pulley using the formula in b(5)
t e n t i o m e t e r switch (19) to the "CAL
above:
POT" position.
(6) L e a v e the switch (18) in the "LO"
position, d(3) above, and turn the
t a c h o m e t e r indicator calibrating po-
(2) Install the pulley (driver) (8, fig. 20)
tentiometer (58) until the speed
a n d the pulley-driven generator or
(rpm) calculated in (1) above (16,000
a l t e r n a t o r (9, fig. 20) on the high
r p m ) , is indicated on the tachometer
speed driving head (4, fig. 7) as pre-
i n d i c a t o r meter (3) (lower scale on
scribed in paragraph 95.
meter).
(3) T u r n the tachometer indicator high-
(7) A f t e r tests are completed, stop the
low switch (18) to the "LO" position
v a r i d r i v e assembly as prescribed in
a n d the tachometer indicator direct
drive calibrating potentiometer switch
tor or alternator from the test stand.
( 1 9 ) to the "DIRECT DRIVE" posi-
tion.
e. Example II. The preset speed (rpm) of
(4) S t a r t the varidrive assembly as pre-
t h e pulley (driver) (8, fig. 20) is 6,000, the
scribed in paragraphs 93a and b a n d
diameter of the driven pulley of the generator
turn the handle of the speed control
or alternator (9, fig. 20) is 3 inches, and the
( 3 2 ) clockwise until the tachometer
diameter of the pulley (driver) (8, fig. 20) is
indicator meter (3) reads 6,000 rpm.
4 inches.
(5) T u r n the tachometer indicator cali-
(1) Determine the speed (rpm) of the gen-
brating potentiometer (58) to the
erator or alternator (9, fig. 20) driven
48
