US 3581981 A
Description (OCR text may contain errors)
United States Patent [5 6] References Cited UNITED STATES PATENTS  Inventor Allen Latham,.lr.
Jamaica Plain, Mass. 761,558
2,536,793 l/195l Anderssonetal............ 3,317,127 5/1967 Cole..................... Primary Examiner-William 1. Price Attorney-Bessie A. Lepper [2i Appl. No.
 Filed Sept. 23, 1968  Patented June I, 1971  Assignee Cryogenic Technology, Inc.
ABSTRACTtAn easily operated chuck for holding a plastic,
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INVENTOR. Allen Lothdm, Jr.
Arrorney PATENIEDJUN Hen 3581.981
' sum 3 UF 5 INVENTOR. Allen Lofhom, Jr.
Attorney PATENIED JUN 1 l97| SHEET u or 5 Fig. 6
INVENTOR. Allen Lofhom, Jr. BY
Attorn ey PATENITEII' JUN H971 SHEET 5 [IF 5 INVENTOR. Allen Lcihum, Jr. BY
Airorney CENTRIFUGE CHUCK This invention relates to a novel chuck for holding .centrifuge rotors and particularly to a chuck which can be easily operated in connection with plastic or metal centrifuge rotors and to acentrifuge assembly incorporating the chuck.
Although the novel centrifuge chuck and centrifuge assembly of this invention will be described in terms of its use with plastic centrifuge rotors particularly adapted for use in processing human blood to prepare it for storage and then subsequently for transfusion to a recipient, it may also, of course, be used in conjunction with any other suitable centrifuge rotor.
Long term storage of human blood requires that it be frozen in a liquid medium to protect it during storage. U.S, Pat. No. 3,145,713 describes and claims a preferred method and apparatus-for handling-blood which-is to be stored. The blood is collected directly into a one-use sterile plastic liner placed in a centrifuge rotor wherein the red cells are stored after gradual replacementof the intracellular and intercellular water by glycerol. When the blood is to be used, it is brought up to temperature, the liner is placed again in the centrifuge-rotor and the glycerol is gradually replaced by asuitable saline liquid while the red cells remain in the centrifuge liner. Thus the centrifuge becomes a very important piece of apparatus in blood collection centers as well as in hospitals, and its operation is in the hands of a large number of technicians of varied skills which often do not include mechanical skills.
It is therefore essential to the efficientoperation of the newly developed techniques for handling blood to have centrifuge equipment which may be made available in large numbers for operation by individuals who are generally not trained in the handling of mechanical equipment. One of the important aspects of centrifuge use lies in the installation and removal of the centrifuge rotor from the centrifuge driving means. This in turn involves the operation of the centrifuge chuck which holds the centrifuge rotor firmly to the rotating mechanism of the centrifuge. Another important aspect lies in the proper placement of the rotor in the centrifuge assembly to permit its being connected to inlet and discharge lines during all steps of its use.
It is therefore a primary object of this invention to provide a novel improved chuck for a centrifuge which can be easily operated in connection with plastic centrifuge rotors. Another object of this invention is to provide a chuck of the character described which is safe, inexpensive and easily operated. A still further object is to provide an improved centrifuge assembly incorporating the chuck. Other objects ofthe invention will in part be obvious and will' in part be apparent hereinafter.
The invention accordingly comprises the features of con-.
struction, combinations of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
For a fuller understandingof the nature and objects of the invention reference should behad to the following detailed description taken in v connection with the accompanying drawingsin which:
FIG. 1 is a side elevational view, partly in cross section, of a centrifuge assembly incorporating the chuck of this invention;
FIG. 2 is across section of the centrifuge chuck;
FIG. 3 is a side elevational view ofthe braking cam;
FIG. 4 is a side elevational-viewof the ejector cam;
FIG. 5 is a top plan view, partly in cross section, showing one embodiment for actuating the cams;
FIG. 6 is a perspective view, partly in cross section, of the cable system for operating the cams;
FIG. 7-is a side elevational view, partly in cross section of the clamping arm assembly for holding the stationary inlet and outlet passages nearthe top of the centrifuge rotor;
' FIG. 8 is a cross-sectional view. of the inlet and outlet passages for making fluid connections with the centrifuge; and
FIG. 9 is atop plan view of the clamping arm assembly.
The chuck of this invention provides rapid, easy registry of the rotor and a peripheral O-ring for gripping the rotor on a sloping reentrant peripheral shoulder and a registration surface at the periphery of the rotor to secure the base of the rotor in a plane perpendicular to the axis of rotation. The O- ring gripping ring is loaded by an annular array of stacked washer spring; and two concentric cams, torsionally joined but free to move separately along their axes, serve the multifunctional roles of braking the centrifuge chuck, releasing the grip of the O-ring and actuating ejector pins for ejection of the rotor. The cam which releases the O-ring grip also serves to brake and hold the spindle stationary. There are three use positions for the cams; l. chuck-gripping the rotor, brake released and ejector pins withdrawn to permit the rotor to 'be rotated; 2. brake set, chuck not gripping and ejector pins withdraw; and 3. brake set, chuck not gripping and ejector pins protruding to put the rotor in condition for easy removal from the centrifuge. The rotor inlet and outlet passage means and the stationary member of the rotary seal means are held near the upper end of the axis of rotation of the rotor in a clamping assembly.
FIG. 1 illustrates the centrifuge rotor in position in the chuck and shows the general relationship of the various components associated with the centrifuge. Centrifuge rotor 10 is held in the chuck 12 which in turn has a braking mechanism 14 and a driving means 16. Two clamping arms i8, affixed to support posts 19 (to be described) serve as an integral part of the chuck mechanism for supporting the stationary feed tube 20 and stationary effluent tube 21 in correct operational relationship to the centrifuge rotor and complete the centrifuge assembly.
The chuck mounting 23, which also provides a chuck housing 24, defines an emergency liquid drainage channel 25 which discharges into two or more quick-discharge conduits 26. The chuck, centrifuge rotor, support system and feed and effluent tube assembly are enclosed by upper centrifuge housing 28 having a cover member 29. The centrifuge spindle (not shown in FIG. 1) and its associated cooling and driving means are located in a lower centrifuge housing 30.
The chuck in the embodiment illustrated in FIG. 1 is operated manually by the arcuate movement of two radial chuck levers 31 and 35 (see also FIG. 5). These levers terminate external of the housing 30 in handles 32 and 36. Clamps 33 and 37 affix the cable to the levers and the levers pivot on shaft 38 mounted in supports 34. Each lever is therefore attached to the inner wall of lower housing 30 in a manner to permit its arcuate motion.
The spindle, its bearings and cooling system are enclosed in housing 412. In a copending application Ser. No. 761,663 filed Sept. 23, 1968 I have described a preferred form of spindle with cooling means which'permit the spindle to rotate at high speeds without transferring any appreciable amount of heat to the centrifuge rotor or to the contents contained therein.
The centrifuge chuck is illustrated in detailed cross section in FIG. 2 wherein like numerals refer to like components of FIG. 1. In order to illustrate all of the components clearly, they. are shown spaced apart, not necessarily representing any one operational mode. The exact interrelation of each component will be described in the detailed description of its operation.
That part of the chuck 141 which grips the centrifuge rotor comprises a rotor chuck closure ring 45, having an upper peripheral, inwardly turned lip 46, and a rotor chuck body 48. This chuck body 48 is, in turn, formed of an upwardly extending'vertical ring section 49 integral with a horizontal annular section 51 having an annular groove 52 into which the ejector pins extend. The annular section 51 in turn is integral with a central, heavy-walled hub 53 which provides for attachment of the chuck 12 to the spindle 54. The upper surface of the hub 53 is machined to provide a relative small circular registry section 55 for centering the centrifuge rotor.
Positioned between the under surface of lip 46 and the top edge of the vertical ring section 49 of the chuck closure ringis a flexible, elastomeric gripping O-ring 58 preferably formed of a synthetic rubber of medium hardness. When maximum separation exists between lip 46 and the top edge of ring 49, the gripping ring assumes its natural circular cross section and the rotor may be removed. However, as long as the chuck closure ring 46 is forced downwardly (by means to be described) the gripping ring is forced to expand toward the center and thus grips the surface of the centrifuge rotor 10 (see the eutaway section of FIG. 1) to hold it fast during centrifuging. The annular ring section 51 of the chuck body 48 has drilled in it an annular array of holes 60 (only one shown) to receive spring guides, and also three holes 61 for the ejector pins.
The chuck section 12 is completed with a rotor brake disc 65 having a central opening 66 and being fastened to the lower end of the chuck closure ring 45 by means of rotor brake disc retainer ring 67. The rotor disc brake 65 has an annular array of holes 70 drilled in it to correspond in position to holes 60 in the annular ring 51 as well as larger diameter wells 71 to seat washer closure springs 72 which are located on guide pins 73. The purpose of washer springs 72 is to force the gripping ring to grip the centrifuge rotor.
The braking and ejecting means generally indicated by the numeral 14 in FIG. 1 comprise the mechanism for first positively actuating the braking of the rotation of the chuck and its centrifuge rotor and then for positively actuating the release of the O-ring grip and finally for actuating the ejector pins. This is accomplished through the use of two cams.
Braking is achieved by use of a cam torque cap 80 which is comprised of an annular cap 81 having a braking surface 82 formed of a material such as a paper-filled phenolic laminate. When the cam torque cap 80 is raised upwardly the braking surface 82 makes frictional contact with the bottom surface 68 of rotor brake disc 65. The cam torque cap has a central opening 84, and depending from and integral with the annular cap 81 is an annular vertical section 83 which surrounds the upper portion of chuck housing 24. While the centrifuge is rotating, the cap 82 sits on the ring defined by the upper edge of housing 24. On one side of the vertical section 83 of the cam torque cap is a torque cable clamp 88 which in FIGS. and 6 will be seen to have a small protuberance 89 contoured to fit a groove 90 cut into an enlarged section 91 of the vertical section 83, this enlarged section also having a cable groove 92 (FIG. 6). The purpose of this arrangement is to lock cable 95 to the cam torque cap, the ends of the cable being alfixed. to the chuck levers 31 and 35 as will be described in conjunction with the detailed description of FIGS. 5 and 6.
Affixed to the cap 81, through a series of screws 99, is the annular braking cam 100 seen in FIG. 3 to have three cam faces cut into its surface and spaced equidistantly around the cam surface. Each of the cam faces are comprised of a horizontal section 101 and an upwardly inclined section 102 which terminates in an uppermost section 103. The horizontal section corresponds to brake engagement, the upwardly inclined section 102 to brake disengaging, and the uppermost section 103 to brake disengagement. Detent 104 is provided as a means to identify and maintain the position of the cams for insertion of a rotor in the chuck while ring 58 is relaxed and ejector pins 130 are withdrawn. The brake cam 100 has splines 105 around its inner surface and an annular array of holes 106 drilled through it which open into an enlarged bottom central opening 107. Three cam rollers 110 corresponding to the three cam faces in the braking cam are mounted for free rotation on shafts 111 which are pressed into holes drilled in housing 24.
It will be seen that by proper movement of the cam torque cap 80 back and forth through a relatively small are, it is possible to raise and lower the braking cam affixed to the cam torque cap.
The ejector cam 115 is shown in FIG. 4 to have three cam faces, namely, pin withdrawn face 116 and a steeply inclined face 117 connecting face 116 with pin engagement face 118. The outer periphery of the upper portion of the ejector cam has splines 120 which engage splines 105 of the brake cam.
Thus the brake and ejector cams are torsionally locked but free to move axially with respect to each other. This means that the arcuate movement of the torque cam cap also moves the ejector cam through a small angle sufficient to cause the ejector cam rollers 122 which are freely rotatable on shafts 123, to engage the desired cam face of the ejector cam.
An ejector pin ring 128 is slipped around the hub 53 of the chuck body 48 and is held in place by means ofa retainer ring 129. Three ejector pins 130 are mounted in the pin ring and they extend upwardly through the central openings 84 and 66 of the cam torque cap and brake disc 65, respectively, and then through the holes 61 in the horizontal annular section 51 of the chuck body 45. Thus ejector pin ring 128 and the ejector pins rotate with the chuck. Each ejector pin has a spring 131 to maintain the ejector pin in a normally unprojected state with the top surface of the pin below the level of the walls defining annular groove 52 until actuated by the ejector cam 115. Likewise, a series of springs 13S extend between the bottom surface of torque cam cap 80 and a peripheral ring 136 of the ejector cam passing through holes 106 in the braking cam. These springs are held in position by dowel pins 137 which are mounted in ring 136. The purpose of springs is to maintain the engaging surface 138 of ejector cam 115 in spaced, free-running relationship with the engaging bottom surface 139 of ejector pin ring 128 during centrifuge rotation.
The spindle 54 on which the chuck is mounted is encased throughout most of its length in a bearing spacer 144. An oil pump rotor 1.45 and a typical ball bearing assembly 146 are associated with the upper end of the spindle below hub 53, and a similar ball bearing assembly 147 is held between ring 148 and shoulder 153. Bearing 147 is locked to the spacer 144 by nut 154 acting through the hub of pulley 150 to take all of the axial force of the system when the brake is applied. The upper bearing assembly 146 in effect floats against a flexible bearing mount 149, the purpose of which is to case the local and fric' tional heat generated in the bearing due to any minor unbalance of the rotating parts. The rotor is preferably part of an oil pump which is used in connection with the spindle cooling apparatus described in my copending application Ser. No. 761,663. Pulley drives the spindle through a key 151 and it is driven by a motor (not shown) through belt 152.
FIGS. 5 and 6 illustrate an embodiment of the chuck of this invention wherein manual operation of two levers is used to operate the chuck. In FIGS. 5 and 6, like numerals are used to identify like components in FIG. 2. FIG. 5 is a top plan view partly in cross section, with the vertical ring 83 of the cam torque cap and one cable housing being shown in cross section and the outline of the cam torque cap 81 being shown by a dotted line. FIG. 6 is a perspective view of the cable system used to move the cams.
Affixed to or integral with chuck mounting 23 is a left-hand I pulley housing 155 (FIG. 5) providing a recess in which a cable pulley 156 may rotate on shaft 157. In a similar manner, there is provided a right-hand pulley housing 160 for pulley 161 rotating on pulley shaft 162 (FIG. 6). FIG. 6 illustrates the manner in which the cable is connected to the left-hand lever 31 and right-hand lever 35. Cable 95 is attached by means of cable clamp 33 to lever 31, then it passes over pulley 156 through the groove 92 in the enlarged section of the vertical cap ring extension 83, over right-hand pulley 161 and is attached by means of cable clamp 37 to right-hand lever 35. The torque cable clamp 88 anchors the cable to the cam torque cap. Movement of the levers 31 and 35 effects the shifting of the cam torque cap 81 through a predetermined angle. Thus actuation of the brake, chuck, gripping ring and ejector are positive movements which are made in proper order.
FIGS. 7-9 illustrate the centrifuge clamping arm assembly which, along with the chuck, completes the mechanism for holding the centrifuge rotor as well as the stationary feed and effluent tube connections which are in fluid communication with the interior volume of the rotor. In these figures, as well as in FIG. 1, like reference numerals refer to like components.
Two support posts l9 (one of which is shown) are mounted to the housing so that they are in a position to hold two pivoting arms 18 above the centrifuge rotor. FIG. 7 illustrates onehalf of the clamping arm assembly, the other half being in a mirror-image relationship thereto as shown in FIG. 9. The support post 19 carries a collar I65 which has a locking notch 166. The clamping arm 18 has a pivot connecting section 168 which is adapted for free pivotal movement on support post extension 169. The other end of the arm is adapted to hold the tube assembly of FIG. 8 in an arcuate surface 172 (half of which is defined by each arm) and in horizontal groove 173. Conical, arcuate surface 171 joining 172 and 173 serves as a cam to raise the feed and effluent tube assembly into operating position when support arms 18 are swung into operating position. Extending upward from the arm is a pressure plate 174 which may be grasped to swing the arm back and forth.
When the-clamping arm 18 is swung into place for operation, the plunger I75 slips down into notch 166 to hold the arm in place as shown in FIG. 7. The plunger is held locked in place by the action of spring 176 and may be pulled upward by knob 177 to disengage the arms from the feed and effluent tube assembly by rotation of the arms 18 in the directions of the arrows in FIG. 9.
The header and tube assembly which provides fluid communication with the internal volume of the centrifuge rotor is shown in FIG. 8. It comprises header I80, feed tube 182 and effluent tube 185 bonded or mechanically joined for leaktight connection. The header 180 has surfaces matching surfaces 171, 172 and 173 of the arms 18 to provide accurate positioning of the feed and effluent tube assembly and to provide good contact for conduction of heat to the arms asa means of dissipating frictional heat generated by the rotary seal which is used (see U.S. Pat. No. 3,409,213). In the header, central passage 189 serves to conduct fluid to the lower central portion of the rotor while annular passage I88 conducts fluid from the upper portion of the rotor as described in U.S. Pat. No. 3,145,713. Nipples 186 and 187 serve for easy connection of external tubes to the effluent and feed passages, respectively.
The operation'of the chuck of this invention may now be described, beginning with the chuck and rotor in position during the actual centrifuging process. This requires that the cen-- trifuge rotor be tightly gripped, that the brake be released and the ejector pins be withdrawn. In the embodiment shown in the figures, this means that the left-hand handle is up and the right-hand handle is down. Braking cam rollers 110 engage the braking cam 100 in position 103 and ejector cam rollers 122 engage the horizontal face 116 of the ejector cam to cause both the braking cam and ejector cam to occupy their lowermost positions. Thus there is no contact between braking surfaces 82 and 68 and no upward force on ejector pin ring 128, a fact which maintains the ejector pins retracted and permits the centrifuge rotor to be gripped in operation position. The clamping arm assembly will be locked into place as shown in FIG. 9 and the inlet and effluent tubes engaging their respective connections.
At the end of centrifuging the drive motor is shut off and the left-hand handle is depressed slightly to actuate the brake. Then the release knobs 177 are pulled upwardly and clamp arms 18 are swung outwardly to free the feed and effluent tube assembly at its upper end. Then the left-hand handle is moved downwardly to the limit of its motion so that cam torque cap 80 is moved clockwise to move both the braking cam and the ejector cam. These cams are so aligned that the braking cam rollers M0 first engage the downwardly inclined faces 102 of the braking cams to force braking surfaces 68 and 82 into engagement to stop rotation of all rotating members. Continued movement of the braking cam applies additional upward force Complete downward movement of the left-hand handle causes the ejector cam rollers 122 to engage cam surfaces 117 and 118 which forces ejector pin ring 12% and the ejector pins into their protruding position, thereby ejecting the centrifuge rotor from the chuck.
Prior to insertion of a centrifuge rotor in the chuck, the right-hand handle is moved about halfway down until the brake cam rollers engage detents 104. In this position of the cam assembly the ejector pins are lowered into their retracted position and the chuck-gripping ring is relaxed. After insertion of the rotor the right-hand handle is depressed all of the way down to lower the braking cam, first to permit washer springs 72 to force the upper edge of the chuck body vertical ring 419 and the lip 46 of the chuck closure ring toward each other to deform gripping ring 58 into gripping position and then to release the braking surfaces from contact. Support arms I8 are swung around and locked into operating position. The centrifuge rotor and connecting tubes are now in position for normal operation. It should be noted that all external connections to the rotor may remain connected during insertion and removal of the rotor so that the sterile interior of the rotor is not subjected to possible contamination.
From the above description it will be seen that there is provided an easily operated, relatively inexpensive centrifuge chuck. Since it requires only the operation of two handles and two supporting arms (or their equivalents in buttons operating motor-driven actuating means) in a simple predetermined sequence, the individual using the centrifuge need not be technically trained in the art of mechanical operations.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the scopeof the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
1. In a chuck adapted to hold a centrifuge rotor for spinning, means for gripping said rotor to said chuck comprising in combination a. an annular elastomeric gripping ring;
b. pressure-applying means adapted to force said gripping ring to be distended inwardly to grip the surface of said rotor; and
c. spring means adapted to actuate said pressure-applying means and to retain said ring in gripping position in the absence of any external force to overcome the force of said spring means.
2. In a chuck adapted to hold a centrifuge rotor for spinning, means for gripping said rotor to said chuck, comprising in combination a. a closure ring having an inwardly extending peripheral b. aezhuck body having a vertical annular ring member;
0. an elastomeric gripping ring positioned between said lip of said closure ring and the upper edge of said annular ring member; and
d. an annular array'of springs adapted to force said lip of saidclosure ring against said gripping ring whereby in the absence of external force applied to said springs said elastomeric ring is distended inwardly to grip the outer surface of said centrifuge rotor.
3. A centrifuge chuck, comprising in combination a. a closure ring having an inwardly extending peripheral lip terminating its upper edge;
b. a chuck body having a vertical annular ring member and being adapted to hold a centrifuge rotor in registry;
c. an elastomeric gripping ring positioned between said lip of said closure ring and the upper edge of said annular ring member of said chuck body;
d. a brake disc affixed to the lower edge of said closure ring;
e. a plurality of ejector pins mounted in an axially movable ejector pin mounting ring and passing through openings in the bottom of said chuck body;
f. an annular array of springs positioned between said chuck body and said brake disc and adapted to force said lip to said closure ring against said elastomeric gripping ring whereby in the absence of external force applied to said springs said elastomeric ring is distended inwardly to a gripping position;
g. a cam torque cap having a braking surface adapted for braking engagement with said brake disc and for applying external force to said springs;
h. annular braking cam means affixed to said cam torque cap;
i. annular ejector cam means torsionally connected to said braking cam means but free to move axially with respect thereto and adapted to move said ejector pin mounting ring upwardly thereby to cause said ejector pins to protrude into said chuck body and raise said centrifuge rotor; and
j. cam actuating means.
4. A centrifuge chuck in accordance with claim 1 wherein said cam torque cap has a vertically extending portion and said cam actuating means comprises 1. a cable anchored at its center point to the side of said vertically extending portion, and
2. means for moving said cable through a predetermined distance thereby to move said cam torque cap and actuate said braking and ejector cams.
5. A centrifuge in which fluid communication is provided with the internal volume of the centrifuge rotor during centrifuging, characterized in that the means for maintaining said rotor and associated fluid connections in operational position during centrifuging comprises in combination a. a chuck adapted to grip the lower portion of said rotor,
said chuck comprising 1. an annular elastomeric gripping ring,
2. presure-applying means adapted to force said gripping ring to be distended inwardly to grip the surface of said rotor, and
3. spring means adapted to actuate said pressure-applying means and to retain said ring in gripping position in the absence of any external force to overcome the force of said spring means;
b. stationary fluid inlet and outlet-connecting means providing fluid communication between the internal volume of said rotor and tubing means; and
c. clamping means adapted to hold said connecting means in position and to provide free rotation of said rotor.
6. A centrifuge in accordance with claim 5 wherein said clamping means comprises two pivotable arms supported above said rotor and adapted to lock said connecting means between them.
7. A centrifuge in which fluid communication is provided with the internal volume of the centrifuge rotor during centrifuging, characterized in that the rotor holding means comprises in combination 8. A centrifuge in accordance with claim 7 wherein said arms incorporate cam surfaces adapted to raise said head means into operating position thereby to permit said free rotation of said rotor.
a. a chuck, comprising 1. a closure ring having an inwardly extending peripheral lip terminating its upper edge, 2. a chuck body having circular, peripheral flat registra tion means and central circular registration means of a size to match and engage corresponding registration means in said rotor base adapted to maintain rotational alignment of said rotor, and having a vertical annular ring member, an eiastomeric gripping ring positioned between said lip of said closure ring and the upper edge of said annular ring member of said chuck body,
4. a brake disc afflxed to the lower edge of said closure ring,
5. a plurality of ejector pins mounted in an axially movable ejector pin mounting ring and passing through openings in the bottom of said chuck body,
6. an annular array of springs positioned between said chuck body and said brake disc and adapted to force said lip of said closure ring against said elastomcric gripping ring whereby in the absence of force applied to said springs said elastomeric ring is distended inwardly to a gripping position,
7. a cam torque cap having a braking surface adapted for braking engagement with said brake disc and for applying force to said springs,
8. annular braking cam means affixed to said cam torque cap,
9. annular ejector cam means torsionally connected to said braking cam means but free to move axially with respect thereto and adapted to move said ejector pin mounting ring upwardly thereby to cause said ejector pins to protrude into said chuck body and raise said centrifuge rotor, and
10. cam actuating means; and
b. clamping assembly means, comprising in combination I. header means providing stationary inlet and outlet connections with the interior volume of said rotor,
2. two pivotally mounted clamping arms adapted for engagement with said header means for positioning said header means to permit free rotation of said rotor,
3. arm support means on which said arms are mounted, and
4. means to lock said arm in engagement with said header means.
9. A centrifuge in accordance with claim 7 wherein said arms incorporate thermal contact means adapted to dissipate heat from said header means.