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.

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AAA Ground Recognition Signals

The following comments from the commander of the U.S. 5th Armored Division on the proper use of ground recognition signals were published in “Antiaircraft Artillery Notes,” No. 5, November 22, 1944.

Subject: Use of Ground Recognition Signals
Source: AA Section, Headquarters Twelfth Army Group

The following extract is taken from AAA Situation Report No. 98, First US Army:

*    *    *    *

“a. The following is quoted from a letter received at this headquarters from the Commanding General, 5th Armored Division:

“‘1. At approximately 1630, 2 November 1944, nine to twelve P-38s approached the CP of the 47th Armored Field Artillery Battalion located in a group of buildings about fifty (50) yards south of paved highway one mile southeast of ROETGEN (K-919273). After circling the CP twice, the three lead planes broke out of the circle and flew off in the direction of ROETGEN. The next three planes made a diving attack of the CP, dropping six bombs. ******* The 440th AAA thereupon fired six recognition flares, at which the remaining planes pulled out of dive without dropping bombs and dipped their wings and left the area.*******

“‘3 ******* AA did not fire on planes, other than recognition flares.’

“b. The AAA complied strictly with standing instructions, by firing flares and withholding fire of their weapons. The friendly A/C, recognizing the signal and the lack of fire from the ground, immediately ceased the attack. This exemplifies the manner in which such incidents must be handled.”


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


Airframe Album – Fw 189 Uhu

Valiant Wings Publishing has announced the sixth volume in their Airframe Album series: Airframe Album No. 6: The Focke-Wulf Fw 189 Uhu, A Detailed Guide to the Luftwaffe’s Flying Eye by Richard A. Franks. According to the publisher, the book will include numerous historical photographs; detail pictures; detailed study of the structure, equipment and armament; isometric views by Wojciech Sankowski of prototype and production airframes; color profiles and camouflage details by Richard J. Caruana; and lists of all model kits, accessories and decals in all scales. List price is £16.95.



Valentine Tank Bogie Wheels

Diagram of Valentine tank bogie wheels from the WW2 Russian manual.


M26 Armored Tractor

Diagrams of the M26 armored tractor from TM 9-767: 40-Ton Tank Transporter Truck-Trailer M25, War Department Technical Manual, U.S. War Department, February 1944. The M25 Tank Transporter, nicknamed the “Dragon Wagon,” was a heavy tank transporter and tank recovery vehicle used in World War II. The M25 was composed of the M26 6×6 armored tractor and M15 40-ton trailer.




P-61 Black Widow Cockpit

P-61 Black Widow cockpit instrument diagrams from the Pilot Training Manual for the Black Widow, P-61, Office of Assistant Chief of Air Staff Training, Headquarters AAF, Washington, D.C.

p61-black-wido-cockpit-front-panelControls, Switches, Instruments (Front Panel)

1. Remote compass
2. Airspeed indicator
3. Rate of climb indicator
4. Altimeter
5. Turn and bank indicator
6. Gyro horizon
7. Dials of automatic pilot
8. Pilot’s gunsight
9. Manifold pressure indicator
10. Oil temperature indicator
11. Oil pressure indicator
12. Carburetor air temperature indicator
13. Lower cowl flaps control valves
14. Upper cowl flaps control valve
15. Clock
16. Tachometer
17. Cylinder head temperature indicator
18. Fuel pressure indicator
19. Wheel and flap position indicator
20. Fuel gage
21. Oil cooler flap indicator

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Short-Field Takeoffs in the P-61

Instructions for short-field takeoffs in the P-61 Black Widow reproduced from: Pilot Training Manual for the Black Widow, P-61, Office of Assistant Chief of Air Staff Training, Headquarters AAF, Washington, D.C.



Suppose you are on a field pitted with bomb holes. You must get off the ground as soon as possible. However, we’ll assume there are no obstacles to clear. Therefore, you do not have to pick up altitude quickly.

1. Make the usual pre-takeoff check.

2. Lower your wing flaps 2/3.

3. Line up for takeoff as close to the end of the runway as possible.

4. Run the engines to full takeoff manifold pressure (54″ Hg.) against the brakes.

5. Release the brakes and start your run, but keep the nosewheel on the ground as long as you can while picking up speed.

6. Pull the nosewheel off the ground and take off as soon as you have reached flying speed (75 mph at 29,000 lbs. gross weight). Then, raise the wheels and level off to attain critical single engine speed before climbing.

In short-field takeoffs, you may use your water injection system to increase the engines’ horsepower and help you get off sooner.



Fields bordered by obstacles generally are also short. To take off under these conditions, follow the procedure of a short-field takeoff, with the following exceptions:

1. Take off at the last possible moment.

2. After getting off the ground, raise your wheels and climb steeply until you have cleared the obstacle. Then level off to gain speed.


M46 Twin MG Pedestal Mount

Illustration of the M46 pedestal mount for twin water-cooled .50 caliber machine guns. (Source: TM 9-230: Machine Gun Mounts for Boats, War Department Technical Manual, October 1943.)

Figure 3—Twin Cal. .50, Machine Gun, Pedestal Mount M46, with Water-cooled Guns

Figure 3—Twin Cal. .50, Machine Gun, Pedestal Mount M46, with Water-cooled Guns


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.

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