PS Magazine Issue 053 1957 Series [53 ed.]

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Issue No. 53

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1957 Series

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

IN THIS ISSUE nATURE ARTICLES Connie saw two tanks the other day. They must'vc been about the same ageserial numocrs almost identicaL But were they different! I'll tell you, Man. One looked like it had been through the wars. It'd seen its beSt days. But the ocher ... now there was a tank that was the most. It was spic 'n span and purred like a kinen. She was adjusted and tuned and pampered and cared for like nobody's business. Didn't look like the ocher one at all. The not-so-funny thing about it was that these two tanks had been through the same service. The only difference was they had belonged to different next-door outfits. One outfit had been careless of its preventive maintenance. Result: One tank ready to be scratched. The other outfit knew that preventive maintenance was the most. So, their tank (and all their tanks) was real on-the-ball and ready ro fight when needed. Just like your tank (or gun or truck or whatever you've got). If you keep up your everyday preventive maintenance, that is.

Blank Firing Attachnuant VS. Short-Round Stop Skysweeper Maintenance Tank Talk Battery Stond-In 5-10n Dipsticks Stgnols for Scraper Operators DO Form 110 for Stationary Equipment Cummins Generators

2

6 16 23 25

50 54 58

DEPARTMENTS Connie Rodd

26 38

Half-Mast

42

Chemical Ovortermoster En9i~r

46 50

Contributions Connie Rodd's Briefs

62 65

PSwants your i~as 3rnJ contributions. amt"ts glad to answer your qUf.!stions. Just write to: Sgt HaH· I Mas~ PS. ArsenaL Metw:hen. New lersey. Names- and addresses are kept,'in confideoc.e.

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When disconnecting batteries, 01· ways take the ground strap loose first. It'll help prevent those sparks which can set off any

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YOUR 90·MM TANK GUN-

There's Nothing Wrong With MU$clemen Firing It, But ... Take a long, co ld look at the equipment be low. Know what it is? It's a busted hand firing mechan ism bracket for the 90-mm gun. Some of you guys probably have seen tbe real McCoy and know what caused the break.

That's r ight ... some Joe played grabs with the hand firing lever whi le man· ually letting go with a round. He held on "to the handle and kept pulling after the gun fired. That kept the firing plunger to the rear. The gun went through its counter-recoil cycle. Something had (0 give. Bam-it did. And one busted firing mechanism bracket was chalked up. The break also threw the hand firing lever shah and the firing lever plunger actuating shaft out of alignment. The fir ing mechanism on the 76-mm gun isn't the same as the 90-mm, but the same thing has been happening. A gunner pushes on the firing handle and holds it in. \\lhammo . .. and a requisition is put in for new firing mechanism parts. There's al~o been some talk about breaking the firing mechanism brackets when trying to hand fire the 90-mm gun with safety ON (up). The thing breaks in the same spot as when the hand firing handle is pulled too far back with the safety OFF. \\lhat happens is that the detem on the lever shaft runs smack into the plunger, wh ich has nowhere to go without breaking something because the safety is ON. 'Course ... it takes a man with a mighty powerful pull to wreck the works. But, it's happening. What are the answers?

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TURN T HE PAGE • 19

NUMBER ONE-treat the hand flfing lever Irke 0 hot potato. Give it a sharp rap with the inside of your fingers, like you do when 1you're roking in your first pot ofter three "hours of ploy. And he sure never to put! on fir· ing lever while the gun's being reJooded.

AND LET GO

NUMBER TWO-olwoys make sure the solety i. OFF when you're hand firing, H there's no "give" to the handle when you.rop ~ slIarply, you'll probably find you lorgot obout the .olety.

NUMBER THRH-make sure there's a 1/32·in deoronce between the firing plunger cop and the trigger plunger. You con get the proper deoronce by puning the sofety ON . then loosening the jam-nut ... and finally adfusti~ the firing plunger cap.

You A Circuit Breaker? Something else to think about ...

You can crawl over many sections of an M48A 1 tank without doing any damage, but you've gona be especially careful with one piece of equipment that goes with it-the solenoid on the .sO-cal machine gun mount. Unless you watch what you're doing when you enter or leave the tank, you can rip the wire from the top of the solenoid. Same thing'll happen if you remove the gun from the mount when you've got your thinker turned off.

You can help matters by not connecting the caps over the coupling when you hook up the lead wires. This way it'll become a break-away connector. 20

Now'd also be a good time to talk about the solenoid trigger bar actuator. When installing the backplate, make sure the actuator (also known as the "flipper") is to the right or down over the energizer shaft so's it touches the trigger bar of the gun. Many a firing failure has been traced to a misplaced flipper.

INSTALL BACKPLATE SO "FLIPPER ' IS IN RIGHT PLACE

M13 Elevation Quadrant-

Pull A Switch- With The M36 It's easy to solve the problem of not along with the level vial bubble. ·Course. that M36 instrument light is seeing the M13 elevation quadrant level vial bubble in the M48 tank. Get a little normally used with the T156El tele· scope. That means you can pull her off light on the subject, that's all. Fellows complain they can't see the the telescope and put her on the M13 level vial bubble using the M30 instru- elevation quadrant only when using ment light. All th ey need is this indirect fire. To light things up like a Christmas switch fix: Substitute the M36 instrument light tree in a lighthouse. pull the lamp for the M30. You can guide the light bracket off that. M36 light. Everything beam anywhere you want, because the gets all lit up. But first, find out if lamp's on a flexible cord. Adjust her to you're gonna violate blackout restricshine on the scales and minometer tions before pulling off that bracket.

assembly-wherever it reach for instruments. 21

Even the "Shad ow" d oesn', know about those ..

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Any guy nOt off his cocker wou ldn ' t kick his T31 ballisriccompuccr or throw it o ut of his M48 tank and bet on the bounce. But there're some screwy operating methods that'll d o just about as much harm. F'cinstance, w hen selecting an ammunition cam, before doing it, turn the am mo selector h and le to STO P ... which is abou t 30 degrees clockwise (straight up and down). 'T hen the handle can be moved in or om for selection.

prob'ly not. Pushing the crank puts you on manual, and pressing the button putS you on power opera tion. A push-press on both at th e same time strips gears.

Another goof is forgetting to throw the circuit brea ker to OFF before removing and rep lacing the ballistic cams. Forget and the gears strip jf the reset button is pressed with the cams removed.

Forget to do it that way, and it's a goof. A detent gets damaged first, then the roller gets sheared by the cam fol· lower. Crazy as it sounds, some guys h ave pushed the reset button a nd elevation hand crank at the same time. Why? Maybe " th e Sh adow" knows, but

Narch, you wouldn 't do any of those things. But keep on the looko ut for eight-balls who might. 22

8A.,..,.ERY S.,.AND-.N Here's a resistor made by the Illinois National Guard. It's used in place of batteries when running up their stored vehicles. • A truck can be started with a slave cable and run without a battery, but this has a tendency to cause g lazing of the generator commutator . But, the use of ~either batteries or a proper resistor will let the generator produce a 5-: to 8ampere output without doing any harm. These resistors arc made from a standard heater element, cone type, screw-in, U5-v, lOaO-watt.

Use ohmmeter FSN 17-V-80S with selector switch set on Rxl. (ontact the [enter post with one-lead and fry along the outside with the other lead until· you find Q spot thot gives you about 3 ohms. (ut the resistor wire at this point and discord the wire between your wI and the bottonr terminal. Carefully stretch the fop portion ond rewind this shortened coil on the whole COfe, then fosten end under the bottom termino!.

CAREFUL: NEVER USE THIS WITH A IIO-VOLT CURRENT. ~ . .~

To mount this shortened resistor, use 0 standard porcelain socket. ~ The bose ... use a 9 x lO-in piece of It..-in bo)(wood. For 0 (over use on~old con With, lot. • 01 .entilotion holes ton enough to cleM the , element. Allow a (ouple of inmes above the , _ ~ .element fOf (ooling. " t j ~, - ~ 9ftf the open end of the tin con with onother ~ ,. ~ .-= piece of wood and (enter it on your base. -_ Get so... osbestos poper, Eng Stodt No. 33~I-------- 107624.005.150, ond lode 'em to the