Image: Seen amongst spectacular scenery, three of New Zealand-based Baker Construction’s International PayHaulers, (two 340s and a 350) pose beside Lake Pukaki. They are being loaded by another International product: a model 560 PayLoader. PHOTO: AUTHOR’S COLLECTION
The model 350 PayHauler owes its origins to an earlier series of machines developed by
International Harvester in the early 1960s and officially introduced in 1964. By Richard Campbell.
International Harvester’s original haul-truck, the model PH180, was the first successful four-wheel-drive off-highway dump truck offered by any manufacturer, and it carried a useful payload of 45 tons.
International engineers had spent considerable time on their all-wheel-drive truck to ensure that it carried 50 percent of the load on each axle, which made for a very well-balanced and stable haul platform.
International’s design brief was for an all-wheel-drive truck with excellent gradeability, useful payload, manoeuvrability and the ability to negotiate soft underfoot conditions without getting stuck, and working in conditions that would usually shut other jobs down.
International Harvester had quite a niche market for these off-highway haulers as no competition existed until the advent of 50-ton capacity ADTs in the 2000s.
International chose a 433-flywheel horsepower GM Detroit Diesel 12V-71N, V-12 diesel to power its PH180 which was connected to a Twin-Disc 10-speed powershift transmission (IH did not manufacture a diesel of its own with a high enough output to be installed in the PH180).
A ‘ready for work’ PH180 PayHauler weighed around 31 tons empty.
Despite some initial industry scepticism, sales of the PH180 PayHauler rose steadily after the vehicle was shown to be a good performer.
This encouraged International to undergo some modifications to the machine, increasing its usable payload to 50 tons. This ‘new’ PH180 was introduced in 1968.
In order to cope with the extra payload, a more powerful engine was installed: the 537-flywheel horsepower GM Detroit Diesel 16V-71N, which was a big V-16 monster.
International also offered, for the first time, an optional Cummins VT1710C, turbocharged V-12 diesel, that also rated at 537-flywheel horsepower, for those customers who preferred the Cummins power plant.
The Twin-Disc powershift transmission was retained.
Front axle steering was fully hydraulic, accomplished by two identical double acting cylinders.
The PayHauler 350 featured dual tyres on both axles, usually 18.00×25, 32-ply, and had air operated shoe brakes on all wheels.
Good old fashioned leaf springs with attendant shock absorbers were the only suspension system offered on the PayHauler and, apart from occasional problems with the front leaf spring packs, these performed well in service.
One of the great benefits of the 350 PayHauler was its very low loading height that allowed loading by a wheel loader, shovel or excavator and presented a good ‘target’ compared to many of its contemporaries.
The dump body was fabricated from 1,000,000 psi high tensile heat-treated steel in a ‘mono-floor’ design and was raised and lowered by two three-stage hydraulic cylinders that could hoist the body to its full dump height of 67° in 17 seconds.
Mounted offset to the left was the operator’s cab. This was not particularly large and had a ‘jump seat’ behind the operator’s seat for a passenger or learner operator.
Visibility, as with any off-highway hauler, was reasonably good to the operators left but marginal at best to the right.
Model 350 PayHauler
By the early 1970s, the PayHauler range needed a revamp, which conveniently leads us to the subject of this article, the model 350 PayHauler.
International essentially modernised the existing PH180 with the new machine, now called the model 350, having an all-new cab and numerous improvements to the suspension system, brakes, service accessibility and adherence to new ROPS regulations.
The new model 350 PayHauler first appeared in 1973 amid much advertising.
Power was still supplied by the naturally aspirated V-16 Detroit Diesel 16V-71N with the Cummins VT1710C V-12 now a standard option. Both engines rated at 537-flywheel horsepower.
The modernising and strengthening carried out by International Harvester to create the new model 350 added over a ton of weight to the base weight of the machine, which rose to approximately 32 tons for the GM-powered units and 32.5 tons for the Cummins-powered examples.
Due to popular demand, International also offered a specific coal hauler version of the model 350 with a high-sided dump body which held over 80 cubic yards of material!
Not one to rest on its laurels, in 1979 International again upgraded the model 350 to the model 350B.
This variant featured more power in the form of an uprated GM 16V-71N-65 V-16 diesel rated at 580-flywheel horsepower, or an upgraded Cummins VT1710C V12 diesel with a 607-flywheel horsepower rating.
One of the more notable changes was in the design and construction of the dump body, which had a reduced number of side stiffening members.
There were also changes to the air induction system allowing the engine to ‘breathe’ more easily.
Records show that more Cummins-powered 350B PayHaulers were delivered than GM-powered examples.
A new company
Regrettably, International Harvester imploded in 1982, and a separate company was set up by ex-employees that they called the Payhauler Corporation.
Production was shifted from Chicago, Illinois to Batavia, Illinois, where the new company continued to manufacture and sell PayHauler 350B’s, and, to the surprise of everyone, in 1986, introduced a further upgrade to the design – the PayHauler 350C!
Payhauler Corp offered Detroit Diesel, Caterpillar, or Cummins engines for its new baby, and offered a new six-speed powershift transmission.
Unfortunately, the new venture did not last very long, and, in 1998, the Payhauler Corporation was bought by Terex which marketed the machine until 2003 when Caterpillar acquired the company.
Since 2003, no new PayHaulers have been produced; Caterpillar electing so far not to proceed with any production or further development of the design.
For the model collector.
Model collectors are in luck as several models of the International PayHauler have been issued over the decades.
Probably the finest of these is a 1:25 scale offering from diecast manufacturer First Gear that is quite a showstopper and exceptionally well-detailed.
There is also a 1:25 plastic kitset offering from Ertl that, with careful assembly, makes up into an impressive model.
Both large 1:25 models represent the initial production version of the machine.
Black Rat models of the UK also produced a PayHauler 350C to 1:50th scale.
The Black Rat model is beautifully made, but virtually unobtainable as it was produced only in very limited numbers (as is the case with all Black Rat models).
