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BELL SYSTEM PRACTICES
AT&TCo Standard
CONTENTS
1 .
GENERAL
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BASIC UNITS ...............
Basic Gear Adjustments
Intermediate gear - transmitter
distributor gear backlash ........
Clutch Mechanism
Armature bail spring . . . . . . . . . . .
Clutch latchlever spring . . . . . . . . .
Clutch magnet assembly
(preliminary )
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Clutch shoe lever .
Clutch shoe lever spring . . . . . . . . .
Clutch shoe spring . . . . . . . . . . . . .
Clutch trip lever . . . . . . . . . . . . . .
Clutch trip lever spring . . . . . . . . .
Main bail latch spring . . . . . . . . . . .
Feed Wheel Mechanism
Feed pawl . . . . . . . . . . . . . . . . . . .
Feed pawl spring . . . . . . . . . . . . . .
Feed ratchet detent spring .
Feed wheel detent. . . . . . . . . . . . . .
Main bail spring. . . . . . . . . . . . . . .
Main bail trip lever . . . . . . . . . . . .
Sensing pin spring
Main Bail Mechanism
Main bail
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Signal Contacts
Drive link spring
Signal contact clearance .
Signal contacts - electrical . . . . . .
Signal contact spring. . . . . . . . . . . .
Start-Stop Switch Assembly and
Tight-Tape Mechanism
Start-stop switch bracket. . . . . . . . .
Start-stop switch bracket (for units
equipped with tape lid sensing lever) .
Tight-tape intermediate arm . . . . . .
Tight-tape intermediate arm
spring . . . . . . . . . . . . . . . . . . . . .
Tight-tape start-stop contact
spring
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Prepared for American Telephone and Telegraph Company by Teletype Corporation
28E AND 28H TRANSMITTER DISTRIBUTOR UNIT
ADJUSTMENTS
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© 1962 and 1963 by Teletype Corporation
All rights reserved
Printed in U. S. A.
Tape Lid
2
Start-stop detent bail spring ...... .
4
Tape guide ................. .
Tape guideplate
Tape lid ...................
Tape lid release plunger spring .. .
Tape lid spring ..............
Tape-Out Switch Assembly
28
Depressor bail torsion spring.
6
Intermediate tape-out bail spring
Tape-out contact assembly. .
Tape-out contact bracket . . . . . . . . .
5
Tape-out sensing pin.
4
Tape - out sensing pin (for units
4
equipped with tape lid sensing lever) . .
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Tape - out sensing pin spring
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Top and Cover Plates
Cover plate
22
Cover plate detent spring. . . . . . . . .
22
Top plate . . . . . . . . . . . . . . . . . . .
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Transfer Mechanism
21
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Locking bail spring
19
Stabilizer spring . . . . . . . . . . . . . .
21
Transfer bail stabilizer
Transfer lever spring.
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VARIABLE F EATURES. . . . . . . . . .
3.
Auxiliary Contacts
25
Auxiliary contact operating
25
bail spring . . . . . . . . . . . . . . . . . .
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Contact sensing arm . . . . . . . . . . . .
25
Contact swinger - operating
bail clearance . . . . . . . . . . . . . . . .
Normally closed contacts. . . . . . . . .
Normally open contacts . . . . . . . . . .
16
Code Reading Contacts
17
Contact assembly positioning . . . . . .
18
Contact sensing arm - upstop
clearance . . . . . . . . . . . . . . . . . . .
18
Contact swinger - sensing
arm clearance .
16
SECTION 573-127 - 703
Issue 5, May 1972
CONTENTS
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Page 1
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Table of Contents
Related Manuals for Bell 28E
Summary of Contents for Bell 28E
- Page 1 SECTION 573-127 - 703 BELL SYSTEM PRACTICES Issue 5, May 1972 AT&TCo Standard 28E AND 28H TRANSMITTER DISTRIBUTOR UNIT ADJUSTMENTS PAGE PAGE CONTENTS CONTENTS Tape Lid GENERAL • • • • Start-stop detent bail spring ..BASIC UNITS ....
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Page 2: Table Of Contents
Contact lever ... This section provides specific adjust - 1. 01 Tape Deflector ments for the 5 - le vel 28E and 28H trans mitter distributor. This section is reissued to Tape deflector bracket add recent engineering changes and additions, Tape deflector spring . - Page 4 SECTION 573-127-703 BASIC UNITS 2.01 Clutch Mechanism Note 1: Remove the transmitter distributor from its base before making a complete re adjustment or spring tension checks. Note 2: Adjustments (A) and (B) are made at the factory and should not be disturbed unless good reasons exist that the require...
- Page 9 ISS 5, SECT ION 573-127-703 Tape Lid (continued) 2. 06 START-STOP DETENT BAIL S PRING CONTROL LEVER To Check Place control lever in run position. Requirement to start detent bail moving away from TAPE GUIDE control lever. TAPE LID RELEASE PLUNGER SPRING To Check Unlatch tape lid.
- Page 13 ISS 5, SECTION 573-127-703 Tape-Out Switch Assembly 2.10 TAPE-OUT CONTACT ASSEMBLY To Check Loosen spring bracket and move downward until tape-out pin extension no longer touches insulation on contact swinger. Requirement to separate normally closed contacts. Requirement Min 0.008 inch---Max 0.015 inch between normally open contacts.
- Page 17 573-127-703 SECTION 2.14 Tight-Tape Mechanism START-STOP SWITCH BRACKET (For Units Equipped with Tape Lid Sensing Lever) To Check Place intermediate tight-tape arm to center of its adjusting range with the contact arm. Requirement CONTACT C O NTAC T PILE-UP Tight-tape start-stop contacts to: MOUNTING SCREWS Remain closed when tight...
- Page 19 ISS 5, SECTION 573-127-703 2.16 Feed Wheel Mechanism MAIN BAIL TRIP LEVER Requirement (Replace top plate) Unit in stop position, clearance between tip FEED RATCHET DETENT SPRING o f highest sensing pin and top s urface of tape guideplate should be flush to 0. 005 Requirement i n c h below.
- Page 23 ISS 5, SECTION 573-127-703 2.20 Transfer Mechanism TRANSFER LEVER TRANSFER LEVER GUIDE POST TRANSFER LEVER SPRING To Check Disengage unit clutch. Requirement TRANSFER LEVER to start each transfer lever spring SPRING mo ving. (Rear View) (B) LOCKING BAIL SPRING Requirement to pull locking bail spring to its installed length.
- Page 25 ISS 5, SECTIO N 573-127-703 2. 22 Signal Contacts SIGNAL CONTACT CLEARANCE ( C) SIGNAL CONTACT SPRING (T RANS MITTE R DIST RIBUTOR SETS ONLY) To Check Remove cover plate and signal contact To Check box cover. Engage the unit clutch and Place transmitter in stop position.
- Page 28 SE CTION 573-127-703 2. 25 Clutch Mechanism (continued) CLUTCH MAGNET ASSEMBLY (Preliminary ) (Continued) Requirement With armature electrically held against its magnet core, clearance between vertical surfaces of the main bail and its latchlever Min some To Adjust With magnet bracket mounting screws friction tight, move bracket to its lowermost position, then position bracket by means of adjusting lug on bracket (visible through hole in rear plate).
- Page 29 ISS 5, SECTION 573-127-703 either direction when the scale is posi Signal Contacts - Electrical tioned so that the variation is centered about the 0-scale mark of the START seg 2. 26 strobing adjustment procedure is ment. used for checking and adjusting signal contacts electrically, a nd at the same time,...
- Page 30 SECTION 573-127-703 Note: On units equipped with signal regener THEM UNSUITABLE FOR LOW-VOLTAGE 1.12 APPLICATIONS. REFER F O R ators, remove regenerator circuit card be fore app lying test set probes to contact ac SERVICING INSTRUCTIONS. cess terminals. CAUTION: APPLYING OPERATING VOLT 2.
- Page 31 573-127-703 ISS 5 , SECTION Follow the general provisions outlined in Paragraphs 2. 2 7 and 2. 28 substituting the appropriate 2. 3 0 data from the following table. PULSE DATA TABLE 7.42 FIVE- LEVEL UNITS, UNIT CODE PULSE MARKING SPACING RANGE NOMINAL...
- Page 32 SECTION 573-127-703 Follow the general provisions outlined Paragraphs 2. 27 and 2. 28 substituting the appropriate data from the following table. PULSE DATA TABLE SIX - LEVEL UNITS, 8.50 UNIT CODE PULSE MARKING SPACING TOLERANCE RANGE NOMINAL TOLERANCE NOMINAL BEGIN ±8 DIV 0 (STOP) BEGIN ±7 DIV 0 (STOP)
- Page 33 ISS 5, SECTION 573-127-703 2. 32 Basic Gear Adjustments TRANSMITTER DISTRIBUTOR GEAR ----- (Left Side View) INTERMEDIATE S HAFT INTERMEDIATE REAR B EARING ASSEMBLY DRIVING GEAR BRACK ET TRANSMITTER DISTRIBUTOR GEAR DRIVE SHAFT TRANSMITTER- DISTRIBUTOR MOUNTING SCREWS INTERME DIATE GEAR - TRANSM ITTER DISTRIB UTOR GEAR BACKLA SH {Left Side View) To Check...
- Page 34 573-127-703 S E C T ION VARIABLE FEATURES 3.01 Tight-Tape and Tape Shoe Mechanism TIGHT-TAPE SWITCH To Check Place control lever in run position. Requirement 9/32 inch---Max 13/32 inch to open contacts when tight-tape arm is raised. To Adjust Loosen clampscrew. Using adjusting slot, position tight-tape intermediate arm to meet this requirement.
- Page 35 ISS 5, SECTION 573-127-703 3.02 Tape Feed Assurance Mechanism TAPE SENSING FEED WHEEL PHASING DETENT LEVER SPRING To Check To Check Place fresh, fully perforated tape (10 Hold contact lever away from detent lever. holes per inch) on tape guideplate across the feed wheel and tape feed as...
- Page 36 SECTION 573-127-703 3.03 Tape-Out Mechanism T APE-OUT CONTACT To Check To Adjust Loosen contact bracket mounting Bend contact swinger. Recheck screws. Pivot contact assembly requirement under To Check until pad on tape -out pin extension above. is not touching the swinger pad. Check gap between normally open To Check (top) contact points.
- Page 38 SECTION 573-127-703 3.05 Code Reading Contacts Remove code reading contact Note MOUNTING PLATE assembly from transmitter distributor NORMALLY unit before making initial adjustments. CLOSED CONTACTS Note When using the contact spring bender, start with the contact pile -up farthest from the handle of the tool and work toward the handle so as not to disturb adjustments already made.
- Page 40 SECTION 573 -127-703 3.07 Code Reading Contacts (continued) CONTACT SENSING ARM- UP-STOP UPPER CLEARANCE CONTACT LEAF To Check Rotate main shaft until sensing arms are in their highest positions. Engage clutch. Select a LETTERS combination. Requirement Min some---Max 0.008 inch clearance between upper contact leaf and its backstop.
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Page 41: Contact Swinger -Sensing Arm Clearance (Strobing)
ISS 5, SECTION 573-127-703 3.08 Code Reading Contacts (continued) C ONTACT SWINGER - SENSING ARM Requirement Contacts must open and close within CLEARANCE (STROBING) the range specified on the Contact Note When strobing the code reading Operating Requirements Table. contacts, use a DXD scale whose unit cor responds to that of the unit being checked. -
Page 42: Normally Closed Contacts
SECTION 573-127-703 3.09 Auxiliary Contacts Note: Make initial adjustments with the auxiliary contacts removed from the trans mitt er distributor unit. NORMALLY OPEN CONTACTS Requirement 5-1/2 oz---Max 6 oz to move normally open contact away from stiffener. To Adjust Bend normally open contact leaf to meet requirement. - Page 44 SECTION 573-127-703 3.11 Auxiliary Contacts (continued) CONTACT SWINGER- O PERATING BAIL CLEARANC E Note: When strobing the auxiliary con corresponds to that of the unit being checked. (Refer to Contact Operating Requiremen ts Table. ) Synchronize the signal generator of the transmitter distributor with the DXD so that the end of the stop pulse image is in line with the end of the stop pulse on the DXD scale when transmission is continuous.
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Page 45: Switch Lever
ISS 5, SECTION 573-127-703 3 .12 Tape Lid Sensing Lever SWITCH LEVER SPRING To Check Open tape lid. Requirement TAPE LID to separate the switch lever from the SENSING TOP PLATE contact swinger pad. LEVER WEAR P LATE TAPE GUIDE- PLATE TAPE-OUT SWITCH... -
Page 47: Contact Bracket (Strobing)
ISS 5, SECTION 573-127-703 3.14 Start-Stop Pulse Contact CONTACT LEVER To Check Remove contact assembly from unit. Insure that no clearance exists be tween the contact lever and insulator. Requirement to move insulator from contact operating lever. To Adjust Bend lower contact spring. 4-- ·- UPPER CONTACT SPRING LOWER CONTACT SPRING... - Page 48 SECTION 5 73-127-703 3.15 Start-Stop Pulse Contact (continued) CONTACT BRACKET (STROBING) Note 1: When strobing auxiliary contacts, Requirement use a 7.42 unit DXD scale. Synchronize the Contacts must close within the following signal generator of the transmitter distribu range. tor with the DXD so that the end of the stop pulse image is in line with the end of the stop pulse on the DXD scale when trans...
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Page 50: Tape Notch Sensing Contact
SECTION 573-127-703 3 .17 Tape Notch Sensing Mechanism TAPE NOTCH SENSING PIN SPRING To Check Place sensing pin in highest position. Requirement to push sensing pin flush with surface of top plate. TAPE NOTCH SENSING CONTACT To Check Check the location of the insulator with relation to the extension on sensing pin. - Page 51 SECTION 573-127-703 Tape Notch Sensing M echanism (continued) 3.18 CONTACT BRACKET {STROBING) Note: When using the tape notch sensing (FOR UNITS WITHOUT TAPE SLACK ARM) 7.42 unit DXD scale. Synchronize the transmitter distributor Requirement so that the end of the stop pulse image is The contact should close no earlier in line with the end of the stop pulse on the than the...
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Page 52: Transmitter Stop Mechanism
SECTI ON 573-127-703 3.19 Transmitter Stop Mechanism START-STOP CONTACT GAP (FOR TABULATOR CONTROL) To Check Place timing bail on lower part of its cam. Check start-stop contact gap. Requirement • Min 0.018 inch---Max 0.025 inch To Adjust Loosen clampscrew securing yield arm to timing arm friction tight. - Page 54 SECTION 573-127-703 3.21 Tape Withhold Mechanism MAGNET ARMATURE GAP (B ) BLOCKING BAIL ARM ECCENTRIC To Check To Check With the armature attracted, check the Place sensing pins in their lowest gap between the end of the armature position. Place high part of block bail adjusting screw and the plate.
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Page 55: Early Models
ISS 5, SECTIO N 573-1 2 7 - 703 EARLY MODELS To Check 4.01 Tape Lid Mechanism ( 2 ) Tape lid front bearing surface should N ote: Remove top and tape guideplate. rest squarely against tape guideplate, Check rear bearing surface clearance. Lubricate before adjustment.