(Editor’s Note – the following article appeared in the June 25th, 1975 edition of Construction Equipment Guide).
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. A person standing near one would be in awe at just how big these trucks are and Business was frequently discussed in the dump body that was converted into an office.
Below are some of the highlights of these exhibits.
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 ’75. 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.
The new trucks present the culmination of more than two years of design, engineering, static and field testing by Euclid engineers to develop 35-ton and 50-ton capacity haulers.
Design parameters included better load balance between front and rear axles, lower loading heights, improved operator visibility, lower net weight, outboard-mounted hoist jacks, improved accessibility to major service components, greatly improved braking capability and improved body strength to take the load impact from today’s larger loaders.
Key to the new design is its lighter, welded steel frame assembly, which has three basic functions: as a major load carrying member; as the mounting structure for the suspension, power train and load carrying components; and to permit easy access to operating components.
The frame on both units is a combination off castings and fabricated sections. The assembly has undergone extensive static testing. Two fabricated box section main rails provide superior torsion resistance. These main rails are tampered outward to the front to permit easier access to the power train, while maintaining acceptable vehicle width. Main rails are bridged by only four cross members, along with a front bumper and front suspension tube. Reduction in the number of cross members, plus a shorter wheel base, allows a lighter main frame than in earlier vehicles of the same capacities.
Cross member castings, formed from high strength alloy steel, serve multiple functions. For example, the rear casting only serves as a cross member between the main rails, but as the body hinge mounting and the rear suspension mounting.
Main rails are designed to permit automatic CO2 arc welding, assuring uniform, high quality yields, superior penetration and good finished appearance.
A new suspension system with variable rate energy absorbing rubber elements contained in cylinders in both front and rear, and independent trailing arm for each front wheel are used. Inner and outer bearing life, on both front and rear wheels, has thus been balanced and substantially increased. Resulting improved weight distribution means longer tire life under normal operating conditions.
Front brakes have a far greater front axle braking capacity than previously available. “A” frame construction of the rear axle assures simple removal of the differential without removal of the rear axle itself.
All-steel cab of the R-35 and R-50 rear dumps is designed to permit greater operator visibility and, at the same time, make the vehicle easier to service and operate.
Forward placement of the cab in front of the front axle centerline offers excellent visibility and provides engine accessibility. Dash panel is full width and readily removed for instrument access. To reduce inside sound levels, the steer valve is located outside cab. In addition, cab interior is fully insulated for noise and temperature control.
Steering system has been simplified by reducing the number of valves in the system and by simplifying linkage and plumbing. Performance is improved by increasing available steer effort and reducing steer turns. Time and number of steer turns from lock to lock have been reduced, as well as the turning cycle. Body of the new off-highway haulers is specifically designed to permit low loading heights and greater load impact and to present a better loading target. The R-50 body easily carries 50 tons (45.4mt) with a 37.9 cu. yd. compatibility with front end loaders is assured in four ways. First, the low loading height – in the R-50, 11’-7½’’ (3543mm), in the R-35, 9’11’’ (3023mm) – allows popular loader sizes sufficient clearance to clearly dump a bucket load. Second, the long body length – the R-50, over 21’ (6.4m), the R-35, over 17’ (5.2m) – accommodates wider loader buckets.
Third, the large target area – in the R-50, 241 sq. t. (22.4m2), in the R-35, 191 sq. ft. (17.8m2) – minimizes bucket spot time and shortens load time. And fourth, the “horizontal floor” allows proper heaping and load distribution by the front end loader.
Side impact resistance is provided by an award-winning side rail design which spreads the shock loading along the length of the panel similar to a highway guard rail. The side rail, top rail and bottom rail form a “sandwich” panel with the outer “skin” and side plate. The outer body skin serves as a tension member to prevent inner vertical buckling of the side panel. Vertical impact resistance to large bucket loads is accomplished by closely spaced floor stiffeners and 100,000 psi (689MPa) yield strength steel ¾’’ in the R-50, and 5/8’’ in the R-35. Outboard mounted, two-stage hydraulic jacks assure fast discharge with minimum side sway during dump.
Euclid, Inc., also has 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 wheel base of 18’-6’’ and a front axle track of 17’-7’’ gives the new vehicle excellent balance, a low center of gravity, and a loading height of only 17’-5’’. Because of the truck’s low profile, load shifting is less likely, reducing stress on the suspension. Tire life is also extended considerably.
The R-170 is equipped with a front trailing arm suspension (similar to those proven on the other Euclid haulers), and a rear “A” frame linkage. Ride struts front and rear use a unique, energy-absorbing compressible fluid, operating on a displacement principle. The piston rod entering the cylinder tube displaces the volumes occupied by the fluid, forcing it into compression. The special silicone-based fluid has a 12 percent compressibility factor which allows, through proper sizing of components, a suspension system yielding a soft ride when empty and a firm ride when loaded. The fluid does not require a nitrogen pre-charge, as do many competitive units.
The design maintains independent front wheel suspension, contributes to greater tire life preventing tire “skuffing,” increases comfort and production because operator averages higher haul road speeds.
A 1600 hp diesel engine, direct-linked to an alternator, provides through a rectifier the power to the individual electric drive motors in each rear wheel. The R-170 power module is designed to give fast acceleration under load, reaching operating speed quickly without excessive engine wear.
Dynamic electric retardation is achieved by direct current wheel motors, linked to a resistor grid package located on the cab deck. The system provides up to 2300 hp in braking for controlled, safe descent for down-hill hauls. Optional extended range retardation is available for severe down-grades where slower speeds are required.
A new heavy duty, 55-ton hauler with 665 gross horsepower was displayed for the first time as part of the TEREX Division of General Motors exhibit at Chicago’s CONEXPO ’75 February 9-14, 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.
The low rail height, 12 feet, and rectangular body design simplify loading by providing a wide target area for both front-end loaders and shovels. The 33-09 is well matched with the TEREX 72-81 loader.
The new 33-09 hauler is equipped with a nitrogen over oil suspension system which compensates to match the load and reduce shock loading. The system reacts rapidly to road shock, thus reducing tire flexing.
As with all TEREX haulers, easy access is provided to service points and major components. Systems such as air filters, hydraulic tanks, fuel and other filters are easily reached. Steps are provided on both sides of the unit, and the large service decks are equipped with safety guard rails. These areas are skid resistant coated.
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 horsepower. 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.
The TEREX 33-07 is 27’7’’ long and 13’4’’ wide with a 13-foot wheel base. It has a 42-degree turning circle on full hydrostatic closed center steering with positive steer feedback. Steering hydraulics are separate from body hydraulics.
An important design feature on TEREX haulers is the full box section frame which incorporates high alloy steel castings of 95,000 PSI yield strength. The wide radii castings feature torque tubes with the frame to reduce stress concentration in critical joints.
The smallest of the three TEREX haulers on display was the 33-05, a 28-ton class truck ideal for small quarry and general contractor work.
Equipped with a Detroit Diesel 8V-71T turbocharged engine, the 350 gross horsepower engine gives the 33-05 a high top speed. Its Allison fully automatic transmission has reverse and five forward gears with lockup.
As with all TEREX 33 series haulers, the 33-05 is designed to increase comfort and, there by productivity of the operator. The plush two-man cab interior includes wrap-around dash console, large window area and tinted glass for road visibility. Adjustable four-position steering wheel and six-way adjustable operator seat provide additional operator comfort.
The cab is acoustically thermatically insulated, and includes heater, door locks and simulated wood grain dash console paneling as standard features. Cab air conditioning is available as a factory-installed option.
The 33-05 relies on drum and shoe-type brakes with separate braking systems for front and rear. An Allison transmission retarder provides additional braking control. A wet-dry road valve with control mounted on the instrument panel enables the operator to adjust front wheel braking to slippery road conditions.
A mechanical safety brake actuator lock keeps the 33-05 parking brake applied, serves as backup to the air system and meets OSHA requirements for parking full loads on a 15 percent grade.
Caterpillar displayed the 777 Off-highway Truck with 85-ton (77 Mg) capacity at CONEXPO ’75. 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 FWHP (649 kW), the same engine currently used in the Cat 992B 10-yard (7.65 m3) Wheel Loaders. The loaded weight to horsepower ratio is 336 lb-hp (204 kg-kW), lowest and best in its size class.
The automatic power shift transmission, controlled by a single lever, has 7 forward speed ranges to 33 mph (53 km-h) and one reverse speed. 1st and reverse are torque converter drive for high torque to quickly overcome inertia. The 2nd range is converter drive with automatic shifting to direct drive. The remaining ranges through 7th are all fuel-saving direct drives with momentary converter drive between each. This cushions and smooths the shift, helping to retain the load during the haul. The transmission will automatically shift up or down between the 1st gear and whatever other gear the operator selects.
Cat oiled-disc brakes at the drive axle perform regular service and emergency braking and all parking and retarding. The sealed and fade resistance brakes have a continuous retarding capacity including engine resistance of 110 hp (820 kW).
The suspension system is Caterpillar oil-pneumatic. Two independent, self-contained nitrogen-over-oil cylinders on each axle absorb the loading and hauling shocks for increased structural life, greater operator comfort and control.
Box-section construction assures strength and rigidity of the main frame. This backbone supports the other frame members through steel castings at the critical stress areas. The castings allow moving the weld joints from the high stress to the low stress areas. This helps combat fatigue from the twisting, bending forces, assuring durability.
The body’s floor, front and sides are of 90,000 psi (621 mPa) yield strength steel, supported by ten wrap-around ribs. The box-section ribs use steel castings at the intersection of the floor and sidewalls to strengthen that critical area. Heavy duty body liners are available for abrasive and impact applications.
The truck’s loading height is 13’7” (4140 mm) with body width of 15’1½” (4610 mm) to accommodate various loading systems with ease. The body will hold 47.5 cu. yd. (36.3 m3) struck and 67 cu. yd. (51.3 m3) heaped with a 2:1 slope load. The truck’s overall length is 32’1” (9780mm).
The all-steel cab is sound suppressed, insulated and features integral ROPS and excellent visibility. Standard accessories include emergency steering, downshift inhibiter, emergency brakes, parking brake, heater, defroster, windshield wiper and washer, international dash gauge symbols, full suspension seat, seat belts and visual and audio devices warning operator in advance of pending system problems.
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.