TM 9-4910-663-34
CAUTION
If a diode is being replaced, make sure that the correct polarity is observed when the diode is being
inserted into the printed circuit board holes. (See FO-1.)
3-19.
VARIDRIVE ASSEMBLY
a.
Removal and Replacement of Varidrive Belt (fig 3-4).
(1)
Set circuit breaker switch CB1 (fig 2-8) to the ON position, start the varidrive, and adjust the varidrive
speed to high.
Stop the varidrive and set circuit breaker switch CB1 to the OFF position.
(2)
Remove eight 1/4-20 screws from both the upper and lower rear panels of the test stand, and remove the
upper and lower rear panels.
(3)
Remove the right side cover from the varidrive.
(4)
Remove screws (8) and lockwashers (8.1) that attach tachometer generator with bracket (9) to the
varidrive, and remove the tachometer generator with bracket and coupling bushing (7) from the test stand. Remove the
bearing retainer attaching hardware from support bracket.
(5)
Unscrew plug adapter (6) from support bracket (5) end of the variable shaft.
(6)
Remove cap screws (4 and 14), lockwashers (4.1 and 14.1), support bracket (5), and end cover (13).
(7)
Place a block of wood between variable discs (1 and 2) to block them open. Use care not to nick or
otherwise damage the disc faces.
(8)
Carefully mark the axial and radial position of stationary varidisc (11) in relation to shaft (19), as shown in
figure 3-4.
(9)
Loosen clamping bolts (12) on varidisc split hub (11), and remove split hub stationary varidisc (11) from
shaft (10). Wedge open the split hub if the varidisc is tight on the shaft.
(10)
Withdraw the varibelt over shaft (10), over varidisc (2), and through the opening in frame case (3).
(11)
Insert the replacement varibelt through the opening in frame case (3), and insert it between driven discs (1
and 2) and around shaft (10).
(12)
Install split hub varidisc (11) in its original premarked position on shaft (10). Make sure the positioning is
correct because this affects belt alignment.
Change 1 3-34
