Like all M1917s, this little vehicle is crowned by a flat-plated octagonal turret. The commander was provided with a cupola, or tower as it was called at the time, with three vision slits for rudimentary visibility. The cupola cover could not be opened all the way due to a stop on the rear of the cover. Entry for the commander was through two hatches in the rear of the turret. The large weapon is a replica, apparently of the 8mm Hotchkiss machine gun fitted to French FTs, but the gun mount appears to be a late-production one for the 37mm gun. The US machine gun mounts provided barrel shrouds, and consequently the barrels could not be seen. The anti-ditching tailpiece is visible, and an engine muffler would normally be installed between the two vertical mounts on the hull side. On French FTs, the engine muffler was on the opposite side of the hull.
This view illustrates one of the extra driver's vision slots placed in the triangular armor plates in the American version of the FT. The circular hole in the turret is a pistol port, or loophole as they were known.
This tank, tied down on a transporter, is armed with the 37mm gun in an early-production mount. (Picture available from the National Archives.)
These tanks are armed with the Marlin machine gun. The near machine has a mud-covered 10-ton (9,100kg) jack stowed on the suspension girder. (Picture taken 24 May 1919; available from the National Archives.)
The gun shield and mount on this tank are representative of the ball mount fitted for the Browning tank machine gun, which can be contrasted with the Marlin-armed vehicles above.
The gun mount appears to be for the Browning M1919 machine gun. Tool stowage loops are present along the vehicle's side, a long shovel on top and a mattock below.
The doors in the turret rear can be seen, as well as the engine compartment air intake and details of the attachment of the tailpiece. The tailpiece was originally rectangular in shape, but the corners were rounded off once service use showed that the 90° corners were a danger with the tank in motion.
The tailpiece has not been fitted to this machine, but the engine muffler is mounted. Stowage for a shorter shovel can be seen forward of the muffler. With the tailpiece removed, it is easier to see the attachment shaft for the hand crank to start the engine.
The engine hand crank is attached here.
The engine compartment was fed air through this raised louvre arrangement. Hinges that allowed access to the engine compartment can also be seen.
Details of the attachment of the tailpiece are shown in this image, including the handle that screws onto the top threaded rod.
The vehicle's suspension is highlighted here. The front bogie had 3 rollers in front and two in the rear, while the rear bogie had two bogies in each position. The springing of the return roller bracket and the return rollers themselves can be seen.
Details of the sprocket wheel and tracks are shown here.
This picture is taken from above and behind the drive sprocket, facing forward. The transmission is in front of the engine, and the reduction gearing from the transmission to the drive sprocket consequently works its way backwards.
The wheels on the tank have a center flange that rides in the channel created by the track link rails.
The mechanism for moving the large idler wheel forwards or backwards to adjust the track tension is shown here. Unlike the French FT on which the design was based, the US tank used an all-steel idler wheel and an adjustment screw for each side of the wheel.
The return rollers were mounted on a frame that was pivoted at the rear and sprung on the front, allowing the long-pitch tracks to compress the springs as they moved over the front roller.
The driver was provided with steps on each side of the tank's nose. The suspension frame pivoted around the rear axle and was sprung at the front by a large coil spring.
Two of the driver's doors are open on this model; the front plate with the forward vision slit could also be swung up to gain access to the tank. The driver's seat was elevated about 6" (15cm) above the tank's floor, and the black webbing slung across the hull served as a backrest for the driver. The steering levers, topped by round black knobs, are visible. When parked, the steering levers were secured by chains hung on the sides of the driver's compartment. The gearshift lever is visible just outboard of the right-hand steering lever. Visible on the rear bulkhead is the interior starting crank for the engine.
The front flap is raised on this machine. The gearshift lever can be seen to the driver's right. On the engine compartment bulkhead, the larger upper hole for the interior engine crank was for the handle attachment, and the lower smaller hole was for the engaging plunger.
This view illustrates more of the driver's controls. The pedal on the driver's left is the clutch, while the brake pedal is on his right. The accelerator pedal is on the linkage forward of the brake and clutch pedals, and appears to be rotated 180° toward the front of the vehicle.
The commander's cupola did not open all the way, and the stop attached to the rear of the cupola is seen here.
The turret interior of the M1917 is visible here. The open rear door is to the left in this view, with the gun mount to the right. The commander's tower is painted green, and a loophole is visible towards the right of the picture. A canteen holder is mounted by the gun mount, and a sling seat for the commander is hooked on the mounts on either side of the turret.
This is a closer view of the commander's tower. The observation slots are overpainted with white on this vehicle, and the leather padding for the commander's head is obvious. The turret rear was composed of two doors, and the left door is just visible here.
The diminutive size of the tank is well illustrated by the mannequin standing in the turret of this 37mm-armed M1917.
This tank is having its transmission removed. The large brake drum assemblies are the transmission's most prominent feature in this image. The engine in the M1917 was to the rear of the transmission. (Picture taken in 1925 by Harris & Ewing, Inc.; available from the Library of Congress.)
The engine compartment doors are open on this machine, allowing a view of the Buda HU engine. The radiator is visible to the front, and the engine's flywheel would be facing forward to the transmission. The transmission was ahead of the engine, and a gear train worked its way back to the drive sprockets, part of which can be seen in the bolted enclosure to the lower right.
This more vertical view shows the exhaust manifold and outlet to the muffler through the left-hand armor plate.
This partially-disassembled tank provides more detail of its engine. (Picture taken 22 Dec 1919 by J.H. Saum; available from the National Archives.)
This Marine tank is one of the signals vehicles that came equipped with a fixed superstructure mounting a radio instead of a gun turret. The radio set used was originally the tank radiotelegraph SCR-78A, which could both send and receive signals out to 6 miles (10km) to headquarters or 3 miles (5km) to another tank. By 1934, this was widely being replaced by the lighter SCR-189, which could send radiotelegraph signals to 8 miles (13km) while in motion and voice signals to 3 miles (5km). This version of the tank weighed 15,400lbs (6,990kg) and was 70.5" (179cm) tall. The crew remained 2 men. (Picture from Tank Data, vol. 2.)
The obvious visual difference between the M1917 and M1917A1 is the latter's longer and taller engine compartment. This was necessary to accommodate the bigger Franklin engine. The position of the muffler on the left side of the tank can also be seen in this view. The air intake and exhaust arrangement was changed from the earlier armored cover to three separate grilles on each side of the rear deck. The new side hull plates were single pieces, and not top and bottom halves as found on the base vehicles. The armament in this tank appears to be the Browning machine gun. (Picture from Development of Armored Vehicles, volume 1: Tanks.)