US3092345A

US3092345A - Braking mechanisms

Info

Publication number: US3092345A
Application number: US68894A
Authority: US
Inventors: Richard W Clayton; Arnel E Jackson
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1960-11-14
Filing date: 1960-11-14
Publication date: 1963-06-04
Anticipated expiration: 1980-06-04
Also published as: GB964035A; DE1424444A1; NL271320A

Description

June 4, 1963 R. w. CLAYTON ETAL 3,092,345

BRAKING MECHANISMS Filed Nov. 14, 1960 2 Sheets-Sheet l INVENTORS f/c/mo l lMm ra/v 5 A0154 5.14000 June 1963 R. w. CLAYTON ETAL 3,092,345

BRAKING MECHANISMS 2 Sheets-Sheet 2 Filed Nov. 14, 1960 INVENTORI ,fimm'a m (Z/rrrm/ 5 BY4AM6L E E a 50M United States Patent 3,092,345 BRAKING MECHANISMS Richard W. Clayton, Toms River, and Arnel E. Jackson, Audubon, NJ., assignors to Radio Corporation of America, a corporation of Delaware Filed Nov. 14, 1960, Ser. No. 68,894 13 Claims. (Cl. 242-5542 The present invention relates to braking mechanisms, and more particularly to a braking mechanism for use in a reeling system.

The invention is especially suitable for use in apparatus for handling a reelable medium, such as a record tape. Apparatus for handling magnetic record tapes is known as a tape transport.

In a tape transport, it is necessary, during braking, to apply more braking torque to the reeling device which is supplying the tape than to the reeling device which is taking up the tape. If the proper braking torques are not applied to the reeling devices, adequate tape tension will not be maintained and the tape will be reeled out of the supply reeling device faster than it is taken up by the take-up reeling device. This causes the tape transport to throw loops of tape which can become tangled. On the other hand, tape tension should not be so great as to cause the tape to break or to stretch out of shape.

Another problem arises, during braking, when the reeling device which supplies the tape is emptied. It is then important to stop the take-up reeling device rapidly to prevent the end of the tape from whipping excessively and tearing should it engage some part of the tape transport.

Accordingly, it is an object of the present invention to provide an improved braking mechanism which will apply the braking torques to the reeling devices of a reeling system so that throwing of loops of the medium being reeled and damage to the medium is prevented.

It is a further object of the present invention to provide an improved braking mechanism in a reeling system which applies greater braking torque to the reeling device sup plying the medium being reeled than to the reeling device which takes up the medium when it is Wound on both the supply and the take-up reeling devices and which applies increased braking torque to the reeling device which takes up the medium when the medium is wound only thereon, as by being emptied from the supply reeling device.

It is a still further object of the present invention to provide an improved braking mechanism which is simple to construct and has fewer parts than known braking mechanisms of the type which provide differential braking action.

Briefly described, the invention includes a pair of brake bands which are associated, separately, with a pair of reeling devices between which a medium, such as a record tape, is adapted to be reeled. The brake bands are constructed to expand or contract under braking stresses. A rigid member is connected between one end of each of the brake bands. The other ends of the brake bands are each anchored. When the brake bands are brought into contact with the reeling devices, the rotational energy of the reeling device which supplies the tape is transmitted from the brake band associated therewith through the rigid band-interconnecting member to the other brake band which cooperates with the reeling device which takes up the tape. The brake bands associated with the reeling devices which are supplying and taking up the tape respectively expand and contract so that the bands and the interconnecting member are displaced. The brake band associated with the take-up reeling device is self-relieving since, in its displaced position, less braking is applied, while the Patented June 4, 1963 ice brake band associated with the supply reeling device is self-energizing in its displaced position since more braking is applied. Differential braking action is therefore produced. Since greater braking torque is applied to the supply reeling device than to the take-up reeling device, proper tension is maintained in the tape to prevent the throwing of tape loops.

When the tape is emptied from the supply reeling device, or when the supply reeling device is stopped, forces are no longer supplied through the rigid, band-interconnecting member to the brake band associated with the take-up reeling device. Accordingly, the bands return to their position prior to displacement and full braking torque is applied to the take-up reeling device. The take-up reeling device is then rapidly brought to a stop. This minimizes the whipping and tearing of the end portion of tape as it is reeled onto the take-up reeling device. Thus, damage to the tape is prevented.

The invention itself, both as to its organization and method of operation, as well as additional objects and advantages thereof, will become more readily apparent from a reading of the following description in connection with accompanying drawings, in which:

FIGURE 1 is a plan view showing a braking mechanism in accordance with the invention, the brakes being disposed in released position;

FIGURE 2 is a view similar to FIG. 1, but showing the braking mechanism with the brakes applied; and

FIGURE 3 is a fragmentary view of another form of brake mechanism according to the present invention.

Referring to the drawings, there is shown a pair of reeling devices 10 and 11. These reeling devices include reel drive shafts 12 and 13 which may be driven by separate electric motors (not shown). Brake hubs 14 and 15 are secured, respectively, to the shafts 12 and 13. Turntables 16 (shown in phantom) are also attached to the shafts 12 and 13. Reels 17 and 18 (shown in phantom) are adapted to be carried by the respective turntables. These reels carry a magnetic record tape 20. The tape is reeled between the reels along a path which extends past a tape guide 19, a magnetic erase head 21, and a magnetic record-reproduce head 22, and also between a capstan 23 and a pressure roller 24. The

heads

21 and 22, the capstan 23 and the pressure roller 24 may be of the type well known in the magnetic recording and reproducing art. The capstan may be driven by a separate drive motor (not shown), and the pressure roller may be associated with a linkage (not shown) for the purpose of moving the pressure roller towards the capstan to pinch the tape therebetween. This linkage may be designed in accordance with techniques known in the magnetic recording and reproducing art.

The motors which drive the shafts l2 and 13 are adapted to rotate in opposite directions and at different speeds. For either the recording or the reproducing operation, the motor which drives the shaft 13 normally rotates the shaft in a counterclockwise direction, as indicated by the arrow around it in FIG. I, at relatively slow speed to take up the tape 20 as it is fed by the capstan and pressure roller arrangement from the reel 17 to the reel 18. The reel 17 therefore is normally the supply reel and the reel 18 is normally the take-up reel. This terminology is used solely for purposes of convenience in description. The shaft 13, which drives the take-up reel 18, may also be driven at relatively high speed in the counter-clockwise direction to rapidly wind the tape thereon. The latter operation is known in the art as fast forward feed." Alternatively, the shaft 12, which drives the supply reel 17, may be driven at high speed in a clockwise direction, as indicated by the arrow around shaft 12 in FIG. 2, for the purpose of rewinding the tape.

The brake mechanism according to the invention includes a brake band 25 which cooperates with the brake hub 15 and another brake band 26 which cooperates with the brake hub 14, the brake bands being disposed around at least part of their respective brake hubs. Each of these brake bands is a spring member and may be constructed of annealed spring steel which has been hardened. The brake bands 25 and 26 have

angular bends

27 and 28 formed therein, respectively. These bends partake in providing self-energizing and self-relieving braking action and also smooth the braking action to prevent breakage of the tape when the tape is stopped as it is reeled at high speed during fast-forward or fastrewind operations. The ends of the brake bands 25 and 26 near the

bends

27 and 28 therein are respectively anchored in blocks '29 and 30. These blocks may be secured to the deck of the tape transport. A rigid bar 31 interconnects the opposite ends of the brake bands 25 and 26. This bar acts as a floating support between the opposite ends of the brake bands and rests on

stops

32 and 33 when the brakes are released, as shown in FIG. 1. A brake lining 34 is secured to the brake band 25, and a similar brake lining 35 is secured to the brake band 26. A pair of brake band stops 36 engages the back surface of the brake band 25 when the brakes are in release position, as shown in FIG. 1. Another pair of brake band stops 37 serves a similar purpose in connection with the brake band 26.

Two springs 40 and 41 are connected, respectively, between the bar 31 and brake pressure adjusting mechanisms 42 and 43. The bias of these springs 40 and 41 causes the brakes to be applied. The brakes are maintained in released position by a rotary solenoid 44 having an arm 45 secured thereto. This arm is pivotally secured to a brake rod 46 which is fastened to the bar 31. When the solenoid is energized, the bias of the springs 40 and 41 is opposed and the brakes are maintained in released position, as shown in FIG. 1. Another spring 47 is connected between the arm 45 and the bar 31 to eliminate play in the linkage including the arm 45 and the rod 46. Elimination of play results in quiet operation of the braking mechanism.

Each of the brake pressure adjusting mechanisms 42 and 43 includes a separate L-shaped bracket 48 which is mounted on the tape deck, and a screw 49 which is threaded into the associated bracket. The screws 49 are respectively connected to the springs 40 and 41. The tension in the springs 40 and 41 may be adjusted by locking the screws 49 in difierent positions by means of nuts 50.

In operation, the solenoid is de-energized to apply the brakes. Referring to FIG. 2 and assuming, for the purpose of illustration, that a rewind operation is in process when the brakes are applied, the brake linings 34 and 35 will then be forced under the bias of the springs 40 and 41 into engagement with the brake hubs 14 and 15. Due to the rotational energy of the reeling device 11, including the reel 18, the tape wound thereon, the hub 15, and the rotor of the motor coupled to the shaft 13, a large inertia is developed. A torque due to this inertia will be applied to the brake band 25 through the lining 34. This torque effectively expands or lengthens the band 25, since the bend 27 in the band 25 yields and tends to straighten. The brake band 25 thus becomes wrapped more tightly around the brake hub 15 and the braking torque on the hub 15 is increased. In other words, a force is applied due to the rotational energy of the reeling device 11 which aids the bias of the springs 40 and 41 against the hub 15. Accordingly, greater braking torque is applied by the brake band 25 to the brake hub 15 of the reeling device 10, which is paying out the tape 20, than due to the bias of the springs 40 and 41 alone.

The force due to the rotational energy of the reeling device 11 is also transmitted through the bar 31 to the brake band 26. This force is in a direction to oppose the bias of the springs 40 and 41 so that the braking torque developed due to the springs 40 and 41 against the hub 14 is somewhat relieved. The bar 31 is displaced from right to left as seen in FIG. 2. The force \applied to the band 26 by the bar 31 effectively contracts or shortens the band 26 by increasing the angle of bend 28. The angle of the bend 28 is thereby decreased and the brake band '26 recedes from the brake hub 14, whereby the lining 35 recedes somewhat from the brake hub. Accordingly, less braking torque than is due to the bias of the springs 40 and 41 alone is applied to the supply reeling device 10 which is taking up the tape during rewinding. The action of the braking mechanism is therefore self-relieving in the case of the reeling device which is taking up the tape and self-energizing in the case of the reeling device which is paying out the tape. The braking mechanism provided by the invention therefore accomplishes regenerative and degenerative braking in a simple manner which requires relatively few parts as compared with known regenerativedegenerative braking mechanisms.

Another feature of the braking mechanism provided by the invention is that, as the reeling device which is paying out the tape is emptied, the braking force thereon decreases while the braking force on the reeling device which is taking up or winding the tape increases. Moreover, when the reeling device which is paying out the tape stops, the full braking force due to the bias of the springs 40 and 41 is applied to the reeling device on which the tape is wound. The reeling device from which the tape is emptied will stop first, since it has less inertia than the reeling device on which the tape is completely wound. Accordingly, the brake mechanism provided by the invention will apply full braking torque to the reeling device on which the tape is entirely wound and will bring that reeling device to a rapid halt. This counteracts whipping and tearing of the end of the tape as it dangles from the reeling device on which it is being wound.

In the case where the tape is being re-wound on the reeling device 10, which is the case discussed above, the inertia of the reeling device 11 which is paying out the tape decreases as tape is unwound therefrom. Since the rotational force which is applied to the brake band 25 when brakes are applied and which is transmitted through the bar 31 to the brake band 26 depends upon the rotational energy (inertia) in the reeling device 11, this force will decrease as the tape is unwound from the reel 18. Accordingly, the braking force on the reeling device 11 will gradually decrease while the braking force 10 gradually increases. It will be remembered, however, that, so long as the reeling device 11 is rotating, some force will be transmitted from the band 25 to the band 26, so that regenerative and degenerative action will be maintained. The reeling device 11 will come to a stop before the reeling device 10 because of the lower inertia in the reeling device 11. As soon as the reeling device 11 stops, the force which is transmitted by way of the bar 31 to make the brake action on the reeling device 10 self-relieving disappears. The full bias of the springs 40 and 41 is then applied to the brake band 26. Increased brake torque is then applied to the brake hub 14 and the reeling device 10 comes to a stop rapidly. The reeling device 10 is stopped before the end of the tape can move and tear excessively, as by being Whipped against the heads, guides or other parts of the tape trans- The

bends

27 and 28 provide smooth braking action since they absorb transients when the brakes are applied or released. The initial forces developed due to the rotational energy of the reeling device 10 or 11 causes the angles formed by one of the

bends

27 or 28 to increase while the angle formed by the other of the

bends

27 or 28 decreases. The transient motion of the bands 25 and 26 is therefore absorbed by the compression or expansion of the bends and the bands provide for smooth braking action. During fast forward winding operating (i.e., from the reeling device to the reeling device 11), the same action as described above takes place, but, of course, in the reverse direction.

Referring to FIG. 3, a modified form of braking mechanism adapted to be associated with the brake hub 14 of the reeling device 10 is shown. This mechanism is the same as shown in FIG. 1, except that a helical spring 50 is secured at one end to the anchor block 30 and at its opposite end to the brake band 26 and the bend 28 is omitted. The spring 50 is a tight spring and has spring characteristics similar to the bend 28. The end of the brake band is therefore effectively anchored and fixed to the block 30 as though the spring 50 were an integral part of the band 26. Expansion and contraction of this spring 50 will occur during braking, as explained in case of the bend 28. The bend construction may be preferred, since the band 26 may be conveniently formed with the bend 28 as an integral part thereof. A spring similar to the spring 50 may be associated with the band 25, and the bend 27 therein may be omitted.

From the foregoing description, it will be apparent there has been provided an improved braking mechanism which provides degenerative and regenerative braking action. The mechanism also has features of simplicity of construction and operation not obtainable with known regenerative or degenerative braking mechanisms. it will be appreciated that variations in the illustrated embodiments of the braking mechanism described above, as well as other embodiments thereof, all within the scope of the invention, will become apparent to persons skilled in the art. Accordingly, the foregoing description should be taken merely as being illustrative and not in any limiting sense.

What is claimed is:

1. A brake mechanism for cooperation with a pair of rotatable reeling devices comprising a pair of brake members disposed for braking engagement with respective ones of said reeling devices, and a freely floating bar interconnecting said brake members and arranged for simultaneously expanding one of said brake members and contracting the other of said brake members for providing differential braking when said brake members are applied in said braking engagement.

2. A brake mechanism for cooperation with a pair of reeling devices comprising a pair of brake bands dis posed for braking engagement with respective ones of said reeling devices, each having a braking portion disposed around the periphery of a different one of said reeling devices, one end of each of said braking portions being yieldably anchored, and a freely floating bar interconnecting the other ends of each of said braking portions for simultaneously expanding one of said brake bands and contracting the other of said brake bands for providing differential braking when said brake bands are applied in said braking engagement.

3. A brake mechanism for braking a pair of rotatable members between which a reelable medium is adapted to be reeled which comprises a first brake band around at least part of one of said rotatable members, a second brake band around at least part of the other of said rotatable members, said brake bands each having a resilient, yieldable portion, a freely floating bar connecting the free ends of said bands to each other and movable in op posite directions from one of said pair of rotatable members to the other, and means for moving said bar to engage said bands in and disengage said bands from braking relationship with their respective said rotatable members, said yieldable portions being free to yield upon engagement of said bands in and disengagement of said brake bands from said braking relationship.

4. A brake mechanism for braking a pair of rotatable members "between which a reelable medium is adapted to be reeled which comprises a first brake band around one of said rotatable members, a second brake band around the other of said rotatable members, a freely floating bar connected to and between free ends of said bands and movable in opposite directions from one of said pair of rotatable members to the other, and means for moving said bar without restraining its floating action to engage and disengage said bands from braking relationship with said rotatable members.

5. A brake mechanism for cooperation with reeling devices between which a tape is adapted to be reeled, said reeling devices having axes in a common plane, said mechanism comprising a pair of bands of spring material each having an angular, resilient bend therein, means for mounting said bands each around a different one of said reeling devices, said last-named means including means for fixedly mounting one end of each of said bands and a freely floating, rigid member connecting the free ends of said bands, said rigid member being movable in opposite directions from one of said devices to the other, and means for moving said rigid member in directions along a plane perpendicular to said common plane for applying and releasing said brake bands.

6. A brake mechanism for cooperation with a pair of rotatable reeling devices which comprises a pair of brake members which eliectively expand and contract separately disposed for lbralking engagement with respective ones of said reeling devices, and a freely floating bar interconnecting said brake members movable in opposite directions from one of said devices to the other for simultaneously expanding one of said brake members and contracting the other of said brake members or vice versa when said brake members are disposed in said braking engagement.

7. A braking mechanism for cooperation with a pair of reeling devices between which a reelable member is adapted to be reeled, which mechanism comprises a pair of brake members each separately disposed for braking a different one of said pair of reeling devices, a portion of each of said brake members being yieldable for expanding and contracting each of said brake members, and means comprising a freely floating member interconnecting said brake members and displaceable in opposite dircctions one for alternately expanding one of said members while contracting the other and vice versa.

8. A braking mechanism for cooperation with a pair of rotatable reeling devices which comprises a pair of brake bands separately disposed around peripheries of different ones of said reeling devices, one end of each of said bands being fixed, a freely floating bar connected to the free ends of said bands at opposite ends of said bar and movable in opposite directions from one of said devices to the other, and effectively expanding and contracting spring means constituting at least a portion of each of said bands.

9. A braking mechanism for cooperation with a pair of rotatable reeling devices which comprises a pair of brake bands separately disposed around peripheries of difierent ones of said reeling devices, one end of each of said bands being fixed, a bar connected to the free ends of said bands at opposite ends of said bar, and effectively expanding and contracting spring means constituting at least a portion of each of said bands, said spring means comprising angular bends integral with said bands.

10. The invention as set forth in claim 8 wherein said spring means are helical springs having one end thereof effectively providing the fixed end of each of said bands.

11. A braking mechanism for a pair of rotatable, spaced reeling devices between which a reelable medium is adapted to be reeled, which mechanism comprises a pair of brake bands separately disposed adjacent the peripheries of different ones of said reeling devices, one end of each of said brake bands being fixed, a rigid bar connecting the free ends of said bands, portions of said bands being made of yieldable material whereby said bands alternately contract and expand when said bar moves in opposite directions, springs means for biasing said bar in a direction to move said bands into braking engagement with said reeling devices, a rotary solenoid, and

means linking said solenoid and said her :for controlling 6 movement of said bar.

12. A brake mechanism for cooperation with a pair of reeling devices comprising a pair of brake bands of resilient material associated separately with each of said reeling devices, means for securing one end of each of said bands in a fixed position, and means for applying a regenerative braking force to one of said reeling devices while simultaneously applying a degenerative braking force to the other of said reeling devices, said last named means including a freely floating, rigid mem ber interconnecting the opposite ends of each of said bands and movable in opposite directions from one of said devices to the other.

13. A brake mechanism for cooperation with a pair of reeling devices comprising a pair of brake bands associated respectively with each of said reeling devices, a different resilient coupling between one end of each band and a fixed point, a freely floating, rigid member interconnecting the other ends of each of said bands and movable in opposite directions from one of said devices to the other, and means for moving said rigid member thereby to apply said bands in, and release said bands from,

10 braking relationship with said device.

References Cited in the file of this patent UNITED STATES PATENTS Selsted Ian. 13, 1959 2,911,162 Kyle Nov. 3, 1959