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ConExpo 1975 Keeps on Truckin’ - ConExpo 1975 Part 5

Part five in a look back at ConExpo '75.

Thu August 01, 2013 - National Edition
Construction Equipment Guide

These ConExpo articles were published in Construction Equipment Guide (CEG) on March 5, 1975 and June 25, 1975, respectively. These and other ConExpo articles to follow will be part of a continuing series that take a look back at ConExpos past through the reporting of CEG. We hope you enjoy these retros as much as we did searching for them deep in our archives.

Every year brings new and bigger construction equipment and the developments in off-highway trucks have proved no exception. All types and sizes were on display at ConExpo in 1975.

Euclid Trucks

Euclid Inc. a subsidiary of White Motor Corporation, Cleveland, Ohio, introduced two brand new rear dump off-highway haulers to the construction industry at ConExpo 1975. These new units in 35-ton and 50-ton capacities are the beginning of a family of off-highway haulers, which embodies major design changes.

The new design advances on the R-35 and R-50 permit greater payload per tire, reduced wheel weight, increased bearing life, greater braking capacity and vehicle maneuverability and simplified accessibility for in-frame maintenance. These new units will be used primarily in heavy construction, mining, and quarrying service.

Euclid also introduced a 170-ton capacity electric wheel drive rear dump hauler.

The units are designed for heavy-duty service in moving overburden and ore in large mining operations.

The R-170, is an extension of the proven design concepts which have made the company’s trucks synonymous with excellent off-highway performance and durability. In appearance, the R-170 strongly resembles Euclid’s new family of trucks.


A new heavy duty, 55-ton hauler with 665 gross hp was displayed for the first time as part of the Terex Division of General Motors exhibit at Chicago’s ConExpo February 9 to 14, 1975.

Equipped with 24.00 x 35 tires, the new 33-09 can maintain high haul road speeds making it one of the fastest medium-sized haulers on the market. This, combined with the highest gross horsepower in its class, and a capacity of 55 tons, makes the Terex 33-09 an excellent performance machine big enough for large mining operations and quarries, yet nicely suited for highway jobs.

The Detroit Diesel 16V-71T turbocharged two-cycle diesel engine, coupled with a six forward speed Allison transmission (and lock up in the six forward ranges) provides the hauler with the necessary reserve power to take steep grades well. And the 33-09 is well suited for high country since it can maintain its rated horsepower to 10,000 feet.

Also on display was the Terex 33-07, a 40-ton range hauler with a Detroit Diesel 12V-71T turbocharged engine capable of producing 252 gross hp.. A high capacity air introduction system provides clean air, which contributes to long engine life. The engine combined with a six forward speed Allison Transmission, with lockup, permits the 33-07 hauler to utilize high haul road speeds.


Caterpillar displayed the 777 off-highway truck with 85-ton (77 Mg) capacity. This is the third and largest model in the line and has the same design benefits already proven in the 773 and 769B trucks: high productivity, reliability and easy servicing.

Maintenance in terms of convenience, reduced time and less effort is an outstanding feature of the 777. Only diesel fuel and hydraulic oil sight-gauge checks are at ground level; all the rest of the daily routine checks are easily made from the roomy, skid-resistant maintenance platform. The truck has “in-frame” serviceability without tight quarter confinements. The engine, torque converter, drive shaft, transmission and pump groups are easily reached without restrictive cross-over wires, lines or hoses. These components are also removable individually if desired.

The hauler is powered by the D348 V12 diesel engine rated at 870 hp, the same engine currently used in the Cat 992B 10-yd. wheel loaders. The loaded weight to horsepower ratio is 336 lb.-hp, lowest and best in its size class.

International Harvester

International Harvester entered the off-highway truck business in 1957 with the introduction of two vehicles — the 18-ton Model 65 PAY hauler and the 24-ton Model 95 PAY hauler. In the following 17 years, International’s PAY hauler line has evolved through new design concepts into a totally different, much improved version of its predecessor.

The original units followed standard design practices of that time … rear axle drive with the weight concentrated on dual rear tires to provide traction. The front axle carried only about 30 percent of the weight. Its main responsibility was steering.

This was a good concept according to International engineers, but there were some drawbacks:

1) Bodies were high and difficult to load because of the clearance needed for the large rear tires.

2) All the power went through a single drive axle, requiring large, expensive components that were difficult to service.

3) Tire overloading became a serious problem as truck capacities and haul speeds increased.

Changes were necessary. With the goal in mind of obtaining capacities of up to 50 tons in a truck that had the same physical characteristics as a conventional 35-ton unit, the engineers came up with a revolutionary solution: a truck with all-wheel drive and 50-50 weight distribution.

Using this approach, the company offered, after intensive engineering and field testing, the 180 PAY hauler 1963. The first completely new, off-highway truck in 30 years, the 180’s design parameters answered all the problems inherent in off-highway trucks at that time.

Here was a truck that applied one-quarter of its power to each wheel. And with equal weight distribution, one-fourth of the load was applied to each wheel. With equal power and equal load at each set of wheels, the truck obtained maximum traction and gradeability, according to IH.

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