Upton Tractors (This article is taken from the August 1979 Power Farming Magazine, it is not intended for commercial purposes)

A CHAMPION FOR THE TWO WHEEL DRIVE

While tractor makers around the world have turned to four-wheel drive to utilize the engine power available in today's large agricultural tractors, a young enthusiastic engineer and tractor maker in Australia crusades strongly for the two-wheel drive configuration.
Carl Upton, of Upton’s Engineering, a country manufacturing outfit in southern NSW, is a delightful young man with a strong pas­sion In life — building farm tractors which are heavier and better than any he knows. And even more importantly, to de­monstrate a principle he has long espoused in tractor de­sign. He believes, up to a point, two-wheel drive trac­tion will do everything and more than four-wheel drive. The point is up to 350 horse­power! But what you really have to like about Carl Upton is that he is prepared to put his money where his mouth is. Further, he is also prepared to lake his giant tractors to ma­jor field days and "take on" the big four-wheel drives, Pulling some or the giant rigs on demonstration.
Some of the major makers look askance when Carl, Un­deterred, backs up to a huge machine that has some of the biggest 4-wds scratching to pull them. In turn, heads are scratched when he walks away with the load.
What's the secret? Carl says there is none. It's just a matter of weight — plenty of it in the right place — and lyres big enough to accept the load at reasonable wheel slip per­formance.Well, if it's weight you need. the tractors built by Carl Upton are not lacking. How docs an operating weight in excess of 23-000 kg (51 000 Ib) for a two-wheel drive trac­tor sound? Admittedly, we are talking about a 350 hp tractor (gross engine) but that's con­siderably more weight than found in many of the big four-wheel drives.
Carl Upton has been custom building big tractors for some years and is adamant that four-drive wheels arc not needed for tractors under 350 horse­power. Many tractor men would argue about that and are skeptical about Carl's philosophy and his claims that he can build tractors up to 350 engine horsepower that have lower wheel slip than 4-wds and consequently higher drawbar efficiency. ,
You may ask — how does he achieve such massive weight? If we take a brief look at the biggest Upton unit yet built — the HT 14/350 (14 fwd gears 350 hp) the weight of material used in the back end is nothing short of stag­gering.The rear halt of the chassis is constructed from 4 in. thick plate and the bare chassis weight is 6 tonnes, with main front chassis members con­structed from 15 x 6 x 1/1/2 channel.
Another example of the massive weight and strength built into the Upton machine is the 350 gal fuel tank which has a floor made from 2-3/8 in. plate with the balance of the construction utilizing 1 in. plate. Weight of the fuel tank empty is 3 tonnes.
The eye-opener drawbar needs special mention, as I doubt if there is a more massive similar component on any (arm tractor in the world It weighs about 680 kg (1 500 Ib) and is made from 6 x 4 in. plate and is contained within a 4 in. plate frame. And just for the record, the pull is taken on a 3 in. diameter hardened steel pin!
With existing agricultural tires being too small to meet the traction demands of two drive wheels only, Carl Upton turned to earthmover tires and is more than happy with the result. The HT 14/350 is equipped with 33.5 x 33 x 20 ply tires which have a circumference 20% greater than the 30.5 x 32 agricultural tires commonly used on big tour-wheel drives.
Carl is satisfied that the earthmovers have more than lived up to his expectations, providing u high efficiency of traction with adequate flexing for agricultural work during extreme drawbar pulls.
In more philosophical' detail, Upton claims that any 2-wd tractor should carry most of its weight on the rear drive wheels. The Upton trac­tor puts this into effect with static weight of 20% on the front and 80% on the rear and the long (3.9 m) wheelbase helps stabilize weight transfer and provides a smooth ride.
In fact, when the tractor is under load, dynamic weight on the drive wheels can be as high as 88% of the total vehicle weight.
Although overall, of rigid frame design, the tractor frame is built in two sections of the dimensions referred to earlier. The rear portion of the frame as can be seen in the photographs is of massive box construction to resist distor­tion in any direction.
The drive axle has a capaci­ty of 29 545 kg (65 000 lb) and the planetary gearing in­corporates guided needle rollers and nitrided gearing. Reduction ratio is 4.32:1.
The driving head assembly is an Eaton 23121 series with a 6.17:1 ratio. Overall ratio is 26.65:1.
The axle is wholly of Australian design and manufacture, excepting the Eaton driving head.
The only tires offered, as mentioned, are 33.5 x 33 20 ply E-2 earthmover singles. Because of the weight, width and tangential pull limita­tions, any smaller tire dualled would be overloaded, says Carl.
Adequate flotation is provided by a large ground contact area of 5 907 sq cm (900 sq in.) per tire.
Operators are well protected from the elements by the cab which is of module design located on four rubber mounts and is a self contained unit.
Whatever conjecture there may be about Carl Upton's philosophy on 2-wd v 4-wd, it would be hard to find a critic of the finish of his product. In particular, the cabin and cabin layout is exceptional in concept and comfort. The cabin, one of the biggest in the game, probably the biggest, is designed for function and comfort down to the last detail.
Electrical connections are handled by bulkhead connec­tors on the firewall. All other controls are cable operated so no solid metal shafts can transfer noise and vibration and cause dust sealing problems-Gauge instrumentation in­cludes a temperature gauge, oil pressure gauge, ammeter, tachometer, hour meter and exhaust pyrometer and turbo-charger boost pressure gauge.
Indicator lights monitor engine oil temperature, transmission level, low air pressure, tow water level and the park brake operation. In addition, a Micro guard engine protection system op­erates on the engine water temperature, engine block water pressure and engine oil pressure.
An exclusive feature of the cab control layout is the method of mounting the throttle, pneumatic gear shift valve and the parking brake valve on the side of the swiveling seat. This permits the operator to control tractor speed and gear changes regardless of the direction he is facing inside the cab.
Also, by grouping the con­trols in this way, the tractor can be driven through the gears similar to a road transport, when operating on the road, pulling large four-wheeled trailers.
Among other standard cab features are air conditioning, stereo radio, interior light, two speed windshield wiper and washer, a soft feel steering wheel, and lockable door.
A fail-safe airbrake system has been included to ensure the vehicle has excellent brak­ing performance. This system has proven to be extremely safe, reliable, and virtually maintenance free.
The 514 mm x 178 mm drum brakes are operated by Westinghouse spring brake chambers. If for any reason air pressure is lost, the brakes will automatically be applied.
However, if this should happen, the brakes can still be operated by an emergency over-ride system. All the brake system components are common to the transport in­dustry, with service and spare parts readily available throughout the country.
The tractor is powered by a turbocharged and after-cool­ed Cummins 6-cyl diesel engine which produces 261 kW (350 hp) at 2100 rpm. Maximum torque is 1 365 Nm (1 006 lb ft) at I 500 rpm with a torque rise of 15% .
Driveline components in­clude a Spicer two-plate 15-1/2in. clutch, a Spicer SST-14 transmission and Spicer 1710 series universal joints.
Performance-wise, Upton claims that field tests have in­dicated that the HT 14/350 can produce a sustained pull in excess of 90 kN (20 000 lb) without water ballast in the rear tires. With the tractor fully ballasted, a drawbar pull of 133 kN could be realized it is claimed.
It is also said that despite its high engine power for a 2-wd configuration, the engine can be full loaded in the field at speeds as low as 6.4 km/h. The low speed lugging ability can be attributed to the high weight to horsepower ratio of 147 Ib/hp. The adjustable height drawbar (through 24 in.) fully utilizes weight transfer and provides in­creased traction under load.
Carl Upton rightfully claims that the HT 14/350 must surely be one of the world's most unique farm tractors.
And in talking to him, he frequently gets back to the theme that the ability of the tractors he builds to transmit full engine power through two driving tires must surely place a big question mark on the need for four-wheel drive tractors in the high horse­power range as used in large scale farming operation.