THE 75MM PACK HOWITZER M1A1 - CARRIAGES M1, M8 - STANDARD

 

Special thanks to Mr. Matthew Seelinger,  Chief Historian, and Mr. Seth Paltzer, Assistant Historian,
The Army Historical Foundation, Arlington, VA.

 

Article from The American Arsenal: 
The World War II Official Standard Ordnance Catalog of Small Arms, Tanks, Armored Cars, Artillery, Antiaircraft Guns, Ammunition, Grenades, Mines, Etc. 

 

This book is essentially a 1996 reprint of Catalog of Standard Ordnance Items , produced by Office of the Chief of Ordnance Technical Division in 1944. The reprint was published by Greenhill Books of London, UK.

 

 

75 mm PACK HOWITZER, ON CARRIAGE, M1

 

The 75 mm pack howitzer was originally designed for pack transport, animal draft, and low-speed towing. Animal draft has been discontinued and the special accessories made obsolete. In modified form it has been adopted for many uses.


Development of the weapon, begun in 1920, culminated in standardization of the M1 in 1927. Slight changes in the M1 were made later, and the new model given the designation of M1A1. The primary use of this howitzer was for operation in mountainous terrain. With the round H.E., A.T., M66, the M1A1 howitzer is capable of engaging antitank targets, as the projectile will penetrate 3 inches of armor plate at howitzer range.


HOWITZER, M1

The Howitzer, M1, consists of a tube assembly and a breech mechanism, joined by interrupted threads for rapid assembly and disassembly. The breechblock is of the hand-operated, sliding-wedge type. Firing is accomplished by a continuous-pull mechanism known as Firing Lock, M13. The tube and breech mechanism comprise two loads for transport.


HOWITZER, M1A1

This howitzer differs from the M1 only in slight modifications of the breech ring and the breechblock. These parts are not interchangeable in the two models.


PACK HOWITZER CARRIAGE, M1

This carriage is separated into six loads for pack transport. It has a hydropneumatic recoil system composed of a recoil cylinder and a recuperator cylinder connected with the bottom sleigh which forms a seat for the howitzer and maintains alignment of the tube and breech ring when assembled. A top sleigh covers the howitzer and retains it in the bottom sleigh. Steps on the bottom sleigh are fitted to ways on the cradle, and the recoil-cylinder piston rod is connected to the cradle by means of the piston rod latch. In recoil and counterrecoil, the cylinders and bottom sleigh move with the howitzer, while the cradle remains stationary. Traverse is along the axle, accomplished by a traversing nut operated by a handwheel.


Rockers, which pivot on trunnion pins, are located on either side of the cradle.


The box trail is divided into two groups, the front trail and the rear trail, fastened together by fittings strong enough to withstand firing stress. The elevating mechanism, rockers, and equilibrators are assembled to the front trail and are carried with it in the pack. The wheels are of wood with steel tires.


AMMUNITION

Ammunition for the 75 mm Pack Howitzer, M1A1, is in the form of semi-fixed rounds. It consists of H.E. Shell, M41A1, with P.D. Fuze, M48; H.E. Shell, M48, with P.D. Fuze, M48, and T. & S.Q. Fuze, M54; and H.E., A.T. Shell, M66, with B.D. Fuze, M62.

 

 

PRINCIPAL CHARACTERISTICS OF 75 mm PACK
HOWITZER, M1A1, AND CARRIAGE, M1

HOWITZER

Caliber

75mm

Weight

341 lb.

Overall length

52 ins.

Length of bore

15.93 cals.

Muzzle velocity

700, 800, 950, 1,250 f./s.

Travel of projectile in bore

39.2894 ins.

Maximum powder pressure

26,000 lb./sq.in.

Type of block mechanism

Sliding block

Rate of fire

6 rds./min.

Range, Shell, M41A1

9,760 yds.

RECOIL MECHANISM

Type Hydro-pneumatic
Weight 211 lb.
Normal recoil 32 ins.
Maximum recoil 33.65 ins.
Maximum piston-rod pull 5,188 lb.
CARRIAGE, M1
Total weight without howitzer 927 lb.
Length of carriage (muzzle to spade) 144 ins.
Width over hub caps 47 ins.
Maximum height at 0 35 ins.
Type box trail Axle traverse
Elevation (maximum) 45
Depression (maximum) -5
Traverse (right) 3
Total weight of howitzer, recoil mechanism, and carriage in firing position 1,269 lb.

 

AMMUNITION M41A1 M48 H.E., A.T., M66

Weight of complete rounds

17.32 lb. 18.12 lb. 16.3 lb.

Weight of projectile

13.76 lb. 14.60 lb. 16.3 lb.

Weight of projectile explosive charge

 1.11 lb.  1.47 lb.    1 lb.

Weight of propelling charge

    .92 lb.  .41 lb.

Type of ammunition

    semi fixed


 

Sighting and Fire Control Equipment

 

On Carriage Equipment

Panoramic Telescope, M1

Telescope Mount, M3

 

Off Carriage Equipment

Bore Sight

Gunner's Quadrant, M1

Aiming Circle, M1

Compass, M2

1-Meter-Base Range Finder, M7 or M1916

B.C. Telescope, M65 or M1915A1

 

 

Trainer

 

The 37 mm Subcaliber Gun, M1916, and Subcaliber Mount, M5, are used for practice in laying and firing the 75 mm Pack Howitzers, M1 and M1A1.


REFERENCES: TM 9-2005, v.3; TM 9-320; TM 9-1320.


CARRIAGE (AIRBORNE), M8

The 75 mm Pack Howitzer Carriage, M8, was developed to provide airborne troops with a light, powerful weapon which could be transported as a unit to the combat area by glider or airplane. When the airplane lands at its destination the howitzer and carriage can be unloaded and maneuvered into position by hand or be towed by a prime mover. The howitzer and carriage can also be disassembled, packed in paracrate loads, and dropped by parachutes from an airplane in flight. When the paracrates reach the ground the individual loads are unpacked and the howitzer and carriage are assembled for action.


The standard 75 mm Pack Howitzer, M1A1, is mounted on the Carriage, M8. This carriage is identical to the 75 mm Pack Howitzer Carriage, M1, except for the substitution of steel disk and rim type wheels equipped with 6.00 x 16 pneumatic tires in place of the 29 inch wooden wheels used on the M1 carriage.
 

REFERENCES: OCM 20196; TM 9-319.

 

 

Sighting and Fire Control Equipment

 

On Carriage Equipment

Telescope Mount, M3

Telescope Adapter, M9

Elbow Telescope, M62

 

Off Carriage Equipment

Gunner's Quadrant, M1

Aiming Circle, M1

Hand Fuze Setter, M1912A4, M15, or M16

 

 

 

75 mm PACK HOWITZER, M8, FOR AIRBORNE USE

 

From the Technical Manual TM 9-319:

 

 

75-mm Pack Howitzer M1A1 and carriage M8 - left rear view

 

 

 

75-mm Pack Howitzer M1A1 and carriage M8 - right front view

 

 

 

75-mm Pack Howitzer M1A1 and carriage M8 - in towing position

 

 

 

PARACRATES M1, M2, M3, M4, M5, M6, M7, Parachest M8, Paracaisson M9

 

In order that the disassembled 75 mm Pack Howitzer, M1A1, and Carriage, M8, together with fire control instruments, and accessories, could be safely delivered by parachute from an airplane in flight, a series of containers known as paracrates, parachest, and paracaisson, were evolved to hold the nine loads to be dropped. Fabrication of these containers was begun in September, 1942, and they were standardized in May, 1943, as Paracrates, M1 to M7, Parachest, M8, and Paracaisson, M9.


Paracrates, M1 to M7, are constructed of plywood, each paracrate being designed to accommodate a specific load. When the load is packed it is secured to bomb shackle and parachute harnesses by means of a quick-release fastening. A standard 24-foot cargo parachute is attached to each load, the parachutes being colored to differentiate between the loads and hasten identification.


Paracrate Loads, M1 to M5, together with Paracrate Load, M9, are fastened to and dropped from parachute pack racks beneath the airplane. Paracrate Loads, M6 and M8, are carried as a daisy-chain load inside the fuselage, from which they are pushed out through the doorway of the airplane.

 

 

 

PARACRATE, M1 (FRONT TRAIL), CRATE SUSPENDED (Left)
AND PARACRATE, M2 (REAR TRAIL AND AXLE), CRATE LOADED (Right)

 

PARACRATE, M1

This paracrate consists of front and rear reinforces and a wooden brace for the howitzer front trail assembly, together with a canvas paracrate cover with parachute harness attached. When packed it holds the front trail and a lifting bar.

 

PARACRATE, M2

Paracrate, M2, includes a canvas cover with parachute harness attached, wooden supports, and a wooden hexagonal reinforcing housing. The load comprises the howitzer rear trail, axle and traversing mechanism assembly, trail handspike, sponge staff, aiming post sleeves, and a box containing spare parts and tools.

 

PARACRATE, M3

This paracrate is in the form of a plywood box with pentagonal ends and a hinged cover. The load consists of the howitzer bottom sleigh and recoil mechanism, a lifting bar, an aiming circle with case, circular  wooden supports, a shock block, and a shock pad.

 

 

PARACRATE, M4 (CRADLE AND TOP SLEIGH), CRATE LOADED (left) AND
PARACRATE, M5 (TUBE), CRATE SUSPENDED (right)

 

PARACRATE, M4

Paracrate, M4, is similar in shape to Paracrate, M3. The load is made up of the top cradle and sleigh of the howitzer, a shock block, and a shock pad. Paracrates, M3 through M6, have the bomb shackle and parachute harnesses separated from the paracrates.

 

PARACRATE, M5

This paracrate is a rectangular plywood box with a hinged lid. Its load is composed of the howitzer tube, a muzzle cover, a tube thread cover, a lifting bar, lifting straps, a shock block, and a shock pad.

 

 

 

PARACRATE, M6 (BREECHBLOCK AND SIGHT), CRATE LOADED (left) AND
PARACRATE, M7 (WHEELS), CRATE SUSPENDED (right)

 

PARACRATE, M6

Paracrate, M6, is a rectangular plywood box with a detachable padded lid. The load consists of the howitzer breech mechanism, the hub caps, the panoramic telescope and telescope mount in a special container, the telescope mount support, and a lifting strap.

 

PARACRATE, M7

Paracrate, M7, consists of a square wooden frame, the inner sides of which are beveled. The parachute harness is attached to the frame. The load is composed of the howitzer wheels and hub plugs.

 

 

 

PARACHEST, M8, (AMMUNITION), CRATE COMPONENTS
 

PARACHEST, M8

This parachest is made of plywood, and consists of a large section to which a slightly smaller section is added as a continuation. The cross section of each portion is six-sided, in the form of a square on which is imposed a truncated triangle. The front end of the large section is hinged, so that it can be opened for loading. The parachute harness is separate and when assembled on the parachest has skids lashed to it to facilitate landing. The load is composed of ten complete rounds of 75 mm howitzer ammunition, each of which is packed in a fiber container.

 

 

 

PARACAISSON, M9, (AMMUNITION CART), CART ASSEMBLED
 

PARACAISSON, M9

Paracaisson, M9, is a manually drawn, knockdown cart with a plywood body of hexagonal cross section, demountable steel wheels, and an axle assembly, drawbar, tongue,

and drawlines, all of which can be packed in the body when the paracaisson is disassembled for transport. A wheel spacer, a brace support, a drawbar tray, an axle tray, tray side braces, and tray top braces are utilized in packing the components of the paracaisson. The bomb shackle and parachute harness are separate.

 

The paracaisson is used to transport ammunition, eight complete rounds in individual fiber containers constituting a full load. When assembled, the paracaisson is normally pulled by two men who grasp the drawbar at the free end of the tongue. When it is necessary for four men to tow the cart two drawlines are attached to the axle by means of drawline hooks which hook through holes in the axle.

 

The howitzer, caisson and cart, with ammunition, are packed in nine paracrate loads having a total weight of 2,571 pounds. The component parts of these loads and the equipment required for assembling them are as follows:

 

 

Paracrate Load, M1

Front Trail

263 lb.

Paracrate, M1, including cover, front reinforce, rear reinforce and wooden brace

58 lb.

Lifting bar

9 lb.

Parachute

23 lb.

Total weight

326 lb.

Paracrate Load, M2

Rear Trail

95 lb.

Axle

65 lb.

Trail handspike

7 lb.

Sponge staff

6 lb.

Spare parts and tool box

40 lb.

Paracrate, M2, including cover, wooden supports, and wooden hexagonal housing

38 lb.

Parachute

23 lb.

Total weight

274 lb.
Paracrate Load, M3

Bottom Sleigh and recoil mechanism

203 lb.

Aiming circle with case

18 lb.

Paracrate, T3

73 lb.

Lifting bar

9 lb.

Parachute

23 lb.

Total weight

326 lb.
Paracrate Load, M4

Cradle

100 lb.

Top sleigh

121 lb.

Paracrate, M4

87 lb.

Parachute

23 lb.

Total weight

331 lb.
Paracrate Load, M5

Tube

221 lb.

Paracrate, M5

49 lb.

Lifting bar

9 lb.

Parachute

23 lb.

Total weight

302 lb.
Paracrate Load, M6

Breech assembly

121 lb.

Paracrate, M6

13 lb.

Telescope panoramic w/mount

45 lb.

Parachute

23 lb.

Total weight

202 lb.
Paracrate Load, M7

Wheels (two)

180 lb.

Paracrate, M7

14 lb.

Parachute

23 lb.

Total weight

217 lb.
Paracrate Load, M8

Ammunition, 10 rounds in indiv. fiber cont.

220 lb.

Parachest, M8

47 lb.

Parachute

23 lb.

Total weight

290 lb.
Paracrate Load, M9

Paracrate cart

105 lb.

Ammunition, 8 rounds in indiv. fiber cont.

176 lb.

Parachute

45 lb.

Total weight

304 lb.