4
tors are designed to be adjusted for minimum
backlash, approximately .002 inch. The worm
gear and anti-backlash nut are manufactured to
have a clearance between their surfaces of 1/2
the thread thickness. When adjustments have
been made to the point where all this clearance
is gone, 50% of the thread thickness is gone
and replacement is necessary. (See paragraph
2-8 for a detailed explanation of how the anti-
backlash nut functions.)
Note
For loads of from 25% to 100% of actuator
capacity, torque requirements are approximately
proportioned to the load.
8. The lubrication procedures for normal and
severe service conditions, as described in
Section II, paragraph 2-1, should be closely
followed.
1-5. Warranty and Warranty Repair
Subject to the conditions stated herein, Duff-
Norton will repair or replace, without charge, any
parts proven to Duff-Norton's satisfaction to have
been defective in material or workmanship. Claims
must be made within one year after date of ship-
ment. Duff-Norton will not repair or replace any
parts that become inoperative because of improper
maintenance, eccentric loading, overloading, chemi-
cal or abrasive action, excessive wear, or other
abuse.
Equipment and accessories not of Duff-Norton's
manufacture are warranted only to the extent that
they are warranted by the manufacturer, and only if
the claimed defect arose during normal use, appli-
cations and service. Equipment which has been
altered or modified by anyone without Duff-Norton's
authorization is not warranted by Duff-Norton.
EXCEPT AS STATED HEREIN, DUFF-NORTON
MAKES NO OTHER WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING WARRANTIES OF MER-
CHANTABILITY AND FITNESS FOR A PARTICU-
LAR PURPOSE.
If you have any questions concerning warranty
repair, please contact Duff-Norton. Authorization for
return must be received from Duff-Norton before
returning any equipment for inspection or warranty
repair.
Section II
Maintenance
2-1. Lubrication
Unless otherwise specified, actuators are
shipped packed with grease which should be suffi-
cient for one month of normal operation. For normal
operation, the actuator should be lubricated once a
month using Extreme Pressure grease Shell Oil Co.
Albida LC EP #2 (Shell Product Code 70311).
This grease has been thoroughly evaluated in
Duff-Norton actuators and has demonstrated supe-
rior lubricating properties affecting both wear life
and maximum duty cycle.
Duff-Norton is not aware
of an equivalent grease.
If this grease is not
available in your area please contact your local
supplier for their recommendations. Greases con-
taining molybdenum disulfide should never be used.
For severe service conditions, the actuators
should be lubricated more frequently using the
above grease (daily to weekly depending upon the
conditions). If duty is heavy, an automatic lubrication
system is strongly recommended.
CAUTION
Where lifting screws are not protected from
airborne, dirt, dust, etc., bellows boots should
be used. Inspect frequently at regular intervals
to be certain that a lubricating film is present.
Lifting screws should never be run dry.
2-2. Rebuild Procedure
Duff-Norton recommends the following proce-
dures for assembly and disassembly of actuators.
1. Tag critical parts to facilitate reassembly.
2. Mark mating surfaces to ensure proper meshing.
3. Clean and lubricate all parts as required.
4. All seals must be replaced when rebuilding.
5. All screws, washers and other small common
parts must be replaced if damaged in any way.
6. Replace damaged or frozen lubrication fittings
with new ones.
2-3 Required Tools
A bearing puller or press, and common hand
tools are necessary for proper assembly and disas-
sembly.
2-4. Disassembly (Refer to Figure 3-1)
1. Remove lifting screw (5) from actuator.
2. Remove bottom pipe (4) from shell (3) (upright
models) or shell cap (2) (inverted models) or
base plate as applicable.
3. Loosen and remove set screws (1) in cap (2)
and remove cap from shell (3).
Note
It may be necessary to break shell cap or base
plate loose with a hammer.
