The 4-ton Diamond T trucks were originally developed at the behest of the Quartermaster Corps to serve as a prime mover for the 155mm howitzer. However, due to the success of these trucks, they were soon adapted to other roles as well.
Early models of these trucks were all built in the closed-cab version of the Diamond T chassis. While the hood and fenders were strictly military, the cab itself was based on Diamond T’s commercial truck cabs. During June and July of 1943, this was replaced with the military-style open cab, which allowed greater visibility and better air defense.
A Hercules RXC 529-cid inline six-cylinder engine powered most of these trucks. The high-torque engine and low gearing of the five-speed transmission and two-speed transfer case allowed a highway towed load rating of 12 1/2 tons.
967, 968, 968A, & 968B Cargo Trucks
These trucks were referred to as short wheelbase trucks and were intended to transport personnel, general cargo, or to act as a prime mover for 155mm Howitzers. Like almost all the WWII cargo trucks, the beds of these trucks initially were made of steel, but were changed to wood construction early on. The two spare tires were carried across the front of the bed.
The Model 967, produced in early 1941, was first in the Diamond T series and was powered by the Hercules RXB 501-cid inline six-cylinder engine. The 967 is easily distinguished by its one-piece brush guard, which extends to protect the headlamp. Later models have a narrower brush guard, with separate guards for the headlights.
The Model 968, introduced later in 1941, was upgraded to the larger, more powerful Hercules RXC engine.
The Model 968A, which began production in November 1941, featured the military-type instruments instead of the civilian style used previously.
The Model 968B was the final version of the short wheelbase 4-ton Diamond T.
G-509 Cargo Truck Specifications
ENGINE MAKE/MODEL: Hercules RXC
NUMBER OF CYLINDERS: 6
CUBIC-INCH DISPLACEMENT: 529
HORSEPOWER: 106 @ 2300 rpm
TORQUE: 342 lbs.-ft. @ 900 rpm
GOVERNED SPEED (rpm): 2300
NET WEIGHT: 18,450 lbs.
GROSS WEIGHT: 34,500 lbs.
MAX TOWED LOAD: 25,000 lbs.
TIRE SIZE: 9.00-20
MAX SPEED: 40 mph
FUEL CAPACITY: 60 gal
RANGE: 180 mi
ELECTRICAL: 6/12 pos
TRANSMISSION SPEEDS: 5
TRANSFER SPEEDS: 2
TURNING RADIUS FEET: 37.5 R, 39 L
Overall dimensions listed in inches.
* Inside/outside width at tires.
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