Duff-Norton SK6415-300 (SPA Series DC) User Manual

Page 8

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Duff-Norton recommends the use of the following
lubricants in conjunction with proper maintenance
procedures of this unit:
Gear Box & Brake — Shell Oil Co., Aeroshell #6
Lifting Screw & Nut — W.I. Grace Co., Duboise M.P.G.


Required Tools

A bearing puller, press, soft jaw table clamp and
common hand tools are required for proper disassembly
and assembly.


General Procedures

Duff-Norton recommends following these procedures
during disassembly and assembly:
1. Tag critical parts to facilitate reassembly.
2. Mark mating surfaces to ensure proper meshing.
3. Clean and lubricate parts as required.
4. All seals must be replaced at time of rebuild,
if damaged.
5. All screws, washers and other small common parts
must be replaced if mutilated in any way.



Disassemble the 6415 Series DC actuator as follows
while referring to Figure 5-1. Read instructions
thoroughly before disassembling.


Disassembly should be accomplished on a clean cloth.
1. Clamp actuator housing (42) in vise (use soft

jaws). Unit should be in horizontal position with
outer tube (55) up.

2. Remove screws (1) from limit switch box

cover (11) and remove limit switch box cover
(11) and gasket (12).

3. Remove nut retainer (14).


If unit has potentiometer assembly (26) and
potentiometer (26a) or gear (26b) is not damaged
proceed to Step 4.

a. Loosen nut (26c) and remove potentiometer
assembly from nut retainer (14).
b. Remove gear (26b) from potentiometer (26a).
Washer and nut do not have to be removed from
potentiometer (26a).


Take care not to damage potentiometer when removing
4. Remove screws (1) from capacitor box cover

(2) and remove cover (2) and gasket (3).
Remove insulation (4) from capacitor box.

5. Remove capscrews (71) from cover (9) and

remove fuse holder (70) from cover (9) (until
lower terminal of fuse is exposed). Remove
fuse holder cap (70) and fuse (72) from fuse
holder body (70). Remove fuse holder body (70)
completely from unit.

6. Disconnect jumper wires (17 and 18) and

motor (53) lead wire terminals from switches
(16). Remove jumper wires (17 and 18) and pull
motor (53) lead wires into capacitor box.

7. Remove set screw (36) from housing (40).
8. Disassembly of Motor

a. Remove motor thru-bolts. (It is not
necessary to remove screws totally from motor.)
With screwdriver, pry (front end bell near
housing) motor (53) away from housing (42)
(care must be taken to prevent motor end bells
from separating from motor (53) shell and that
motor lead wires are not damaged).
b. Remove “O” ring (52) and rubber grommet

9. Remove button head cap screws (7) and lock washers

(8). Remove cover (9) and gasket (41). (Cover
may have to be pried up with screwdriver, or
lightly tapped up with wooden or plastic
hammer.) Remove dowel pins (27).

10. Remove thrust washer (35) and thrust bearing (36)

from cover (9). Thrust washer (35) and thrust
bearing (36) may stay on spacer nut (37) in
housing (42) and can be removed in Step 18.

11. Remove limit switch shaft assembly, consisting of

limit switch shaft (22), limit switch nuts (23)
and worm (24), from cover (9). Allow limit
switch shaft (22) to drop out of flange bearing
(25). Tilt shaft assembly and remove from
cover (9).


If limit switch nuts (23) or worm (24) do not have to be
replaced, proceed to Step 14.
12. Thread limit switch nuts (23) off of limit switch shaft (22)
13. Remove worm (24) from limit switch shaft (22).


If switches (16), insulation (19) or limit switch bracket (21)
do not have to be replaced, proceed to Step 16.
14. Remove screws (20) and bracket (21) from cover (9).
15. Remove screws (15), switches (16) and insulation (19)

from bracket (21).

16. Press clevis end bushing (6) out of cover (9). If bushing

(6) is not damaged it should not be removed.

17. Remove bearing (28), bushing (34) and flange bearing

(25) from cover (9).