Joyce RWB3250 - Manual (Page 5)

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D. (1) Worm – item 10
E. (1) Thrust bearing lower– Item 11
F. (1) Thrust bearing upper – Item 12
G. (1) Wormgear – Item 13
H. (1) Ball nut (return tubes and balls only for rebuild)– Item 16
I.
(1) Ball screw – item 17
J. (1) Ball screw shaft seal, KFTN only – item 25 (inverted), item 20 (upright)
K. (1) Boot and clamps for translating jack–Item 22, 23, 24
L. (1) Boot (lower) and clamps for KFTN– Item 27, 28, 29
M. (1) Boot (upper) and clamps for KFTN – Item 30, 31, 32
2-3 Disassembly of Ball Screw Jacks
Use the appropriate disassembly procedure. If the ball nut (with the re-circulating ball
bearings) is on the screw outside the sleeve, the jack is a Keyed for Traveling Nut (KFTN). This
is also called a “rotating screw” jack. If the ball nut is inside the jack sleeve, the jack is a
translating model. Handle machined parts with care, and maintain an “order of disassembly”
to aid in re-assembly. Remove all couplings, screw support bearings, etc. before beginning
disassembly.
Disassembly Procedure for KFTN (rotating screw) Models: Sections 3-1 & 3-2
1. Tape or otherwise secure the ball nut (item 16) to the ball screw (item 17). Removal of the
ball nut from the screw would allow all of the ball bearings to be released. Remove the boot
clamps (item 27,29,30,32) and collapse boots (item 28, 31) if the jack is equipped with boots.
2. On upright jacks loosen the (4) set screws (item 19) in the sleeve cap assembly, which
includes the sleeve cap (item 14), bushing (item 15) and seal (item 20) and loosen the
sleeve cap assembly by rotating counter-clockwise (CCW.)
3. On inverted KFTN models remove the sleeve cap (item 14) by loosening the (4) set screws
(item 19) and rotating CCW. The inverted model has a solid sleeve cap without a bushing or
seal.
4. On upright KFTN models, the ball screw assembly (with the sleeve cap assembly) can now
be removed from the jack sleeve. The ball screw assembly consists of the ball screw (item
17), the ball nut (item 16), the thrust bearings (item 11,12), the thrust sleeve (item 33), the
retaining nut (item 22), the key (item 21) and the wormgear (item 13). The retaining nut (item
22) can be removed from the ball screw assembly by loosening the setscrew (item 23) and
unthreading the retaining nut. The wormgear will then slide off the end of screw and the
upper thrust bearing, the sleeve cap assembly can be removed from the ball screw. Note:
The thrust sleeve is secured to the ball screw with a thread adhesive. Removal of the thrust
sleeve may be necessary for the sleeve cap removal. The thrust sleeve and retaining nut
must be heated to 500° Fahrenheit to be removed.
5. On inverted KFTN models, the ball screw assembly is removed from the bottom of the
sleeve. First, remove the upper thrust bearing (item 12) and then remove the set screw (item
23) from the retaining nut. The retaining nut (item 22) can now be un-screwed from the
wormgear. Remove the inverted bushing (item 26) or the key will damage the seal (item 25).
Push the ball screw (item 17) and the key (item 21), out the bottom of the sleeve only when
the retaining nut and bushing have been removed. Remove the wormgear (item 13) and the
lower thrust bearing (item 11) from the sleeve. Note: The thrust sleeve is secured to the ball
screw with a thread adhesive. It is not necessary to remove this adhesive when removing
the sleeve cap. If removal becomes necessary, heat the thrust sleeve and retaining nut to
500° Fahrenheit.
6. It is not recommended to remove the ball nut (item # 16) from the ball screw (item 17)
unless it is being replaced. For instructions on removing the ball nut, see Section 2- 6, Ball
nut disassembly and rebuild.
7. Remove (6) screws, 3 per side (item 8) from the bearing cap (item 7). Remove the bearing
caps and seals (item 9) carefully to avoid damaging seals. Make sure worm shaft keys have
been removed first. Note: the one-ton jack has retaining clips.