ARMY TM 9-6115-604-12
NAVY NAVFAC P-8-633-12
(4)
Carefully tag and disconnect cable lugs (1, figure 4-37) from top and bottom switch terminals according to
phase.
(5)
Remove chain drive assembly (3) from switch drive assembly (2) at side of the disconnect switch frame,
loosen one chain turnbuckle (4) and remove chain assembly from sprocket gear on switch drive assembly
(2).
(6)
Remove hexagon head screws (5), flat washers (6) from lower cabinet A compartment and hexagon nuts
(7) and lockwashers (8) from rear cabinet A interior to remove main disconnect switch S120 (9). Lift out
main disconnect switch from lower cabinet A.
(7)
Remove four hexagon head screws (10) and lockwashers (11) holding the main disconnect switch handle
assembly (12) to the cabinet frame. Remove main disconnect switch handle assembly (12).
c.
Install.
(1 )
Mount replacement main disconnect switch S120 (9) Inside lower cabinet A compartment using four
hexagon head screws (5) and flat washers (6). Install and tighten hexagon nuts (7) and lockwashers (8) at
rear cabinet A interior Reinstall rear cabinet A access panel.
(2)
Install main disconnect switch handle assembly (12) with chain (3) attached, on front right exterior of
compartment using four hexagon head screws (10) and lockwashers (11). Install and tighten switch handle
mounting hardware (10 and 11) from inside the compartment.
(3)
With switch handle assembly (12) In CLOSED (up) position and the main disconnect switch S120 (9)
closed, position the drive chain assembly (3) over the drive sprockets Inside both the switch handle
assembly (12) and on the disconnect switch drive assembly (2). Ensure that the chain links are engaged
on the sprocket teeth when securing drive chain assembly (3) with the turnbuckles (4). Position drive chain
assembly (3) so that the two turnbuckles (4) are aligned with each other and positioned midway between
the switch handle assembly (12) and main disconnect switch S120 (9). Tighten turnbuckles (4) as needed
to hold the drive chain assembly (3) in position. This may require further adjustment to ensure proper
chain tension.
(4)
Install CLOSED (up) and OPEN (down) plate indicators on switch handle assembly (12) it removed.
(5)
Open and close main disconnect switch S120 several times using switch handle assembly (12) to check
chain drive operation. Loosen or tighten the turnbuckles (4) as needed to ensure smooth switch handle
operation.
(6)
Reconnect switch cables according to phase as tagged. Remove and discard tags.
(7)
Close lower cabinet A compartment.
d.
Align.
(1)
Perform substeps b(1) through (4), above.
(2)
Open switch by pulling switch handle assembly (12) downward to OPEN position.
(3)
Tighten pressure adjusting nut (13, Figure 4-37) one-half turn at a time on each switch blade, If needed.
(4)
Move blades back and forth 90 degrees to centerline of base to observe contacts with the hinge. The
blades should be moderately snug against both sides of the hinges at all times. Use thin shim to check for
blade contact.
(5)
Connect wires as tagged. Remove and discard tags.
(6)
Close cabinet A compartment.
4-101
