The Allis-Chalmers 12G loader

Allis-Chalmers, in its heyday, was known as a very innovative company. Be it in engineering or design, it could be counted on to provide the goods and the model 12G loader was no exception to this rule.  By Richard Campbell

Up until the early 1960s, all of Allis-Chalmers’ track type loaders had been based on the chassis of one of its existing crawler tractors, and identified by the letter ‘G’ after the model number.

For example, the model HD-6’s equivalent track loader variant was the HD-6G, HD-11 the HD-11G and so on.

The Tractomotive Corporation was the major supplier of track loader conversions for Allis-Chalmers, and by 1959, had become a wholly owned subsidiary of Allis-Chalmers, supplying both track and wheel loaders.

During the 1960s, the requirement for more modern track loaders in everyday earthmoving was increasing all the time, and in a forward thinking move, Allis-Chalmers engineers designed its very first, fully integrated track type loader, the model 7G in 1961.

This was intended to compete with Caterpillar’s new 955H and International Harvesters model 175B, both of which had been introduced to the market the year before and were doing well sales wise.

Allis-Chalmers did not wish to be left out of the picture, and its existing models of track loaders were by now getting quite long in the tooth, so a change was required.

The model 7G introduced by Allis-Chalmers in 1961 was broadly based on the previous HD-6G but was a completely integrated track loader from the outset and featured pedal steering which considerably reduced operator fatigue compared to the lever steer track loaders of the opposition.

Allis-Chalmers, delighted with the success of the 7G, pursued the idea of an even larger variant of the 7G and came up with the prototype 12G in 1966.

After a period of testing in the company’s Arizona proving grounds, the type was put into full production in 1967, being officially announced to the public at the 1967 CONEXPO.

As well as having pedal steering, the 12G also had its radiator and oil coolers relocated to the rear of the machine where they were far less vulnerable to damage.

This was particularly important in the kind of work undertaken by larger track loaders such as landfill, demolition and logging skid sites.

The initial production model 12G weighed approximately 22 tons and was equipped with a 3 cubic yard bucket.

Allis-Chalmers chose one of its own model 11000 six-cylinder diesel engines to power the 12G and this was rated at 185 flywheel horsepower.

The 12G was a direct competitor of the Caterpillar 977L and International Harvester model 250C.

Constructed around a massive steel tub for utmost protection, the Allis-Chalmers 12G had a solid nose cone, and as mentioned previously, the radiator and oil coolers were in the rear.

These were cooled by a fan, driven off an extension shaft from the engine.

The fan was a blower type but could be reversed in winter to provide some heating for the operator in colder climates.

Allis-Chalmers used a two speed forward and reverse powershift transmission, manufactured by Twin-Disc which allowed a top speed of around five miles per hour.

Steering was accomplished by multiple steering clutches and contracting band brakes which, given the mass of the 12G, were oil cooled.

The machine rode on a 7-roller track frame with grease tension adjusted front idlers.

Nominal track shoe was an 18-inch triple grouser type but other sizes and configurations could be installed to suit the customers requirements.

The loader frame itself was of the parallel linkage type and could accept a variety of bucket types and sizes.

A special version of the machine was also created especially for demolition work, which included increased thickness belly guards, engine bay guarding, a beefed up track frame with heavy duty roller guards, and either single or double grouser track shoes as standard equipment.

These machines were usually supplied with a 4-in-1 bucket and extra counterweight (or a ripper) on the back.

Neither the ripper or counterweight interfered with engine cooling.

In 1971, the 12G got an upgrade resulting in the new model 12G-B.

Externally there were very few differences apart from the application of ROPS mounting pads.

Under the bonnet, the engine output was increased by another 10 horsepower (up to 195) and the hydraulic pump was replaced with a higher output type which increased the bucket breakout force from 13 tons to 16 tons.

Interestingly, overall weight of the 12G only rose by about a quarter of a ton.


Apart from the special demolition spec machines, there were a number of extra items you could hang off your 12G.

These included a ROPS canopy, full ROPS cab (with heater & demister), track guards, ripper, winch, extra counterweights, log forks and various capacity buckets with or without teeth.

Interest in large track loaders began to wane in the mid-1970s.

Allis-Chalmers, who had now become Fiat-Allis, were not immune to this downturn which also saw the complete exit of some of its competitors from the track loader market.

Ultimately in 1974, the plug was pulled on the 12G-B and the type faded into history.

Total sales of both the 12G and 12G-B was around 2,500 machines.

Owners and operators of the 12G and 12G-B considered it a fine well balanced machine with few vices.

The New Zealand Connection

Regrettably, no records exist of Allis-Chalmers model 12G importations (if indeed there were any).

Prior New Zealand Allis-Chalmers dealer CablePrice records are non-existent due to company reorganizations, shifts etc.

Your author has never sighted any in New Zealand but that is not to say that there aren’t any about.

If you know where a 12G is in this country, please let us know.

For the Model Collector

The Ertl 1:16th scale Allis-Chalmers 12G loader

There is one model of the Allis-Chalmers 12G loader available and it was first offered for sale over 40 years ago!

It was made by Ertl and is to approximately 1:16th scale.

Basically resembling a 12G, the model was really designed for the sandpit and has over scale moving parts and rubber tracks.

It has been issued several times over the years, latterly in Fiat-Allis garb, labeled incorrectly as a “12G-B”.

A good example will set you back over US$350.


Brief Specifications – Allis-Chalmers 12G (1969)

Engine:                        Allis Chalmers model 11000, 6-cylinder, turbocharged diesel rated at 185 flywheel  horsepower at 2000 rpm.

Transmission:             Twin-Disc 2-speed forward & reverse powershift transmission

Top Speed:                  5 mph

Steering:                      Combination steering clutch & brakes

Track Gauge:              76”

Track Frame:              7-roller

Track Chain:               42-section, sealed

Standard Shoe:            18” triple relieved grouser

Standard Bucket:        3 cubic yard, general purpose

Operating Weight:      22 tons

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