Joyce RWB3250 - Manual (Page 7)

7
2. Inspect the cleaned sleeve (item 1) and sleeve cap (item 14) for any signs of stress or
facture, especially around the mounting bolt locations.
3. Inspect the worm (item 10) and thrust bearings (item 11,12) for any signs of Brinelling,
abrasive wear or spalling. Test for smooth, quiet operation of bearings.
4. Inspect bearing caps (item 7) for any signs of stress.
5. Inspect the keyway on the worm (item 10) and roll worm on a flat surface to look for
wobble in the shaft. Threads on worm should not show a heavy buildup of bronze gear
material.
6. Replace all seals when a complete disassembly is done.
7. Inspect Aluminum-Bronze wormgear (item 13) for signs of excessive wear.
8. Check boots for wear or cracks
9. Check ball screw (item 17) for straightness or excess wear in ball threads.
2-5 Assembly of Ball Screw jacks
1. Assure that all bearings are packed with grease. Coat seals with light oil and put masking
tape on keyway and other sharp surfaces to avoid seal damage.
2. Assembly of jack is reverse of the disassembly procedure. Make sure all bearings and
seals seat properly. The bearing cap screws and sleeve cap should only be hand tightened
initially. Some jacks may require the wormgear and thrust bearing be installed first, as they
will not pass the worm, if already installed.
3. Tighten bearing cap bolts. Check the input shaft for excessive axial or lateral movement. If
the input shaft feels loose remove shims, if it feels tight, add shims. Give the input shaft a
solid blow on each end (in axial direction) with a soft mallet and re-check the feel. If it feels
OK, continue to next step, otherwise continue adding (if tight) or removing (if loose) shims.
This is a trial and error operation. The correct set-up has a solid feel without play (axial or
lateral) and the input shaft rotates with an even, smooth but snug feel.
4. When jack is re-assembled, the thrust bearing pre-load needs to be set. Check by rotating
the input shaft, while tightening the sleeve cap. Continue to check the rotation of the input
shaft as sleeve cap is tightened. Use a dead-blow hammer on top of sleeve cap to help it
seat. Tighten sleeve cap until it will not tighten further by hand.
2-6 Ball Nut Disassembly and Rebuild
1. This requires the use of an arbor. An arbor can be acquired from Joyce/Dayton, or
manufactured. The arbor is usually a tube or bar that can be made out of plastic, stiff
cardboard or steel and should be at least 4 inches longer than the ball nut. The outer
diameter is approximately equal to the minor diameter of the ball screw thread. Its
purpose is to prevent the ball bearings from falling out of the ball nut. Place the arbor at
the end of the screw and carefully un-thread the ball nut onto the arbor. After the ball nut
is transferred to the arbor, secure it in place with tape or a clamp.
2. Remove the return tubes, one at a time and empty ball bearings from return tube and
internal ball nut path in ball nut into a container.
3. Continue to remove ball return tubes and empty all ball bearings. There could be up to
three return tubes and ball bearing paths.
4. Discard the return tubes and used ball bearings (if ball nut is being rebuilt.)
5. Flush all components with a clean degreasing solvent.
6. Check ball nut threads for damage and replace if necessary.
7. Check retaining wire location. Some are free to rotate to other part of nut when the return
tubes are removed.
8. Lightly oil (Spindle or 10 weight) all components to aid in re-assembly.
9. Thread ball nut onto ball screw or arbor.
10. Begin re-filling ball bearing paths and return tubes. After the return tube is filled, a small
dab of grease will hold the balls in the tube during assembly. Remove one or two balls (for
clearance) and assemble return tube and ball nut.