2100 AD 015 0009 Mirror Elevator Ball Nut Replacement Procedure Derek Guenther 1/28/2015 Rev. Purpose The purpose of this document is to describe the procedure necessary to replace one of the ball nuts in the 4 meter mirror elevator. Refer to 2100 AD 015 0002 (50 Ton Actuator Installation Plan) for the original actuator installation. The following procedure was performed on Slave 2 while installing the clearance ground ball nut in the system on 1/8/2015. A ground nut was already installed in the Master position. After the removed nut is clearance ground it will be installed in the Slave 1 position. Preparation 1. Raise the elevator platform about 6 from the down position. 2. Turn off the power box on the elevator room and lock it out with the safety lockout tags 3. Install the wood cribbing and the 2 mechanical jacks in the hammer head section. 4. Install the chain come along from the drive plate to the mast at the location you are working on. 5. Wipe down the end of the ball screw to allow removal of the encoder without contacting the grease. 6. Disconnect the motor encoder and install the shorting plug. Roll the cable up and tie it out of the working area. Use a grounding strap connected to the motor when working on the encoder. Remove the encoder. 7. Disconnect the brake switch wiring in the brake switch junction box. Remove the conduit from the box and the motor in the process remove the wire from the conduit and tie it up out of the way on the motor. 8. Disconnect the cable from the Twiflex brake at the connector and tie it up out of the way if necessary. 9. Place the ¼ plate on the fork lift. Clamp the plate to the forks with C clamps. Motor Removal 10. With the motor wiring conduits still connected, raise the fork lift up under the motor. Remove the 4 attaching bolts that go through the gray gear box flange. 11. Install the 2 pieces of all thread on opposite sides where the attaching bolts were removed. Lower the motor until the nylon coupling can be removed.
12. Remove and inspect the coupling. 13. Lay the motor and brake assembly on a dolly and roll it out of the way. Actuator Removal 14. Measure and record the location of the disc on the Twiflex brake. Measure from end of the shaft to the Taperlok coupler. Alternatively, a scribe mark can be put on the shaft showing the location of the coupler. 15. Disconnect the copper line from the Twiflex brake. Close the valve to copper line and open the valve to the quick disconnect. 16. Hook up a temporary air hose to the quick disconnect in order to release the brake pads. 17. Remove the Twiflex brake and disconnect the airline from the brake and place it out of the work area. 18. Remove the brake disc by removing the set screws in the Taperlock hub. It may be necessary tap a screw driver into the split line in the hub to spread it enough to slip it off of the shaft. 19. Remove the gear box from the actuator. Roll it out of the work area with the fork lift and place it on the floor. a. On slave 2 and the master it will be necessary to lower the actuator and then rotate the actuator until the gear box is accessible. 20. Remove the ¼ plate from the fork lift and install the actuator lifting pads. Place the pads toward the inside of the fork lift. 21. Scribe around the base of the actuator to indicate the location for the reinstallation. 22. Removed the 4 actuator retainer bolts. Hold the actuator so it does not rotate while removing the last bolt. 23. If space around the actuator permits, carefully rotate the actuator until is near the end of the screw. 24. Once the actuator is near the end of the screw, bring the fork lift up under the actuator. Make sure that the brass ends of the fixture are seated in the actuator mounting bolt counter bores. 25. Place the ball retainer tube under the end of the screw and hold it in place with wood wedges. 26. Put the wrench adapter (2100 ME 600 2007) on the worm shaft. 27. Rotate the actuator down with a ratchet wrench while lowering the fork lift to follow the actuator. When the top of the actuator is about 27 from the floor the actuator will be off of the ball screw. 28. Lower the actuator with the fork lift until it is below the end on the screw.
Actuator Disassembly 29. Roll the actuator out from under the screw. Lower the actuator until the retainer tube protrudes out of the top of the actuator about an inch. 30. Put a hose clamp on the upper end of the retainer tube. 31. Center punch the bearing retainers and the housing to show the original side and orientation of the bearing retainer. Place 2 matching punch marks on the gearbox side and 1 set of punch marks on the brake side. 32. Lay out plenty of Pig Mat under the actuator and on a dolly. 33. Remove both bearing retainers while keeping the original shims with the retainers. 34. Retract the 2 set screws on the lower housing flange. 35. Unscrew the lower housing down onto the dolly. 36. Scrape as much grease as possible off of the nut while it is still in the housing. 37. Lower the actuator until the exposed nut just touches the top of another dolly covered with Pig Mat. 38. Tap on the end with a soft hammer and rotate the worm shaft. Once the bearings slip out of their bores the nut should come free from the housing. Lift the actuator with the fork lift and roll it back from the nut while laying the nut down on the dolly. 39. Remove the upper thrust bearing and the two races from the worm gear. 40. Remove the ball retainer tube and allow the majority of balls to fall out of the nut. 41. Remove the lower thrust bearing and race from the lower cover. 42. If the nut is going to be serviced, remove the lower race shoulder. It is attached to the nut body with two set screws. 43. Check the upper end (worm gear end) of the redundant load path by feeling just below the brush for chips. If chips are missing from the actuator, the housing must be completely cleaned. 44. If the nut is going to be reground, wipe the nut down and box it for transport to Tucson. Ball Nut Redundant Load Path Regrinding 45. Remove the ball guide return tubes from ball nut. 46. Clean the assembly in a parts washer. 47. Using a slide hammer puller remove the pin that locks the worm gear to the nut. If the hole will be reused and there are other holes, mark the one that the pin came out of. 48. Unscrew the worm gear off of the nut body. 49. Remove the two brush seals on either end of the nut body.
50. Place the nut body in the large V block with a sheet of Teflon between the nut and V block on the Lucas table. 51. Place the all thread with the plastic simulated thread in the chuck of the Lucas. 52. With the grinder on the Lucas table remove.050 from the side of the load path that contacted the screw. Remove.020 from the other side of the load path. 53. Using a die grinder, radius the upper edge of the load path. Ball Nut Reassembly 54. Thoroughly clean the ball nut and the worm gear. 55. Install the brush seals in both ends of the nut body. 56. Screw the worm gear onto the nut body. Make sure that the worm gear tightens all the way down to the nut body. 57. If the existing hole lines up tap the dowel pin into the hole. If the hole does not line up, bore a new pin hole about 90 from the original one. Box the nut and ship it to the 4 meter. Ball Nut Reassembly 58. With the nut body horizontal on a dolly, install the ball retainer tube through the nut. 59. Lightly grease the balls before installation into the nut. With 1 person rotating the retainer tube, install the balls into the ball nut body. Install 57 balls in each track. Install 5 balls in each return tube before placing it on the nut body. 60. With all 186 balls (62 per track) and 3 return tubes installed, install the sheet metal return tube retainer. Actuator Reassembly 61. Set the actuator housing on a dolly with the open side facing up. Apply grease to the bearings and to the worm. Slide the worm shaft with the bearings on it into the housing. Leave one bearing just on the outside of the housing with the other bearing inside of the housing. 62. Apply grease to upper thrust bearing and both races. Install one race and the bearing in the housing. Install the other race on the worm gear. Make sure that the race that is placed in the housing is a slip fit over the worm gear. 63. Apply grease to the teeth on the worm gear. While holding the race in place lower the ball nut, worm gear first, into the housing while turning the worm. 64. Once the nut is seated on the thrust bearing, rotate the worm while tapping on it with a soft faced hammer.
65. Once the worm bearings are inserted into the housing, install the bearing retainers and gearbox adapter. 66. Install the lower race retainer (shoulder) on the nut and tighten the two set screws. 67. Grease the two lower races and the lower thrust bearing and place them on the ball nut. 68. Pump the actuator full of grease while rotating the worm in order to fill the worm cavity completely. 69. Cover the outside of the nut body with as much grease as possible. 70. Lower the bottom housing over the ball retaining tube. Slowly rotate the bottom housing CCW until the thread start is felt. Rotate CW until the thrust bearings are in contact. Tighten the bottom housing an additional 1/2 to preload the thrust bearings. The cover can be driven with a wood block. If the set screws don t line up with the original counter bores in the housing, replace the set screws with cup point screws and tighten them. Rotate the worm shaft by hand to check for excessive preload. 71. Using the chain fall located near the stairs, pick the actuator up with a sling looped over the two ends of the worm shaft. Turn the actuator right side up and lift it with the forklift. Remove the sling. 72. Move the actuator over to screw where it will be installed. Move under the screw and wedge the ball retainer tube under the ball screw. 73. Remove the hose clamp from the ball retainer tube. 74. Slowly lift the actuator with the fork lift while rotating the worm until the actuator starts climbing the ball screw. Continue raising the actuator with an air ratchet or rotate the actuator until it contacts the drive plate. 75. Align the actuator with the scribe marks from before it was removed. Install the bolts and tighten them. Make sure that the screw is roughly centered in the drive plate. 76. Install the gear box on the actuator. Level the gearbox flange and tighten the attaching bolts. 77. Install the nylon coupler in the gear box. 78. Put the ¼ plate back on the fork lift and place the motor on it. 79. Raise the motor up into the gearbox. Install the all threads in two of the bolt holes. Carefully lift the motor up until the coupling is engaged. 80. Remove the all threads and install the four bolts. 81. Install the Twiflex brake disc at the position previously measured. 82. Apply air to the Twiflex brake and install it. 83. Remove the airlines and place the valves on the operating positions. Reconnect the copper airline.
84. Reinstall the conduit and reconnect the brake switch wiring in the junction box and plug the connector into the Twiflex brake. 85. Reinstall the motor encoder. Make sure the encoder motor shaft clamp is tight before reinstalling the protective cover and reconnecting the cable. Use an ESD wrist strap as in the removal step. 86. Run the air powered grease gun for about 5 minutes adding grease to the actuator.