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Replacing M4 Tank Final-Drive Assemblies

Instructions for replacing the final-drive assembly on the M4 Sherman tank, from Army Motors, Vol. 6, No. 2, Maintenance Division, Office, Chief of Ordnance, May 1945.

Replacing M4 Tank Final-Drive Assemblies

Time was when M4 medium tanks with damaged power trains had to run home to mother for mending–like little apple-filchers with buckshot in their final drive assemblies. Now, when your M4-series job (or related gun or howitzer motor carriage) has something more like dribble where the drive should be, you don’t have to pack it off to some 4th-echelon tank hospital for a slow cure. Instead, you can put in a whole new controlled differential and transmission final-drive assembly right there in the field, according to TB ORD 275.

Four of these assemblies, complete with everything but whistles, have at last been made authorized items of issue for lower echelon installation. They are:

—  1-piece differential housing, single-anchor-brake type, Ord. Part No. A5700061, Official Stock No. G104-5700061.

—  1-piece differential housing, double-anchor-brake type, Ord. Part No. A5700062, Official Stock No. G104-5700062 (Fig. 1).

—  3-piece differential housing, single-anchor-brake type, Ord. Part A5700060, Official Stock No. G104-5700060 (Fig. 2).

—  3-piece differential housing, double-anchor-brake type, Ord. Part No. A57000196, Official Stock No. G104-57000196.

They’ll be assembled at your favorite base shop or Ordnance supply depot from parts and housings already in stock or made available through cannibalization. No important difference between any of them, and they’re all yours for the asking.

Final Drive Assembly

All you have to do is install ‘em and send back the has-beens. But remember that the whole system will break down if you don’t send back complete assemblies. Only the final-reduction sub-assemblies (A294625) should be removed from a damaged unit before its sent to the rear for reconditioning.

Continue reading Replacing M4 Tank Final-Drive Assemblies

Don’t Be A Dope VI

An illustration from the “Don’t be a Dope!” series was included in the M36 tank destroyer technical manual.



M3 Medium Tank Armament

Diagram of the armament and ammunition storage of the M3 Medium Tank. (Source: TM 9-750: Ordnance Maintenance, Medium Tanks M3, M3A1, and M3A2, Technical Manual, U.S. War Department, May 1942.)

M3 Medium Tank Armament


P-47 Pilot Preflight Check

P-47N pilot’s preflight check, from: Pilot Training Manual for the Thunderbolt P-47N, Headquarters, AAF Manual 51-127-4, Army Air Forces, Washington, D.C., September 1945.


Pilot’s Preflight Check

The preflight check starts before you reach your airplane. Survey the proposed taxiing route for any possible future obstruction, such as a fuel truck about to move. Study the ramp area for stray equipment or rubbish and rags that might be blown into the airscoop or tail assembly by prop blast.

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B-32 Dominator

Introduction to the Consolidated B-32 Dominator heavy bomber from the training manual: Airplane Commander Training Manual for the B-32 Dominator, AAF Manual 51-126-7, Headquarters Army Air Forces, 1945.


The B-32’s Past

The history of your B-32 Dominator starts in 1940, when the Army accepted Boeing, Martin and Consolidated Vultee designs for VHB aircraft. Martin designs were not completed, but the end results of those Boeing and Convair plans are the present B-29 and B-32 airplanes. Between the first 32 design and the airplane you’re flying today, however, is a long succession of changes.

The originally planned XB-32 was an airplane with several similarities to the present Superfortress. It had pressurization and remotely controlled turrets. It also had a double tail, wing guns and cannon, and other features which it doesn’t have today. The Army decided not to put all its eggs in one basket, but to have at first only one airplane with the new features of the 29, and to duplicate its purpose in another model of more conventional design.

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A-26 Upper Turret Angles

Diagram of the upper turret fire interruption angles for the A-26, from: Pilot’s Handbook for Army Models A-26B and A-26C Airplanes, AN 01-40AJ-1, August 1945, revised January 1946.


This illustration shows the gunfire intercepting areas and the margins of interruption (approximately) and indicates the limits of gunfire from the upper turret for efficient use of the guns by flight personnel.


M4 Medium Tank Characteristics

Summary of M4 SHerman tank characteristics from the training booklet Tracked Vehicle Chassis Units, The Armored School, Fort Knox.




2. DESCRIPTION. a. Characteristics

    76-mm Gun, M1A1
    2 cal .30 machine guns
    1 cal .50 machine guns

    71 rds 76-mm
    6250 rds cal .30
    660 rds cal .50

Fire Control Equipment:
    Telescope, M71D
    Periscope, M10 or M4A1
    Elevation Quadrant, M9
    Gunner’s Quadrant, M1

Vision Devices:
    Vision cupola
    Periscopes, M6 (4 each)

    5 men

    Ford, 500 HP @ 2800 rpms
    Model GAN, V-8

    Double plate

    Synchromesh, 5 speeds forward and 1 reverse

    Controlled differential

    23″ steel chevron, rubber backed, double pin, T80
    23″ rubber chevron, double pin, T84

    Length, 247″
    Height, 124 7/8″
    Width, 118″

    Combat loaded, 71,175 lbs

Fuel Capacity:
    168 gallons

Cruising Range:
    100 miles

Maximum Speed:
    25 mph

Ground Clearance:

Fording Depth:


12-Inch Mortar M1912

Description and characteristics of the 12-inch Mortar M1912 from TM 9-458: 12-inch Mortar M1912 Mounted on 12-inch Mortar Carriage M1896MIII, U.S. War Department Technical Manual, Washington, D.C., August 1942.

12-inch Mortar M1912 Mounted on 12-inch Mortar Carriage M1896MIII


These 12-inch mortars are comparatively short-barreled weapons able to fire in all directions (360° traverse) but only at high angles of elevation. The maximum elevation attainable is approximately 65°. The minimum elevation (just clearing the emplacement walls) is 45°. The weapon must be depressed to 0° between rounds for loading. These mortars are no longer manufactured.

FIGURE 1.--12-inch mortar M1912 on mortar carriage M1896MIII.

FIGURE 1.–12-inch mortar M1912 on mortar carriage M1896MIII.

Continue reading 12-Inch Mortar M1912

Buckingham I Aircraft Recognition

Buckingham I aircraft recognition from “Antiaircraft Artillery Notes,” No. 6, November 28, 1944.

Subject: Aircraft Recognition
Source: AA Section, Headquarters, Twelfth Army Group.

a. A new type medium bomber, the BUCKINGHAM I, is just becoming operational with the RAF. All AAA gunners in the Theater should be on the lookout for this aircraft.

b. The following information is available on the BUCKINGHAM I:

(1) Type: Twin-engine medium bomber (British).
(2) Manufacturer: Bristol.
(3) Engines: Two Bristol Centaurus.
(4) Wing span: 71′ 0″.
(5) Length: 46′ 6″.
(6) Armament: Forward – 4 x .303
                    Top – 4 x .303
                    Bottom – 2 x .303
(7) Description:

(a) Head on view – A flat mid-wing monoplane, with rectangular shaped fuselage. Two engines, underslung. Dual fin and rudder, outboard of engine nacelles.

(b) Plan view – Two engine nacelles extending almost as far forward as nose of aircraft. Nacelles protrude beyond trailing-edge of wing slightly. Wing is swept back and slightly tapered with rounded tips. Tailplane is long, straight, with square tips.

(c) Side view – Top and underside line of fuselage broken with gun blisters. Oval-shaped fin and rudder.

c. Silhouette views of BUCKINGHAM I are shown in Incl. 1.

Bristol Buckingham Aircraft


Cause and Effect

A cartoon shows the results of trying to circumvent the censor: from “Don’t Shoot the Censor,” Bureau of Naval Personnel Information Bulletin, February 1944.

Cause and Effect

CAUSE AND EFFECT: Sailor drops letter into local mail-box (A) in foreign port. Letter slides down tube into room (B) and is thoroughly read by Nazi agent, who then slips it through slot into trouble-distilling apparatus (C). Burning letter boils witch’s brew (D), causing thermometer (E) to rise rapidly. Janitor (F) starts down basement stairs to fix furmace, stepping on teeter-totter (G) and catapulting projectile into loading chute (H) of gun (I), which is swung into position by secret range finder (J). Gun is fired and eliminates letter writer (K). Next of kin will now hear about him after all.