Celebrating 50 Years

Caterpillar’s medium wheel loader range clocks up half a century

In December of 1959, the first production Cat wheel loader – the 944 Wheel Traxcavator – was driven off the assembly line at the Caterpillar plant in Aurora, Illinois.

The 944, fitted with a 2yd3 (1.5m3) bucket and available with either a 105hp (78kW) gas or diesel engine, was the culmination of a seven-year development effort and the beginning of five decades of Caterpillar machines in the worldwide market for mid-size wheel loaders.

The 944 was joined in 1960 by two additional models, the 80hp (60kW) 922 model and the 140hp (104kW) 966 model, using buckets of 1.25 and 2.75yd3 (0.92 and 2.1m3) respectively. A 1960 Caterpillar press release stated ‘these machines are operated by conveniently located controls, have a two-speed forward/two-speed reverse powershift transmission and attain a maximum reverse speed of 30 miles/h.’

The release also quoted W.S. Zeigler, domestic sales manager, who summed up Caterpillar’s goal for developing the new wheel loader line: ‘These new Traxcavators will enable operators to perform their work quickly and well, and give them safer working conditions’.

Time changes almost everything, but the basic qualities Mr Zeigler noted about the first Cat wheel loaders have remained constant throughout 50 years of continual refinement and through the placement of more than 100,000 Cat medium wheel loaders in the hands of customers.

Although the Cat wheel loader line today ranges from the 55hp (41kW) 904B to the 1,577hp (1,176kW) 994F, the eight-model line-up of medium wheel loaders — 938H, IT38H, 950H, 962H, IT62H, 966H, 972H and 980H — remains the foundation of the line and serves the largest market segment. These models offer standard buckets from 3 to 8yd3 (2.3 to 6.1m3), can be fitted with a diversity of work tools and can take on the toughest jobs in applications as varied as material handling, scrap yards, quarrying and forestry.

Developing new products in the 1950s was a long, laborious process, necessitating many prototype models and thousands of hours of in-the-dirt testing. Today, the power of computer-aided design allows the testing of virtual prototypes, and today’s engineers can perform more evaluation in a matter of hours than could their 1950s counterparts in months of field testing.

However, the basic philosophy of Caterpillar’s product development process has not changed; when designing the 944, engineers asked customers what features they wanted in wheel loaders, and Caterpillar engineers are still asking that question today. The 944 engineers learned, for example, that wheel-loader users wanted loader arms and hydraulic cylinders positioned in front of the operator’s compartment, because the side-mounted loader arms of the day’s competitive designs brushed past the operator’s elbows with every bucket load.

Through the decades, the design of Cat medium wheel loaders has continued to reflect customer input and the best technology to yield efficient, durable, safe and economical machines.

The 944’s pre-combustion-chamber diesel engine, for example, gave way in the early 1980s to more efficient direct-injection engines, then to electronically controlled engines, and finally to the Cat ACERT diesels that deliver a combination of fuel efficiency, emissions control and power density that 1950s engineers would have thought impossible.

Likewise, early loader hydraulic systems, using gear-type pumps and mechanical controls have been refined into efficient load-sensing systems that use variable-displacement pumps and pressure-compensating valves to reduce horsepower draw and save fuel. In the cab, long-throw hydraulic control levers gave way to lower-effort pilot controls, then to intuitive electro-hydraulic joysticks that provide precise hydraulic response in all operating situations.

Caterpillar were also early pioneers of articulated steering, using proprietary center-hinge designs that greatly improved manoeuvrability — and today’s optional Command Control Steering allows lock-to-lock articulation through just ±70° of wheel turn. Similarly, the 944’s drum brakes gave way to more efficient disc brakes, then to internal multiple-disc brakes in the Cat four-piece axle, which is an exclusive component in every medium wheel loader.

Powershift transmissions, once controlled by mechanical linkage, are now electronically managed and feature Variable Shift Control to match gear-change patterns to the application. Belt-driven cooling fans have given way to fuel-saving ‘on-demand’ fans; loader linkages have been strengthened and simplified; and the stark operator stations of early loaders are now the ultimate in comfort, convenience and safety (even allowing hands-off operation when the optional Aggregate AutoDig system is used to automate the loading process).

And compared to the 944, today’s Cat medium wheel loaders actually do ‘think’ for themselves. The Cat Monitoring System continually checks machine health; Product Link, a satellite-based system, provides two-way information exchange between on-board machine systems and the Caterpillar Network Operations Center; and the Equipment Manager System places Product Link data on the owner’s computer screen, allowing efficient management of machine utilization, maintenance/repair decisions and security risks. 

W.S. Zeigler’s words are still true of Cat medium wheel loaders. Today’s machines continue to deliver the essential reliability and durability that has been the hallmark of Cat wheel loaders from the start. And building on the persistent refinement of their predecessors, they continue to add greater value for the operator, the owner and the environment.