Allis-Chalmers’ modern horsepower fleet

In 1957 the future of Allis-Chalmers (AC) tractors was revealed in a dandy 34-hp. tractor. Heralding a significant departure from its past tractor designs, the D14 was the vanguard of AC’s D Series and represented a complete modernization of its tractor line.

And just in time. Farms were growing in size and farmers were demanding not only more horsepower but also better features on that horsepower.

Recognizing that need, Allis engineers set about designing a new generation of horsepower and brought out the D14. This model would soon be joined by six additional tractors ranging in power from 31 engine hp. up to 114 engine hp.

After planting a stake to identify the future of its tractor line, AC wasted little time bringing out a model that drew the attention of larger farmers. The company’s D17, introduced in 1957, would prove very popular — nearly 85,000 units were built. The D17 went through several upgrades including the Series II (in 1959), Series III (1964), and Series IV (1965).

The original model was offered in gas, LP gas, and diesel versions. Each of the engines was paired with an eight-speed transmission. Priced at $3,550 (with standard gas engine), the D17 offered such amenities as Allis-Chalmers Traction Booster draft control, power steering, a power-adjustable front axle, and rear-wheel track adjustment.

All other D Series tractors, with the exception of the D21, would operate with the company’s unique hand-operated, shift-on-the-go hand clutch in addition to a foot clutch. Dubbed the Power Director, the hand clutch would shift the transmission on the go: low gear range when the handle was pulled back, neutral in the middle handle position (which allowed the PTO to continue to operate), and high gear range when the handle was pushed forward. This feature let the farmer downshift without clutching when tilling conditions got tough.

In 1959 Allis-Chalmers cemented its sales to small farmers with the introduction of the D10 and D12. Both ran with an Allis-built 138-cubic-inch engine that turned out

31 hp. That engine was replaced with a 149-cubic-inch four-cylinder. The only difference between the two models was that the D12 had longer front-axle sleeves and a wider front-axle adjustment. The D10 would be in production until 1967, whereas the D12 was still available until 1968.

At this point, AC broadened the line’s appeal by offering the four models in as many as 50 configurations.

At the start of the 1960s, the D14 was replaced with the D15. This model ran with the same engine as the D14 but at a higher compression ratio and higher rpm. Buyers could go with that 149-cubic-inch gas or LP engine or a 175-cubic-inch diesel in the D15.

An upgraded version of the tractor, the D15 Series II, came out in 1963 and with it came the same gas and LP engine that had been bored 0.125 larger. With a $4,400 price tag, this model would remain in production until 1968.

First with a turbo

The trend in Midwest and Western agriculture was definitely toward larger horsepower machines. So in 1961 Allis engineers finished a tractor that employed the Allis-built Model D262 diesel that increased by 90 hp. to the flywheel, thanks to a standard-equipment innovation not yet seen on tractors — the turbocharger. The tractor was also sold with a 262-cubic-inch gas or LP gas engine.

Cellulose air filter

The D19 also set another industry standard by being the first tractor to use a cellulose air filter. At first blush, this advance may seem trivial. Oil-bath filters, the industry standard at this time, suffered very low airflow rates and were not efficient at cleaning the air even when adequately maintained. If oil level got low or if the canister filled with the muddy oil-dust mixture, filtering efficiency of the oil-bath design was significantly degraded resulting in engine damage.

Cellulose filters were simple and fast to change, removed even fine dust, and allowed a large supply of airflow. (This last characteristic was crucial on larger diesel platforms.)

Breaking 100 hp.

The crown of the D Series line, the Model D21, was introduced to eager farmers in 1963. Besides being the first AC tractor to break the 100-hp. barrier (rated at 103 hp.), the D21 ran with a 426-cubic-inch six-cylinder diesel that at first was not turbo-charged.

When it did get a turbo in 1965 with the upgraded D21 Series II, the tractor’s power output jumped to 130 hp., making it the largest row crop tractor on the market.