Teletype 28 Manual page 114

SECTION 573·115-700TC
3. 38 Universal Contact (Stunt Box) Mechanism (continued)
8. NORMALLY CLOSED CONTACTS (100 WPM USED IN DELTA AND UNITED AIRLINES SYSTEM)
WHEN NORMALLY OPEN CONTACTS ARE NOT USED, THE NORMALLY CLOSED
CONTACTS SHOULD REMAIN OPEN FOR 53.88 MILLISECONDS OR 400 + 15 DISTORTION TEST SET
DIVISIONS.
TO ADJUST
REFINE THE DRIVE CAM (3.36), TRIP CAM (3.35) AND, IF NECESSARY, THE BRACKET POSITIONS
TO MEET THE TIMING REQUIREMENTS. TIGHTEN SCREWS.
NOTE 1:
THi'NORMAL 0.003 TO 0.008 INCH OVERTRAVEL OF THE LATCH CAM OVER THE LATCH LEVER
WITH THE DRIVE LINK IN ITS UPPERMOST POSITION MUST BE INCREASED IN ORDER TO
DECREASE NORMALLY CLOSED CONTACT GAP IN THE LATCHED POSITION OF THE LATCH
CAM. THIS PREVENTS THE CONTACT FROM BOUNCING WHEN THE LATCH LEVER IS
RELEASED.
NOTE 2:
Wi'fifTHE LATCH CAM IN ITS LATCHED POSITION, THERE SHOULD BE 0.015 INCH MINIMUM
CONTACT GAP BETWEEN THE NORMAllY CLOSED CONTACTS.
GENERAL REQUIREMENTS AFTER TIMING ADJUSTMENTS
NOTE: IT IS VERY IMPORTANT THAT THE FOLLOWING REQUIREMENTS BE MET
A. WITH THE DRIVE LINK IN ITS UPPERMOST POSITION:
1. THE LATCH CAM SHAll NOT OVERTRAVEL OR HANG UP ON THE SWINGER INSULATOR.
2. THERE SHAll BE AT LEAST 0.003 INCH CLEARANCE BETWEEN THE LATCHING SURFACE
OF THE LATCH CAM AND THE LATCHING SURFACE OF THE LATCH LEVER.
3. THE CLEARANCE BETWEEN THE NORMALLY OPEN CONTACT SPRING AND ITS
STIFFENER SHAll NOT EXCEED 0.025 INCH.
B. WITH THE DRIVE LINK IN ITS LOWERMOST POSITION:
1. THE TOP OF THE SWINGER INSULATOR MUST CLEAR THE CUT-OUT SECTION OF THE
LATCH CAM.
2. THERE SHALL BE AT LEAST 0.003 INCH CLEARANCE BETWEEN THE FRONT EDGE OF THE
LATCH LEVER LATCHING SURFACE AND THE HIGH PART OF THE LATCH CAM.
C. WITH THE LATCH CAM IN ITS LATCHED POSITION, THERE SHALL BE AT LEAST 0.005 INCH
CLEARANCE BETWEEN THE NORMALLY OPEN CONTACT SPRING AND THE UPPER END OF
ITS STIFFENER.
D. THE LATCHING SURFACE OF THE LATCH LEVER SHALL COVER THE WIDTH OF THE TRIP
CAM AND LATCH CAM.
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