Centrifuge

• US 4,822,331 A
• Filed: 11/09/1987
• Issued: 04/18/1989
• Est. Priority Date: 11/09/1987
• Status: Expired due to Fees

• Current Assignee: David C. Taylor
• Original Assignee: David C. Taylor
• Inventors: Taylor, David C.
• Primary Examiner(s): Simone, Timothy F.
• Application Number:
  US07/118,570
• Time in Patent Office: 526 Days
• Field of Search: 494/1, 494/16, 494/7-9, 494/13, 494/16, 494/47, 494/61, 494/84, 494/83, 494/52, 494/46, 494/23, 494/37, 494/39, 318/542, 318/361
• US Class Current: 494/16
• CPC Class Codes: B04B 2007/025 Lids for laboratory centrifuge rotors
• CPC Class Codes: B04B 5/0414 comprising test tubes
• CPC Class Codes: B04B 7/06 Safety devices ; Regulating
• CPC Class Codes: B04B 9/02 Electric motor drives dynamo-electric machines associated with centrifuges H02K7/16

Abstract

A centrifuge, including a motor assembly with a low-speed brushless induction motor connected to the spindle assembly and controlled by an electrical circuit for gently shifting phases of operation but with rapid acceleration and deceleration, the centrifuge rotor for use on the spindle assembly having interlocks with the electrical circuit and being completely enclosed for safety, the resulting motor mechanism and rotor being comparatively quiet in operation, the motor and spindle assemblies being capable of use with rotating devices and loads other than centrifuges and the centrifuge rotor being capable of holding various insertable tube carriers to provide operation with wide variety of test samples while also being substantially free of corrosion from sample spillage.

Claims

1. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm;

a spindle assembly vertically mounted in the baseplate and having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate;

a rotor including a rotor base with a flat base portion and a cylindrical portion and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

a tube carrier removably mounted in the rotor base and including a plurality of tube holders;

an enclosure mounted on the baseplate enclosing the motor assembly and the spindle assembly and the rotor, the enclosure having an access door above the rotor;

a locking mechanism mounted on the enclosure at the access door to prevent opening of the access door during operation of the rotor;

a stop switch located at the upper end of the motor assembly adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch; and

an electrical circuit means including the locking mechanism and the stop switch and further including means to activate the motor with a starting torque, said electrical circuit further including means to reverse the motor torque to a braking torque opposite from the starting torque and to increase substantially the starting and braking torque of the motor.

2. A centrifuge according to claim 1 wherein the motor assembly further includes;

a roller mounting bracket mounted on the motor at the lower end of the motor with a means mounted on the mounting bracket to permit the motor assembly to move in relation to the baseplate;

a tension arm affixed to the roller mounting bracket and pivotably mounted on the baseplate;

a tension spring affixed to the end of the tension arm closest to the point where the tension arm is pivotably mounted on the baseplate and affixed to the baseplate so as to tighten the drive belt, said tension spring being located in a generally horizontal position;

a U-bracket mounted on the upper end of the motor assembly, the stop switch being mounted on the U-bracket;

a pair of hold-down springs extending from the U-bracket to the baseplate, one hold-down spring being substantially vertical and being located adjacent the tension spring and the other holddown spring extending at an incline to the vertical to assist the tension spring in tightening the drive belt.

3. A centrifuge according to claim 1 wherein the spindle assembly further includes:

a spindle housing rigidly secured to the baseplate;

a lower shaft and an upper shaft; and

a flexible coupling, the lower shaft and the upper shaft each being connected at one end to the flexible coupling, the lower shaft and the upper shaft and the flexible coupling being rotatable mounted in the spindle housing, the end of the upper shaft remote from the coupling having a tapered end with a cross pin through the upper shaft adjacent the taper.

4. A centrifuge according to claim 1 further including:

an adapter mounted on the upper end of the spindle assembly having a generally cylindrical shape with a female tapered opening and extending into the rotor base.

5. A centrifuge according to claim 1 wherein the rotor cover includes:

a concentrically located grip sleeve which extends upwardly from the rotor cover and having an upper end, the upper end of the grip sleeve being flared;

an outer sleeve threaded into the grip sleeve, said outer sleeve having a ball groove and a counterbore;

an inner sleeve having an upper end and a lower end slidably mounted within the outer sleeve, clearance holes being disposed radially in the inner sleeve near the upper end of the inner sleeve and clearance holes disposed radially in the inner sleeve near the lower end of the inner sleeve;

a push button slidably mounted within the inner sleeve, said push button including a circumferential groove and a magnet being secured within the top of the push button, said circumferential groove in the push button being located above and adjacent the clearance holes in the upper end of the inner sleeve;

an adapter having an opening which engages the upper end of the spindle assembly, and having a circumferential groove, said circumferential groove in the adapter being located adjacent the clearance holes in the lower end of the inner sleeve;

locking balls in the clearance holes in the upper end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby permitting the inner sleeve to release from the adapter and the rotor cover to be released;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the groove, said circumferential groove in the adapter being located adjacent the clearance holes in the lower end of the inner sleeve;

locking balls fitted within the clearance holes at the upper end and at the lower end of the inner sleeve, the locking balls in the clearance holes at the lower end of the inner sleeve extending into the circumferential groove of the adapter holding the inner sleeve to the adapter, the locking balls in the clearance holes at the upper end of the inner sleeve extending into the ball groove in the outer sleeve until the push button is depressed causing the locking balls in the clearance holes in the upper end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby premitting the inner sleeve to release from the adapter and the rotor cover to be released.

6. A centrifuge according to claim 1 wherein the rotor cover includes:

a concentrically located grip sleeve which extends upwardly from the top of the rotor cover, with an upper end, the upper end of the grip sleeve being flared;

an outer sleeve threaded into the grip sleeve, said outer sleeve having a ball groove and a counterbore;

an inner sleeve having an upper end and a lower end slidably mounted within the outer sleeve, clearance holes being disposed radially in the inner sleeve near the upper end of the inner sleeve and clearance holes disposed radially in the inner sleeve near the lower end of the inner sleeve;

a push button slidably mounted within the inner sleeve, said push button including a circumferential groove and a magnet being secured within the top of the push button said circumferential groove in the push button being located above and adjacent the clearance holes in the upper end of the inner sleeve, said push button further having a concentric opening extending through it;

an adapter having an opening which engages the upper end of the spindle assembly and having a circumferential groove, said circumferential groove in the adapter being located adjacent the clearance holes in the lower end of the inner sleeve, the adapter further having a concentric opening extending through the adapter and aligned with the concentric opening in the push button, said spindle assembly having a bolt threaded in it, said bolt extending through the adapter;

locking balls fitted within the clearance holes at the upper end and at the lower end of the inner sleeve, the locking balls in the clearance holes at the lower end of the inner sleeve extending into the circumferential groove of the adapter holding the inner sleeve to the adapter, the locking balls in the clearance holes at the upper end of the inner sleeve extending into the ball groove in the outer sleeve until the push button is depressed causing the locking balls in the clearance holes in the upper end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby permitting the inner sleeve to release from the adapter and the rotor cover to be released.

7. A centrifuge according to claim 1, further including:

a cooling fan mounted in the enclosure and connected to electrical circuit means, the electrical circuit means including a temperature sensitive element to reduce the speed of the cooling fan after the motor has stopped.

8. A centrifuge according to claim 1 further including

a belt switch mounted in the baseplate adjacent to the motor assembly, said belt switch being connected to the electrical circuit means to deenergize the motor when activated.

9. A centrifuge according to claim 1 wherein:

the motor assembly includes a tension arm located between the baseplate and the motor, the tension arm being rigidly secured to the motor and being pivotably mounted in the baseplate; and

further including;

a spring means connected to the motor assembly to hold the motor assembly against the baseplate and to rotate the motor assembly away from the spindle assembly, said motor assembly being retained from rotating away from the spindle assembly by the drive belt.

10. A centrifuge according to claim 1 wherein:

the motor assembly includes a tension arm located between the baseplate and the motor, the tension arm being rigidly secured to the motor and being pivotably mounted in the baseplate; and

further including

a spring means connected to the motor assembly to hold the motor assembly against the baseplate and to rotate the motor assembly away from the spindle assembly, said motor assembly being prevented from rotating by the drive belt; and

a belt switch mounted on the baseplate adjacent to the motor assembly and adapted to be activated by the motor assembly when the drive belt breaks, said belt switch being connected to the electrical circuit means to deenergize the motor when activated.

11. A centrifuge according to claim 1 further including:

a magnet located in the rotor cover; and

a rotor sensor switch mounted on the access door above the rotor and included within the electrical circuit means, said rotor sensor switch being normally open and being closed by close proximity to the magnet when the rotor cover is properly affixed to the rotor base.

12. A centrifuge according to claim 1 wherein the electrical circuit means further includes:

a main power switch;

a brake switch;

a run switch;

a timer;

an interval timer control switch, the main power switch, the brake switch, the run switch and the timer all being located in the enclosure;

means coextensive with the means to increase the starting torque and braking torque including a pair of capacitors;

means including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor;

means including a single capacitor and a fixed resistor connected in series to delay the actuation of the switching means to connect the capacitors in parallel both when the torque of the motor is in the starting torque and when the torque of the motor is the reverse torque;

means including a first temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the starting torque;

means including a second temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque; and

a unidirectional clutch mounted in the reverse detection arm, the upper shaft of the motor being mounted in the unidirectional clutch, said unidirectional clutch being adapted to rotate with the upper shaft only in the direction of rotation of the starting torque causing the reverse detection arm to strike the stop switch when the reverse direction of rotation begins, the stop switch being adapted to stop the operation of the motor.

13. A centrifuge according to claim 1,

wherein the electrical circuit means further includes:

a main power switch;

a brake switch;

a run switch;

a timer;

an interval timer control switch, the main power switch, the brake switch, the run switch and the timer all being located in the enclosure;

means coextensive with the means to increase the starting torque and braking torque including a pair of capacitors;

means including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor;

means including a single capacitor and a fixed resistor connected in series to delay the activation of the switching means to connect the capacitors in parallel both when the torque of the motor is the starting torque and when the torque of the motor is the reverse torque;

means including a first temperature sensitive element to reconnect the pair of capacitors in series when the torque of the motor ia the starting torque;

means including a second temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque;

a unidirectional clutch mounted in the reverse detection arm, the upper shaft of the motor being mounted in the unidirectional clutch, said unidirectional clutch being adapted to rotate with the upper shaft only in the direction of rotation of the starting torque causing the reverse detection arm to strike the stop switch when the reverse direction of rotation begins, the stop switch being adapted to stop the operation of the motor;

a cooling fan mounted in the enclosure, the first temperature sensitive element and the second temperature element being located in the close proximity to the cooling fan; and

means including a resistor and a third temperature sensitive element in parallel with one another and in series with the cooling fan to reduce the voltage, and further including means to connect the resistor and third temperature sensitive element in series with the cooling fan when the motor is deactivated by the stop switch.

14. A centrifuge according to claim 1 wherein the tube carrier removably mounted in the rotor base includes two rows of concentric tube holders, each row mounted at the maximum spin radius of that row.

15. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm mounted on the upper end, a unidirectional clutch being mounted in the reverse detection arm;

a spindle assembly vertically mounted in the baseplate end having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate, said spindle assembly including a spindle housing, a lower shaft, an upper shaft and a flexible coupling, the lower shaft and the upper shaft each being connected at one end to the flexible coupling and the lower shaft and the upper shaft and the flexible coupling being rotatable mounted in the spindle housing, the spindle housing being rigidly secured to the baseplate;

a rotor including a rotor base with a flat base portion and a cylindrical portion and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly, the rotor cover including a concentrically located grip sleeve extending upwardly from the rotor cover and having an upper end, the upper end of the grip sleeve being flared, an outer sleeve threaded into the grip sleeve, an inner sleeve slidably mounted within the outer sleeve, a push button slidably mounted within the inner sleeve, a magnet mounted in the push button,

an adapter having an opening which engages the upper end of the spindle assembly and fits within the inner sleeve;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

an enclosure mounted on the baseplate enclosing the motor assembly and the spindle assembly and the rotor, the enclosure having an access door above the rotor;

a stop switch located adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch; and

an electrical circuit means including means to activate the motor and the locking mechanism and the stop switch, said electrical circuit further including a pair of capacitors to increase the starting and braking torque of the motor to a level substantially in excess of the operating torque of the motor.

16. A centrifuge according to claim 15 wherein the motor assembly further includes;

a mounting bracket mounted on the motor at the lower end with a means mounted on the mounting bracket to permit the motor assembly to move in relation to the baseplate;

a tension arm affixed to the roller mounting bracket and pivotably mounted on the baseplate;

a tension spring affixed to the end of the tension arm closest to the point where the tension arm is pivotably mounted on the baseplate and affixed to the baseplate so as to tighten the drive belt, said tension spring being located in a generally horizontal position;

a U-bracket mounted on the upper end of the motor assembly, the stop switch being mounted on the U-bracket; and

a pair of hold-down springs extending from the U-bracket to the baseplate, one hold-down spring being substantially vertical and being located adjacent the tension spring and the other holddown spring extending at an incline to the vertical to assist the tension spring in tightening the pulley.

17. A centrifuge according to claim 15 wherein:

the outer sleeve has a ball groove and a counterbore;

the inner sleeve has an upper end and a lower end with clearance holes disposed radially in the inner sleeve near the upper end of the inner sleeve and clearance holes disposed radially in the inner sleeve near the lower end of the inner sleeve;

the adapter having a circumferential groove located adjacent the clearance holes in the lower end of the inner sleeve;

said centrifuge further including;

locking balls fitted within the clearance holes at the upper end and at the lower end of the inner sleeve, the locking balls in the clearance holes at the lower end of the inner sleeve extending into the circumferential groove of the adapter holding the inner sleeve to the adapter, the locking balls in the clearance holes at the upper end of the inner sleeve extending into the ball groove in the outer sleeve until the push button is depressed causing the locking balls in the clearance holes in the upper end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby permitting the inner sleeve to release from the adapter and the rotor cover to be released.

18. A centrifuge according to claim 15 wherein the electrical circuit means further includes:

a main power switch;

a brake switch;

a run switch;

a timer;

an interval timer control switch, the main power switch, the brake switch and the timer all being located on the enclosure;

means including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor;

means including a single capacitor and a fixed resistor connected in series to delay the actuation of the switching means to connect the capacitors in parallel both when the torque of the motor is the starting torque and when the torque of the motor is the reverse torque;

means including a first temperature sensitive element to reconnect the pair of capacitors in series when the torque of the motor is the starting torque;

means including a second temperature sensitive element to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque;

a cooling fan mounted in the enclosure, the first temperature sensitive element and the second temperature element being located in close proximity to the cooling fan;

means including a resistor and a third temperature sensitive element in parallel with on another and further including means to connect the resistor and third temperature sensitive element in series with the cooling fan when the motor is deactivated by the stop switch, the unidirectional clutch being adapted to rotate with the upper shaft only in the direction of rotation of the starting torque causing the reverse detection arm to strike the stop switch.

19. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor being a brushless, induction motor, said motor assembly further including a reverse detection arm mounted on the upper end, a unidirectional clutch being mounted on the reverse detection arm, said motor assembly further including a roller mounting bracket mounted on the motor at the lower end with a pair of rollers in contact with the baseplate mounted on the roller mounting bracket, a tension arm affixed to the roller mounting bracket and pivotably mounted on the baseplate, a tension spring affixed at one end to the end of the tension arm closest to the point where the tension arm is pivotably mounted on the baseplate and is affixed to the other end of the baseplate, said tension spring being located in a generally horizontal position, a U-bracket mounted on the upper end of the motor assembly, the stop switch being mounted on the bracket, and a pair of hold-down springs extending from the U-bracket to the baseplate, one hold-down spring being substantially vertical and being located adjacent the tension spring and the other hold-down spring extending at an incline to the vertical to assist the tension spring in tightening the drive belt;

a spindle assembly vertically mounted on the baseplate and having a lower end and a upper end, the lower end of the spindle assembly extending through the baseplate, said spindle assembly including a spindle housing rigidly secured to the baseplate and a lower shaft and an upper shaft and a flexible coupling, the lower shaft and the upper shaft being connected at one end to the flexible coupling, the lower shaft and the upper shaft and the flexible coupling being rotatably mounted in the spindle housing, the end of the upper shaft remote from the coupling having a tapered end with a cross pin through the upper shaft adjacent the taper;

a rotor including a rotor base with a flat portion and a cylindrical portion and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted in the upper end of said spindle assembly, said rotor cover including a concentrically located grip sleeve which extends upwardly from the rotor cover and having an upper end, the upper end of the grip sleeve being flared, an outer sleeve threaded into the grip sleeve, said outer sleeve having a ball groove and a counterbore;

an inner sleeve having an upper and a lower end slidably mounted within the outer sleeve, clearance holes disposed radially in the inner sleeve near the upper end of the inner sleeve and clearance holes disposed radially in the inner sleeve near the lower end of the inner sleeve, a push button slidably mounted within the inner sleeve, said push button including a circumferential groove and a magnet being secured within the top of the push button, said circumferential groove in the push button being located above and adjacent the clearance holes in the upper end of the inner sleeve;

an adapter having an opening adapted to engage the upper end of the spindle assembly, the adapter having a circumferential groove, said circumferential groove on the adapter located adjacent the clearance holes in the lower end of the inner sleeve, locking balls filled within the clearance holes at the upper end and at the lower end of the inner sleeve, the locking balls an the clearance holes at the lower end of the inner sleeve extending into the circumferential groove of the adapter holding the inner sleeve to the adapter, the locking balls in the clearance holes at the upper end of the inner sleeve extending into the ball groove in the outer sleeve until the push button is depressed causing the locking balls in the upper clearance holes in the end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby permitting the inner sleeve to release from the adapter and the rotor cover to be released;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

a tube carrier removably mounted in the rotor base and including a plurality of tube holders, each row mounted at the maximum open radius of that row;

a locking mechanism mounted on the enclosure at the access door to prevent operation of the motor assembly when the access door is open;

an electrical circuit means including a stop switch located at the upper end of the motor assembly adjacent to the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch, and further including means to activate the motor and the locking mechanism, said electrical circuit further including a main power switch, a brake switch, a run switch, a timer , an interval timer control switch, the main power switch, the brake switch, the run switch and the timer all being located in the enclosure, means including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor, means including a single capacitor and a fixed resistor connected in series to delay the actuation of the switching means to connect the capacitors in parallel both when the torque of the motor is the starting torque and when the torque of the motor is the reverse torque, means including a first temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the starting torque, and means including a second temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque.

20. A mechanism for use in a rotating apparatus such as a centrifuge, said mechanism comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, the motor assembly including a reverse detection arm mounted on the upper end and a unidirectional clutch being mounted in the reverse detection arm, said motor assembly further including a roller mounting bracket on the motor at the lower end with a pair of rollers mounted on the roller mounting bracket, said rollers being in contact with the baseplate, a tension arm affixed to the roller mounting bracket and pivotably mounted on the baseplate, a tension spring affixed to the end of the tension arm closest to the point where the tension arm is pivotably mounted on the baseplate and affixed to the baseplate, said tension spring being located in a generally horizontal position, a U-bracket mounted on the upper end of the motor assembly, a stop switch being mounted on the bracket, and a pair of hold-down springs extending from the U-bracket to the baseplate, one hold-down spring being substantially vertical and being located adjacent the tension spring and the other hold-down spring extending at an incline to the vertical to assist the tension spring in tightening the drive pulley;

a spindle assembly vertically mounted on the baseplate and having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate, said spindle assembly including a spindle housing rigidly secured to the baseplate and a lower shaft, an upper shaft and a flexible coupling, the lower shaft and the upper shaft being connected at one end to the flexible coupling being rotatably mounted in the spindle housing;

a drive pulley mounted in the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley, the drive belt being tightened by the tension spring; and

an electrical circuit means including means to activate the motor with a starting torque, said electrical circuit further including means to reverse the motor torque in a direction opposite from the starting torque and to increase substantially the starting torque and the braking torque of the motor, the means to increase substantially the starting torque and the braking torque including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor, means including a single capacitor and a fixed resistor connected in series to delay the actuation of the switching means to connect the capacitors in parallel both when the torque of the motor is the starting torque and when the torque of the motor is the reverse torque, said switching means including a first temperature sensitive element to reconnect the pair of capacitors in series when the torque of the motor is the starting torque and a second temperature sensitive element to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque.

21. A mechanism for use in a rotating apparatus such as a centrifuge, said mechanism comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm;

a spindle assembly vertically mounted in the baseplate and having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate;

means for connecting the motor assembly to the spindle assembly to cause the spindle assembly to rotate;

a stop switch located at the upper end of the motor assembly adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch; and

an electrical circuit means including means to activate the motor with a starting torque, said electrical circuit further including means to reverse the motor torque in a direction opposite from the starting torque and means including pair of capacitors to increase the starting and braking torque of the motor to a level substantially in excess of the operating torque of the motor, means including switching means to connect the pair of capacitors in parallel to obtain maximum torque from the motor and in series to obtain reduced torque from the motor, means including a single capacitor and a fixed resistor connected in series to delay the actuation of the switching means to connect the capacitors in parallel when the torque of the motor is the starting torque and when the torque of the motor is the reverse torque, means including a first temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the starting torque;

means including a second temperature sensitive element to actuate the switching means to reconnect the pair of capacitors in series when the torque of the motor is the reverse torque.

22. A centrifuge comprising:

a motor assembly;

a spindle assembly;

a rotor including a rotor base and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on said spindle assembly, said rotor cover including a concentrically located grip sleeve which extends upwardly from the top of the rotor cover, and having an upper end, the upper end of the grip sleeve being flared;

an outer sleeve threaded into the grip sleeve, said outer sleeve having a ball groove and a counterbore;

an inner sleeve having an upper end and a lower end slidably mounted within the outer sleeve, clearance holes being disposed radially in the inner sleeve near the upper end of the inner sleeve and clearance holes disposed radially in the inner sleeve near the lower end of the inner sleeve;

a push button slidably mounted within the inner sleeve, said push button including a circumferential groove said circumferential groove in the push button being located above and adjacent the clearance holes in the upper end of the inner sleeve, said push button further having a concentric opening extending through it;

an adapter having an opening which engages the upper end of the spindle assembly and having a circumferential groove, said circumferential groove in the adapter being located adjacent the clearance holes in the lower end of the inner sleeve, the adapter further having a concentric opening extending through the adapter and aligned with the concentric opening in the push button, said spindle assembly having a bolt threaded in it, said bolt extending through the adapter;

locking balls fitted within the clearance holes at the upper end at the lower end of the inner sleeve, the locking balls in the clearance holes at the lower end of the inner sleeve extending into the circumferential groove of the adapter holding the inner sleeve to the adapter, the locking balls in the clearance holes at the upper end of the inner sleeve extending into the ball groove in the outer sleeve until the push button is depressed causing the locking balls in the clearance holes in the upper end of the inner sleeve to enter the circumferential groove in the push button thereby permitting the outer sleeve to move upwardly in relation to the inner sleeve permitting the locking balls in the clearance holes at the lower end of the inner sleeve to enter the counterbore of the outer sleeve thereby permitting the inner sleeve to release from the adapter and the rotor cover to be released; and

drive means for connecting the motor assembly to the spindle assembly to rotate the spindle assembly.

23. A centrifuge according to claim 22 having a magnet secured within the top of the push button.

24. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm;

a spindle assembly vertically mounted in the baseplate and having a lower end and an upper end of the spindle assembly extending through the baseplate;

a rotor including a rotor base and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly, a seal being located between the rotor cover and the rotor base, the rotor base including a lip which extends vertically above the seal and inwardly toward the rotor cover to form an enclosure outside and around the seal;

a rotor including a rotor base with a flat base portion and a cylindrical portion and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

a tube carrier mounted on the rotor base and including a plurality of tube holders;

an enclosure mounted on the baseplate enclosing the motor assembly and the spindle assembly and the rotor, the enclosure having an access door above the rotor; and

a stop switch located at the upper end of the motor assembly adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch.

26. A centrifuge according to claim 24 wherein the rotor base provides radial support for the tube carrier.

25. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm;

a spindle assembly vertically mounted in the baseplate and having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate;

a rotor including a rotor base and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly, a seal being located between the rotor cover and the rotor base, the rotor base including a lip which extends vertically above the seal and inwardly toward the rotor cover to form an enclosure outside and around the seal;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

a tube carrier removably mounted in the rotor base and including a plurality of tube holders;

an enclosure mounted on the baseplate enclosing the motor assembly and the spindle assembly and the rotor, the enclosure having an access door above the rotor;

a locking mechanism mounted on the enclosure at the access door to prevent opening of the access door during operation of the rotor;

a stop switch located at the upper end of the motor assembly adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch; and

an electrical circuit means including the locking mechanism and the stop switch and further including means to activate the motor with a starting torque, said electrical circuit further including means to reverse the motor torque to a braking torque opposite from the starting torque and to increase substantially the starting and braking torque of the motor.

27. A centrifuge comprising:

a baseplate;

a motor assembly with an upper end and a lower end pivotably mounted in a vertical position on the baseplate and including a motor having an upper shaft at the upper end and a lower shaft at the lower end, the lower shaft extending through the baseplate, said motor assembly further including a reverse detection arm;

a spindle assembly vertically mounted in the baseplate and having a lower end and an upper end, the lower end of the spindle assembly extending through the baseplate;

a rotor including a rotor base with a flat base portion and a cylindrical portion and a rotor cover, said rotor cover being removable from said rotor base, said rotor being mounted on the upper end of said spindle assembly;

a drive pulley mounted on the lower shaft of the motor assembly and a driven pulley mounted on the lower end of the spindle assembly, the drive pulley having a diameter substantially larger than the diameter of the driven pulley;

a drive belt mounted on and connecting the drive pulley and the driven pulley;

a tube carrier removably mounted in the rotor base and including a plurality of tube holders;

an enclosure mounted on the baseplate enclosing the motor assembly and the spindle assembly and the rotor, the enclosure having an access door above the rotor;

a stop switch located at the upper end of the motor assembly adjacent the reverse detection arm to deactivate the motor when the reverse detection arm strikes the stop switch; and

an electrical circuit means including means to actuate the motor with a starting torque and to reverse the motor to a braking torque opposite from the starting torque and to increase substantially the starting and braking torque of the motor, said electrical circuit further including means to maintain constant the interval of increased starting and braking torque of the motor regardless of ambient temperature changes.