Allis-ChalmersClassic Machines

The early Allis-Chalmers HD-16

One of the most popular of all Allis-Chalmers’ track-type tractors, the D8-sized model HD-16, first appeared in 1955 following the discontinuation of the former model HD-15. By Richard Campbell.

Like many of its competitors, Allis-Chalmers (A-C) got into the earthmoving business by acquisition, in its case, via the Monarch Tractor Company in 1928.

Monarch manufactured a line of successful small gasoline-powered track-type tractors, and A-C engineers began to improve upon these designs, creating a whole new range of machines.

These tractors began to appear in 1946, progress having been halted by World War II.

At this stage, A-C did not manufacture its own diesel engines and struck up a deal with General Motors to supply diesel engines for its new range of track-type tractors.

While not an ideal situation, it did get A-C products into the general marketplace and proved the feasibility of the company’s new tractor designs.

A-C had a stroke of good fortune when, in 1953, it acquired the Buda Engine Company which had been manufacturing engines since 1910, and built a wide variety of well-regarded diesel engines.

Buda had come up for sale and A-C wasted no time in finalising the deal; this provided it with a good range of proven engines.

The purchase of Buda came at a time when A-C engineers had been upgrading their tractor designs to make them more efficient and competitive against their rivals (principally Caterpillar and International Harvester).

This month’s subject, the HD-16, replaced the former model HD-15 which had been powered by a GM 6-71 diesel engine.

Launched with much media fanfare in 1955, physically, the HD-16 was a little larger than its predecessor and featured one of the newly acquired Buda diesels, a model HD-844.

This was a six-cylinder, naturally aspirated inline diesel and had a 148 flywheel horsepower rating.

A great selling feature of the HD-844 engine was its direct electric starting at a time when both of A-C’s major competitors still relied on alternative (gasoline) methods to start their diesel engines or offered direct starting as an option at considerably increased cost.

Two transmission types were offered: a six-speed direct drive manual transmission in the HD-16A and a three-speed torque converter drive type in the model HD-16AC.

It is worth noting at this point that A-C was a pioneer in the use of torque converters, its first tractor featuring this device (the model HD-19) appearing in 1947, several years before any other track type tractor manufacturer.

With standard transmission, the HD-16 was capable of 5.8mph and, with the torque converter transmission option, a slightly faster 7.2mph.

At the drawbar, in low gear, an HD-16 could pull 16,300kg with the direct drive transmission and 27,200kg with the torque converter transmission.

Like most track-type tractors of the era, the HD-16 was steered by hydraulically controlled steering clutches and contracting band brakes.

The brakes could be adjusted externally without having to get into the main case; quite a labour-saving feature and a feature common to A-C track tractors.

Both the HD-16A and HD-16AC were 74 inch gauge tractors with a six-roller track frame with two carrier rollers per side.

Standard tracks were 38-section with 20 inch track shoes, although optional shoes sizes could be fitted as the customer required.

It is worth noting that A-C were the first track-type tractor manufacturer to offer extended life rollers and idlers at a time when most track-type tractor manufacturers’ machines had to have their track rollers and idlers lubricated on a daily basis.

The operator had good visibility to both sides of the machine, and, due to the narrow width of the fuel tank, an excellent view to the rear as well for monitoring towed equipment.

Also, the hood was tapered from the rear (narrowest) to the front and, apart from the obligatory air cleaner, this allowed for a very good view forward for dozing operations.

An adjustable well-padded seat was supplied as standard equipment.

Full instrumentation was provided for the operator to monitor critical machine functions.

An enclosed cab with a heater was optional for winter operations.

Shipped bare from the A-C factory, an HD-16A weighed just over 14 tonnes and an HD-16AC around 14.2 tonnes.

Operational equipment antics

Prior to the introduction of the HD-16, A-C did not manufacture any of its own attachments, instead purchasing its blades, cable controls, rippers, and towed equipment from outside suppliers.

A-C traditionally used three main suppliers for this equipment: LaPlant-Choate, Garwood, and Baker.

Paradoxically, A-C purchased two of these manufacturers in order to become completely self-sufficient and build everything “in-house”.

LaPlant-Choate was its first acquisition in 1952.

LaPlant-Choate manufactured a full line of attachments and were also (up until 1946), a preferred supplier to Caterpillar.

This was a major strategic buy-out as LaPlant had developed its own motor scraper line and A-C were very keen to get a piece of that action.

Baker Manufacturing, a respected builder of bulldozer blades (cable and hydraulic), cable control units, rippers, and smaller towed scrapers, was purchased in 1955.

So, by the time the HD-16 tractor was introduced, A-C had a complete line of equipment to outfit its tractors! 

The HD-16 is upgraded

Over the 1955-1960 period, various tweaks were made to the machine in order to improve performance and increase productivity.

In 1960, two new versions of the HD-16 were introduced by A-C: the HD-16D and HD-16DC.

These did not replace the existing A and AC models but, in fact, had longer seven-roller track frames and, consequently, heavier base wights.

In 1964, a power shift transmission version of the tractor was offered for the first time.

This was the model HD-16DP, powered by a new 163 horsepower A-C 16000H naturally aspirated diesel engine and featuring a three-speed forward and reverse transmission.

Both the HD-16A and HD-16AC tractors were discontinued in 1964 with sales having dropped off due to customer preference for the longer track frame versions of the machine.

A further upgrade was undertaken in 1970 resulting in the model HD-16B. Still, this machine, quite different from the original HD-16, falls outside the scope of this article and will be covered in a later feature.

For the model collector

Unfortunately, at the time of going to press, I cannot find any models available in any scale of an A-C HD-16 other than a rather crude 1:87 scale offering intended for HO scale model railways.

For such an important and widely produced tractor, this is somewhat of a travesty, and it is hoped that some manufacturer will redress the situation before too long.

There are, however, models available of the HD-16’s larger sibling, the HD-21, but that is not really the point!

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