I.

DESCRIPTIONAUXILIARY RELAYS - FORM C

The relays covered by this Maintenance Instructionare all of the same basic construction and are used ina wide variety of applications, see Fig. 1. They differonly in number, rating, contact arrangement andoperating values.

The coils of these auxiliary relays operate off 74 voltcontrol circuits in most cases. The contact arrange-ments are designed to set up a variety of controlcircuits for product operation. The individual

\ wiring diagrams will indicate relay function.

MAINTENANCEDue to simplicity of construction employing aminimum of moving parts together with golddiffused silver alloy contacts and dust free enclosure,these auxiliary relays will provide satisfactoryservice over a long period of time. Maintenancerequirements center primarily around occasionalinspections to qualify the relays for continuedservice.

I: 14750,

INSPECTION

At the time of inspection, the relay cover should beremoved and the contacts checked for pitting orburning, see Fig. 2. Use a low pressure stream of drycompressed air and blow out any dust or dirtaccumulation. Check for an accumulation ofmetallic dust adhering to the blowout magnets. Inthe event that badly burned or pitted contacts areapparent, the relay must be removed from theinstallation for overhauling. Do not file or dressrelay contacts. Relay contacts will turn black(tarnish) in time with normal operation. This willnot impair relay operation or indicate a need forservicing.

Inspect the electrical connection for tightness andelectrical contact. Inspect the operating coil forburns or discoloration. Check resistance of the coilaccording to values given in the Service Data.Electrically inspect the relay for pickup and dropoutusing the values tabulated in the Service Data.

Check the movable mechanical parts of the relay forproper function. Do not apply lubrication of anytype to these relays.

Fig.1 - Typical Auxiliary Relays

*This bulletin is revised and supersedes previous issues of this number.

DE-LMPR September 1981

M.I. 5386

OLD DESIGN1 . Flag Arm 7 .2. antam~,ousing 8.

Reinforcing Post

9.Relay HousingCarrier3 . Coil 10.

4. 8low0ut Magnets

Relay Frame Assembly

11.5. Wave Washer 12.

Armature SpringCoil Core

6. Relay Cover

-iil=--iNEW DESIGN

1. Coil Core 7. Reinforcing Post2. CooMousing 8.

9.Flag ArmRelay Housing

3 . Coil 10. Carrier Assembly4. 8lowou1 Magnets 11. Relay Frame5. Wave Washer 12. Armature Spring6 . Relay Cover

26209

DISASSEMBLY PROCEDURE

Fig.2 - Cutaway Views Of Relays

After relay cover is removed, the entire workingmechanism of relay can be disassembled from relayhousing by removing the two flat head screws onterminal side of relay and the large flat head screwand washer on decal side of relay, see Fig. 2. Onolder devices, the relay mechanism is secured to theback of the housing by a flat head screw through thecover and the end of the reinforcing post. This screwmust also be removed.

Remove armature spring from carrier assembly andrelay frame. Be careful in removing spring so as notto stretch it to the extent of changing its tensionstrength. The relay core and wave washer can nowbe removed from the relay coil. To remove the relaycoil, unsolder the two coil leads from terminals Yand Z with a 100 watt soldering iron.

If the carrier assembly and the contact housingassembly are both being replaced, no furtherunsoldering is necessary. In the event either one ofthe assemblies is being replaced it will be necessaryto unsolder the leads connectetiito the individualterminals to separate the carrier assembly from thecontact housing assembly.

REASSEMBLY PROCEDURE

To reassemble the relay, follow a reverse order tothat of disassembly. Make certain all parts arecleaned thoroughly before reassembly. The armaturespring should have a free length measurement of1.421” and should stretch to 1.646” with a l-1/2 lb.load +, 10%. Solder with resin core solder only. Donot use acid core solder nor use more solder than isnecessary to make a good electrical connection.Make certain the locating tabs of the coil frame fitinto the holes in the relay housing, and the threadedhole in the core aligns with the hole in the housing tosecure the coil and frame assembly to the relayhousing with flat head screw and lockwasher.

CHECKING AND ADJUSTINGRELAY CONTACT PRESSURE

Replace the pan head screw that holds the cover, foraccurately locating the contact housing assemblyduring the checking and adjusting procedure, but donot install the relay cover until the tests have beenmade. On newer devices, the two screws securing theterminal side of the relay to the reinforcing post willensure correct alignment. Again, there is no need to

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1 .

install the cover before testing. Check the pressurerequired to open all normally closed contacts with agram gauge (5 to 150 range). This check can be madeby connecting the normally closed contacts in serieswith a simple low voltage (6 volt) lamp circuit. Thereading should be taken at the position the lamp isde-energized. Place the probe of the gauge up closeto the movable contact, see Fig. 3. A minimumreading of 40 grams is acceptable before contactopening.

Location of gauge probe for proper

Fixed ContactsMovable Contact

14726

Fig.3 - Location Of Gauge Probe

With a DC voltage of approximately 2 to 3 voltsabove the rated pickup voltage, energize the relaycoil. Check the pressure required to open allcontacts which close when coil is energized. Aminimum reading of 40 grams should be obtainedon this test.

If the minimum reading of 40 grams is not obtained,the contact brush assembly will have to be adjusted.Using a bending tool described in Fig. 4, makegradual adjustments along the length of the contactbrush assembly. Do not make any sharp creases orbends in the assembly. When making a correctionfor a pressure reading of the normally closedcontacts, this will affect the pressure reading of thecontacts that are closed when the coil is energized.Therefore, all contacts should be recheckedwhenever an adjustment is made.

.035” Slot

3/l 6” x 3/l 6” H.R.S.

14727

Fig.4 - Example Of Relay Adjusting Tool

Check the air gap between all normally opencontacts and between open contacts when the relayis energized. This air gap should be .045” minimum.

) Check the travel gap from the center of the relaycore to the carrier assembly. This travel gap shouldbe -038” minimum, see Fig. 2.

M.1. 5386

PICKUP AND DROPOUTTEST VOLTAGE

In order to make the pickup and dropout checks, avariable DC voltage supply should be connected tothe relay coil. See Fig. 5 for a schematic wiring of atest setup. Proper readings for various operatingvoltages will be found in the Service Data.

50 w. Pot D.C. Voltmeter Relay Under+\

- - - -

D.C. Supply (lo suit max.relay operating voltage)

14728

Fig.5 - Suggested Test Setup

Set the 50 watt potentiometer shown in Fig. 5 tomaximum resistance, then gradually increase thevoltage applied to the coil. An indicating lampconnected across the contacts will mark the pickupor dropout points. Slowly reduce .the appliedvoltage to determine the dropout point; theindicating lamp will go out when the point isreached.

If the pickup and dropout points are not obtained asoutlined in the Service Data section, check leadarrangement, contact pressure and carrier travelgap. Readjust if necessary. Check the armaturespring to be sure it is in good condition and that itmeets specifications as outlined under “ReassemblyProcedure” in this instruction.

Check to be sure that the carrier assembly ispositioned properly so that the contact arms arecentered between the blowout magnets. Manuallycenter the carrier if necessary.

Install the relay cover by removing the pan headscrew and then assembling the cover to the relayusing this same screw to secure cover to housing. Onnew devices, simply attach thecover using three panhead screws at top center and bottom two corners ofrelay terminal side.

The relay should be cycled 25 to 50 times with a 6volt, 4 milliamp load (test lamp) connected acrosseach set of contacts. Positive contact should beaccomplished on each cycle or the relay must bereworked.

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M.I. 5386

SERVICE DATA

Part No.Contacts:Interlocks

8357415 3NO-3NC 1128 -t 15%8363168 2NO-2NC 1853 & 15%8364979 2NO-2NC 702 + 12%8369626 2NO-2NC 296 + 12%8370794 3NO-3NC 4320 k 15%8370839 2NO-2NC 1853 + 15%8383678 2NO-2NC 1128 f 15%8392855 2NO-2NC 1128 + 15%8398823 2NO-2NC 180839958 1

f 15%3NO-3NC 702 + 15%

8403578 2NO-2NC 1128 Z!I 15%8405985 INO-1NC 1853 31 15%8407979 3NO-3NC 176 + 10%8408359 2NO-2NC 1128 + 15%8408975 3NO-3NC 1128 & 15%8428700* 3NO-3NC 1128 + 15%8451991 3NO-3NC 16,500 + 20%**9516672 4N04NC 1033 z!I 5%9535873 4N04NC 682 + 5%9535874 4N04NC 173 -I- 5%9535875 4NO-4NC 4500+ 5%9535877 4NO4NC 13,680 2 lo%**9535878 4NO4NC 26,680 + IO%**

*No blowout magnets.

Operating CoilResistance

@ 25” C - OhmsOperating Voltage @ 25O C

Working Max. Pickup Dropout

747448281207474741204874

z747474

120AC744824120

120AC220AC

4848

::984848489036354818484848

98AC46361890

93AC186AC

5-285-285-18l-9

12425-285-285-28

28-652-184-285-28

5%5-285-28

5-65AC5-282-18l-9

10-50lo-56AC

20-l 12AC

NOTE

**Operating coil resistance from “Y to “Z”. This includes resistance of diodes used to rectifyAC input voltage. Use Model #260 Weston meter with the RX 100 scale.

The following items are applicable to all relays listed above.

Armature SpringFree Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.421”Stretch Length . . . . . . . . . . . . . . . . . . . . . . . . . . 1.646” with a l-1/2 lb. load + 10%

Contact Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Grams Min.

Contact Air Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .045” Min.

Hi-Pot Data (60 Cycles)

Coil to Ground . . . . . . . . . . . . . 600 V.RMS for 8428700 only - all others are 1000 V.RMSCoil to Contact 2400 V.RMSContacttoContadt’::::::::::::::::::::::::::::::::::: 24OOV.RMSContact to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2400 V.RMS

0 0 0 0 A Seryice Deparhnent Publication l l l l

EkctmMotiva Division Of General Motors La Graqe. Illinois 60525

-4- Litho in USA

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