PS Magazine Issue 43 1956 Series [43 ed.]

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Citation preview

PS MAGAZINE 1956 Seri••

Issue No.4l

Published by the Department 01 the Army for tile informa-

tion of organizational maintenance and suppl, personael. Distribution is made through normal publication· channels. Within limitations of availability, older issues-may be obtained direct from Preventive Maintenance Agency, Raritan Arsenal, Metuchen, New Jersey.

IN THIS ISSUE FEATURE ARTICLES

~

l00-Ampere Charging System Your Truck's Cooling System (Cartoon Section) That New Meter's Ready Anti-Freeze-In or Out? M48 Tank Tarpaulin Nike Roundup 9O-MM AAA GUn Check Save Those Rod Bearings' Winch Cable Tips

21 29 31 33 34 38 42 44

DEPARTMENTS Connie Rodd Half-Mast Armament Engineers

29 31 37 42

Publications Contributions Connie Briefs

46

47 49 PS Magazine wants your ideas ,and contributions, and is glad to answer your questions. Just write to: Sgt Half·Mast,

_~~dMaaj;~~~:esR:~~t~~:n~nca~n~J:~~~.en, New Jersey. Names

Tilt ,.-iltilll" f PS _azine, till PREVENTIY£ MAINTENANCE MONTHLY, is a,,..ne~ by the Director, Burl... of the BU~let (4' Alii. 53), aid is distri· blted as loins: DISTRIBunON: ACTIVE ARMY: Gel Staff, OA (1) exce,t

~~~r;E~:l~ ~: T:: i~ ~c (:):c~:~J~A~~r~);C~:E~~~ ~~~d ~~~O= Base Ce.~ (3); MOW (5); Anliu (50l; COlPS (3); Diy (2) ucept Anld Ow (100), Till Diy (50); Brig: (3); RegtlGp (3); Bn (5); C. (18) exee,t C.J Ce (8), Md C. (8), QM C. (8); Ft & Cp (6); GeR , Br Svc Sc~ (5) ucept Elllr 5th (100), Ord Sell (25); USMA (25); Joillt 5th (5); Specialist Sch (5); PMST (3) e.ee,t PMST OnIROTC Ulns (25); Gen De,.ts (5); SIP Sec, Gil Ol",ts (5); Oe,8ts (5); AH (5); RTC (100); Trns fer.ina! COIId (3); ArMY Ter.iul (3); OUILP Agmies (2); PG (5); Arsenals (25); DB (25); Crait Mai. Sta (3); Div hlr (2); Dist Engr (20). NG: State AG S,ecial List. USAR: Mil DistS,eciaIList.FOfex,lallltiolefah~rniatiolSase~seeSR321I·5H

PS MAGAZINE 1956 Series

Issue No.43

Published by the Department of the Army for the information of organizational maintenance and supply personDel. Distribution is made through normal publication· channels. Within limitations of availability, older issues-may be obtained direct from Preventive Maintenance Agency, Raritan Arsenal, Metuchen, New Jersey.

IN THIS ISSUE FEATURE ARTICLES l00-Ampere Charging System Your Truck's Cooling System (Cartoon Section)

That New Meter's Ready Anti-freeze-In or Out? M48 Tank Tarpaulin Nike Roundup 9O-MM AAA G"(fn Check

Save Those Rod Bearings' Winch Cable Tips

21 29 31 33 34 38 42 44

DEPARTMENTS

Publications Contributions

29 31 37 42 46 47

Connie Briefs

49

Connie Rodd Half-Mast Armament Engineers

PS Magazine wants your ideas .and contributions. and is

glad to answer your Questions. Just write to: Sit

Half·Mast.

,~~dM:!d~~~:e::~~ak~:n~~~n~det~6:.en, New Jersey. Names

. The printing, of PS Mag,ziae, the PREvENTIVE MAINTENANCE MONTHLY, is _'PfoYed by the Direct.r, Bllreal .f tbe a.lltet (4' Aug. 53), _n~ is distrl· ~uted as fallows: DISTRIBUnON: ACnVE ARMY: Gen Staff, DA (1) except DCSPER (2); SS, DA (1); Tee Svc,~ DA (5) except COfENGR (15~ COFOID (215), Adlli" &. Tee Svc Bd (5); H~ CONARC (10); OS M.j CI..d (5), OS

r,~Soi, CT:d D\!)'{5~~WD:~~' {M;II~':z3:~ {~j?:n (~~; D~ W8ix::rep:r~:, ~~ : (8~ Med Co (8~ liM Co (B), Ft & Cp (6); Gen & Dr Svc Sch (5) except Engr Sch {100~ Drd Scb {25l; USMA (25), Jlint Scb (51; S,eeia~st Sch (5); PMST (3) except PMST Drd ROTC Units (25); Sen De~als (5); Su, Sec, Sen Depots (5), Depols (51; AH (5); RTC (10o); Trans Terminal COlld (3l; AlII' Tel'llin.1 (3); OS· SliP AgetlCies(2); PS(5), Arsenals (25), DB (25l; Cruit Main St. {ll; Diy Engr (21; Disl E"lr (20).NG: State AG Special List USAR: Mil Dist Special Lisl For explanation of abllreviations used see SR 320·50·1.

nel carriers, and will be installed in kit form on Commander's jeeps, command trucks and other vehicles which are required to keep constant radio watches. This system is different from any battery charging system now installed on military vehicles. Instead of a bigger DC generator, it uses an alternator which puts out alternating current. They chose the alternator because it offers several advamages over the direct current generator. In the first place, an alternator can be built which has a lOO-ampere capacity and is only slightly larger than the 25-ampere generator it the alternator has better output at low RPM's, so it can keep your batteries up and supply your radios when the engine is idling or running slowly. This is just what you .need when you .a re 'Standing ready .waiting for orders. Another tbing, since the alcernator has

HARGING SYSTEM

Everybody who has to keep a constant radio contact from a jeep or command truck or armored carrier has been screaming for a larger capacity charging sys-

tem to keep their batteries up. So it's on the way. The new IOO·ampere rectified AC charging system is · being installed as original equipment in the M59 armored person· nel carriers, and will be installed in kit form on Commander's jeeps, command trucks and other vehicles which are required to keep constant radio watches. This system is different from any battery charging system now installed on military vehicles. Instead of a bigger DC generator, it uses an alternator which puts out alternating current. They chose the alternator because it offers several advantages over the direct current generator. In the first place, an alternator can be built which has a lOO-ampere capacity and is only slightly larger than the 25-ampere generator it the alternator has better output at low RPM's, so it can keep your batteries up and supply your radios when the engine is idling or running slowly. This is just what you need when you are standing ready ,waiting for orders. Another thing, since the alternator has 2

one-piece slip-rings instead of commutator bars to carry current into the rotor, you don't have any mica insulators to be undercut, and brushes will last longer on t~e smooth slip ring. And the brushes do not carry the whole loo-ampere output as they do on a generator, but only the field current. Since they are carrying less current, they naturally last longer. O'course, you never get something for nothing, so the AC system does have a couple of disadvantages. The main one is that you can't charge a storage battery with an alternating current. So you have to have a rectifier to straighten out the back-and·forth currents from the alternator output and get them all headed the same way to your battery. This rectifier has to be cooled, so it is installed in fcont of the radiator on the '4 - and % - ton vehicles where the air stream can cool it. Unfortunately, air isn't the only thing that strikes the rectifier-so does any mud you happen to run through. If you-run the rectifier when it is covered with mud or dirt, it can get too hot and burn out, so wash the rectifier when you wash the vehicle. But the many advantages of the system far outweigh the few disadvantages. So, let's look at what you've got. First of 3

HARGING SYSTEM

one-piece slip.rings instead of commutator bars carry currene into the rotor, you don't have any mica insulators CO be unclercut, and brushes will last to

longer on t~e smooth slip ring. And the brushes do not carry the whole lOO-ampere output as they do on a generator, but only the field current. Since they are carrying less current, they naturally last longer.

O'course, you never get something for nothing, so the AC system does have a couple of disadvantages. The main one is thac you can't charge a storage battery with an alternating current. So you have to have a rectifier to

straighten out the back-and-forth currents from the alternator output and get them all headed the same way to your battery. This rectifier has to be cooled, so it is installed in front of the ,r adiator on the ~. and % - ton '?[--""",:y- vehicles where the air stream can cool it. Unfortunately. air isn't the only thing that strikes the rectifier-so does any mud you happen to run through. If you-run the rectifier when it is covered with mud or dirt. it can get too hot and burn out. so wash the rectifier when you wash the vehicle. But the many advantages of the system far outweigh the few disadvantages. So, let's look at what you've got. First of 3

all there is the alternator. This looks much like the generators you are used to. It is beltdriven from the cooling fan pulley of the M59 and from the crankshaft pulley of the other vehicles. You may notice that, unlike the completely sealed 24-volt waterproof genera tors, the alternator has a fan and has air holes which permit cooling air to pass through the machine. However, it still can go under water. It may stop charging for the time you actually have it under water, but it will pick_right up again when you come out. comes a shielded harness with plug-in connectors screwed down just like the direct current generator. This harness runs to the rectifier. The rectifier is mounted ahead of the radiator and in the cooling air Stream, both in the M 59 and in the wheeled vehicle kits. Another waterproof and shielded harness comes from the rectifier and funs to the voltage regulator. The voltage regulator is a sealed box with the carbon pile in a castiQg on its lid. From the regulator a third harness ruos to the banery and the loads on the vehicle. This system is durable. Generally speaking, it won't give you any trouble unless you give it a hard time first. But there is one thing it will nol stand hitched for-if you put either you~ batteries or a slave cable into this system backwards-if you reverse the polarity of the battery your renifier and regulatOr are gone! That's gOnt~ because there is no reverse currene cutout in this system. The recrifif!c serves to prevent battery current running back to the alternator. So if you hook the banery up backwards there is no protection, and full battery current· goes sizzling through the alternator and the rectifier. This skittles the rectifier right off and causes a shorr circuit across the ba.ttery ter- ~~~~~1 minals through the load rclay contans. But outside of goofing it up by outside error, this system is pretty rugged as long as you keep the rectifier clean. However, no machinery runs forever, so here's how you check it out, juSt in case it does lie down on you. 4

The second-echelon maintenance on this system is just the same as on the direct current system, with one exception. In other words you only test to find out which of the three units, alternator, rectifier or voltage regulator is bad;or which harness is faulty, and replace the unit. You are authorized to set the output voltage on the voltage regulator. More about this later. So assume that you have a buggy with this system installed and you think it's not working. Either you are having trouble starting or your battery indicator does not go over into the green when you run your engine. There are two ways you can check this system, depending on equipment you have at hand or can gee. The simplest-and far and away the best method-calls for an AC-DC volt-ohmmeter which is carried under Federal Stock No. 17 -V -808. This meter recently became a patt of the second-echelon tool set~ If you have lots of vehicles equipped with this AC system, your Ordnance supply officer may be able to pry one loose for you. Or you may be able to borrow the loan of one from the comma section or the fire-control boys. The other way is with the low-voltage circuit tester. For those having only low Voltage Circuit Tester 117-T-5575-501 jump to page 12.

CHECKS WITH VOLT- OHMMETER ... '.''. :'>-~ ',": ,\ -

~.

'.

Now, assuming you have such a voltohmmeter here's how you use it to check the system out. (Later, we'll get down to how you do it with the low-voltage circuit tester.) You start by making a bactery check. With the meter set for SO volts, DC, you connect the leads to the slave receptacle of your M59, or from the starter post to ground on your wheeled vehicles. (If working alone, M37 and M42 men can make this check faster by hooking up to the batteries directly, which means they can have the meter right beside them in the cab.) First of all you read off the battery voltage with no load. (Remember to 'curn on the master switch in the MS9's.) This will be close to 24 volts, no less than 22. Now crank the engine with the starter, with the ignition switch ofT for not over 30 seconds. Watch the meter. The voltage should not drop below IS volts. If it does, replace or recharge the batteries and go on from there. Next, you turn the ignition on and start the engine. The voltage will either come back to your first reading, battery voltage, or it will rise to a higher level. If it comes up to 27.5 volts, your system is OK. If the voltage comes up above battery voltage but is greater than 2S volts or less than 27.5 volts, the system is working, but the voltage needs adjusting. In order to properly adjust the regulator, run the system for 15 to 20 minutes with the headlights on to provide a load. You 6

~

SWITCH ON

make this regulator adjustment by way of the plug in the voltage regulator box. {he M59's you take our the plug on the side of the control box and look in. You will see a slotted shaft, into which you fit a screw driver. Turning {his shaft, which controls the voltage adjusting rheostat, clockwise will increase the voltage. Turning it coun· terclockwise will decrease the voltage. On the M59's, adjust voltage with the master switch open. On the M37's and some other vehicles equipped with the IOO'ampere AC·DC system, the regulator box also has a plug in the cover, removable with a wrench. Looking down this hole will reveal a black knurled disk which is on the shaft of the rheostat. Use a small screwdriver to turn the disk. As installed on the M37, you would turn r-_.t..cL, the top of this disk to the center of the L-_~~ vehicle to increase voltage, outward to flc crease it. If you find that by this adjustment you can set the voltage at 27.5 your troubles arc over, batten things down and take off. WHEElED VEHICLES But if the voltage shown on your meter docs not climb above battery voltage when the engine is running, or drops out when ==:-L'"'iln , ~-"l:._= you open the master swiech, it means you L-~_~ have some sort of trouble in your system, and you've got to hunt it out. First of all, you nuke a visual check. Be sure the belts are not loose or. broken, and that the alternator is turning. Then kill the engine and check for loose harnesses-all the connections tight? Take a good look at the rectifier-is it clean? Any burned or blistered paint? Any bent or obviously damaged plates? Anything you find by looking, you correct, of course. If this doesn't cure your troubles you have to go on into the meter checks. 7

With the meter still set on the 50-volt DC scale you disconnect the regulator-to-battery harness at the reguiacor. Check from contact "AU to ground. This should show you battery voltage.

by the ignition switch is also OK. If not, of course, you ran your trouble down in this circuit. Now while the regulatorto-battery harness is disconnected, you can make Ohmmeter tests of the regu lator. With your meter set on (he "RXIOO" scale you check like this: Pin "F" to pin "C',line switch coil, 175 8

±

10 ohms.

With the meter still set on the 50-volt DC scale you disconnect the regulator-to-battery harness at the regulator. Check from contact "A" to ground. This should show you battery voltage.

by the ignition switch is also OK. If not, of course, you ran your trouble down in this circuit. Now while the regulatorto-battery harness is disconnected. you can make Ohm.meter tests of the .regulator. With your meter set on the "RXIOO" scale you check like this;

Now from pin "A" to socket "C", contact resistor with the meter on "RXIOO" scale. You should read approximately 330 ohms. (On later models this wiIl be open circuit-reading, "infinite").

With the meter on the "RXIOO" scale, connect the red lead (+) to the "D" pin on the rectifi'er-to-regulator side and touch the other lead to each of the three large sockets on the rectifier-to-alternator side (Sockets "A", "B", & "C"lYou will get high resistance reading 100 to 2 50 ohms. If you get a variation of more than 25 ohms, your rectifier may be faulty. 9

Now from pin "A" to socket "C", contact resistor with the meter on "RXlOO" scale. You should read approximately 330 ohms. (On later models this will be open circuit-reading, "infinite").

not get any any of the circuits. ",',pp'p'" "p'h;r"" with the meter on scale, check from each pin shield, and from each pin to you should get infinite resist(no reading) on aU checks. If either

red lead (+) to the "D" pin on the recti6er-to-regulator side and touch the other lead to each of the three large sockets on the reaifier-to-alternator side (Sockets "A" , "B", & "C" lYou will get high resistance reading 100 to 250 ohms. If you get a variation of more than 25 ohms, your rectifier may be faulty. 9

This checks half of the rectifier. For the other half place the black ( - ) lead on pin "C" rectifier-to-regulator side and touch the other lead (+) to each of the three large sockets on the rectifier-to-alternator side sockets "A", "B" and "C". You should get the same reading. Before passing the rectifier as OK, check the field circuit through it. From small pin "8" to socket "D" and from small pin "En to socket toE" you should have no appreciable . resistance. While you cannot repair the rectifier. you can check this circuit for loose wires, since it consists simply of two jumpers running from one connector right over to the other one.

"D" to pin "E" approximately 2 ohms. This is rhe rotor coil resistance. However, since you are checking through the brushes and the slip rings, any reading from 1.7 to 5 ohms is probably OK. Now from anyone of the big pins, "A", "B" or "C" to rhe others, you should have. no measurable resistance. With the meter on "RXlOO" scale, take a resistance check from each pin to the alternator ground. The reading should be infinite. Somewhere along this list of checks you almost have to find onc that didn't agree with the stated figures, or your system will work. However, the proof of the pudding comes when you hook everything up again except the alternator. While someone else turnS on the ignition switch, listen carefully at the regulator box. You should hear the load relay close. Now check with your meter on the 50-volt DC scale and see if you get approximately battery voltage between small 10

This checks half of the rectifier. For the other half place the black (-) lead on pin "C' rectifier-to-regulator side and touch the other lead (+) to each of the three large sockets on the rectifier·to-alternator side sockets "A", "B" and "C". You should get

the same reading. Before passing the rectifier as OK, check the field circuit through it. From small pin "B" to socket "D" and from small pin "E" to socket "E" you should have no appreciable resistance. While you cannot repair the recti· fier, you can check this circuit for loose wires, since it consists simply of two jumpers running from one connector tight over to the other one.

"D" to pin "E" approximately 2 ohms. This is the rotor coil resistance. However, since you are checking through the brushes and the slip rings, any reading from 1.7 to 5 ohms is probably GK. Now from anyone of the big pins, "A", "B" or "C" to the others, you should have. no measurable resistance. With the meter on "RXlOO" scale, take a resistance check from each pin to the alternator ground. The reading should be infinite. Somewhere along this list of checks you almost have to find one that didn't agree with the stated figures, or your system will work. However, the proof of the pudding comes when you hook everything up again except the alternator. While someone else turns on the ignition switch, listen carefully at the regulator box. You should hear the load relay close. Now check with your meter on the 50-volt DC scale and see if you get approximately battery voltage between small 10

socket "D" and small socket "E" at the alternator end of the alternator·to-rectifier harness. Kill the switch and finish connecting up, being sure all the connections are tight. Start your engine and run it at about 700·800 RPM. With your meter set on the 50-volt AC scale, check from each of the three AC connections on the rectifier to the other two. (Yellow dot on the connecthree together on one side of the rectifier, in front on the wheeled vehicles. ) Now watch this one or it will fool you. Due to the peculiarities of AC current, your meter doesn't read the peak voltage of each back-and-forth (alter· nating) cycle, but only gets an average value. So, even though you have an output of 27.5 or more volts on the direct current side of the rectifier, you will only get a reading of about 22 volts on the AC side. It may not even be exactly 22 volts, but the point is, all three possible checks he·re should be very close to the same voltage. If they vary more than a volt, replace the alternator and send it back for checking. Now on the M59's, you can switch your meter back to the 50·volt DC scale and check the DC voltage at the slave receptacle, which should be 27.5 jf your adjustment is - OK. On the wheeled vehicles, it is almost impossible to get at the DC terminals of the rectifier, so you go back to the starter terminal. Make your final adjustment of output voltage and button up. (NOTE: On M59's, the voltage ' adjustment should be made with the master switch open and no load except the ignition.; 11

socket "0" and small socket "E" at the alternator end of the alternator·to·rectifier harness. Kill the switch and finish connecting up, being sure all the connections are tight. Start your engine and run it at about 700·800 RPM. With your meter set on the 50-volt AC scale, check from each of the three AC connections on the rectifier to the other two. (Yellow dot on the connecthree together on one side of the fier, in front on the wheeled vehicles.) Now watch this one or it will fool you. Due to the peculiarities of AC current, your meter doesn't read the peak voltage of each back-and-forth (alternating) cycle, but only gets an average value. So, even though you have an output of 27.5 or more volts on the direct current side of the rectifier, you will only get a reading of about 22 volts on the AC side. It may not even be exactly 22 volts, but the point is, all three possible checks he·re should be very close to the same voltage. If they vary more than a volt, replace the alternator and send it back for checking. Now on the M59's, you can switch your meter back to the 50-volt DC scale and check the DC voltage at the slave receptacle, which should be 27.5 if your adjustment is - OK. On the wheeled vehicles, it is almost impossible to get at the DC terminals of the rectifier, so you go back to the starter terminal. Make your final adjustment of Output voltage and button up. (NOTE: On M59's, the vottage ' adjustment shotttd be made with the master switch open and no load except the ignition.) 11

T E STING THE 100-A MPERE

AC d~

CHARGING SYST EM WITH ff ~~ THE LOW-VOLTAGE CIRCUIT TESTER

::m

" '~ ~o~ That's the 'way of it IF you can get a voltg ~~ --;-> ~ ohmmeter with AC-DC-scales. Now if you . ." . -Jr- ;>yi'b a lrnlil>;u'for l:g~h,i"Ji siitQ.?thne,;s .oi':';peracion" .elevate: aoadepcess ·iIi.: mOUnt:tir hand between

iWpcr and lower stops. ~. travers€: irU4:00 mils mcheck freedom of

m _o _v_e_ me~t ~~JZ~:undue bin~::

40

back_!1S_h_ 'o_O __rd~

I

90MM

{ ) RECOIL MECHANISM-Chedc nitrogen pressure for leakage with soap suds. (Check TB ont 605 for proper rec:oil oil rewve.)

:8'. GAS AND 011 nlUNG VALVES-Improperly seated. : A

' :0

' ' COUHTER-RECOIL BUff£R-Rod not following gun out of battery. gun not slamming into battery. RECOIL lINGTHS-(hedt at 0 and 80 degr....

'8,

ELEVATION. LIMIT STOt:s-GUn not stop~ing at fulllimtl·.:l, , GUN BORE AND CHAMIfR-Rust, (afroSion, fouling .

"

• ~O' OUTRIGGERS-Rusted joints and surfotts.

~O HYDRAUU( JACK$-(Extend ram and oijram and wiper weekly.)

~ ·D: EL£CTIU~ ,BRAKf-Loose, broken (onnedtons or wires. / , "~, pJugs;drum ond'mo9oetJlIcillgs.

,,0

:0

MOTOR BELT-Frayed, smeared with oil or grease. ; :D,TRANSMISSION-ICh"k'p'rat;on by mov;ng flywheel "unf,.lade·

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.

dirty sockets, ,

HAND BRAKE-Bad adjustment.

, . ~~ ,.O.,.;~~:~:I~o:~U~l~~:~~I::'~' J ... ' '0:.

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manuoUy.)

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