not be in excess of 30 seconds. Before starting
b. Pull the pivot arm (2) outward along the
tests operate the varidrive assembly over the
pivot shaft (1) far enough to clear the hexagon
entire speed range of 11000 to 1830 rpm (revo-
studs (3) and swing the pivot arm in position
lutions per minute) by turning the handle of
with the driving head, a above. Aline the two
the speed control (32, fig. 16) clockwise and
stud holes in the pivot arm with the two hexa-
then counterclockwise.
gon studs (3) and push the pivot arm inward
allowing the two hexagon studs to enter the
the "STOP" button to supply current to the circuitry
stud holes.
of the test stand when performing tests that do not
c. Install the mounting flange adapter (10)
require the use of the varidrive assembly.
on the pivot arm (2) and secure with 12 hexa-
Caution: Repeated starting of the magnetic
gon plain nuts (8). Mount the direct driven
motor starter at frequent short intervals may
generator (7) over the middle row of studs on
damage starter coil and contacts by over-
the adapter (10), sliding the splined shaft of
the generator into the adapter (6), Secure the
c. Check for correct rotation of the unit un-
generator on the adapter with the six hexagon
dergoing test and if it is necessary to reverse
plain nuts (8). Figure 19 shows the direct-
the direction of rotation, this may be accom-
driven generator in the installed position.
plished by stopping the varidrive assembly and
placing the reversing switch (fig. 12) in the
the driving head shafts after tests have been
opposite position.
completed. Remove the couplings and machine
Warning: High voltage exists in the area
key (9) and place in the stowage compartment.
near the drive reversing switch. Place the
on-off input power toggle switch (fig. 11) in
the "OFF" position before reaching into this
area to change position of this switch.
Note. The key numbers shown below in parentheses
d. Depress the "STOP" button on the drive
refer to figure 20 except where otherwise indicated.
control (33-C, fig. 16) to stop the varidrive
a. Pull the pivot arm (2) outward along the
assembly.
pivot shaft (1) far enough to clear the hexagon
Caution: The varidrive assembly must be
studs (3) and swing the pivot arm in position
stopped completely before changing position
with the proper driving head (high speed or
of the drive reversing switch (fig. 12).
low speed) (4 or 5, fig. 7), which is determined
Warning: Do not remove any units being
by the speed range of the generator (table 1
tested or connections from the test stand until
below) or applicable manufacturer's test spe-
the varidrive assembly has come to a complete
cifications. Aline the two stud holes in the pivot
stop.
arm with the two hexagon studs (3) and push
the pivot arm inward allowing the two hexagon
studs to enter the stud holes.
b. Insert the machine key (6) in the keyway
Note. The key numbers shown below in parentheses
on the shaft of the driving head and install the
refer to figure 18 except where otherwise indicated.
mounting flange adapter (5) on the pivot arm
a. Install the machine key (9) and the
(2). Secure the adapter with 12 hexagon plain
adapters (5 and 6) on the shaft of the proper
nuts (4). Install the pulley (8), (select the
driving head (high speed or low speed) (4 or
proper size pulley to match the generator pulley,
5, fig. 7), which is determined by the speed
refer to appendix II and fig. 67) on the pulley
range of the generator (table 1, par. 95) or
shaft and bearing adapter (7) and secure it
applicable manufacturer's test specifications)
on the adapter. Aline the keyway in the shaft
and secure with the set screw (4).
of the adapter (7) with the machine key (6)
Note. The splined adapter (5) is made to fit a gen-
and slide the adapter (7) on the shaft of the
erator or alternator with a large splined shaft and the
driving head and over the middle row of studs
generator or alternator is mounted directly into this
on the adapter (5). Secure the adapter (7) on
adapter without the adapter (6).
