This M113 has been modified to armored cavalry assault vehicle (ACAV) standard. Originally conceived by the Army of the Republic of Vietnam, ACAVs had two 7.62mm machine guns on either side of the cargo hatch in addition to the .50cal MG at the commander's station, and these vehicles were used as light tanks instead of armored personnel carriers. Gun shields were provided to protect the gunners from return fire. Four hundred seventy-six standardized armor kits were ordered from FMC Corp., and these were shipped in July 1966 to Vietnam. The machine guns could be replaced by 40mm grenade launchers or recoilless rifles. Note the height of the idler wheel compared to the road wheels on this early machine.
The engine exhaust pipe is seen rising out of the exhaust grille. The air intake grille can be seen inboard of the exhaust grille. A lifting eye is bolted to the front slope. Below the lifting eye is the right headlight cluster; inboard of the lifting eye is the horn and stowage for a shovel.
An entry door was provided in the rear ramp, and it is open on this vehicle. A water can is stowed on the right rear fender, and a tow cable is wound on the rear ramp. The right hand taillight can be seen above the water can, and inboard of this is a telephone connector.
This view is through the open rear door. Troops were provided with a bench on each side of the hull, and a rear-facing jump seat was attached to the post for the commander's seat in the center of the compartment. The large roof hatch is distinct with its darker paint. Radio stowage is visible on the left behind the driver.
The driver was provided with an instrument panel to his left and steering levers and a bank of warning lights to his front. The large perforated pedal on the right is the accelerator, and the round black-knobbed handle on the right is the shift lever. The ramp actuation lever is just below the shift lever with a flat black-tipped handle.
Visually, there was very little external difference between the M113 and M113A1.
External features are labeled in this diagram. (Picture from TM 9-2350-261-10.)
The rear of the vehicle is shown here. (Picture from TM 9-2350-261-10.)
There were five drain plugs and a larger access hatch on the underside of the hull. (Picture from TM 9-2350-261-10.)
A look into the personnel compartment is provided in this sketch. (Picture from TM 9-2350-261-10.)
This ghosted image shows the location of the fuel tank and batteries. (Picture from TM 9-2350-261-10.)
The drivetrain is diagrammed in this picture. (Picture from TM 9-2350-261-10.)
The suspension layout is illustrated here. (Picture from TM 9-2350-261-10.)
The orientation and mounting of a shock absorber and road wheel arm are shown here. (Picture from TM 9-2350-261-10.)
Differences in the drive sprockets for the two different tracks can be gleaned from this drawing. (Picture from TM 9-2350-261-10.)
This M113A2 has been outfitted to look like a Vietnam-era ACAV vehicle, but its raised idler wheel and revised engine exhaust outlet give it away. Smoke grenade launchers are not fitted to this vehicle.
These two pipes are for the personnel heater. The exhaust elbow is in the foreground, and the intake elbow is partially hidden behind it.
At the left rear corner of the hull is the rear bilge pump outlet. A lifting eye is just to the right of the pump outlet, and below these are the right tail light and the telephone connector.
The driver's position can be seen to the right of this image, and the vehicle commander was placed directly ahead of the camera. The mesh grille just to the driver's right is for engine air intake. An exhaust grille was placed to the right of the air intake grille. Tow hooks can be seen stowed above the shovel.
As above, two bench seats for passengers are placed along the hull sides, and a single jump seat is directly behind the vehicle commander's position. The roof hatch is open on this vehicle. The dark green device in the front right corner of the passenger compartment is the personnel heater.
A closer look at the interior is provided here. The radio and intercom installation is on the left side of the vehicle, and just ahead of this is a fire extinguisher bottle. The driver's adjustable seat post is at the front of the vehicle, and the steering levers, instruments, and accelerator pedal are all visible. The black-knobbed lever placed high to the driver's right is the transmission shift lever, and just below this is the ramp actuating lever.
The vehicle commander's seat here is folded up in front of the post in the middle of the fighting compartment. The seat back for the single jump seat is attached to the opposite side of the post. The height adjustment for the commander's seat is obvious.
A closer view of the personnel heater is provided here. The large attachments to the left of the image hold the rear power plant access panels.
The right side of the passenger compartment is shown in this image. The rear ramp is painted darker than the rest of the interior, and the right side bench seat is folded up. The tube climbing the rear wall is the rear bilge pump outlet.
The left side of the driver's position is shown here. The green intercom control box is mounted behind the stowage spot for the driver's infrared periscope M19. The master electrical box is below the driver's instrument panel. The rearmost switch on this box is the master switch, and the larger gray auxiliary power receptacle is just to the front of the master switch. The IR power supply is in front of the electrical box.
From left to right, the warning lights on the driver's warning light panel are for high differential oil temperature, high transmission oil temperature, and high engine oil temperature. To the right on this panel are buttons for the horn and headlights. Three of the four M17 periscopes that ring the driver's hatch can be seen to the top of the image. The transmission control lever is on the right wall, and below this is the ramp actuation lever. From top to bottom, the three handles to the driver's right front are for fuel cutoff, throttle control, and air vent control. The headlight dimmer switch can be seen between the steering levers, and clips for M16 rifle stowage are mounted in the front left corner. The downward-oriented levers in front of the steering levers are the pivot steer levers. Pulling on one of these would apply the disc brake and thereby lock the track on that side, allowing the vehicle to pivot around that track.
The control box for the personnel heater is mounted on the vehicle's left side, behind the driver.
The markings on the transmission shift control lever are for, front to back, reverse, neutral, 2-3 gears, 1-3 gears, 1-2 gears, and first gear. The ramp actuation lever to the bottom would be swung forward to lower the ramp.
The locks for the rear ramp are controlled by a lever over the driver's right shoulder. The right rear of his hatch is visible to the top of the image, and a power plant compartment access door is marked with a yellow warning sticker.
This Mazda RX-8 is seen through the driver's front M17 periscope.
Besides the external fuel tanks and the absence of a trim vane, there's not much externally to visually distinguish an M113A3 from the above M113A2. (Picture from TM 9-2350-277-10.)
The rear of the carrier is shown here. (Picture from TM 9-2350-277-10.)
This view is looking into the open passenger compartment. The spall liners can be contrasted with the above vehicle. (Picture from TM 9-2350-277-10.)
The relocation of the fuel tanks allowed the interior stowage to be slightly reworked. (Picture from TM 9-2350-277-10.)
The positions of the crew and passengers are sketched here. (Picture from TM 9-2350-277-10.)
The original driver's station is drawn here. A steering yoke has replaced the earlier steering levers, and stowage was provided near the driver for an AN/VVS-2 night vision periscope. Since with the new transmission the carrier would pivot regardless of the transmission controller position, the steering wheel needed to be centered and locked whenever the vehicle was started, shut down, or idled. The transmission did have a specific pivot (PV) setting. The upper brake pedal was used when the driver's seat was in the raised position. The parking brake handle simply locked the service brakes into position; pressure was applied to the brake pedal, then the parking brake handle was pulled. (Picture from TM 9-2350-277-10.)
The newer configuration replaced the AN/VVS-2 with the AN/VAS-5 driver's vision enhancer. (Picture from TM 9-2350-277-10.)
The external fuel tanks are mounted on this M113A3. The door in the left side of the rear ramp can also be seen. This vehicle was awaiting deployment at Hunter Army Airfield. (Picture taken 28 Feb 2001 by Donald Teft; available from the Defense Visual Information Center.)