It's obvious how the 105mm HMC M7 acquired the nickname of "Priest" when one notes the pulpit-like .50cal machine gun mount to the right of the howitzer. This machine has the three-piece final drive and differential cover and the early suspension bogies with smaller springs and return rollers directly on top of the bogie frames. The boxes around the headlight guards are for storing track grousers, and additional stowage boxes are mounted on the hull rear. (Picture from TM 9-2800 Standard Military Motor Vehicles.)
The rear of the vehicle is shown here. Stowage boxes are mounted on the sides of the rear hull deck. A towing pintle is visible under the engine doors, and directly above these doors can be seen the engine's exhaust outlets. The engine air cleaners are behind the rear armor plate outboard of the engine access doors.
Tool stowage on the rear of the vehicle is shown in this technical manual image. Stowage baskets have been added to the stowage boxes on the hull rear. Note the different rear armor plate configuration compared to the vehicle above. (Picture from TM 9-731E Carriage, Motor, 105-mm Howitzer, M7.)
The 105mm howitzer M2A1 is shown here in its mount M4. The weight of the howitzer tube and its breech mechanism was ~1064lb (~482.6kg). (Picture from TM 9-1325 105-mm Howitzers M2 and M2A1; Carriages M2A1 and M2A1; and Combat Vehicle Mounts M3 and M4.)
In this image, the ordnance and mount are installed in the vehicle. (Picture from TM 9-1325 105-mm Howitzers M2 and M2A1; Carriages M2A1 and M2A1; and Combat Vehicle Mounts M3 and M4.)
Some of the instruments labeled above can be seen in this image of a museum vehicle.
The right-hand final reduction assembly has been removed from the vehicle in this picture. (Picture from TM 9-731E Carriage, Motor, 105-mm Howitzer, M7.)
Details of the steering brakes can be seen in this image. Engaging both steering brakes slowed the vehicle, and an individual brake slowed one track to change direction. When the brake on one track is applied, a planetary gear on that side of the differential goes into motion, slowing that track and speeding the opposite one. Vehicles based on the medium tanks M3 and M4 were not able to lock one track; both tracks were always in motion, no matter how much force was applied to the steering brake. (Picture from TM 9-731E Carriage, Motor, 105-mm Howitzer, M7.)
Crew positions are show here mounted (left) and ready for action (right). (Picture from FM 17-63 Service of the Piece, 105-mm Howitzer, Self-Propelled.)
This is an M7B1, sporting the one-piece final drive and differential housing, heavy-duty suspension bogies, and fold-up armor towards the rear of the hull. Stowage baskets are present on top of the rear stowage boxes.
Late-model M7s were quite similar to the M7B1, but this rear view establishes that this vehicle is derived from the M4A3 Sherman, marking it as the latter. The rear plate dips below the sponson line, and the exhaust deflector grid can be seen below the rear plate. The rear stowage boxes and baskets are visible, as are handles on the side of the hull. Attachment points for various tools are welded to the rear plate.
The labeled parts to the howitzer and mount are as follows: A. Sleigh, assembly. B. Telescope mount. C. Breech ring. D. Operating lever handle. E. Range quadrant. F. Firing lock. G. Elevating handwheel. H. Firing mechanism. J. Cradle. K. Lanyard handle. L. Leg. M. Traversing handwheel. N. Hinge pin. P. Nut. (Picture from TM 9-1325 105-mm Howitzers M2 and M2A1; Carriages M2A1 and M2A1; and Combat Vehicle Mounts M3 and M4.)
Compared with the M7B1 above, it is easy to see how this M7B2's howitzer has been raised, resulting in more elevation. The machine gun pulpit has had another section added to ensure a complete field of fire over the howitzer.
This side view provides a better view of the raised MG position. The folding armor flaps can also be seen behind the MG pulpit, above the side hull handles.
Like the medium tank M4A3 from which it was derived, the engine grill doors on this M7B2 run totally across the rear deck. The rear hinged armor plate is folded down, and is visible to the left in the picture.
The driver's door is open on this vehicle, and this is a view through it into the interior. One circular seat for a member of the gun crew remains on the vehicle's left, and the mount for a portable fire extinguisher is visible in the left rear corner of the fighting compartment. One hundred-five millimeter ammunition racks line the hull sides, and the howitzer mount can be seen to the driver's right.
The M7B2 used driving controls common to the M4A3 tank, and they are illustrated here. The steering levers are in front of the driver's seat, and the gearshift lever is to the driver's right. The transmission itself is visible beside the driver's position.
The 105mm howitzer M2A1 was mounted in the M7B2 by sticking the top half of the standard field carriage in the fighting compartment. The breech handle can be seen sticking up above the front of the breech. The handwheel to the front was for azimuth, and the elevation handwheel is to the rear. The howitzer shield can be seen on either side of the ordnance's barrel. The open driver's door is visible to the howitzer's left, and the inside of the machine gun position is visible to the right.
The heavy-duty suspension bogies carried over from the medium tanks M3 and M4 had both track return rollers and track skids. The skid design changed with modifications to the bogie, and this vehicle is equipped with the final design. Since the front of the track skid makes a loop and runs to the rear before it reaches the bogie frame, it indicates that the this bogie has its trunnion centers raised from earlier types, which improved spring stability. The front volute spring can also be seen.
The innards of a vertical volute spring suspension bogie are illustrated here. The support bracket for the track return roller is visible at the top, and one of the volute springs can be seen in the center of the picture. Rubbing plates were positioned between the ends of the top lever and wheel arm, and the rubbing plate retaining screw can be seen at the end of the top lever.
Postwar, another cannoneer was added to the vehicle. He is number 5 in these images. (Picture from FM 6-74 105-mm Howitzer M2A1 on Motor Carriage M7B1 and M7B2.)