Mack NR (1942)
USA (1942). (16,548 built)
The Mack NR was a heavy 6x4 cargo truck designed and produced from 1942 by U.S. manufacturer Mack Trucks. It was used first, and mainly by the British Army to transport cargo and materiel over long distances, starting wih the Tunisian Campaign, Sicily, Italy, and in Europe from D-Day onwards. The official U.S. Army designation was: Truck, 10 ton, 6x4, Cargo and Mack G-number was G-528. Over 16,000 were manufactured until V-Day, declined in many versions, and postwar it was still used for almost two decades by the Netherlands, France and Belgium (also Denmark and others when resold).
Origins and Development
Before the outbreak of World War II, starting in September 1939, France saw its armies unprepared for a modern war and lacking among others, thousands of trucks. A large part of its infantry division moved by foot and there was still an abnormally large proportion of horse-drown carriages for supply and artillery (this was the same for the Wehrmacht by the way). So the French Government decided to purchase a large number of existing trucks in the United States, notably to supply some niches that were ill-adressed, notably tanks transpoters and heavy duty trucks.
At the time, only Berliet was provided these, and production was anemic. So an order "of the shelf" of 210 Mack EXBX heavy trucks was made to transport tanks. The latter had indeed much more flexibility than tanks to reach any part of the front rapidly. This was moreover important for French tanks which famously lacked the range and speed to be reapidly relocated on the front.
However, this was too late already. The outcome of the Battle of France prevented delivery of these trucks to France. Instead, they were taken over by Great Britain, which found these quite handy to transport its own tanks, and the British Purchasing Commission, acting in the United States for lend-lease acquisutions, ordered more of these Mack trucks. In between, Mack reworked the design for military use (the EXBX was a civilian model), resulting in the NR series. Every order was given its own number, despite the fact performance were the same and differences were minimal. This wetn from NR-1 to NR-20
Production Variants
NR-1 to NR-7
In 1940, an initial order was placed, for 90 trucks in the 10-ton category (NR-1), similar to the previous EXBX used already from the French order with British troops, but not specifically equipped for tank transport, for rapid conversion for other uses. The NR-1 was a variant of a baseline civilian model already marketed in 1938 by Mack. The main change was a solid grill forward to protect the radiator and headlamps, and double above the cab to prevent overheating (the lower roof was open topped). These were well suited for operation in the Middle East and the Far East, where they were sent, taking part notably in the 1941 Invasion of Iran.
These NR-1 had a six-cylinder Mack-Lanova ED engine rated for 131 HP at 2,000 rpm, connected to a TR 12 Duplex transmission, with five gears. The rear wheels had 13.50-20 tyres, and were driven, unlike the forward axle only used for steering. Hence the NR-1 was a 6x4 designation. The front wheels had narrowr tyres as well, of the 10.50-24. Empty weight was 10 tons for a cost of $9,000 each.
This was followed by two more orders, the NR-2 and NR-3. The NR-2 was a proper military version of the Model 270 driver's cab. This rigid, all-metal cab was used until the open cabin arrived. It resembled the civilan model but was simplified in some ways. The British ordered 330 NR-2. In 1941, 61 NR-3 model followed, optimized for long-distance transport in the Middle East. They were used by the logistics department of the British Army, as well as the Royal Army Service Corps (RASC) -carrying downed or just dismounted aircraft. The NR-2/3 measured 8.2 meters long, for 2.6 meters wide, 2.5 meters high for an empty weight a bit lower than the NR-1 at 9.3 tons, and new wheel measuring 11.00-24 forward and 14.00-20 at the rear).
Then came the NR-4. Still based on the basic Mack EXBX, it was optimized soleley for tank transport. On August 21, 1941, an order was placed for 200 of them, identical to the NR-3 but with a new rear flat-floor cargo area. The spare tyre notably was replaced by a winch, plus ramps were stored on the side of the plateau to upload the tank on the cargo area. Empty weight rose to 11.7 metric tons, total weight when loaded 22.7 tons. Deployed in North Africa, it became the chosen "mount" for the
M3 Stuart light tank (13 tons) but soon proved to able to carry the
Cruiser Mk II A10, and
Valentine. The NR-5 then followed, ientical to the NR-3 as cargo, but not upgraded to a Duplex TRD 37 gearbox. The NR-6 and 7 were identical to the NR-5 essentially as follow-up orders.
NR-8 to 16
The biggest change was with the NR-8: Under US influence for simplification, now that the US were at war with a reorganized truck production. The NR-8 indeed was the first to introduced an open driver's cab. Instead of a more labour and materials intensive fully enclosed metal cab, there was now an open cabin covered with a canvas roof. The double, flat windshield also could be folded down on the bonnet. There were now wipers and rear vision mirrors as well asn other details. The dashboard was also simplified, omitting certain elements.
The dors were now narrower, and there was folding framing to support the rear-mounted top cover (tarpaulin), fixed when in use on the forward windshield. In winter, like other open top cabs, there were removable, folded canvas windows that can be fitted over the doors and fully enclose the cab. The small windows were in platic.
The NR-9 to NR-13 came as follow-up were nearly identical to the NR-8. However, the NR-14 produced from 1944, saw the biggest change, so to be better in traction off-road, and upon insistance of the US logistic corps, rear wheels became dual with a wheel size of 11.00-24. Many NR-15 were also shipped to Iran became inmportant to carry lend-lease heavy equipments to the Soviet Union via the Persian Corridor (alternative route to the perilous arctic convoy). These had new fuel tanks with a capacity of 280 liters (75 US-gallon) mounted on either side.
The next NR-16 was the last order placed, 455 units, delivered in 1945. The order for the NR-17 was canceled as the war ended and postwa, 600 more were order to provide the European armies when re-established: Belgium, Netherlands (150 NR-18 and NR-19) and France (300 NR-20). The grand total thus would be 16,548, although anouther account gives 16,338. Due to their good quality and reliability, they remained in service for some until 1960. For all vehicles, the brakes were pneumatic and the electrical system was rated for 12 volt (24 volt starting).
Variants
| Type | Model | Number Built | Years Produced |
Enclosed cab, single rear wheels: 1,370 built. |
|
| Cargo transport (civilian cabin) | NR-1 | 90 | 1940 |
| Cargo transport (Model 270 cabin) | NR-2 | 330 | 1941 |
| Cargo transport | NR-3 | 61 | 1941 to 1942 |
| Tank transporter | NR-4 | 200 | 1941 to 1942 |
| Cargo transport | NR-5 | 189 | 1941 to 1942 |
| Cargo transport | NR-6 | 500 | 1942 |
| Cargo transport | NR-7 | 500 | 1942 to 1943 |
Open cab, single rear wheels: 5,696 built. |
|
| Cargo transport | NR-8 | 700 (150 + 550) | 1942 to 1943 |
| Cargo transport | NR-9 | 900 | 1943 to 1944 |
| Cargo transport | NR-10 | 1,257 | 1943 to 1944 |
| Cargo transport | NR-11 | 239 | 1943 to 1944 |
| Cargo transport | NR-12 | 1,320 | 1943 to 1944 |
| Cargo transport | NR-13 | 1,280 | 1943 to 1944 |
Open cab, twin rear wheels: 9,272 |
|
| Cargo transport | NR-14 | 7,080 | 1944 to 1945 |
| Cargo transport | NR-15 | 847 | 1945 |
| Cargo transport | NR-16 | 445 | 1945 |
| Cargo transport | NR-17 | none | order cancelled |
| Cargo transport (Belgium) | NR-18 | 150 | Post-war |
| Cargo transport (Netherlands) | NR-19 | 150 | Post-war |
| Cargo transport (France) | NR-20 | 300 | Post-war |
Mack NR specifications |
| Dimensions (L-w-h) | 8,2 x 2,6 x 2,5m (322.8 x 102.4 in x 98.4 in) |
| Wheelbase | Unknown |
| Curb weight | 9.2 ton (empty) |
| Payload | 10 ton (cargo capacity) |
| Crew | 1 driver |
| Propulsion | Mack-Lanova ED diesel engine, 6-cyl. 131 hp |
| Transmission | 6x6 |
| Top speed | Unknown |
| Max range | 682 liter (150 gallons), Unknown |