Power Jacks E-Series - Ball - Manual (Page 7)

7
Metric Series – Ball Screw Jacks
6 Disassembly / Assembly Instructions (D.A.I.)
6.1 Translating Screw D.A.I
6.1.1 Main Gearbox Unit
IMPORTANT
Disassembly should be accomplished on a clean cloth. This is particularly important when
disassembling the ball nut assembly.
1. Remove any end fixture from the end of the ball screw (17).
2. Remove the ball screw guide bushing (4).
3. Remove the bottom pipe (22) or top pipe (23).
4. Ensure that shell cap set screws (27) are slackened back clear of drill dimples in shell (1) before
unscrewing shell cap (2). Note: it may be necessary to tap shell cap loose.
5. Remove the top load bearing from the shell cap.
CAUTION! It is very important that the ball screw (17) not be allowed to run out of the ball nut (18).
At this point it is advisable to wrap tape around the last few ball screw threads to prevent this from
happening.
6. On some models it will be necessary to remove the worm shaft (5) before the worm gear assembly can
be pulled clear of the shell.
7. Take care not to lose the flange shims (10 & 11) if removing the worm shaft assembly.
8. To remove the ballscrew assembly (17 & 18) from the worm gear (16), first remove the retaining disc &
bolt (19,20 & 21) from the end of the ball screw (17).
9. Remove set screws (26) and unscrew the ball nut (18) from the gear (6). Note on re-assembly it may be
necessary to re-drill dimples for the set screws (26).
10. Check all parts for damage or excessive wear and replace where necessary. Note some ball screw and
nut assemblies (17 & 18) can be refurbished dependant on the extent of wear/damage.
11. After re-assembly of the worm shaft assembly, strike each end of worm sharply with a wooden or fibre
mallet to seat bearings properly. If new parts have been fitted it may be necessary to increase or
decrease the number of shims to obtain the correct endplay – the worm shaft should turn freely with the
minimum of endplay.
12. Press oil seals (13) into worm flanges (12) with the sealing members pointing inwards.
13. When re-assembling the worm gear and load bearings ensure that the bearings are fitted so that the
plate with the smallest bore size fits over the worm gear spigot.
14. The shell cap should be fitted after the worm shaft assembly has been securely clamped and with the
worm gear assembly in position. Tighten the shell cap until a slight drag is felt on rotating the worm
shaft by hand.
15. Tighten shell cap set screws (27). It may be necessary to drill new dimples in the shell if new parts have
been fitted or if re-adjustment for wear is necessary.
16. Attach the bottom pipe (22) or top pipe (23).
17. Attach the ball screw guide bushing (4).
18. Re-assemble any end fixture to the ball screw (17)
6.1.2 Instructions for fitting detachable ends on lifting screws
It is important that the detachable ends are securely fixed to the lifting screws and the following procedure
should be adhered to.
1. Thread the detachable end on to the lifting screw and tighten up as hard as possible without damaging
the components.
2. Select a twist drill which is a free fit in the tapped holes of the detachable end. Using these holes as a
drill guide, drill dimple only into the lifting screw. Clean out swarf and remove detachable end. Select
another drill which matches the set screw diameter and, using the drill dimples as a guide, drill into the
lifting screw a full diameter depth of 1mm below the root diameter of the threads. Refit detachable end.