All Wheel Drive ?

[Grant Bowker]

Another vehicle that doesn't seem to fit the SAE classifications given above is the M135. Basically full time power to all wheels with an over-running clutch to the front axle that was locked automatically in reverse.

[Lang]

Grant is this not an "On Demand" system. It gives power when driven and lays idle when not? There are thousands of ways to achieve this result in the gearbox, transfer case, centre differential or front axle as in the M135

Lang

[Lang]

This is interesting as Timkin claim to be the first driver selectable four wheel drive in 1934.This leads to the conclusion everything before then was either fixed or had some sort of centre differential or over run device.

Also the Russians and Japanese were years ahead of the Americans with a military jeep-like vehicle.

1930s–1944[
The American Marmon-Herrington Company was founded in 1931 to serve a growing market for moderately priced four-wheel-drive vehicles. Marmon-Herrington specialized in converting Ford trucks to four-wheel drive and got off to a successful start by procuring contracts for military aircraft refueling trucks, 4×4 chassis for towing light weaponry, commercial aircraft refueling trucks, and an order from the Iraqi Pipeline Company for what were the largest trucks ever built at the time.

Dodge developed its first four-wheel drive truck in 1934 — a military 1½ ton designated K-39-X-4(USA), of which 796 units were built for the U.S. Army in several configurations. Timken supplied front axles and transfer-cases, added to militarized a civilian truck. The Timken transfer case was the first part-time design,that allowed the driver to engage or disengage four-wheel drive using a lever inside the cabin.[In spite of the limited 1930s U.S. military budgets, the ’34 truck was liked well-enough that a more modern 1½ tonner was developed, and 1,700 RF-40-X-4(USA) trucks were produced in 1938, and 292 TF-40-X-4(USA) in 1939.]

Starting in 1936, Japanese company Tokyu Kurogane Kogyo built approximately 4,700 four-wheel-drive roadsters, called the Kurogane Type 95 reconnaissance car, used by the Imperial Japanese Army from 1937 until 1944, during the Second Sino-Japanese War. Three different bodystyles were manufactured; a 2-door roadster, a 2-door pickup truck and a 4-door phaeton, all equipped with a transfer case that engaged the front wheels, powered by a 1.3 litre, 2-cylinder, air-cooled OHV V-twin engine.

The 1937 Mercedes-Benz G5 and BMW 325 4×4 featured full-time four-wheel drive, four-wheel steering, three locking differentials, and fully independent suspension. They were produced because of a government demand for a four-wheel-drive passenger vehicle. The modern G-series/Wolf such as the G500 and G55 AMG still feature some of the attributes, with the exception of fully independent suspension since it can compromise ground clearance. The Unimog is also a result of Mercedes 4x4 technology.

The first Russian produced four-wheel-drive vehicle, also in part for civilian use, was the GAZ-61, developed in the Soviet Union in 1938. "Civilian use" may be a bit of a misnomer, as most if not all were used by the Soviet government and military (as command cars), but the GAZ-61-73 version is the first four-wheel drive vehicle with a normal closed sedan body. Elements of the chassis were used in subsequent military vehicles such as the 1940 GAZ-64 and the 1943 GAZ-67, as well as the post-war GAZ-69, and the properly civilian GAZ-M-72, based on the rear-wheel drive GAZ-20 "Victory" and built from 1955-1958. Soviet civilian life did not allow the proliferation of civilian products such as the Jeep in North America, but through the 1960s the technology of Soviet 4×4 vehicles stayed on par with British, German, and American models, even exceeding it in some aspects, and for military purposes just as actively developed, produced and used.

It was not until "go-anywhere" vehicles were needed for the military on a large scale, that four-wheel drive found its place. The World War II Jeep, originally developed by American Bantam but mass-produced by Willys and Ford, became the best-known four-wheel-drive vehicle in the world during the war.