Top bearing
Remove the cotter pin and remove the castle nut.
Remove the pulley and the top plate assembly from the
screw. Remove the bearing case from the top plate.
Remove the ball bearing, spacer and inner race of the
tapered roller bearing. Wash all parts thoroughly.
Inspect the bearing rollers and raceways for signs of
pitting or wear. Inspect the domed end of the bearing
case and inside the top plate for signs of wear.
Regrease the bearings and refit to the case. Grease the
outside of the bearing case and fit it into the top plate.
Brake
Remove the screw pulley from the top plate. Measure
the overall length of the brakeshoe. If it is less than
60mm long, it must be replaced. Inspect the inside of
the pulley where the brake rubs. If it is worn more than
1 mm or is badly scored, the pulley must be replaced.
Wash the inside of the pulley and the end of the
brakeshoe to remove all traces of oil or grease.
To Re-assemble Column
1. Thoroughly clean the inside of the column where
the rollers and sliders travel, then smear with
grease.
2. Refit the carriage and position it about 500 mm up
from the bottom.
3. Check the plastic key covers are still in the carriage.
4. Fit the lift nut on to the keys, with the trigger arm
through the hole in the back of the carriage.
5. Fit the load ring between the lift nut and the carriage
load bar.
6. Fit the safety nut on to the keys in the carriage, with
the brush towards the front. Leave about a 6 mm
gap between the lift and safety nuts.
7. Carefully fit the lift screw to the column and into the
lift nut. Support the top of the screw on a spacer
inside the column.
8. Wind the lift screw through the lift nut and safety
nut. Check the gap between the nuts is 6 mm.
9. Fit the reservoir tube over the bottom end of the lift
screw. (square end first)
10. Put some masking tape over the thread and keyway
on the 28 mm diameter section of the lift screw.
Liberally smear grease over the end of the screw
and masking tape. Carefully fit the bottom bearing
housing, seal first, over the end of the screw and
past the keyway. Make sure the seal is not
damaged by the keyway or the step in the shaft and
that the seal spring stays in place.
11. Push the lift screw down through the bottom of the
column. Put some loctite on the cap screws and
bolt the bottom bearing in place. Fit the reservoir
tube on to the bearing housing, making sure it will
clear the carriage when it is lowered.
12. Fit the key, bottom collar and Nyloc nut to the
bottom of the screw.
13. Fit the top plate and bearing assembly over the
top end of the lift screw. Fit the proximity switch
through the hole in the top plate. Remove the
spacer under the lift screw then fit the top plate to
the column. Fit and tighten the four M16 nuts.
14. Fit the key to the lift screw. Use a spanner on the
brake shoe to rotate it and compress the brake
spring. Fit the screw pulley over the end of the lift
screw and over the brake shoe taking care not to
put any side load on the brake shoe. Fit the castle
nut and do it up until the bottom collar is 0.5 to 1mm
away from the bottom of the column. Fit the cotter
pin.
15. Tighten the bottom collar Nyloc nut to 80 Nm
torque, push the carriage down hard towards the
bottom of the column and recheck the 0.5 to 1 mm
gap between the collar and the column.
16. Fit the proximity switch to the top plate and fit the
cable into the clip. Adjust the proximity switch so
It is 0.8 to 1 mm away from the screw pulley. Push
the carriage down hard towards the bottom of the
column and recheck the 0.8 to 1 mm gap between
the pulley and proximity switch. Note: It is vital that
the proximity switch is adjusted correctly otherwise
it may not operate correctly or may be damaged by
hitting the pulley.
17. Check the two vee belt pulleys are aligned, fit
and tighten the vee belts to give less than 10 mm
deflection when pressed firmly in mid-span with a
thumb.
18. Fit the lubricating brush to the front of the safety nut
and adjust it so the bristles are just touching the
bottom of the screw thread. Pour a trickle of
extreme pressure gear oil along the length of the
lift screw.
19. Refit the blind. Tighten the two top screws until the
blind springs are fully compressed, then undo them
one turn.
20. Measure the height of the carriages on both
columns and adjust them to the same height. Roll
the column over onto its front.
21. The rest of the assembly can be done by following
steps 4 to 7, 12 to 13, and 16 to 25 in the
installation instructions with the additional step of
measuring the gap between the lift and safety nuts
after installation is complete. If new nuts have been
fitted, stamp the new initial nut gap on the front of
the carriage.
Note: It is vital that all the tests in steps 17 to 25
are done to make sure the hoist is operating
correctly and is safe to use.
This hoist is fitted with a special safety interlock
which renders the hoist inoperable should the lift
nuts fail completely. The interlock is fitted to both
columns and will stall the hoist approximately
300mm off the ground. Operation of the interlock
can be checked using gauge G15-1-51 according
to its instructions.
Page 10
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