The M-129 Semitrailer, Van, 12-ton, 4-wheel is intended for use in transporting military supplies and general cargo. The M129 Semitrailer Van was designed to be towed by an M52 5-ton, 6x6 truck tractor or similar vehicle equipped with fifth wheel, air supply, and a 24-volt electrical system. If a 24-volt electrical system is not available, an alternate towing vehicle with a 12-volt electrical system may be used with the M128. The towing vehicle supplies brake air pressure and control of brakes.
The M129 van is based on the M126 semitrailer chassis. The chassis frame is welded into a single integral unit, with an upper fifth wheel plate and king pin coupling at front. The two rear axles are on leaf-spring suspension. Two foot-type retractable landing legs are provided for front end support when the semitrailer is not attached to a truck tractor.
The 12-ton payload can be carried by the M129 semitrailer van at 50 mph on a highway or cross-country at 20 mph.
The M129-series vans are used for supply operations. The van body has seven windows with blackout covers. The front window is stationary while three windows on each side of the trailer are retractable. A lever is used to open and close the retractable window sash. The M129 series vans have an additional 110v AC electrical system with dome lights, wall receptacles, circuit breakers, and a switch box.
The M129 series semitrailers have two doors at the rear of the body. A stepladder is provided to aid in climbing in and out of the van body. The stepladder hangs on the left rear door when not in use. It is held in place by removable pins fastened on a chain to the body. A chain holds up the retractable step when not in use.
The M129A1 is the base model of the M129 semitrailer van series of vehicles. These features apply to the M129A1 and M129A1C:
Military standard axles, hub and drum, air chamber (bogie assembly and brakes)
Military lights, service, tail and stop
Military type blackout lights
4-wheel internal brakes located within brake drum, consists of 4-hydraulic operated FR2S-type wheel brake assemblies self-centering
Equipped with lifting rings for hoisting the semitrailer
24-volt electrical system and a separate 12-volt lighting system
The Model M129A2C Van has these differences:
Later design of bogie assembly and service brakes (axle, spring seat, “U" bolts, torque rods, hardware and brakes)
Two tail, stop, turn and marker lights in each voltage, 12-volt and 24-volt. Marker lights in 24-volt.
Some other small differences are noted in TM 9-2330-207-14 for M129A2C semitrailer vehicles produced by Kasel Manufacturing Company, referred to as the M129A2C Kasel Model.
M-129 Semitrailer, Van, Supply, 12-ton, Cargo, 4-wheel Characteristics
28 ft 8 1/4 in.
11 ft 7 3/8 in
Loading height, empty
4 ft 10 1/2 in
Eight 11.00x20 Military NDCC
Departure angle, loaded
Table data is basaed on the M129 Semitrailer, from TM9-2330-207-14.
Manuals for the M-129 Semitrailer, Van, 12-ton will be in the TM 9-2330-207-xx series, where the xx represents the maintenance level. The first parts list is ORD 9 SNL G-750, dated 13 April 1953. The NSNs for the M129 variants are:
Later Variants: M129A3 and M129A4
The M129A3 Van and M129A4 Van are later variants of the M129 series semitrailer vans. Separate manuals are available for the newer variants.
The M129A3 Semitrailer, Van: Supply, 12-ton, is very similar to the M129A2C with few differences. The Technical Manual for the M129A3 is TM 9 2330-374-14&P.
The M129A4 Semitrailer, Van: Supply, 12-ton, at 37 feet long (with platform retracted), is larger than the earlier variants, used to provide temporary electronic work and storage space. There are many differences between the M129A4 and earlier variants of the M129 series. It shares the manual with the similar XM1063 Semitrailer. The Technical Manual for the M129A4 is TM 9 2330-380-14&P. For a reset program, an M129A4 Modified Replacement Van Body (NSN 2510-01-549-4721) has been defined.