety assembly. Preferably the wheel 70 and the brake 80, if used in combination, would be concentrically joined and coaxially positioned about a common axis of rotation.

Claims

1. A safety device for selectively controlling the movement of a moving surface, by a stationary surface, comprising means defining a first cavity defined a flexible member partially contacting a first rigid member, said flexible member being also partially spaced from said first rigid member, means for injecting a fluid under pressure into said first cavity, means defining a second cavity adjacent to said first cavity comprising said flexible member partially contacting a second rigid member, said flexible member being also partially spaced from said second rigid member, a third rigid member within said second cavity contacting said flexible member and spaced from said second rigid member, a resilient compressible means within said second cavity and positioned to simultaneously contact said second rigid member and said third rigid member, and means connecting said stationary surface to said flexible member, the arrangement of the device being such that whenever fluid under pressure is injected into said first cavity, said flexible member is moved away from said first rigid member so as to increase the size of said first cavity, and said flexible member is moved toward said second rigid member so as to decrease the size of said second cavity by compression of said resilient means therein, and so as to move said surfaces away from each other, and such that whenever said pressurized fluid is withdrawn from said first cavity, said flexible member is moved toward said first rigid member so as to decrease the size of said first cavity, and said flexible member is moved away from said second rigid member so as to increase the size of said second cavity by expansion of said resilient means therein, and so as to move said surfaces towards each other.

2. A safety device according to Claim 1, wherein said resilient compressible means comprises a spring means.

3. A safety device according to Claim 2, wherein said resilient compressible means comprises a first spring nested inside a second spring.

4. A safety device according to any one of Claims 1 to 3 wherein said connecting means comprises a fourth rigid member having means for carrying said stationary surface at one end thereof.

5. A safety device according to Claim 4, wherein said connecting means further comprises means at the other end of said fourth rigid member for attaching said flexible member thereto.

6. A safety device according to Claim 5, wherein said means for attaching the flexible member comprises said resilient compressible means pressing upon said third rigid member, which in turn presses upon said flexible member, in order to hold said flexible member tightly against said fourth rigid member.

7. A safety device according to Claim 6, wherein said means for attaching the flexible member further comprises means for coupling said third rigid member to said fourth rigid member so as to fasten said flexible member therebetween.

8. A safety device according to any one of Claims 1 to 7 and further comprising means for positioning said stationary surface around a first movable surface and adjacent to a second movable surface.

9. A safety device according to Claim 8, wherein said positioning means comprises at least one set of ball bearings in a raceway housing.

10. A safety device according to Claim 8 or Claim 9, wherein said means for positioning comprises a first set of ball bearings in a first raceway housing at one end of said safety device, and a second set of ball bearings in a second raceway housing at another end of said safety device.

11. An arrangement comprising at least one safety device according to any one of Claims 1 to 10 and a rotatable wheel adjacent to the or each said safety device.

12. An arrangement comprising at least one safety device according to any one of Claims 1 to 10 and a rotatable disc adjacent to the or each said safety device.

13. An arrangement comprising at least two safety devices according to any one of Claims 1 to 10, a rotatable wheel adjacent to one of said safety devices, and a rotatable disc joined to said rotatable wheel and adjacent to the or each of the other said safety devices, said wheel and disc being concentrically joined and coaxially positioned about a common axis of rotation.

14. A safety device for selectively controlling the movement of a moving surface, by means of a stationary surface, comprising a spring set friction module having means for injecting therein a fluid under pressure for compressing a set of springs within said module, in order to maintain said stationary surface retracted and apart from said moving surface, and wherein a diminution of this fluid pressure enables the previously compressed spring set to expand and to push said previously retracted stationary surface into contact with said moving surface with sufficient force to stop the movement thereof.

15. A safety device substantially as hereinbefore described and with reference to Figures 1 to 5, or Figures 1 to 5 modified as shown in Figures 6 to 9, 10 and 11, 12 and 13 or Figures 14 and 15 of the accompanying drawings.

CLAIMS Amendments to the claims have been filed, and have the following effect: Claim 1 above has been deleted or textually amended.

New or textually amended claims have been filed as follows:

1. A safety device for selectively controlling the movement of a moving surface, by means of a stationary surface, comprising means defining a first cavity defined a flexible member partially contacting a first rigid member, said flexible member being also partially spaced from said first rigid member, means for injecting a fluid under pressure into said first cavity, means defining a second cavity adjacent to said first cavity comprising said flexible member partially contacting a second rigid member, said flexible member being also partially spaced from said second rigid member, a third rigid member within said second cavity contacting said flexible member and spaced from said seconf rigid member, a resilient compressible means within said second cavity and positioned to simultaneously contact said second rigid member and said third rigid member, and means connecting said stationary surface to said flexible member, the arrangement of the device being such that whenever fluid under pressure is injected into said first cavity, said flexible member is moved away from said first rigid member so as to increase the size of said first cavity, and said flexible member is moved toward said second rigid member so as to decrease the size of said second cavity by compression of said resilient means therein, and so as to move said surfaces away from each other, and such that whenever said pressurised fluid is withdrawn from said first cavity, said flexible member is moved toward said first rigid member so as to decrease the size of said first cavity, and said flexible member is moved away from said second rigid member so as to increase the size of said second cavity by expansion of said resilient means therein, and so as to move said surfaces towards each other.