Description and performance data for the M26 armored tractor from TM 9-767: 40-Ton Tank Transporter Truck-Trailer M25, War Department Technical Manual, U.S. War Department, February 1944. The M25 Tank Transporter, nicknamed the “Dragon Wagon,” was a heavy tank transporter and tank recovery vehicle used by the U.S. Army during World War II.
40-TON TANK TRANSPORTER TRUCK-TRAILER M25
DESCRIPTION.
a. The 40-ton, Tank Transporter Truck-trailer M25 is designed for use in recovering a piece of damaged materiel and transporting it to a place where necessary repairs can be accomplished. The M25 unit consists of the tractor truck (M26) and semitrailer (M15), the semitrailer being coupled to the tractor by means of a fifth wheel on the tractor, which automatically locks the trailer to the tractor. Air brakes on the trailer wheels and lighting equipment on the trailer are connected to the tractor air and lighting systems by means of air hose and a jumper cable (carried on the trailer). The trailer air brakes and lights are controlled by the driver of the tractor. The trailer air brakes are automatically set in case the trailer is accidentally, or purposely, disconnected from the tractor.
b. The tractor truck M26 is a self-propelled motor vehicle, powered by a 6-cylinder internal-combustion gasoline engine. There are two front and eight rear dual wheels equipped with desert, or combat type, pneumatic tires. The rear wheels are driven by roller type chains operating on sprockets fastened to the wheel hubs. The power to drive the rear wheels is obtained from the engine, through the clutch, main and auxiliary transmissions, rear differential and jackshafts to the drive sprockets which are bolted to the jackshaft hubs. Roller chains on the jackshaft hub sprockets and on the wheel hub sprockets, drive the wheels. The tractor can be used as a recovery vehicle without the semitrailer, since it is equipped with a front mounting winch, a rear tandem winch, and a vertical lifting device. The cab is armor plated and has hinged armor plate covers for the windshield, radiator, doors, and cab windows. All of these armor plate covers are operated from inside the cab and have peep ports. A pintle hook is bolted to the rear end of the frame. Towing shackles are fastened to the front and rear of the frame. A drawbar and whiffletree are carried on the tractor, for recovery operations. Oxygen and acetylene tanks with equipment for welding or cuttings; vise, Pioneer, and maintenance tools are also carried on the tractor.
c. The semitrailer (M15) is designed to be pulled by the tractor truck (M26) and consists of a low drop frame having a low bed-type platform. Eight single wheels equipped with pneumatic tires are used to carry the semitrailer, which has a maximum pay load of 40 tons to be carried at a maximum speed of 26 miles per hour. The use of walking beams operating on trunnion shafts, allows any one wheel to pass over a 9-inch obstacle while all other wheels remain in contact with the ground. Brakes on the semitrailer wheels are actuated by compressed air supplied from the truck tractor, through removable hose which connect the semitrailer to the tractor. There are four clearance lights, two of which are on the right and left side at the rear cross member, and two are on the right and left front side at the steps. There are four blackout clearance lights which are located directly under the service clearance lights. Two auxiliary clearance lights are stowed on the left side. Two clips are provided to hold clearance lights in stowed position. A blackout taillight, service taillight and stop light, and service stop light, also, a blackout taillight and stop light are located on the rear cross member of the semitrailer and are operated by the same switches that operate the truck tractor clearance taillight and stop lights. Pioneer Tools, recovery equipment, hoist for changing tires and for maintenance work, and maintenance tools are carried on the trailer.
DATA.
a. Tractor w/ Trailer Specifications.
40-ton tank transporter truck-trailer model No. M25 Semitrailer, model No. M15 Tractor truck, model No. M26 Tractor truck manufacturer Pacific Car and Foundry Co. Semitrailer manufacturer Fruehauf Trailer Co. Weight of tractor with semitrailer (gas, oil, water and all equipment) 103,300 lb b. Tractor Specifications.
Curb weight of tractor 42,000 lb Length, over-all of tractor (uncrated) 25 ft 4 in. Width, over-all of tractor (uncrated) 10 ft 10 3/4 in. Maximum fifth wheel load 55,000 lb Height, over-all of tractor (uncrated) 11 ft 5 in. Wheel size 24 in. Tire size 14.00 x 24 Ply 20 or 12 Crew 7 Wheel base of tractor 14 ft 4 in. Tread, front (center to center) 82 in. Tread, rear (center to center) 98 1/2 in. Kind and grade of fuel 70-72 octane gasoline Ground clearance 14 in. Pintle or drawbar height, rear 41 1/2 in. Approach angle 35 degrees Maximum speed (without towed load) 28 mph Ground pressure 90 psi Ground Contact Area: Each front tire 123 sq in. Each rear tire 118 sq in. Ground contact gross (zero penetration-75 pounds per square inch,
tire pressure).c. Performance. Speeds allowable, without front wheels driving:
Main Transmission Lever In Auxiliary Transmission Lever In Speed Obtained first first 1.5 first second direct 2.5 first third O.D 3.8 second first 5.1 second second direct 6.5 second third O.C. 8.1 third first 8.6 third second direct 12.0 third third O.D. 16.0 fourth first 21.0 fourth second direct 26.0 fourth third O.D 28.0 (NOTE: Speeds allowable, with front wheels driving, are the same as given above.)
Minimum turning radius (right) 40 ft (left) 40 ft Minimum turning circle diameter 80 ft Fording depth 56 in. Towing facilities (front) two clevis hooks and tow bar Towing facilities (rear) two clevis hooks and pintle (quick release) Maximum grade ascending ability 30% Maximum allowable engine speed 2,100 rpm d. Tractor Capacities.
Transmission 8 1/2 qt Transfer case 12 qt Front axle 20 qt Rear axle 10 qt Fuel (in two tanks) 120 gal Cooling system 14 gal Crankcase 28 qt e. Semitrailer Specifications.
Length, over-all (with permanent ramps in up position) 38 ft 5 1/16 in. Length, over-all (with permanent ramps in down position) 44 ft 2 in. Width, over-all 12 ft 6 in. Width, over-all (under-construction) 10 ft 4 in. Height, over-all 8 ft 9 in. Height at kingpin 5 ft 7 3/4 in. Ground clearance at lower decking 2 ft 5 1/8 in. Height of lower deck 3 ft 4 1/2 in. Height from lower deck to top deck 3 ft 3 in. Width of decking 10 ft 4 in. Wheel size 24 x 10.00 Tire size 14.00 x 24–20 ply Tire types both combat and desert types are used Tread (center to center) 10 ft 11 in. Weight of semitrailer equipped 36,100 lb Maximum semitrailer gross weight 55,000 lb Minimum ground clearance (unloaded) 13 in.
