The Allis-Chalmers HD-41 crawler tractor: an overview by Richard Campbell

Allis-Chalmers had been working on a ‘super dozer’ for a number of years, with initial prototype machines appearing in 1963. However it had to wait for some considerable time before engines of sufficient horsepower were available and the metallurgy and technology to manufacture such a large machine had been perfected.

It should be noted that Allis-Chalmers had always been an innovative manufacturer, boasting such ‘firsts’ as the application of a torque converter to track type tractors, lifetime sealed rollers and idlers, andlifetime sealed rollers. Allis-Chalmers developed and offered these all before other manufacturers of track type tractors.

The HD-41’s target market was large earthmoving contractors, surface mining and quarry applications and reclamation where a dozer of this size could enhance production significantly and, in a lot of cases, remove the need for blasting because of the machine’s ripping capabilities.

Considerably larger and heavier than any of its competitors’ biggest machines when it was introduced, the HD-41 tipped the scales at well over 60 tons with blade and ripper, and was a formidable piece of machinery.

Although a very capable machine, there were bugs that needed to be ironed out. The most troublesome of these were in the machine’s final drives, which were prone to failure in heavy going – a fault that was never resolved satisfactorily.

As experience in actual work conditions was relayed to the factory, modifications and other fixes were produced to extend the service life of those machines already operating.

All of these changes plus other improvements came together in an upgraded version; the model HD-41B, which was introduced in 1974.

By this time, Fiat, who had had a controlling share in Allis-Chalmers since 1974, exercised its options and the company was formally known as Fiat-Allis from then on.

Fiat-Allis promptly changed the designation on their track type tractor line and the HD-41B simply became the “41B”.

Ironically, Allis-Chalmers, which had begun the giant tractor race was also the first to exit, the last 41B coming off the production line in 1982. Total production amounted to approximately 3000 machines.

Fiat-Allis also produced some other notable large track type tractors subsequent to the demise of the 41B. These included the FD40 and FD50, but were only produced for a very short time before being discontinued.

The Allis-Chalmers/Fiat-Allis HD-41 was a contemporary of the Caterpillar D10, Komatsu D455A and Dresser TD40B.

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