10
11
TROUBLESHOOTING CHART (continued)
TROUBLE
WHAT TO INSPECT
ACTION
Housing Failure
1. Unit Overload
Reduce load or replace with
unit of sufficient capacity.
2. Improper Support
Unit should be supported over
entire base area, not just at bolt
hole locations.
3. Uneven Bolting Torque
Take up evenly on mounting
bolts.
Bearing Failure
1. Unit Overload
See housing failure No.1
2. Excessive Overhung
Load
See worm shaft failure No. 3
3. Coupling Alignment
See worm shaft failure No. 2
4. Coupling Lateral
Alignment
Adjust spacing between con-
necting shafts to relieve end
pressure.
5. Bearing Adjustment
Bearings must not be pinched.
Adjustable tapered bearings
must be set at proper lateral
clearance. All shafts should turn
freely when disconnected from
the load.
6. Bearing Lubrication
Add lubricant if necessary
7. Shock Loading
See worm shaft failure No. 5
Drive Sleeve &
Worm Gear Wear
1. Unit overload
See housing failure No.1
2. Bearing Adjustment
See bearing Failure No. 6.
3. Lubrication
Proper levels and grade must
be maintained. See lubrication
page.
Drive Sleeve &
Worm Gear Nut
Wear
1. Unit Overload
See housing failure No. 1
2. Alignment
Lifting shafts must be perfectly
plumb.
3. Lubrication
See Gear Wear No.3
4. Side Load
Eliminate side load
Lifting Screw Failure 1. Unit Overload
See housing failure No. 1.
2. Alignment
See lifting shaft failure No. 2.
3. Side Load
Check with Nook Industries
Engineering Department for al-
lowable size load.
ANTI-BACKLASH ADJUSTMENT
The anti-backlash feature is set at the factory and normally does not require further
adjustment. However, as wear develops with extended use, it may become necessary
to adjust lash.
ADJUSTMENT PROCEDURE
1. Loosen Locknut (Item a)
2. Loosen Set Screw(s) (Item c)
3. To reduce backlash, rotate Adjusting Cap (Item a) clockwise until resistance is felt.
(Do not over tighten)
4. Place a reference mark between thread on Adjusting Cap and Housing.
5. Rotate Adjusting Cap (Item A) counter clockwise an amount equal to the A dimen-
sion on the o.d. of the threads. (See chart)
6. Tighten Set Screws.
7. Holding Adjusting Cap (Item a) stationary, tighten Locknut (Item b).
8. Operate jack through entire stroke, checking for tight spots. Note: If jack has been
used only over a portion of its stroke, backlash should be adjusted in the least
worn portion of the screw.
CAUTION
- Care should be taken not to overtighten the anti-backlash system in order
to prevent binding or lockup between the drive nut and lifting screw. Overtightening can
cause a destructive heat buildup or failure.
a
b c
A
Item
Description
a
Adjusting Cap
b
Locknut
c
Set Screw
Jack Model
A
1, 2, 2.5-MSJ
7
⁄
32
5, 10-MSJ
5
⁄
16
15, 20, 30-MSJ
3
⁄
8
35-MSJ
1
⁄
2
50-MSJ
11
⁄
16
75-MSJ
13
⁄
16
100-MSJ 1
