Friday, June 27, 2014

Memorable Model: Caterpillar D8H


With an operating weight in excess of 47,000 pounds and a 235 HP turbocharged diesel engine for power, the Caterpillar D8H track type tractor literally changed the face of the world. First introduced in 1958, the D8H had more of an impact on the earthmoving industry than any machine before it and many, many after it. With an innovative new design that optimized operator comfort and usability to help maximize production, the D8H was quickly accepted as the industry standard for large earthmoving applications.

As testimony as to how advanced the tractor was when introduced, consider first that it was in production for almost 15 years. In the world of construction equipment, that in itself is an accomplishment that very few machines have ever attained. During that time span, more than 50,000 D8H tractors were delivered around the world. Their durability and enduring popularity is easily verified by the number of these tractors still in use today in every conceivable type of earthmoving operation imaginable.


The decision for Classic Construction Models to produce a model of the D8H was made in honor of the legendary status this machine earned, as well as to continue our 1:24 precision scale brass models that started with the release of the Caterpillar Seventy in 1996. Following the Seventy, we produced 1:24 scale models of the Caterpillar Ten and D2, the smallest gasoline and diesel powered tractors made by Caterpillar, and the D11R, the largest diesel tractor Caterpillar has manufactured to date. With this well established family of models, the decision to produce an H series D8 in essence the great grandson of the Caterpillar Seventy created a model that fit into the middle of the long line of legendary tractors produced by Caterpillar.

Although this model was released in December of 2004, development actually began in 2002 when CCM acquired a set of factory general arrangement drawings. After discussing the different versions of the H series tractors, it was decided to build a model of an early machine with a direct drive transmission and cable operated blade specifically a circa 1960's 36A machine. With the specific tractor selected, we began the process of sourcing all the information required to build a true, precision scale model.


As it turned out, the primary source of information for creating the model of this vintage machine was not Caterpillar, but instead the photographs, drawings and machine surveys we compiled ourselves. In addition to the schematics and diagrams, hundreds of photographs with measurements were compiled from two separate prototype 36A D8H machines.   

Countless days were spent examining the smallest details and documenting them for the model makers' reference. With this information, the process of creating the first model from raw brass began.

As museum curators know, there is no material better suited for creating mechanically accurate miniatures of complex equipment than brass. The ability to cast, etch, machine and form this metal at any scale is what allowed us to create a model that approaches being a part-for-part recreation of the actual machine. Unlike a die-cast model which must maintain a minimum thickness – regardless of the dimension of the original part – brass can be as thin or as thick as necessary. This means sheet metal on the real machine can be sheet brass on the model and parts that are cast in iron at full scale can be perfectly replicated in reduced size from cast brass. Similarly, the versatility of this metal enabled us to investment cast complete parts with shapes so complex they could never be successfully produced through die-casting or any other metal modeling method. The result, with hundreds of hand-made brass parts laboriously assembled into a single D8H model, is absolutely stunning.


Equipped with a Caterpillar No.30 front cable control unit that operates the working blade, as well as a working Carco J-120 winch mounted on the rear, the D8H model showcases the finest in modeling skills. The highly detailed 235 HP Cat diesel turbocharged engine, direct drive transmission and complete undercarriage are a perfect compliment to the individually-linked, free-rolling tracks complete with spring-loaded track tensioners and roller guards. A close look under the hood shows details such as the shrouded radiator fan with drive belts, as well as fuel injectors, manifolds, fuel lines and complete pony motor. Even the control levers are connected through the control panel into the engine compartment.

Other precision features include a full complement of operator's controls with gauges on the dash, moving levers and diamond plate flooring. Flawless exterior sheet metal work with rivets, accurate perforations on the radiator guard, front and rear spotlights and a working rain cap on the exhaust help complete this truly amazing replica.


With Caterpillar "Hi-way Yellow" paint and vintage markings, this model looks like it just came off the production line in 1960. Although the tool box next to the operator's seat is not strictly factory, it was decided to include it on the model for two reasons: virtually every operator we spoke to said that is where they carried their lunch box and thermos of coffee, and the opening lid on the tool box created the perfect place to put an engraved serial number plate for the model.

Because of the high level of skill required to assemble such a museum-quality model like the D8H, the number that can be produced is obviously very limited. Thus the total production for the model was limited to only 348, each one registered and certified, ensuring collectors the demand for this model will outlive those who created it.

The Cat D8H is one of the best examples of our continuing determination to produce construction equipment models at the highest of standards. We hope this legacy of limited edition models will continue to thrill construction collectors for generations to come, making it a necessity to find room for at least one of these legendary models in their collection.

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