PS Magazine Issue 004 September 1951 Volume 1 Number 4 [1, 4 ed.]

Citation preview

The relationship between a driver and a 2nd-echelon mechanic ca n be beautiful. Instead of rega rding 'the monthlyond semi-'an nual inspections as a pain in the shanks-ond the driyer as the village idiot-the mechanic con -help get the driver on the boll by letting him in on -the little scandals of 'automotive de~ i gn and pointing oul the special nursing that certain assemblies demand ~ The mechanic practically eyery part on the vehicle. He .k nows the stuff they're made of and what they'll stand_ If the driver understands all this, he'll know just how for he can go before the sfrow breaks the came'I's achin ' b-ock, He'll know-if the mechanic tells him . And the time of the scheduled PM servicing, whefl the driver acts as the mecha nic 's qssis'Qnt. is a good time to tell him. Toke the Cose of the Chattering Clutch. Everybody drums into the he ad of the driver the warning to keep the engine mounting· bolts tight. The obvious reason is to keep the engine from dropping out of the truck ., But there's a '~ss obvious reason-the sort of thing that only 0 me~honK: would think to tell a driv er. And thot is that loose engine mounts make the engine too _bouncy-when the clutch is engaged, the engine jumps skittishly oway and the -clutch goes chatteri ng and grGbbing after it. The driver of on up-cnd·coming vehicle like the ca rgo carrier M29 and M29C, toting a load of woun.d ed ove r a muddy posture under enemy fire, con sove the lives of all aboard by ob ~.ervi ng a piece of advice .that a mechanic can best give him . Picture the driver knocking hil'Tlself -outdodge the enemy o rlil lery. He makes a sharp turn out of 0 rut and suddenJy hea~s the heavy thumping that means the trock has tilted a way fr o m th e drive sprocket and is running o ff. Reinstalling the track by the numbe'rs is quic k deoth in a spot like th is. But woiH--the re is 0 trick that will get that tra ck bock on in a split second.' The driver stops ,the ve hi~le immediate ly, throws it in reverse and ba.:k.s up. The track runs back into place ond he 's on his way again, Toddling along be hind a s the me~honic opens the hood of his truck, the driver me ntions that a couple of doys ago he ·had to blowout the gas li ne, but that when he went to tighten up the brass fitting, it leak e d " The mecha riic sho ws ,him how to wind a piece of string or rog around the threads of the fitting 10 moke it seal. There 's a thousand tricks up the man's greasy sleeve. Passed on to the drivef,l they'll fall into willing han ds. For olthough once upon a time ~ heard that the d rive r wa s' a goof-off , we don't he ar it so much anymore. living in the hell of the for,w ord are a s has ~ t,.imm e d the fat oR on our 'h eads.

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Any driver that ha s had it is on " A " student, on eager beaver,CI solid scholar,

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SEPTEMBER 1951

The prime time for him to pick"' up those little extra somethings is the time of th e ·meeting of the Great Minds-the regular scheduled PM servicings. . .

r AND. TODAY·; FROM ·AREADER ' . IN NORTH KOREA' •••

Dear Editor. Our biggest trouble lately has been water in wheel bearings. During the peace talks things have quieted down, so we've ·been cleaning and trying to get vehicles in top shape. 'Drivers seem to think they ·can"t wash a vehicle without getting into water that's way up over the hubs. Our rule is not to get a vehicle in over six inches of water when washing it in rivers or streams. WE HAVE FOUND IT GOOD TO LET DRIVERS REPA'CK ALL WHEEL BEARINGS THEM5ElVES UNDER SUPERVISION OF A MECHANIC!

IN THIS ISSUE ARTICLES

New light Switches and

Other Instruments .I 37 t2Nolt-Jeep Battery ~ 145 Three Field Fixes for M46's 156 Fall Round-Up on M37's -'63 EtTatic Ammeter 165 M44 Brake Cylinder Fix 165 Get, Up To Date _ With Your M38 166 Hand Brake Breaks Chewy. . Oil line 176 ModiAed Battery Clamp 3C

FEATURES

korea Komplaint How To Build and Operate A Spore Parts Supply. Room Joe Dope limerick . Preventive Maintenanc. Service Record · , Damage Equipment Report

DEPARTMENTS

Editorial Combat Maintenance Hand Tool Clinic Connie Rodd Contributions Sgt. Half-Mas.

133 146

154 174 4C 2C

134 140 142 160 170

PS MAGAZINE is published monthly in the interest of Preventive Maintenance for service-wide distribution to all organizations as port of the PREVENTIVE MAINTENANCE PROGRAM, PS Magazine is glad to get your ideas for articles and illustrations, and is glad to answer your questions. Just write to: Editor, PS Magazine Aberdeen Proving Ground, Maryland DISTR18UTlON, Tech 5vs (31• .xce pl 9 nOli Arm & Sv( ad 131; AFF 131; OS Maj Comd (51: Base Comd /31; MDW 131; A (51; CHO f31; D 1501; a /31; R /31: S Bn /31: 8n /51: Se p C lSI: C 1121; FC (101; Sch 1251; PMS&T 131; e xce pt 9 1501: De p 11 01; GH 151; SH lSI; PI: 131; OSD lOrd Offl 121; Ars (101; Dcpln Kks nOI; Rd Sta 131; Div Eng 131; Did 131, Special dj~triblltian . for e xplanation of 4tistribullon lo""ulo see 51 310·90-1 .

133

Cpl. lee R. James All the way (rom Inchon up to the present time I've spent most of my time in Korea behind a recoiJJess rille as one of the five-man crew, either on a jeep or on the ground, depending o n OUf situation. For a while we had :I: pack of trouble with the rifle jamming aftcr about every eight rounds of fast.firing ... and believe me mister, there was times wc'd be lookin'

right down rhe muzzle of a commie 85 mm. At first we didn't understand the . trouble and we'd be in a heavy sweat waiting for the piece CO cool so we could index the next shell. Sometimes took four or five miomcs.

Then we found the trouble and went around kicking each other's buns for nOt catching it sooner. Seems (hat ever so often a gob of unburned liner would be sucked along with the shell ;lnd stick to

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Cpl. Lee R. James All the way from Inchon up to the present time I've spent most of my time in Korea behind a recoil1ess rifle as one of the five· man crew, either on a jeep or on the ground, depending on our situation. Foe a wh ile we had a pack of trouble with the rifle jamming afrer about every eight rounds of fast. firing ... and believe me mister, there was times we'd be lookin' right down the muzzle of. a commie ~5 mm. At first we didn't understand the . trouble and we'd he in a heavy sweat waiting [or the piece to cool so we could index the next shell. Sometimes (ook four or five minutes. Then we found the trouble and went around kicking each other's butts for not catching it sooner. Seems that ever so often a gob of unburned liner would be

sucked along with the shell

;:,~d

stick to

the rifling lands, which is about all it cakes co keep thac projectile f.rom nuzzling home. . Some crews we talked to thought because a jam cleaced after the gun coo led, that the trouble was from barrels expanding from heat of fasc ficing. So they'd pu ll out the stuck shell, and then they'd use sand or emery paper on the ri fl ing lands. Or some of them would try to make it go better by wire.brushing. We didn't foo l around with any of thac kind of trick because we di.dn'c think that was the trouble, and mostly because we knew that if we took any metal off these barrels, the way chat gun works, the propellant gas could blow right out che front and change the whole ve locity of the thing. The real reason the ihell'd . go home after a few minutes could have been because thac 'plastic would get dry and hard when it cooled and move on Out of the way next time the shell was cried. We don't know too much about that, and wI;. didn't cate once we knew what was causing the trouble. Because after we learned to pick those pieces of gook off the lands, she'd take a shell every time. from then on, no matter how much of a rush we were in to feed chose 75's, we'd kneel down real quick between every couple rounds and if we saw anything on the barrel chac didn't belong there, we'd take another second to reach in with a litdc sti.ck and Rick it o ut.

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the ritling lands, which is about all it takes to keep that projectile from nuzzling home. . Some crews we talked to thought because a jam c1eared after the gun cooled, that the trouble was from ba rrels expanding from heat of fast firing. So they'd pull out the stuck shell, and then they'd use sand or emery paper on the riRing lands. Or some of them would try to make it go better by wire-brushing. We didn't fool around with any of that kind of trick beca use we didn't thin k that was the trouble, and mostly because we knew mat if we took any metal off these barrels, the way that gun works, the propellant gas could blow right out thc front and change the whole veloci ty of the thing. The real reason the 5hetI'd . go home after a few minutes could have been because that 'plastic would get dry and hard when it cooled and move on out of the way next time the shell was tried, We don't know tOO much about that, and WI;. didn't care once we knew what was causing the troublc. Because after we learned to pick those pieces of gook off the lands, she'd take a shell every time. from then on, no matter how much of a rush we were in to feed those 75's, we'd kneel down -real quick between every couple rounds and if we saw anything on the barrel chat didn't belong che,re, we'd take another s«ond to reach in with a little stick and Rick jt out.

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C~OG G ED

RADIATORS AND UNSUPERVISED BACKING

Sgt. K. C. Milford Now J can' t say for sure about this, because we couldn't stay around long cnoug h to find our for certain wh('( hcr ie was enemy troops, or old enemy 'poor maintena nce' , Bur anyhow we lost three rrr4A 3's up on T ugok Ridge because one of 'em was overheated . Like I sa id, I ca n'( [ell you if th e radiators was shot up or' just dogged 'up. Co ul d have been eicher onc beca use at rhe tim e we were eak in' a lot of enemy' sm all-a rms fire, and for a long time before that, there wasn't much time fo r prevelltive maintenance. An yhow, when (h at lead tank had CO stop, we got orders fO back dow n rhe so-ca lled road because 1 think rhe)' wanted to try and bypass the sta lled (ank and go another rOute. As we startcd backing we felt the- rank go in g ",er to the side of the road, then th e next ching I knew we had slid do wn a steep slope and inco a gu lly about fifteen feet deep. \,\/ C tried to pull out but the tank wo uldn 't move either fo rwa rd or backwa rd. Next thing you know the tank that had been second in line was right there beside us, almost felf in on top of us. And they couldn·t move either. And the fire gelling holter all the time. Nothing to do but leave 'em there. We managed to crawl out without getting anybody hit, but it was going through my mind that if that one tank hadn·t of overheated, and if olle of the crew had been ceiling us others where to steer while we were backing, we'd stil~ be oper~ acing al1 that equipment.

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AND OTHER INSTRUMENTS ON THE PANEL How they ope'r oteand why t hey wo,n 't if you bruise 'em

and ' 051( for trouble.

That safety lighe-switch on the dash panel of your new vehiclc was· not designed to irritate you, it was worried over for your protection. It may annoy you to always usc ("'''0 paws instcad of onc just to switch a lever and get some light-but keep using the twO hands anyway. The mecbanicallock-switch is there for only one reason, but it's a mighty impol"~ (ant rcason: To keep you from-being a lie· up targer in a black-out. As long as that mechanical switch is on the job, no acci· dental flick of Ibe niain switch is going to leave you sitting lik~ a dllC!\. .. .. . if Thelmechanical switch has be rais(:d .-O(rheld III that r;l.Ised pOSitIOn "htle )OU turn on the main sw.,itch for bright lights -else (he main sv,}itch wont"t turn. That is, it shouldn't turn.

to

Unfortunately, tho ugh, such is not al. ways the case. Somco.nc gets in the cab with more brawn than brain, and can't oc' troubled unlocking the main switch be· fore turning it. Sure it can be forced. It's only a switch, how strong should it be? \X/hat happens then is that the bakelite plate behind the switch face gets crunched like a cracker, leaving you with no switches at all; or, the intcrlocking mechanism between the mechanical and main switches gets destroyed, and your bright lights no longer have a protecting lock. Which leaves you maybe set up for some future trouble. You're smarter if you'll buy the idc:t that thes\"'it,ch is the way it' is for s:tfcty's sake ..• and for your sake.

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MAIN SWITCH When this switch is iI. E)Ff. position, nothing works. You can, without first unlod ing it, tum it to the ~ft and get your black·out marker lights (including. block·cul toil and stop lights) cnd block· out d riving lig hts. But tum if 10 the right only ofter you've raised fm, mechanical switch tc the ~"'odi:ed position. Then you 'll get stop lights for doyljghf dt'wing fdo"', for~t fro lise th.m) Clnd your brights.

Thi$ ~witch will gi"'e you ponel lights w hen the moin switch is m ony ·of -its " e n" positions . But you'll get parking lights from 'his s,wi1ch o nly when.--the moin switch is on Service Drive . When the moin 5~ i tch is OFF . this Qu)(iliof'l , levttr shou ld not be turned--eve-n if you ' forc e it,,..you' ll get nothing becouse, no

circuits ore e ngaged .

138

This is an importont switch , though it hos but o n. job to do , h keeps your se rvice' lights locked; lail lights, stop li g hts , ond he-od lights. If you ' re smo rt, you wo n't itlnore it. You 'll use il to \If\loek those bright lights-ond not try to by-pass it with a browny grip on : the main switch. .

The fuel gage, and the oil and air pres-. sure gages work the same way. They'U stay smack on the r~ading they gave just They may look the same, Qrdit"Jary and ,before the ignition was turned off.

OTHER NEW GADGETS ON THE DASH PANEL

fami~iar-bu( don't be fooled. They are

different. . You've probably already glanced over that chassis with the 24-volt electrical

CHECK BEFORE SCRAPPING

How you ~sk,if all this is the only dif~ system, - climbed into her cab, and felt fereQce, how can you tell a balanced· just like home-coming. Hasn't changed pointer g~.ge from a defective gage? How much here, eh! But it has. And as long can you tell if the gage is supposed to as you',cc already in · the cab, here's a stay put when the ignition's switched ()if, or if ie's staying there because it's g~)flC few tips about the dash panel. Take the gages on the 24-volc systems, haywire? That's a good question. And for example - the (her~lostat, fuel, and here's how they 'can be checked before pressure gages. They look like the same a lot of good gages get yanked out and ' old things. And jf you happen to be sit- tossed away. cing in a WilIys, Studebak.cr, InternaTake the fuc.-l gage:· When you've gOf tional-Harvester; Chrysler, or Reo-they a fulJ tank, does it show a full tank? And could be the same old things. Bpt, they while you're hurning it up, the needle also may not be the kind familiar to you. should sne:lk down accordingly. If your There's a 50-50 chance that you're look· fuel g:lgc shows a half·full tank when ing at gages that operate with a ."bal- you pull up for gas- and it travels to the full. rn :trk and holds steady when you anced pointer". turn on the ignition aftcr ·filling (he tank GAGES DON'T ZERO -you on Ix- sure nothing's wrong. Two types of gages were used in these On ehe ehermo ,!.::3ge: AJlow your hot vehicles~who knows which is in wller n ~w veh id es. On (he Reo it ha ppen s frcGut'm l) (h;l ' rlw iOOl plunger will no longer make u )nract beca m.e o( chI;' (('r min.a ls OI reing It adj u s r.~ (rom I " ro ..j1/2" and