Features
■
■
■
■
No backlash - mounted directly to
potentiometer shaft
For use with precision potentiometers or
other rotating devices up to 30 turns
Compact size - requires only 25.4 mm
diameter panel space
Available with or without brake
H-490 Turns-Counting Dial
Mechanical and Physical Characteristics
Number of Turns ..................................................................................................................................................................................0 to 30
Dial Divisions ...............................................................................................................................................................................100 per turn
Readability - Over 10 Turns ......................................................................................................................................................1 part in 1000
Torque With Brake Engaged .............................................................................................................................350 g-cm (5 oz-in.) minimum
Markings .............................................................................................................................................................White on black background
Locking Brake.................................................................................................................................................................Refer to chart below
Weight ..........................................................................................................................................................Approximately 7 grams (1/4 oz.)
Set Screws .............................................................................................................................................UNC-3A 4-40, 2 screws 120 º apart
Set Screw Tightening Torque ......................................................................................................................22.59 N-cm (2 lbs.-in.) minimum
Hex Key Size ................................................................................................................................................................................0.05 in. hex
Shaft and Bushing Requirements
Shaft Diameter Requirements ........................................................................................................................................Refer to chart below
Shaft Extension Beyond Panel .........................................................................................................................15.75 mm (0.62 in.) minimum
21.21 mm (0.83 in.) maximum
Bushing Extension Beyond Panel .....................................................................................................................9.02 mm (0.35 in.) maximum
H-490 MOUNTING INSTRUCTIONS
1. Discard standard mounting nut and lockwasher supplied with the
potentiometer; they will not be used.
2. Insert potentiometer in panel.
3. Using parts supplied with dial, position anti-rotation washer
against panel. Tangs of washer should stick out from panel.
4. Install mounting nut supplied with dial. Be sure:
a. Shoulder on nut engages hold of anti rotation washer.
b. Tangs of anti-rotation washer are aligned vertically.
This positions the turns-counting window properly.
5. Turn potentiometer shaft counterclockwise to minimum resistance
or voltage ratio. This is not necessarily at the end of travel.
6. Loosen set screw in knob of dial assembly. Set dial to “0.00”
reading. Slip dial assembly over end of potentiometer shaft.
7. Holding outer ring of dial assembly, engage locating tangs on
anti-rotation washer in notches on dial assembly.
8. While holding outer ring, position unit lightly against panel.
Uniformly tighten knob set screws to potentiometer shaft with
furnished hex wrench.
Dimensional Drawings
30
° ±
5
°
45
° ±
10
°
BRAKE
2
0
1
9
18.29 RAD. MAX.
(.720)
12.7
(.500)
8
3
2
7
25.4
DIA.
(1.0)
DIMENSIONS:
MM
(INCHES)
6
5
4
11.18
(.440)
23.11
±
.76
(.909
±
.029)
10.36
(.407)
DIA.
How to Order
Part
Number
H-493-2
H-494-2
H-491-3
H-492-3
H-493-3
H-494-3
H-492-2
Accepts Shaft
Diameter
3.18 mm (.125 in.)
3.18 mm (.125 in.)
6.35 mm (.250 in.)
6.35 mm (.250 in.)
6.35 mm (.250 in.)
6.35 mm (.250 in.)
3.18 mm (.125 in.)
Fits Bushing Size
6.35 mm-32UNEF-2A
6.35 mm-32UNEF-2A
9.53 mm-32UNEF-2A
9.53 mm-32UNEF-2A
9.53 mm-32UNEF-2A
9.53 mm-32UNEF-2A
6.35 mm-32UNEF-2A
Brake
No
Yes
No
Yes
No
Yes
Yes
Body Finish
Black
Black
Satin Chrome
Satin Chrome
Black
Black
Satin Chrome
REV. 04/03
Specifications are subject to change without notice.
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