M-123 Truck, Tractor, 10-Ton, 6x6 (G-792)

The M-123 Truck, Tractor, 10-Ton, 6x6 was produced in model variants that included:

M123 FSN 2320-395-1875. Dual rear winches. LeRoi T-H844 V8 Gas engine.
M123E2 FSN 2320-879-6177. Dual rear winches, Cummins V8-300 diesel.
M123C FSN 2320-294-9552. Single rear winch. Cummins V8-300 diesel.
M123D FSN 2320-542-2509. Dual rear winches. Cummins V8-300 diesel.
M123A1C FSN 2320-226-6081. Single rear winch, 36,000lb lift crane. Cummins V8-300 diesel.

The C variants had a single rear winch and low mounted fifth wheel. The M123D was the same as the M123C, but with dual rear winches. Later M123 variants were assembled by Consolidated Diesel Electric Company (CONDEC) from Mack components. After total production of approximately 4,000 vehicles, the M123 10-ton tractor was superseded by the heavier and more powerful Oshkosh M911 C-HET tractor.

The M123 series trucks were mated with the M15A2 50 ton semitrailer which was later superseded by the M172A2, M747 and other semitrailers.

M-123 Truck, Tractor, 10-Ton, 6x6 Characteristics

Engine: M123 Engine: M123A1C and others	LeRoi T-H844 V8 Gas 297hp@2600rpm Cummins P1525 V8-300 785 cu in, diesel 300hp@3000rpm
Transmission	Constant mesh Mack TRD XT72 5 fwd, 1 rev
Transfer case	Mack constant mesh 2 speed (integrated w/transmission)
Front Axle	Mack triple reduction
Rear Axles	Mack double reduction
Differentials	Mack 10:1
Winch	Garwood 45,000 lbs
Fuel capacity	2 tanks, 83 gal each
Cruising range	300-350 miles
Maximum speed	43 mph
Weight: M123 Weight: M123A1C	32,250 lbs 29,100 lbs
Length	289 inches (7.34 m)
Width	114 inches
Height: M123 Height: M123A1C	113 inches 108 inches
Towed load rating	120,000 lbs highway / 80,000 lbs off highway

For transport, the overall height can be reduced to 93.0 inches (2.36 m) by lowering the windshield and by removing the floodlight, spare wheel, spare wheel davit, trolley tracks, level wind trolleys, hydraulic control handle, and operator's cab cover.

M-123 Truck, Tractor, 10-Ton, 6x6 Manuals and Documentation

Some of the manuals for the M-123 Truck, Tractor, 10-Ton, 6x6 are:

ORD 7 SNL G792 (31 January 1958) Section I, LeRoi engine parts.
TM 9-8002 (1 November 1955)
TM 9-8003-1 (25 June 1956) Ordnance Maintenance for Engine, Engine Accessories and Clutch
TM 9-2815-213-34 Cummins V8-300 Maintenance
TM 9-2320-206-10 (29 April 1977) Operator's Manual
TM 9-2320-206-10 (8 December 1978) HR Hand Receipt
TM 9-2320-206-12 (4 February 1960) Supersedes TM 9-8002 & ORD 7 SNL G792
TM 9-2320-206-20 (22 October 1971) Organizational Maintenance
TM 9-2320-206-20P Parts
TM 9-2320-206-34 Direct & General Support Maintenance
TM 9-2320-206-34P (6 March 1972) Direct & General Support Maintenance Repair Parts & Special Tools List
TM 9-2320-206-ESC
LO 9-2320-206-12 Lube Order

This Olive-Drab.com page describes the manual numbering system.

The M-123 Truck, Tractor, 10-Ton, 6x6 is extensively described on the linked page from the VanNatta Truck Museum with many photos and detailed technical discussion.

M-123A1C Truck, Tractor, 6x6, 10 Ton.

An M-123A1C Truck, Tractor, 10-Ton, 6x6 with an M747 semi-trailer loaded with an M-110 8in (203mm) Self-propelled Howitzer, August 1985.

M-123A1C Truck, Tractor, 10-Ton, 6x6. Photo courtesy Oshkosh Equipment Sales, LLC.

M-123 Truck, Tractor, 10-Ton, 6x6

The M-123 Truck, Tractor, 10-Ton, 6x6 is part of the G-792 series of vehicles which includes the M-125 Truck, Cargo, 10-ton, 6x6. The M123 is a tractor for hauling semi-trailer loads such as heavy vehicles (tanks, bulldozers) or ammunition or other supplies. Its gearing restricts it use to off-road field activity, not line haul.

This huge tractor was manufactured by Mack from 1955 to 1957 (the M123 series) and 1965 to 1969 (M123A1C), the successor to the M26 'Dragon Wagon' tractor. One or two winches, depending on the variant, were mounted behind the cab, used to draw a trailer onto the 3-inch king-pin fifth wheel. Variant differences included the engine, fifth wheel height, and details like a warning beacon, clearance and turn signal lights, and access steps. Tires were 14.00x24 inch.

M-123A1C Truck, Tractor, 10-Ton, 6x6. Photo courtesy Oshkosh Equipment Sales, LLC.