Grayhill Mechanical Rotary Encoders 26 PTT User Manual

Mechanical Encoders

SERIES 26

Pull to Turn

Isolated Positions

BCD or Gray Code

Shaft & Panel Seal

DIMENSIONS in inches (and millimeters)

Optical and Mechanical

DESCRIPTION

An isolated position is one that cannot be reached by normal rotation. This version of the Series 26
mechanical encoder requires that the operator Pull-To-Turn in order to reach the isolated position.
To rotate out of the isolated position, the operator must Pull-to-Turn again.

Use isolated positions to protect a switch position from indiscriminate rotation. This feature is
typically used for positions such as “calibrate”, “off” and/or “stand-by”.

Grayhill part number and date code marked on label.
Customer part number marked on request.
Unless specified otherwise, all tolerances are ± .015 ( 0,38)

SPECIFICATIONS

Encoders

Electrical Ratings

Rated: 25,000 cycles with logic compatible

loads. Make and break 200 mA.
Contact Resistance: 500 milliohms maximum
(less than 100 milliohms initially)
Insulation Resistance: 1000 megohms
minimum (10,000 megohms initially)

Dielectric Strength: 250 Vac minimum

Materials and Finishes

Panel Seal: Silicone Rubber
Shaft Seal: Fluorosilicone
Mounting Nut: Brass, tin/zinc-plated
Lockwasher: Steel, tin/zinc-plated
Detent Balls: Carbon steel, nickel-plated
Detent Spring: Pretinned music wire
Detent Rotor: Thermoplastic
Shaft, Stop Arm and Pins: Stainless steel
Bushing: Zamak 3 zinc alloy, tin plate
Switch Base: Diallyl phthalate
Printed Circuit Board: NEMA Grade FR-4
Terminals: Brass, gold over nickel plate
Contacts: Copper alloy, gold over nickel

Additional Characteristics

Shaft Vertical Travel: .050 +/- .010
Pull Force Required: 1.75 +/- .75 lbs.
Rotational Torque: 7 to 13oz-in
Vibration Resistance: 10 to 55 Hz at

0.060" double amplitude; no damage and
no contact openings per MIL-STD-202,
Method 201A
Shock Resistance: Passes medium
requirement per MIL-DTL-3786

Stop Strength: 5 in-lbs minimum
Mounting Strength: 15 in-lbs max
Relative Humidity: 90-95% at 40oC for

240 hours (MIL-STD-202 Method 103, Test
Condition A)

OPTIONS

Isolated Positions

The Grayhill system for isolating positions lets
you choose the positions to be isolated. Grayhill
inserts isolation posts next to the positions to be
isolated. Consider a continuous rotation switch
with a 22.5° angle of throw. The terminals are
listed here from 1 through 16 with a space
between each to indicate where isolation posts
might be inserted.

16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

To isolate position 1 and position 2 from all other
positions and from each other, indicate isolation
posts as shown here:

16P1P2P3 4 5 6 7 8 9 10 11 12 13 14 15 16

To isolate just position 1, describe like this:

16P1P2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

To isolate positions 1 and 2 from all other
positions, but not from each other, do this:

16P1 2P3 4 5 6 7 8 9 10 11 12 13 14 15 16

Fixed Stop Switches

The switch may have continuous rotation, or
specified to limit the rotation.

When a 1-pole switch has less than the maximum
number of positions, consider also the stop
system. Following is the arrangement for a 6
position switch with the position 1 isolated.

STOP 1P2 3 4 5 6 STOP

The word “STOP” indicates the conventional
switch stops, which limit rotation to positions 1
through 6. To isolate position 1 we insert only
one isolation post–between terminals 1 and

2. The stop system already prevents rotation
beyond terminal 1.

CODE AND TRUTH TABLE

BCD Output* Gray Output*

1 2 4 8 1 2 4 8

Code

Position

Switch

Position

1 0

2 1

3 2

4 3

5 4

6 5

7 6

8 7

9 8

10 9

11 10

12 11

13 12

14 13

15 14

16 15

*Dot indicates terminal tied to common.

ORDERING INFORMATION

Due to the vast number of possible configurations
of isolated positions and stop arrangements,
each Series 26 Pull-to-Turn Mechanical Encoder
will be assigned a unique part number. For
example, part 26YY50202 is a 16 position gray
code switch with positions 1 and 16 isolated and
a STOP at each extreme.

Contact Grayhill or an authorized representative
to create a part number and obtain pricing.

Grayhill, Inc. • 561 Hillgrove Avenue • LaGrange, Illinois 60525-5997 • USA • Phone: [phone] • Fax: [phone] • www.grayhill.com