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Articulating The Point - A 1920s British take on the legendary FWD Model B

Posted in Features on June 16, 2016
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Some 14,473 FWD-designed Model B 3-ton 4x4 trucks were built for the U.S. Government in World War I. Additionally, thousands more were built for the various European countries allied against Germany in that war, including several hundred for the British military. After the war, all those trucks in all those countries were gradually replaced by more modern trucks and sold surplus to begin a second life away from the battlefield. Many were practically in new condition and offered civilians a first chance to enter the motor age. In the case of the four-wheel-drive Model B, the surplus trucks offered buyers a chance at an affordable all-wheel-drive truck. In those days, a new 4x4 truck was about double the cost of a 4x2, so the surplus rigs sold at a fraction of the original cost were a bargain.

In 1921, one of FWD's European sales people, Henry Nyberg, went in with Charles Cleaver, a former British Army "Leftenant," to form the Four Wheel Drive Lorry Company, Ltd. in England, which we will shorten to FWD England. It isn't clear how much of an investment, if any, the American FWD company had in the British outfit. Their business started with buying surplus European military Model B 4x4s for refurbishment and retail sales. They expanded it into specialty conversions of those trucks, including one used to launch British Coast Guard rescue boats from beaches. In 1926, they developed a half-track conversion of the Model B and built two prototypes that were tested by the British War Office as artillery tractors and that got their foot into the door of another military contract.

Who says old trucks can't articulate? The Niblett rear suspension had 20 inches of rear travel, and the tandem rear axle could articulate opposite each other 36 degrees. This image was taken from a 1928 Four Wheel Drive Lorry Company brochure and shows the 6-ton-rated DH doing its stuff. At this point, it was still powered by the fabled American-made Wisconsin Model-A T-head four that made 50 hp at 1,300 rpm from 389 cubic inches. This rig could reach a top speed of 25 mph with 40x8-inch Goodyear diamond-pattern tires.

In 1927, the British War Office invited truck manufacturers to submit prototypes for a six-wheel-drive artillery tractor. To sweeten the pot, they allowed free use of a very limber tandem axle setup designed by Lieutenant Colonel H. Niblett and patented by the War Office. FWD England took up the challenge and added the Niblett tandem axle to a lengthened Model B chassis and rated it for 6 tons. Designated the R.46 by the War Office, it used a largely standard Model B frontend, engine, front driving axle, and transmission/transfer case. In a 1928 brochure, the R.46 design was also marketed as a civilian model in three configurations. The DH had a front section similar to the standard Model B. The DL put the engine in a sidesaddle position alongside the driver. The DB put the driver behind the engine with a conventional hood. The only available images show the R.46 as the DH model, and it isn't clear whether any DL or BD trucks were actually built, nor if any 6x6 DHs were sold in the civilian market.

The R.46 performed well enough in tests for FWD England to get a followup contract for an improved model. This unit would be called the R6T and became a codevelopment of FWD England and the British truck builder AEC. This rig was constructed in 1928 and tested in 1929, largely getting top marks. By this time, FWD England was in very poor financial shape. Period histories report the firm wasn't getting much support from the American side, though it isn't clear how much support FWD in the USA had ever provided. From all appearances, Four Wheel Drive Lorry Company was independent of FWD in America and whatever agreements between them were relatively informal.

A handsome and gnarly truck with a road speed of up to 31 mph. When a larger 95hp AEC engine replaced the Dorman in a second round of tests, the truck performed even better. The ring-and-pinion ratios were 4.31:1 with a 2.33:1 reduction in the hubs for a flange ratio of 10.05:1. Combined with the 4.46:1 First gear and 2.78:1 transfer case low range, this truck had a crawl ratio of 125:1. It could generate 11,800 pounds of drawbar pull with open differentials using the original 78hp engine. You can see the 9 1/2-ton PTO winch and how the cable was fed under the bed to a rear pulley/fairlead assembly. The winch arrangement was noted for its efficiency and one of the reasons this design made the cut.

The FWD R6T was substantially different from the R.46 and contained little, if any, residual DNA from the FWD Model B. Among many other upgrades was a 6.6L Dorman L-head six-cylinder inline engine that made 78 hp. A winch was required for an artillery tractor and the unit on the R6T was rated for a maximum of 9.5 tons, carrying 350 feet of 3/4-inch cable. The R6T was tested in the fall of 1929 and proved very successful. It could tow a 5 1/2-ton, 60 pounder (5-inch) field gun up the vehicle test facility's 28-degree test slope and crank out 18 mph on flat ground fully loaded or 31 mph empty.

The successful tests led to a production contract and a small number of vehicles, alternately called the FWD R6T or the AEC Model 850, were produced to 1936. By 1931, FWD England had fallen flat and the project was absorbed by AEC, who ended up with controlling interest in FWD England. Once AEC had taken over fully in 1932, the FWD name was no longer used. Most of the 58 R6T/850 units known to have been built were configured as artillery tractors but a few were built as tank recovery vehicles. These units saw use at the outset of World War II in 1939 and some references state many of the R6T/850 6x6s were left behind when the British Army retreated from France at Dunkirk in 1940. Several of these highly mobile rigs have survived, including one of the FWD test prototypes.

The Details: 1928 FWD R6T
Engine: 6.6L six-cylinder Dorman 6JUL
Power: 78 hp @ 2,000 rpm
Bore & stroke (in): 3.94 x 5.51
Transmission: 4-spd
Transfer case: 2-spd
Front axle: AEC, bevel gear with 2.33:1 hub reduction
Rear axles: AEC, bevel gear with 2.33:1 hub reduction
Axle ratio: 4.31:1 at ring gear x 2.33:1 at hub = 10.04:1
Tires: 42x10.50
Wheelbase (in): 120
Load Capacity (lb): 16,300
Min. grd. clearance (in): 12

The R6T was a different animal than the R.46/DH. It shared the Niblett rear suspension, but that's about it. It had a shorter wheelbase than the DH (10 feet versus 13 feet) and used axles with planetary gear reduction in the hubs. The R6T was designed to articulate better than the R.46, especially up front. The specs say this setup could use up 19 inches of travel before any significant stress was placed on the chassis. Rough measurements show the rear wheels up on 18-inch blocks and the front about 12. That's pretty good for a ’28 6-ton truck! The tires were 42x10.5. The truck is shown at an early stage and 9x6-foot wooden bed and canvas top was later added.

Graphics of the FWD DH/R.46 suspension articulation indicating the travel limits for the Niblett rear suspension. This didn't change much with the R6T prototype and production models, but the front axle was considerably limbered up.

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