US3923268A

US3923268A - Automatic reel hub assembly

Info

Publication number: US3923268A
Application number: US470127A
Authority: US
Inventors: James P Urynowicz
Original assignee: Ampex Corp
Current assignee: Ampex Corp
Priority date: 1974-05-15
Filing date: 1974-05-15
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: JPS50159713A

Abstract

An automatic reel hub assembly which is easily manufactured and assembled includes an axially movable central shaft, a generally cylindrical support member having a central axial aperture receiving the central shaft, a plurality of shoes mounted on the support member in a circumferentially dispersed relationship for only radial motion with respect thereto, and a plurality of drive links, each providing a pin-free coupling between a different shoe and the central shaft. Apertures within the shoes and the shaft receive opposite ends of the drive links in mating relationships which permit the drive links to translate axial shaft motion into radial shoe motion. A circumferentially extending groove in the outer circumference of the support member and the outer surfaces of the shoes receives a recessed elastic O-ring band which exerts a radially inward force on each shoe without subjecting the band to wear as reels are loaded and unloaded.

Description

' United States Patent Urynowicz Dec. 2, 1975 l l AUTOMATIC REEL HUB ASSEMBLY [75] Inventor: James P. Urynowicz, Los An eles, [57] ABSTRACT I' g Ca An automatic reel hub assembly which is easily manul Assigflei mp P RCdWOOd Ci y, factured and assembled includes an axially movable lif central shaft, a generally cylindrical support member [22] Filed: May 15, 1974 having a central axial aperture receiving the central shaft, a plurality of shoes mounted on the support [2]] Appl. No.: 470,127 member in a circumferentially dispersed relationship for only radial motion with respect thereto, and a plu- [52] us. CL" 242/683; 242/72 rality of drive links, each providing a pin-free coupling [51] Int Cl 2 B65 17/02 between a different shoe and the central shaft. Aper- [58] Field of Search 242/683, 68.1, 68.2, 72, "5? 2"? E f s, j z

242/721, 461 4647 210; 92/89, 92 105 en s o t e rive in s in mating re ations ips w .lC

permit the drive links to translate axial shaft motion [561 Cited lllii fl 3f? QKZFZZELZEZLZZ???lli iilli fi UNITED STATES PATENTS member and the outer surfaces of the shoes receives a 3,3l3,496 4/1967 Northrup 242/683 recessed elastic O-ring band which exerts a 31366343 l/lgfs Messamer a] 242/683 inward force on each shoe without subjecting the band 2:2 :2 21] to wear as reels are loaded and unloaded.

Primary ExaminerLeonard D. Christian 23 Claims, 13 Drawing Figures I U.S. Patent Deci2, 1975 Shet1of4 3,923,268

US. Patent Dec. 2, 1975 Sheet 2 of4 3,923,268

imhmrm 405.200 mmzwwmma Saga and

- g W 2/ Z QM ON J AUTOMATIC REEL HUB ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to reel hub assemblies and more particularly to reel hub assemblies for digital magnetic tape transports which automatically lock a reel in its operating position after it has been manually placed on the hub.

2. History of the Prior Art A magnetic tape transport typically includes a pair of spaced apart reel hubs supporting a removable supply reel and a take-up reel. As the tape transport is operated, tape is passed bi-directionally from the supply reel past tape buffers, magnetic heads, and a drive capstan to a take-up reel. Because of the frequent need to remove one supply reel and replace it with a different supply reel it is desirable that the supply reel hub readily permit the loading and removal of reels of tape. A standard tape reel has a smooth, circular, axially extending-central aperture which receives a reel hub as the tape reel is loaded. After a reel is in place the reel hub must be capable of expanding to engage the inner circumference of the central reel aperture in a non-sliding relationship.

One generally known automatic reel hub assembly includes a central shaft and a pneumatic actuator for selectively moving the shaft axially between releasing and engagement positions. The circumference of the shaft is provided with a conical surface which engages the mating conical surfaces of a plurality of radially extendable collet defining segments which are dispersed about the shaft to define the hub circumference. The collet segments are moved radially outward or inward as the shaft moves axially toward the engagement and release positions respectively. An elastic band about the outer circumference of the collet segments provides structural integrity for the assembly as it biases the segments radially inward and provides a high coefficient of friction element which engages the interior circumference of a reel of tape. However, a complicated pinning arrangement which makes the hub assembly expensive to manufacture and assemble is required to permit torque to be transmitted from a reel motor and through the shaft to the collet. This pinning arrangement must permit the collet segments to move radially while they are closely constrained to a circumference defining configuration and rotational torque is transmitted thereto. The resulting arrangement is relatively complex and contributes substantially to the manufacturing and assembly costs of the hub assemblies. Furthermore, the circumferential band is subject to wear and presents a high frictional surface which often imposes a drag to interfere with the loading and removal of tape reels.

SUMMARY OF THE INVENTION An easily assembled automatic reel hub assembly in accordance with the invention includes an axially movable shaft, a pneumatic or other actuator connected to selectively position the shaft at alternate reel engagement and release positions, a generally cylindrical support member having a central axial aperture which receives the shaft, a plurality of circumferentially dispersed shoes mounted on the support member for only radial motion with respect thereto, a recessed, circumferential elastic band encompassing the support member to bias the shoes radially inward and a plurality of drive links. Each drive link is a small generally radially extending bar which couples a different shoe to the shaft through pin-free connections of first and second opposite ends having curved shapes which matingly engage a shoe and the shaft respectively in a manner permitting axial motion of the shaft to be translated to radial motion of the engaged shoe. This arrangement is very easily assembled, does not require a complicated pinning configuration in order to transmit torque from the central shaft through the shoes to a loaded tape reel, and does not require sliding engagement between two mating conical surfaces. Furthermore, outer surfaces of the shoes may be coated with a high coefficient of friction material such as neoprene, raybestos or rubber for non-slip engagement with the interior circumference of a tape reel aperture. Undesirable contact between the high coefficient of friction surfaces and the interior circumference of a tape reel is avoided as the tape reel is loaded or unloaded by recession of these shoe surfaces below the outer circumference of the support member. Because the support member defines the majority of the hub circumference, this recession of the shoes does not seriously affect the structural continuity of the hub surface. Recession of the circumferential elastic O-ring band in circumferential grooves protects the band from wear as tape reels are loaded and removed.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be had from a consideration of the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view, partly broken away, of an automatic reel hub assembly in accordance with the invention;

FIG. 2 is a sectioned front view of the automatic reel hub assembly taken along the lines 2-2 in the direction of the arrows as indicated in FIG. 1;

FIG. 3 is an end view taken from the rear of a support member used in the reel hub assembly shown in FIG. 1;

FIG. 4 is a section view of the support member taken along the line 4-4 in the direction of the arrows as shown in FIG. 3;

FIG. 5 is an end view taken from the front of a support member collar for the hub assembly shown in FIGS. 1 and 2;

FIG. 6 is a sectioned side view of the support member collar taken along the lines 6-6 in the direction of the arrows as shown in FIG. 5;

FIG. 7 is a fragmentary end in view, taken from the rear and partly broken away, of a hub portion of the support member collar shown in FIGS. 5 and 6;

FIG. 8 is a side view of a drive link used in the reel hub assembly shown in FIGS. 1 and 2;

FIG. 9 is a top view of the drive link shown in FIG. 8;

FIG. 10 is a plan view of a shoe used in the reel hub assembly shown in FIGS. 1 and 2;

FIG. 11 is an end view of the shoe shown in FIG. 10;

FIG. 12 is a plan view of a shaft used in the reel hub assembly shown in FIGS. 1 and 2; and

FIG. 13 is an end view of the shaft shown in FIG. 12 taken from the rear.

DETAILED DESCRIPTION As shown in FIGS. 1 and 2, an automatic reel hub assembly 10 in accordance with the invention is concentrically positioned about a central axis 12 and includes a conventional reel motor 14 mechanically linked to a hub 16 through a multipart hollow shaft 18. The hub 16 includes a generally cylindrical collar 20 which has a disk shaped anterior support wall-22 and which is rotatably mounted on an anteriorly extending portion of a reel motor drive shaft 24. A generally cylindrical support member 26 is fastened in mating relationship to the forward side of the anterior supportwall 22 of collar 20 by three bolts 28 which are dispersed about the central axis 12 at angles of 120 from one another. To-

gether, the support member 26 and collar 20 define three radially extending and circumferentially distributed apertures 30 for receiving shoes 32. The apertures 30 are axially coextensive with a rearward cylindrical portion 34 of the support member 26. A reel 38 having a tape pack 36 also has an axial thickness which is coextensive with cylindrical portion 34 when a rearward surface 42 of the reel 38 is in abutment with an anterior surface 44 of a flange 46 which extends radially outward from the anterior support wall 22 to provide a backstop for loaded reels. A slightly conical anterior circumferential surface 48 of support member 26 is tapered radially inward as it extends forward from cylindrical surface 34 to guide tape reels onto the hub 16. A spring loaded cylindrical plunger 50 is positioned to extend radially through the rearward portion of conical surface 48 diametrically opposite each shoe 32 to provide a detent as reels 38 are loaded and unloaded. A screw 52 protrudes from the plunger 50. The forward portion of hub 16 is defined by a cap 56 having the shape of a truncated cone with a disk shaped anterior wall 58 and a conical outer circumferential surface 60 extending from the anterior wall 58 to the conical surface 48 in alignment therewith. An O-ring 62 is recessed within a circumferential groove 64 in surface 34 of support member 26 and mating grooves 66 in the shoes 32. The O-ring 62 biases the shoes radially inward.

A pneumatic actuator 68 is coupled to radially position the shoes 32 in response to pneumatic pressures generated by a pressure control system 70. The pneumatic actuator includes a diaphragm 72 connected between the cap 56 and the support member 26 along the mating periphery thereof to form a generally cylindrical pressure chamber 74 between the diaphragm 72 and cap 56. A generally disk shaped piston 76 is disposed to support the diaphragm 72 axially rearward of the chamber 74. The piston 76 has a central aperture 78 which is concentric with the axis 12. A threaded screw 80 having a central axial bore 82 therethrough passes through a hole 84 in the diaphragm corresponding to the central aperture 78 in piston 76 and then through aperture 78 to threadingly engage the forward end of an actuator shaft 86 which has an axial central bore 88 communicating with bore 82 and which forms the forward portion of hollow shaft 18. The actuator shaft 86 extends slidingly through the support member 26 and the collar 20 with the rearward end being slidingly received by a central axial bore 94 in motor shaft 24. A diametric bore 96 near the rearward extremity of actuator shaft 86 provides pneumatic communication between the axial bore 94 and the outer circumference of actuator shaft 86. A rear tip 98 of reduced outer diameter is formed on the actuator shaft 86 from a point in front of the diametric bore 96 to the rearward extremity of the actuator shaft 86 to provide pneumatic communication from the diametric bore 96 to the rear- 4 ward extremity. A pushrod 100 of somewhat smaller diameter than the axial bore 94 extending through hollow reel motor shaft 24 has a forward threaded end which mates with a tapped rearward end of actuator shaft 86. The opposite rearward end of pushrod 100 extends rearward beyond reel motor shaft 24.

The pushrod 100 terminates at the rearward end in a small diameter tip portion 102 which extends beyond the rearwardmost extremity of the reel motor shaft 24. Support for the rearward end 102 of pushrod 100 is provided by a spring housing 104. The spring housing 104 is a generally cylindrical member having an inside diameter substantially equal to the inside diameter of reel motor shaft 24 having aperture 106 through a rear wall 108 thereof and an open end through which the rearward end of the pushrod 100 is extended in supporting relationship. At the forward end the spring housing 104 receives the rearward end of the motor shaft 24 in mating relationship and a pair of set screws 110 (only one shown) which are positioned 90 apart are threaded radially through the cylindrical wall of spring housing 104 to engage slots 112 in the outer circumference of motor shaft 24 near the rear thereof to secure the spring housing 104 to the motor shaft 24. A

washer 114 having a central hole approximately equal in diameter to the small diameter end 102 of pushrod 100 receives the small diameter end 102 and is disposed at thetransition from the small diameter end 102 to the larger diameter main portion of pushrod 100. A coil spring 56 is disposed between the rearward surface of washer 54 and the inside surface of the closed end 108 of spring housing 104 to bias the pushrod 100 in a forward direction until the forwardmost surface of washer 54 makes contact with the rearwardmost end of reel motor shaft 24. This forwardmost position is indicated by dashed lines 116 in FIG. 2 and represents a reel release position. A C-clamp 118 is received by a circumferential groove near the rearwardmost end of pushrod 100. The C-clamp 118 is positioned rearward of the closed end of spring housing 104 and limits axial movement of pushrod 100 for ease of assembly or repair at times when such movement is not otherwise limited by engagement of washer 114 with the rearwardmost end of reel motor shaft 24.

A plurality of small holes in the washer 114 are dispersed about the central hole which receives the rear tip 102 of pushrod 100 to permit pneumatic communication between the interior of spring housing 104 and the space between the outer circumference of pushrod 100 and the interior circumference of reel motor shaft 24 even when the washer 114 is in contact with the rearwardmost portion of reel motor shaft 24. Four air holes 120 which are circumferentially positioned at 90 from one another extend through the outer circumference of spring housing 104 to permit pneumatic communication between the interior of spring housing 104 and an interior chamber 122 of a bell housing 124 within which the spring housing 104 resides. The generally cylindrical, non-rotating bell housing 124 provides a pneumatic seal around the spring housing 104 and pushrod 100 which rotate with the reel motor shaft 24. The bell housing 124 has a rearward closed end and a forward open end which is closed by abutment with the rearwardmost portion of reel motor 12. A gasket 126 maintains the airtight seal between the rearwardmost portion of reel motor 12 and a radially extending flange of hell housing 124 which is mechanically connected to the reel motor 12 by four bolts 128 which are spaced around the flange at 90 from one another. A threaded fitting 130 is screwed into a tapped aperture 132 in the outer periphery of bell housing 124 and is connected through suitable tubing 134 to an air pressure control system 136. The air pressure control system 136 operates under control of signals provided by an associated tape transport system (not shown) to selectively provide a positive air pressure through the fitting 130 during normal tape transport operation. The air passes through a tube 134 and fitting 130 to the interior chamber 122 of bell housing 124, and then through apertures 120 to the interior of spring housing 104.

With the pushrod 100 biased to an axially forward or reel release position by a spring 138 disposed concentrically about the rear tip 102 of pushrod 100 between the washer 114 and spring housing rear wall 108, the pressurized air travels through the small holes in washer 114 and then along the space between the inner circumference of hollow reel motor shaft 24 and the outer circumference of pushrod 100 from the rearwardmost portion of reel motor shaft 24 to the forwardmost portion of reel motor shaft 24. Near the forwardmost portion of reel motor shaft 24 the pressurized air travels through apertures 96 to the interior of actuator shaft 86 and then forward through the central axial bore in bolt 84 to the chamber 74. As the pressurized air enters the chamber 74 a rearwardly directed force is applied to diaphragm 72 and piston 76 until the piston 76, actuator shaft 86, and pushrod 100 are driven rearward against the bias of spring 138. The actuator mechanism is driven rearward until either engagement of the shoes 32 with a reel 38 prevents further motion or a rearwardly projecting peripheral flange on piston 38 engages a forward mating surface of support housing 16. This is the position in which the automatic reel hub assembly is depicted in FIG. 2. A circumferential groove 140 in actuator shaft 86 receives one end of each of three drive links 142 which have their opposite end engaged by the three shoes 32 and which translate axial motion of the actuator shaft 86 into radial motion of the shoes 32. Axial motion of the actuator shaft 86 orients the drive links 142 more nearly perpendicular to central axis 12 to drive the opposite ends and coupled shoes 32 radially outward. The total travel distance between the rearwardmost reel engaged position and forwardmost reel release position of the axially moving portions of the automatic reel hub assembly 10 is approximately 0.375 inch. Because the air leakage of the pneumatic actuator is very small, the actuator provides very little air or power drain on the air pressure control system 136 while an associated tape transport is in operation.

The three detent plungers 50 are generally elongated cylinders having a spherical closed end and an opposite bored end which receives a coil spring 143. The coil spring 143 extends from the bored end of the plunger 50 to push against the bottom of a radially extending bore in the support member 26 to bias the plunger radially outward. An axially directed hole 54 in the support member provides communication between the radially directed plunger hole and the rear of the support member 26. This axially directed hole 54 permits a stop member such as a roll pin or the set screw 52 to be inserted into a bore in the sidewall of the plunger 50. The stop member extends beyond the plunger circumference to engage the most radially outward portion of the inside surface of access bore 54 to limit the radially outward travel of plunger 50. As a reel is inserted over the hub 10, it must contact the spherical closed ends of the three detent plungers 50, causing them to be moved radially inward against the force of the springs 84 as the reel is loaded. The three detent plungers 50 are axially positioned such that the rearwardmost portion of the plungers 50 engage the forward edge of a loaded reel 38. The plungers 50 thus provide a detent for maintaining a reel 38 in the proper axial position prior to engagement thereof by the shoes 32.

As shown in further detail in FIGS. 3 and 4 the support member 26 is a generally cylindrical, integrally constructed element which is positioned concentrically about the central axis 12. A forward surface 144 of the support member 26 is formed concave inward, that is axially rearward, and receives the piston 76 and diaphragm 72. Surface 144 defines a relatively flat, disk shaped anterior wall within the outer circumference of the support member but may be radiused at the periphery thereof. The forward edge of the relatively conical circumference 48 terminates in a flat anterior surface 146 lying in a plane which is perpendicular to the central axis 12 and defines the forwardmost portion of support member 26.

At the rear of the support member 26 a very large diameter bore 148 extends axially forward for a short distance to define a rearwardly extending, relatively thin circumferential wall 150 and a planar interior rear wall 152. A medium sized bore 154 extends from the rear wall 152 axially forward to the rear surface 156 of a relatively thin wall 158 having the forward surface thereof defined by surface 144. A small central bore 160 extends through the wall 158 between

surfaces

156 and 144 with a diameter slightly larger than the diameter of the large diameter forward end of actuator shaft 86. Diametrically opposite each of three cylindrical bores 162 for receiving detent plungers 50, a rectangular shoe aperture 164 extends radially outward from the medium sized bore 154 to the outer circumference of the support member 34. The three shoe apertures 164 have a uniform cross section perpendicular to radially extending directions and guide the shoe 32 as they move radially between radially extended reel engagement and radially inward reel release positions. A small shoe restraint bore 166 extends axially forward a short distance into the front wall of each of the three shoe apertures 164. The bores 166 receive a roll pin 168 which extends from the forward edge of each shoe 32. The bore 166 and roll pins 168 limit the radial travel of the three shoes 32. Inasmuch as the bores 166 and pins 168 do not participate in the normal operation of the hub assembly 10 by the transmission of torque or otherwise, dimensional tolerances are not critical. They merely serve to facilitate assembly and to contain the shoes in the event the O-ring 62 should break.

Six uniformly spaced countersunk holes 170 extend forward from the interior rear wall 152 through the forward surface 146 of conical circumferential wall 40 to receive screws 172 (only one shown) for mechanically coupling the support member 26 to cap 56 and diaphragm 72. Three tapped holes 172 in the interior rear wall 152 of support member 26 are spaced radially inward from the holes 170 and receive bolts 28 (see FIG. 2) which mechanically fasten the rearward portion of the support member 26 to a forward facing portion of the collar 20 in mating relationship.

Collar 20 is shown in further detail in FIGS. 5, 6 and 7 to which further reference is now made. Collar 20 comprises a disk or flange portion 176 at the anterior end and a cylindrical hub portion 178 positioned rearward of the disk or flange portion 176. A rectangular cross section circumferential notch 180 defining a forward facing planar surface 182 and a short forward projecting tongue 184 which is received by the large diameter bore 148 of the support member 26 in mating relationship. The tongue 184 is bored axially rearward to the plane of surface 182 with an intermediate size hole 186 which matches medium sized bore 154 of support member 26. Three radially extending slots 188 are also formed in the tongue 184 to an axial depth which is coextensive with the plane of surface 182. These slots 188 are sized and positioned to match the three shoe receiving apertures 164 of support member 26. A small bore 190 for receiving an intermediate sized central portion of the actuator shaft 86 extends from the plane of surface 182 axially rearward part way into the hub portion 178 concentric with the central axis 12.

As best shown in FIG. 7 a narrow diametrically extending slot 192 extends from a planar, rearwardmost surface 194 of hub portion 178 axially forward to approximately the axial midpoint 196 of hub portion 178. A motor shaft bore 202 which is concentric with central axis 12 extends forward from rear surface 194 beyond the extent of slot 192. The motor shaft bore 202 receives the forward portion of reel motor shaft 24 in mating relationship and slot 192 permits the hub portion 178 of collar to be tightly clamped about reel motor shaft 24 by oppositely oriented

bolts

204, 206 which extend through the hub portion 178 of collar 20 perpendicular to slot 192. A pair of

bolt notches

208, 210 are cut into the periphery of hub portion 178 to provide

planar surfaces

212, 214 against which the heads of

bolts

204, 206 may rest. Bolt holes 216, 218 receive the

bolts

204, 206 and are tapped throughout a portion of the hub portion 176 which lies on the opposite side of slot 192 from the

surfaces

212, 214.

As representatively shown in greater detail in FIGS. 8 and 9, the three identical drive links 142 are each generally rectangular bars having oppositely facing broad surfaces 224, oppositely facing side surfaces 226 which are somewhat narrower than broad surfaces 224 and ends 228, 230. The ends 228, 230 are radiused with respect to axes extending parallel to broad surfaces 224 to form smoothly curved surfaces which may be matingly received by the grooves 140 and shoes 32. Each drive link 142 has dimensions of 1.505 inches in length between the extremities of the rounded ends, a width of approximately 0.310 inch across the broad surfaces 224, and a depth of approximately 0.15 inch across side surfaces 226 (between broad surfaces 224). The radiused ends 228, 230 permit the drive link 142 to rotate within drive link receiving apertures within the shoes 32 and groove 140 of actuator shaft 86 as the drive links convert axial motion of shaft 86 to radial motion of the shoes 32.

One of the three identical shoes 32 is representatively illustrated in greater detail in FIGS. 10 and 11. The shoes 32 are generally rectangular in shape with opposing

broad walls

234, 236, opposing

end walls

238, 240, a top 242, and a bottom 244. A slot 246 having interior side walls 248, 250 extends between the two ends 238, 240 upwardly from the bottom 244 to a notched anterior surface having a portion 252 adjacent end 238 which is spaced from top 242 a greater distance than a surface portion 254 adjacent end 240. The displacement of surface portion 252 from portion 254 defines a notch which permits a small bore 256 to extend inward a short distance from end 238. Each bore 256 receives a roll pin 258 which extends beyond end surface 238 to engage an aperture 54 in support member 26 to limit the radial travel of the shoes 32. A small bore 260 extends through each shoe 32 along a central axis which extends perpendicular to

broad faces

234, 236 approximately through the plane of surface 254 to form a circular trough or groove which receives a first end 228 of a drive link 142 in mating relationship. The bore 260 has a radius slightly larger-than the radius of the radiused end 228 of drive link 142. When biased radially inward against the end 228 of drive link 142, the interior portion of bore 260 mates with the end 228 to limit relative movement between the drive link 142 and shoe 32 in non-radial directions. The interior side wall surfaces 248, 250 adjoin the side walls 226 of drive link 142 to limit sideways motion of a drive link 142 relative to a mating shoe. The end 228 of a drive link 142 is then permitted to rotate about the axis of bore 260 within the trough defined by bore 260. So long as shoe 32 is radially biased into engagement with the first end 228 of drive link 142, other relative motion between the shoe 32 and drive link 142 is not permitted. As an alternative to the bore 260, the shoes 32 may be molded with a trough defined in the interior surface 254 which is approximately coextensive with the trough which is defined therein by bore 260. By molding the shoes 32 with the trough already present therein, a manufacturing step of boring the hole 260 may be avoided, thus making the manufacturing process easier.

An axially extending slot 262 which extends between end surfaces 238, 240 is formed in the top 242 of the shoes 32 to receive pads 264 of a high coefficient of friction material such as rubber, neoprene or raybestos. The pads 264 engage the interior surfaces of the hubs of loaded reels when the shoes 32 are extended to grip the reel in a non-slip relationship. A circumferential slot 66 is formed through the pad 264 and top 242 at a location between the

ends

238, 240 to permit alignment with slot 64 in support member 26 to receive an O-ring 62 which extends around the circumference of support member 26 and shoes 32 to bias the shoes 32 radially inward. The

slots

64, 66 permit the O-ring 62 to be recessed below the periphery of the reel hub assembly 10 to prevent contact with tape reels as they are loaded and removed from the hub assembly 10. The resilient O-ring 62 thus permits a radial bias to be applied to the shoes 32 without O-ring 62 being subject to wear and tear as reels are loaded and unloaded. Furthermore, reels 38 need not be subject to accidental engagement with the O-ring 62 which would interfere with loading and unloading.

As shown in further detail in FIGS. 12 and 13, the actuator shaft 86 is a generally cylindrically shaped member having a large diameter forward end 274, a medium diameter central portion 276 and a small diameter rearward portion 278. A front planar surface 280 defines the forwardmost portion of shaft 86 and a planar surface 282 defines the rearwardmost portion of shaft 86. The shaft 86 has a length of approximately 2.72 inches between the two ends 280, 282 and a diameter of approximately 0.60 inch at the large diameter forward portion 274. The medium diameter central portion 276 begins 1.1 1 inches from end 280 and has a diameter of 0.355 inch. The small diameter rearward portion 278 begins 2.04 inches from end 280 and has a diameter of 0.280 inch. A central axial bore 288 extends longitudinally between the two ends 280, 282 with a diameter of approximately O.l59 inch. A tapped forward bore 290 extends part way into the shaft 86 from forward end 280 to receive bolt 80 which fastens the diaphragm 72 and piston 76 to actuator shaft 86. At the rearward end of shaft 86 a tapped axial bore 292 is provided to receive the threaded front end of pushrod 100. A diametrically extending through hole 296 having diameter of 0.l4 inch is disposed between the forwardmost portion of tapped bore 292 and the transition of small diameter rear portion 278 to medium diameter central portion 276 to provide communication between the outer circumference of small diameter portion 278 and the longitudinal central bore 288.

The circumferential groove 140 is formed in the large diameter portion 274 of shaft 86 symmetrically about a plane which lies perpendicular to central axis 12 at 0.74 inch from forward end 280. The groove 140 has a circular radially inward or smaller diameter portion 296 having a radius of 0.093 inch and a smallest diameter about central axis 12 of 0.25 inch. Forward side walls 298 and rearward side walls 300 are generally linear in cross section and extend tangentially from circular bottom portion 296 to the outer circumference of enlarged diameter portion 274. The

side walls

298, 300 intersect a plane 302 which is perpendicular to the central axis 12 at an angle of approximately 40.

The curved groove 140 receives the second end 230 of the three drive links 142 in a mating relationship which permits the second end 230 to rotate within groove 140 as the actuator shaft 86 moves axially in response to actuator 68. The mating relationship between groove 140 and second end 230 prohibits relative axial motion between the three drive links 142 and the groove 140.

Tape reels are loaded and unloaded by directing air pressure control system 136 to release the positive pressure which drives the pneumatic actuator 68. Release of this positive pressure permits spring 138 to drive pushrod 100, actuator shaft 86, and piston 76 axially forward to a release position 116. In this released position 116, the angle of the three drive links 142 is slightly increased with respect to a plane 302 lying perpendicular to the central axis 12. The increase of this angle decreases the radial distance of the three shoes 32 from the central axis 12, permitting disengagement of the three pads 264 from the interior surface of a hub of a reel 38 so that the reel 38 may be removed and replaced with a new reel. A new reel is loaded by pushing at past detent plungers 50 until the rear surface of the new reel engages the planar surface 182 near the periphery of collar 20. Once the new reel is loaded, air pressure control system 136 again creates a positive pressure which is directed into chamber 74 to apply a force against piston 76 and drive the shaft 86, and pushrod 100 axially rearward. Because of the good mechanical advantage provided by the drive link coupling arrangement, the area of the piston and the small frictional forces which are encountered, a positive pressure of 2 PSI has been found to be adequate. The rearward motion of the actuator shaft 86 forces the three drive links 142 to a more nearly perpendicular orientation, causing them to force the three shoes 32 radially outward until the three pads 264 firmly grip the interior surface of the hub of the new reel. At this point the new reel is loaded and tape transport operation may begin.

Although there has been shown and described a particular embodiment of an automatic reel hub assembly in accordance with the invention, for the purpose of enabling a person of ordinary skill in the art to make and use the invention, it will be appreciated that the invention is not limited thereto. Accordingly all modifications, variations and equivalent arrangements within the scope of the appended claims should be considered to be within the scope of the invention.

What is claimed is:

1. A reel hub assembly comprising:

an actuator shaft which is axially movable relative to a radially disposed shoe between a reel lock position and a reel release position, the actuator shaft being adapted at one axial position therealong to receive at least one drive link end in a mating relationship which prevents axial motion of the shaft relative to a mated end of a drive link while permitting radial motion of an end opposite the mated end of a drive link with respect to the shaft;

at least one drive link having opposed ends disposed to extend generally radially with respect to the actuator shaft with one end in a mating relationship with the actuator shaft at the one axial position and an opposite end in a mating relationship with a shoe, both said one and opposite end mating relationships permitting radial motion of the drive link relative to the mate while preventing axial motion of the drive link relative to the mate;

at least one shoe adapted to receive an opposite end of a drive link in a mating relationship which permits radial but not axial motion of said opposite end relative to the shoe; and

an actuator mechanism connected to cause relative axial motion of the shoe and actuator shaft between a reel lock axial position relationship and a reel release axial position relationship to move the shoe between a radially extended position and a radially retracted position respectively.

2. The reel hub assembly as set forth in claim 1 above, wherein the drive link limits the radial proximity of the shoe to the shaft and further comprising a resilient element disposed to radially bias the shoe toward the shaft.

3. The reel hub assembly as set forth in claim 2 above, further comprising a housing having a central axially extending aperture receiving the actuator shaft and a plurality of radially extending apertures, each receiving a different shoe and associated drive link.

4. The reel hub assembly as set forth in claim 3 above, further comprising a thin layer of material having a high coefficient of friction affixed to the most radially outward surfaces of the shoes.

5. The reel hub assembly as set forth in claim 3 above, wherein the actuator includes a second resilient element connected to axially bias the actuator shaft toward the reel release position relative to the shoes.

6. The reel hub assembly as set forth in claim 5 above, wherein the actuator further includes a chamber connected to the housing, the chamber being partly defined by a diaphragm which is coupled to the actuator shaft and which is axially movable in response to fluid pressure within the chamber, and a fluid pressure source coupled to selectively increase the fluid pressure within the chamber to force the actuator shaft to the reel lock position and decrease the pressure within the chamber to permit movement of the actuator shaft to the reel release position.

7. An automatic reel hub assembly comprising:

a generally cylindrical body member having a central axial aperture for receiving a central shaft and having a plurality of radially extending shoe apertures providing communication between the central axial aperture and an outer circumference of the body member, each radially extending aperture being adapted to receive a shoe;

a plurality of shoes, each being disposed for radial motion within a different shoe aperture, each having an outer surface adapted for gripping engagement with an interior surface of a reel hub, and each having an inner surface opposite the outer surface which has a concavity therein, the concavity being adopted to limit nonradial relative motion between the shoe and an end of a drive link received within the concavity;

a central shaft disposed for axial motion within the central aperture, the shaft having a concavity for receiving an end of a drive link which is adapted to limit relative axial motion between the central shaft and a drive link end disposed approximately opposite each shoe concavity;

a plurality of drive links extending between a shoe concavity and an opposite central shaft concavity, each drive link having a first end adapted for mating engagement with a shoe concavity and a second end adapted for mating engagement with a central shaft concavity;

means for biasing each shoe radially inward; and

means for controlling the axial position of the central shaft relative to the body member.

8. The hub assembly as set forth in claim 7 above, wherein the concavity in each shoe is adapted to permit an engaged drive link to rotate through at least a small are about an axis positioned near the first end thereof which is perpendicular to a plane extending through a central axis of the body member and an approximate center point of a concavity and to prevent an engaged drive link from rotating about an axis which is positioned near the first end thereof generally parallel to a central axis of the housing.

9. The hub assembly as set forth in claim 7 above, wherein each shoe comprises a generally rectangular housing having a top, a bottom opposite the top, opposite first and second sides and ends, a slot extending between the two ends and from the bottom to a planar interior surface disposed partway between the top and bottom, and a cylindrical concavity having a central axis lying approximately in the plane of the inner surface perpendicular to the side walls.

10. The hub assembly as set forth in claim 7 above, wherein the drive link comprises a long generally rectangular bar having first and second opposing ends and opposing pairs of side walls and end walls, the first and second ends being rounded about axes of curvature which are perpendicular to the side walls.

11. The hub assembly as set forth in claim 7 above, wherein the central shaft comprises a hollow, axially extending shaft having a single circumferentially extending groove in the outer circumference thereof defining drive link end receiving central shaft concavity.

12. The hub assembly as set forth in claim 11 above, wherein the central shaft groove has a cross sectional shape in a plane passing through a central axis of the shaft of a circular are defining the deepest portion of the groove and straight lines extending tangentially from the extremities of the arc to the outer circumference of the shaft.

13. The hub assembly as set forth in claim 12 above, wherein the arc subtends an angle of approximately about its center.

14. A reel hub assembly comprising:

a plurality of shoes disposed about a central axis, the shoes having radially outward surfaces which are suitable for engagement with a reel, being disposed to move radially outward to engage a reel and move radially inward to release a reel, and having cavities which open radially inward and are adapted for pin-free engagement and retention of first ends of a drive link as drive link ends which are located radially inward from the first ends are moved axially at a fixed radial distance from the central axis to control the radial position of the shoes;

a plurality of drive links, each having a first end in pin-free engagement with a cavity of a different shoe and a second end disposed radially inward with respect to the first end; and i a drive mechanism adapted for pin-free engagement and retention of the second drive link ends, the drive mechanism providing selected axial motion for the second drive link ends while maintaining the radial distance of the second drive link ends from the central axis substantially constant.

15. An easily assembled reel hub assembly comprising an axially movable shaft, a generally cylindrical support member having an axially extending central aperture and receiving the shaft therethrough, a plurality of shoes having radially outward surfaces adapted for engagement with a reel of tape supported by the support member in a manner permitting only radial movement of the shoes, and means for exerting a force on each shoe which is directed radially inward and a plurality of drive links, each coupling a different shoe to the shaft through pin-free connections of first and second opposite ends which engage a shoe and the shaft respectively such that axial motion of the shaft is translated to radial motion of the shoes.

16. For use in a tape transport, a tape reel hub assembly comprising:

a shaft having a central axis and a periphery with at least one cavity therein, the shaft being translationally movable along the axis and connectable for rotation about the axis by a motor;

means for translationally positioning the shaft while maintaining a plurality of shoes in a fixed axial position;

a plurality of drive links, each having a first curved end in mating relationship with a cavity in the shaft and a second curved end opposite the first curved end; and

a plurality of shoes, each having an outer surface suitable for mating relationship with a tape reel and an inner surface with a cavity therein receiving a second curved end of a drive link in a pin-free mating relationship in which the second curved end engages the cavity.

17. A reel hub assembly comprising:

an axially extending actuator shaft disposed for axial positioning, the actuator shaft having at least one concavity in the circumference thereof which is shaped to receive at least one drive link in mating relationship, the actuator shaft further having a central aperture therein which extends axially from one end to a position past the at least one concavity;

an axially flxed wall defining a portion of a chamber which is disposed at said one end of the actuator shaft in communication with the central aperture thereof;

an axially movable wall which defines a portion of the chamber and which is coupled to the actuator shaft, the movable wall and actuator shaft being axially movable in response to fluid pressure in the chamber to axially position the at least one concavy;

at least one shoe which is mounted for radial motion with respect to the actuator shaft;

at least one drive link disposed between a shoe and a concavity in the actuator shaft to radially position a shoe in response to an axial position of the actuator shaft; and

means for biasing the at least one shoe radially inward.

18. The reel hub assembly according to claim 17 above, further comprising a reel motor having a hollow motor shaft coupled in axial alignment with the actuator shaft with the actuator shaft being axially movable with respect to the motor shaft, the motor shaft extending through the reel motor and providing communication between the central aperture in the actuator shaft and a side of the reel motor opposite the chamber.

19. The reel hub assembly according to claim 18 above, further comprising a bell housing fixed to the reel motor on a side opposite the chamber, the bell housing providing a fluid seal about the end of the motor shaft and having an interior which is in communication with a source of pressurized fluid.

20. The reel hub assembly according to claim 19 above, further comprising means coupled to the reel motor shaft on a side of the reel motor opposite the chamber for continuously biasing the actuator shaft axially toward the chamber with respect to the reel motor shaft.

21. The reel hub assembly according to claim 17 above, further comprising a cylindrical collar which is connected to transmit rotational torque between a reel motor shaft and the at least one shoe.

22. The reel hub assembly according to claim 17 above, further comprising a flexible diaphragm disposed within the chamber to provide a non-sliding seal 14 between the fixed wall and the movable wall of the chamber.

23. A reel hub assembly comprising:

a reel motor having a motor shaft having a central axis and a central aperture extending axially therethrough;

a generally cylindrical support member disposed concentrically about the central axis, the support member being adapted to receive and support a plurality of shoes and permit only radial motion of the shoes with respect thereto, being connected in fixed relationship with the motor shaft, and having a central aperture extending therethrough for receiving an actuator shaft;

a plurality of shoes, each being supported by the support member for only radial motion with respect thereto;

an actuator shaft disposed within the central aperture of the support member and adapted for axial motion with respect to the support member, the actuator shaft having at least one concavity in the circumference thereof for receiving a plurality of drive links in mating relationship and having a central bore extending axially therethrough from a forward end rearwardly past the at least one concavy;

a plurality of drive links, each extending between a shoe and a concavity in the actuator shaft to impart radial motion to a shoe in response to axial motion of the actuator shaft;

a fixed wall disposed in fixed relationship with the support member forward of the forward end of the actuator shaft to partially define a chamber which is in communication with the axial bore in the actuator shaft at the forward end thereof;

a movable wall connected to the forward end of the actuator shaft, the movable wall forming a part of the chamber and being operable to axially position the actuator shaft in response to fluid pressure in the chamber; and

means for defining a fluid path which couples a rearward end of the axial bore through the actuator shaft to a source of fluid having a controlled pressure.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,923,268 Dated December 2, 1975 Inventofls) James P. Urvnowicz Page 1 of It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 17, after "pack", "36" should read --40--; line 30, between and the period insert --through an axially extending bore 54-. Column 4, line 13, after 'the", "inside" should read -outside-; line 14, after "24" and before "aperture", "having" should read --and having an--; line 15, after "thereof" and before "through", delete 'and an open end"; line 20, after "apart", insert --and--; line 30, after "spring", "56" should read --115-; line 31, after "washer", "54" should read --l14--; line 34, after "washer", "54" should read --ll4--; line 64, after "motor" and before the period "12" should read --14--; line 66, after "motor", "12" should read --l4--; line 68, after "motor", "12" should read --l4--. Column 5, line 5, after "system" (both occurrences) "136" should read line 14, after "spring", "138" should read --1l5--; line 26, "bolt 84" should read --screw line 30, after "spring", "138" should read line 33, after "piston", "38' should read --76-; line 34, after "support" and before "housing", insert --member or--; line 35, '16" should read -26--; line 51, after "system", "136" should read -70-- Column 6, line 3, after "springs", "84" should read --143--; line 39, after "member" and before the period "34" should read --26--; line 41, after "the" and before "32", "shoe" should read --shoes--; line 57, after "146" and before "conical", "of" should read --adjacent--; line 57, after "wall", "40" Q should read --48--; line 60, after "holes", "172" should read --l74--. Column 7, line 3, after "defining" UNITED STATES PATENT OFFICE CERTIFICATE OF CCRREC'HCN Patam No. 3,923,268 Datmi December 2. 1975 lnvawo hfl James P. Urvnowicz Page 2 of h It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

should read --defines--; line 4, "182" should read --44-@; line 8, "182" should read =44 line 12, "182" should read =44--; line 17, "182" should read =-44=-3 line 19, after "in" and before "7", "Fig." should read Figs. 6 and-. Column 8, line 68, after "bore", "288" should read -88-. Column 9, line 8, after "hole", "296" should read --96--; line 14, after "bore", "288" should read --88--; line 27, after "angle" and before "of", insert line 39, after "spring", "138" should read--ll-; line 50, before "past", "at" should read --it-; line 51 after "surface", "182" should read --44--; line 53, after 'system", "136" should read Column ll, line 14, after "being", "adopted" should read -adapted--; line 61, after "fining" and before "drive", insert --a--.

IN THE DRAWINGS: Sheet 2, Fig 2, reference numeral on pin 258 should read --l58--; insert reference numeral 166 identifying bore within which pin 158 resides; insert reference numeral 78 to identify the axial bore through piston 76; move lead line for reference numeral 84 to identify the bore through diaphragm 72; insert reference numeral 82 to identify the bore through screw insert lead line connecting reference numeral 86 to actuator shaft; insert lead line connecting reference numeral to circumferential groove in actuator shaft 86; insert lead line connecting reference numeral 143 to spring which engages pin 50; insert reference numeral 88 to identify central bore through actuator shaft 86; insert lead line connecting reference numeral 44 to left=hand UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 923, 268 Dated December 2 1915 Inventor(s) James P Urynowicz Page 3 of It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

side of flange 46 near lower left corner of drawing; insert reference numeral 112 identifying slot within which set screw 110 resides; insert reference numeral 115 identifying spring within spring housing 108; insert reference numeral 106 identifying aperture through spring housing 108 which receives axially extending shaft 100; insert reference numeral 124 identifying bell housing; reference numeral 136 should read 70--. Sheet 3, Fig. 3, insert lead line connecting reference numeral 160 to small diameter central bore; insert reference numeral 166 identifying untapped bore within slot 164 (all three occurrences); insert reference numeral 174 identifying tapped bore which is radially inward from counter sunk bore 170 (all three occurrences) Sheet 3, Fig. 4, define small axially extending bore 166 similar to bore 166 in Fig. 2 and strike cross hatching therein; extend lead line for reference numeral 144 to vertically extending surface. Sheet 3, Fig. 6, reference numeral 182 should read --44--; insert reference numeral 46 connected by lead line to righthand side of flange opposite surface 44; insert reference numeral 22 connected by lead line between vertically extending surface between

numerals

20 and 176; insert reference numeral 192 identifying slot in hub of collar 20; insert reference numeral 194 identifying rear surface of hub of collar 20. Sheet 3, Fig. 7, insert reference numeral 192 identifying slot; insert reference numeral 194 identifying rear surface.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,923,268 Dated December 2 1975 Inventor(s) James P. Urynowicz g it of A It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Sheet 4, Fig. 10, insert reference numeral 262 identifying slot which is shown by a broken line. Sheet 4, Fig. 11, inse rt reference numeral 262 identifying the slot; insert reference numeral 246 connected by an arrow to identify slot in bottom of shoe 32; insert reference numeral 248 identifying left side of slot 246; insert reference numeral 250 identifying right side of slot 246; insert reference numeral 32 identifying shoe. Sheet 4, Fig. 12, connect reference numeral 274 to large diameter portion of actuator shaft 86; reference numeral 288 should read -88--;

reference numeral 296 should read --96.

Signed and Scaled this Twenty-sixth D3) of October 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Q Alluring Officer Commissioner ofPatenrs and Trademarks

Claims

1. A reel hub assembly comprising: an actuator shaft which is axially movable relative to a radially disposed shoe between a reel lock position and a reel release position, the actuator shaft being adapted at one axial position therealong to receive at least one drive link end in a mating relationship which prevents axial motion of the shaft relative to a mated end of a drive link while permitting radial motion of an end opposite the mated end of a drive link with respect to the shaft; at least one drive link having opposed ends disposed to extend generally radially with respect to the actuator shaft with one end in a mating relationship with the actuator shaft at the one axial position and an opposite end in a mating relationship with a shoe, both said one and opposite end mating relationships permitting radial motion of the drive link relative to the mate while preventing axial motion of the drive link relative to the mate; at least one shoe adapted to receive an opposite end of a drive link in a mating relationship which permits radial but not axial motion of said opposite end relative to the shoe; and an actuator mechanism connected to cause relative axial motion of the shoe and actuator shaft between a reel lock axial position relationship and a reel release axial position relationship to move the shoe between a radially extended position and a radially retracted position respectively.

7. An automatic reel hub assembly comprising: a generally cylindrical body member having a central axial aperture for receiving a central shaft and having a plurality of radially extending shoe apertures providing communication between the central axial aperture and an outer circumference of the body member, each radially extending aperture being adapted to receive a shoe; a plurality of shoes, each being disposed for radial motion within a different shoe aperture, each having an outer surface adapted for gripping engagement with an interior surface of a reel hub, and each having an inner surface opposite the outer surface which has a concavity therein, the concavity being adopted to limit nonradial relative motion between the shoe and an end of a drive link received within the concavity; a central shaft disposed for axial motion within the central aperture, the shaft having a concavity for receiving an end of a drive link which is adapted to limit relative axial motion between the central shaft and a drive link end disposed approximately opposite each shoe concavity; a plurality of drive links extending between a shoe concavity and an opposite central shaft concavity, each drive link having a first end adapted for mating engagement with a shoe concavity and a second end adapted for mating engagement with a central shaft concavity; means for biasing each shoe radially inward; and means for controlling the axial position of the central shaft relative to the body member.

8. The hub assembly as set forth in claim 7 above, wherein the concavity in each shoe is adapted to permit an engaged drive link to rotate through at least a small arc about an axis positioned near the first end thereof which is perpendicular to a plane extending through a central axis of the body member and an approximate center point of a concavity and to prevent an engaged drive link from rotating about an axis which is positioned near the first end thereof generally parallel to a central axis of the housing.

12. The hub assembly as set forth in claim 11 above, wherein the central shaft groove has a cross sectional shape in a plane passing through a central axis of the shaft of a circular arc defining the deepest portion of the groove and straight lines extending tangentially from the extremities of the arc to the outer circumFerence of the shaft.

13. The hub assembly as set forth in claim 12 above, wherein the arc subtends an angle of approximately 80* about its center.

14. A reel hub assembly comprising: a plurality of shoes disposed about a central axis, the shoes having radially outward surfaces which are suitable for engagement with a reel, being disposed to move radially outward to engage a reel and move radially inward to release a reel, and having cavities which open radially inward and are adapted for pin-free engagement and retention of first ends of a drive link as drive link ends which are located radially inward from the first ends are moved axially at a fixed radial distance from the central axis to control the radial position of the shoes; a plurality of drive links, each having a first end in pin-free engagement with a cavity of a different shoe and a second end disposed radially inward with respect to the first end; and a drive mechanism adapted for pin-free engagement and retention of the second drive link ends, the drive mechanism providing selected axial motion for the second drive link ends while maintaining the radial distance of the second drive link ends from the central axis substantially constant.

16. For use in a tape transport, a tape reel hub assembly comprising: a shaft having a central axis and a periphery with at least one cavity therein, the shaft being translationally movable along the axis and connectable for rotation about the axis by a motor; means for translationally positioning the shaft while maintaining a plurality of shoes in a fixed axial position; a plurality of drive links, each having a first curved end in mating relationship with a cavity in the shaft and a second curved end opposite the first curved end; and a plurality of shoes, each having an outer surface suitable for mating relationship with a tape reel and an inner surface with a cavity therein receiving a second curved end of a drive link in a pin-free mating relationship in which the second curved end engages the cavity.

17. A reel hub assembly comprising: an axially extending actuator shaft disposed for axial positioning, the actuator shaft having at least one concavity in the circumference thereof which is shaped to receive at least one drive link in mating relationship, the actuator shaft further having a central aperture therein which extends axially from one end to a position past the at least one concavity; an axially fixed wall defining a portion of a chamber which is disposed at said one end of the actuator shaft in communication with the central aperture thereof; an axially movable wall which defines a portion of the chamber and which is coupled to the actuator shaft, the movable wall and actuator shaft being axially movable in response to fluid pressure in the chamber to axially position the at least one concavity; at least one shoe which is mounted for radial motion with respect to the actuator shaft; at least one drive link disposed between a shoe and a concavity in the actuator shaft to radially position a shoe in response to an axial position of the actuator shaft; and means for biasing the at least one shoe radially inward.

22. The reel hub assembly according to claim 17 above, further comprising a flexible diaphragm disposed within the chamber to provide a non-sliding seal between the fixed wall and the movable wall of the chamber.

23. A reel hub assembly comprising: a reel motor having a motor shaft having a central axis and a central aperture extending axially therethrough; a generally cylindrical support member disposed concentrically about the central axis, the support member being adapted to receive and support a plurality of shoes and permit only radial motion of the shoes with respect thereto, being connected in fixed relationship with the motor shaft, and having a central aperture extending therethrough for receiving an actuator shaft; a plurality of shoes, each being supported by the support member for only radial motion with respect thereto; an actuator shaft disposed within the central aperture of the support member and adapted for axial motion with respect to the support member, the actuator shaft having at least one concavity in the circumference thereof for receiving a plurality of drive links in mating relationship and having a central bore extending axially therethrough from a forward end rearwardly past the at least one concavity; a plurality of drive links, each extending between a shoe and a concavity in the actuator shaft to impart radial motion to a shoe in response to axial motion of the actuator shaft; a fixed wall disposed in fixed relationship with the support member forward of the forward end of the actuator shaft to partially define a chamber which is in communication with the axial bore in the actuator shaft at the forward end thereof; a movable wall connected to the forward end of the actuator shaft, the movable wall forming a part of the chamber and being operable to axially position the actuator shaft in response to fluid pressure in the chamber; and means for defining a fluid path which couples a rearward end of the axial bore through the actuator shaft to a source of fluid having a controlled pressure.