HISTORY OF TANK COMBAT M48 SERIES

PREPARED BY MOBILE MAINTENANCE TECHNICIAN BRANCH U.S. ARMY TANK-AUTOMOTIVE COMMAND WARREN, MICHIGAN 48090

M48 History

The first recollection of the M48 is when it was originally called the T48. This engineering development was started in Highland Park in late 1950. The M48 tanks were built by Chrysler, Ford and Fisher. The Delaware Tank Plant, Newark, Delaware, produced the M48 tanks for Chrysler Corporation. There was a series of M48C tanks for training purposes which had non-ballistic hulls. The M48 tank had a bracket mounted .50 caliber machine gun on a Chrysler M4 cupola and had a small driver’s hatch.

The entire series of M48 tanks had an elliptical cast hull and welded armor floor plates. All M48 series tanks had a four man crew consisting of a commander, driver, gunner and loader. The M48 tanks mounted a .50 caliber cupola machine gun, a .30 and .50 caliber coaxial machine gun and a 90mm main gun. The main gun has a hydraulic recoil mechanism and a bore evacuator to remove ammunition gases from the turret. The gun design incorporated a quick change tube. The M48 had a stereoscopic rangefinder which coupled to a ballistic computer permitted the commander and gunner to select range data, type of ammunition and when cranked into the computer provided the proper elevation for firing on target.

The commander can override the gunner’s controls and fire the main gun from the commander’s position. The driver and commander had IR visibility during night operations from the sealed beam TR headlamps. Early in the program, 2,000 watt incandescent searchlight kits were added to the tank's night fighting capability. These were later replaced with 2.2 KW Xenon lights. The Xenon lights were equipped with filters so that they provided infrared as well as white light. All M48 tanks are capable of 48 inch shallow water fording and by means of a deep water fording kit could ford to 8 foot depths. An M8 bulldozer kit was also provided for adaption to the M48 tank. The Corps of Engineers also used the basic M48A2 chassis to mount a 60 foot launched bridge. Chrysler corporation also built the M20 turret gunnery trainer's. Several land mine clearing kits were developed for use with the M48 tank.

Reports indicate that M48 tanks of various configurations have been delivered to Pakistan, India, Israel, Egypt, Norway, Italy, Greece, Jordan and Spain. The .448 tanks were developed primarily for the U.S. Army during the Korean conflict, however, it is reported they did not see action in Korea. The M48s have combat records in the Pakistan-India war, the Israeli-Arab war and the M48A3s in Vietnam.

 

M48A1 Tank

The M48A1 tank incorporated many general product improvements and incorporated the Ml cupola and large driver’s hatch, several automotive improvements along with replacing the .50 caliber coaxial machine gun with an articulate telescope and changing the M13 series stereoscopic range finder with the M17 series coincidence range finder. The M48A1 changes were put into producting and a modification program was also introduced.

An experimental M48A1 tank was equipped with five SS10 missiles mounted on the front of the turret around the 90 mm gun.

Picture Doug Kibbey

 

M48A2 Tank

The M48A2 tank built by Chrysler Corporation and the ALCO Company incorporated the new IR top deck grille, and removed the number 2 and 4 track support roller and tension idler arm assembly. This tank also incorporated the Cadillac Gage (constant pressure) turret control system.

 

M48A2C Tank

The M48A2C tank was built at the Delaware Tank Plant and provided a metric unit fire control system which was the major difference with the M48A2 tank. The turret was considered a forerunner to the M60 tank turret. This was the last M48 series tank built in production and was the predecessor to the M60 tank.

The following information pertains to Modification Kit Programs:

 M48A1 90mm to M48A3 90mm

This program is for the U.S. Army and updated the M48A1 vehicle by incorporating improvements in the automotive, turret and fire control areas. It upgraded the driver’s controls (accelerator, throttle, drain valves, steering, shifting and brake linkage). It included the diesel engine with its associated engine transmission mounts, fuel tanks, fuel lines, fender mounted air cleaners, new fender arrangement, shroud and exhaust, and top deck grille. The suspension system was upgraded to include new compensating idler assembly, track adjusting link, the double bump spring and heavy front roadwheel arm. The rear track tension idler was removed from the suspension.

The AVDS-1790-5B gasoline engine was replaced with an AVDA-1790-2A diesel engine and the transmission changed from the CD850-4B to CD850-6A. The auxiliary engine and generator were removed during this program. The air cleaners were changed from the inside oil bath to fender mounted dry type. These changes resulted in considerable hull machining, hull weldment and bulkhead changes. The two shot CO2 fire extinguisher system was incorporated at this time. As could be expected, the changes set forth in this modification program completely revised the turret and hull electrical systems. Because the basic M48A1 tanks were manufactured by three different companies (Chrysler, Ford and Fisher) and each had their own fender and stowage box arrangement, it was necessary to compile several kits in order to overcome the fender differences. Additional kits were required because of U.S. Army and U.S. Marine corps differences in fender stowage and OVE requirements. This program also provided the M2A2 CBR gas particulate to the M48A3 tank.

The turret changes included an improved 90mm combination gun mount with two additional 90mm rounds stowed in the vehicle for a total of 62 rounds. The turret drive mechanism was changed from the Oil Gear type to the Cadillac Gage system. The turret was equipped with provisions for mounting the 2.2 KW Xenon Searchlight, a new waterproofed gun shield cover, and a new nylon inner ballistic shield. The turret and turret platform stowage arrangement was revised considerably. A new inflatable seal was installed between the turret and hull and deep water fording provisions were incorporated throughout the vehicle. Fire control improvements were also incorporated with the most significant changes being the incorporation of the M17B1C coincidence rangefinder, the M10B1 ballistic drive, the M13B1 ballistic computer, M105 telescope and mount, and the M31 gunner's periscope.

 

M48A2C 90mm to M48A2C 105mm

This program was for a foreign government, and as the subtitle implies upgunned the M48A2C from a 90mm gun to a 105mm gun. It included modification kits to the combination gun mount, gun travel lock, gun shield cover, turret and hull electrical, turret and gun controls. It also provided the necessary stowage arrangement for the hull, turret and turret platform as regards the 105mm ammunition. This also provided a new waterproof external gun shield cover and a nylon inner ballistic shield. The vehicle also adapted a 30 lb. C02 single shot fire extinguisher system, and the stowage and outlets for the 2.2 KW searchlight. Also included was the necessary OVE equipment changes. A peculiar modification kit to provide removal of the personnel heaters was also a part of this program.

This vehicle had the AVDS-1790-5B gasoline engine and a CD850-5 transmission. Forty-three rounds of 105mm ammunition were stowed in the vehicle. The basic vehicle was from the M48A2 production.

 

M48A1 90mm to M48A3 105mm

This program provided the direct modification from a M48A1 90mm tank to the M48A3 105mm. It utilized all of the basic automotive and turret control kit as used in the previously described (M48A1 90mm to M48A3 90mm) modification kit program. The differences were in the 105mm gun travel lock, combination gun mount, inner ballistic shield and outer gun shield cover. Other 105mm gun related kits pertain to the turret electrical, turret, platform and hull stowage for the 105mm ammunition. This program was for a foreign government which did not require the personnel heater, therefore, the fuel lines, hull electrical and personnel heater removal kits were affected. This vehicle utilized the AVDS-1790-2 diesel engine and CD850-6 transmission. Forty-three rounds of 105mm ammunition were stowed within the vehicle.

 

M48A1 90mm to M48A3 (Mod B) 90mm

This program was for the U.S. Army and updated the M48A1 90mm tank to the M48A3 (Mod B) 90mm configuration. Essentially this, program provided an updating, utilizing as many M60A1 components as possible. A mixture of modification kits used on the conversion from M48Als to M48A3s were used plus some new kits wherein M60A1 components were utilized. The driver’s controls (drain valve, accelerator, throttle, steering and shifting, speedometer, tachometer) are of the M60A1 configuration. Such items as the air cleaners, shroud and exhaust, gun travel lock, combination gun mount and pintle are of the original M48A3 conversion configuration. The fuel lines are new in that they were relocated from the hull floor to the hull apex. There are two new kits in the suspension system providing a torsion bar knock-out hole in the suspension housings, and a revision to the track support roller and mud shield. All other suspension kits are of the "old" M48A3 configuration. The fire extinguisher is of the two shot CO2 design. The hull stowage is new because of the location of the various controls and weldment changes. The hydraulic brake system has been incorporated into this program. Hull welding and machining is new because of the requirements to the compensating idler boss and top deck grille. A "reggedizing" effect has been added to the rear grille doors and taillights to prevent damage during jungle warfare. New composite headlights (detachable) have been added to this vehicle and constitute a portion of the change to the hull electrical system. A raised fender phone box was incorporated.

Turret area changes that incorporate the "old" M48A3 modification kits are in the turret control mechanism, changing from the Oil Gear to the Cadillac Gage system, the turret hand drive, inner ballistic shield, outer gun shield, turret stowage, and turret traverse gearbox.

In the area of the cupola we have provided a vision ring and a cupola retaining ring. On the back of the turret cargo rack we have provided screening so that small objects would not fall through the rack. The CBR gas particulate unit is the M2A2 configuration.

The current status of the U.S. Army M48A3 program is as follows: We have kit capability for converting the M48Als to the M48A3 Mod B configuration. The entire U.S. Army fleet has been upgraded to the M48A3 Mod B configuration. Production installation and modification drawings are available. A set of conversion-rebuild guides were prepared during this program. The Army carried both the "old" M48A3 and the M48A3 Mod B under the same class and division number until all M48A3s were converted to the Mod B configuration. Not that this is complete the Army has dropped the Mod B designator; however, we still use it for differentiating when discussing conversion programs. A classified project mounting a 1KW Xenon searchlight and a "scanner" on the gun shield provided a thermal night vision capability. This was conducted on an experimental basis on the M48A3 Mod B tank.

Picture Doug Kibbey

M48A4 Program

Primarily the M48A4 uses the same automotive modification kits as the M48A3 Mod B program. There are a few exceptions which are the result of peculiarities when installing the M60 turret on this upgraded chassis. The peculiar kits are as follows" hull weldment and machining requires a seal groove cut into the hull ring area to accept the M60 turret ring and improved inflatable seal. The hull stowage is different and makes provisions for the 105mm ammunition racks. Slight changes in the personnel heater kit are required due to the relocation of the heater duct tube leading to the turret area. The hull electrical is changed in order to utilize the M60 slip ring, and prevent an interference with the bulkhead floor. The cargo rack screen was also added to the turret exterior. This program did not incorporate the "ruggedized" protection components on the rear grille doors and tail lamp and did not incorporate the composite headlamps or raised fender phone box. Chrysler Defense Engineering built one mock-up vehicle which was eventually shipped to Fort Knox. While this vehicle was tested at Chrysler Defense Engineering it was clearly stated it was a mock-up test rig and not to be considered a pilot vehicle.

The intent of this program was to provide use of the M60 turrets removed during a proposed chain reaction type program to utilize M60 turrets when the Army considered placing M60A1E2 turrets on the M60A1 chassis, M60A1 turrets on M60 chassis, and M60 turrets on M48 upgraded chassis. Before this program was killed, a complete set of modification kit and production installation drawings were prepared for this program. Rebuild and conversion guides were also prepared.

 M48A3 Modernization Program

This program provides for the rebuild and conversion of N48A3 tanks being returned from Vietnam into the M48A3 Mod B configuration. This program was initially set up for rebuild at the Anniston Army Depot and was to the same configuration of N48A3 Nod B tanks being converted at Bowen-McLaughlin-York. Later this program was shifted, in part, to the Army Ordnance Depot in Sagami, Japan. While the program utilized M48A3 Mod B kits the primary effort of the modernization program at Chrysler Defense Engineering was to prepare supplementary facility type (TD) drawings and documents to include symbols for reuse, rework, new added parts, parts removed, FSN and MWO information. This supplementary information was not part of a Technical Data Package, but was delivered to the AMCPM-M60 office. This modernization program was required because of the urgency of the SEA war effort and the fact that the Anniston Army Depot did not have the available manpower to provide processing sheets for the rework of these tanks. Therefore, Chrysler Defense Engineering provided the necessary information with regards to reused, discarded, new and special instructions for the program. A special set of brownline drawings were established as the originals for this program. Specific instructions for annotating and maintaining revisions for this program were prepared in order to expedite the preparation of drawings.

M67A2 Flamethrower

This program updated the M67A1 flamethrower into the M67A2 configuration. Because of the flamethrower fuel bottle arrangement we naturally had to prepare peculiar type kits in the area of the bulkhead, hull weldment and machining, fire extinguisher, hull stowage, hull and turret electrical and turret stowage. The driver's controls utilized the modification kits from the M48A3 program. Peculiarities in the gun travel lock and top deck grille, gun shield cover and inner ballistic shield were necessary because of the different gun tube. Because this was a U.S. Marine Corps program, peculiar fender and tripod stowage were required along with deep water fording provisions. This program also incorporated an engine quick disconnect arrangement for electrical, fuel and fire extinguisher disconnect points.

 

M48A5 Program

Major modification required to convert an M48A1 to M48A5.

Major modification required to convert an M48A3 to M48A5. 

This program was previously designated as the "XM736" at one time. Recent work along this line has designated this program the M48A5.

While some work began on this a few years back a renewed interest in the program started in the middle of March 1971. Previous work along this line has been to upgun an M48A3 90mm gun tank with a 105mm gun. Therefore, a series of 105mm gun related kits have been developed. Modification kits in this category are gun travel lock, combination gun mount, gun shield cover, hull, turret and turret basket, stowage arrangements as affects the 105mm ammunition stowage. Turret electrical, gun fire control and OVE have to be revised to reflect the 105mm gun requirements.

The recent program is to utilize the M48A3 Mod B configuration and incorporate the 105mm gun. While we have produced a hardware mock-up of this modification kit program for the M48A3 "old" configuration, we have never made a pilot buildup of a 105 mm gun in the M48A3 Mod B configuration. Therefore, it is anticipated that a combination of kits from the M48A4 program (hull and chassis items) and modification kits from the M48A3 105mm (turret items) could be selected, and with some redesign for interference checkout the drawings could be utilized to come up with the new M48A5 (Mod B) configuration.