Fan Speed Adjustment - Hitachi RUA-13AT3S Instruction Manual

4. FAN SPEED ADJUSTMENT

The unit is equipped with an adjustable motor
pulley. The fan speed can be varied through a
given range by adjustment of the pulley. Table 1.
shows the setting speed and the variable speed
range. To change the speed, adjust the motor
pulley as follows (refer to Fig. 7).
1. Loosen the two bolts on the adjusting bracket
for the fan belt tension and loosen the belt by
pushing the motor upward.
2. Loosen the set screw in the movable pulley
flange.
For Models RUA-13AT3S and RUA-15AT3S
Model
RPM
RUA-13AT3S
PD*
RPM
RUA-15AT3S
PD*
Model
RPM
RUA-20AT3S
PD*
RPM
RUA-30AT3S
PD*
RPM: Fan Speed (RPM)
PD* : Pitch Diameter of Motor Pulley (mm)
RPM/Turn**: Fan Speed Change per One Turn of Movable Motor Pulley Flange (RPM per Turn)
Fig. 7. Adjustable Motor Pulley
Table 1. Fan Speed Adjustment
Regulation Space X of Motor Pulley (mm)
17 18 19
1,120 1,090 1,060
112 109 106
1,120 1,090 1,060
112 109 106
Regulation Space X of Motor Pulley (mm)
0 1 2 3
1,000 980 960 935
150 147 144 140.5
1,000 980 960 935
150 147 144 140.5
3. Turn the movable pulley flange toward the fixed
flange to increase the speed, and turn it away
from the fixed flange to decrease the speed.
Each turn of the movable flange will increase or
decrease the fan speed by 45 rpm for (models
RUA-13AT3S and RUA-15AT3S) and 32 rpm
for (models RUA-20AT3S and RUA-30AT3S).
4. Tighten the set screw in the movable pulley,
which is positioned over the flat surfaces of the
fixed pulley.
5. Adjust the belt tension (approximately 20 mm
deflection with one finger) by pushing the motor
downward and tightening the bolts on the
adjusting bracket.
For Models RUA-20AT3S through RUA-30AT3S
20 21 22 23
1,025 995 960 930
103 99 96 93
1,025 995 960 930
103 99 96 93
4 5 6
910 890 870
137 134 131
910 890 870
137 134 131
FAN SPEED ADJUSTMENT
Factory Set Point
24 x RPM
900
23 930
90
900
21.5 970
90
Factory Set Point
7 8 X RPM
850 830
8 830
128 125
850 830
4 910
128 125
RPM/Turn**
PD*
93 45
99 45
RPM/Turn**
PD*
125 43
137 43
7