This Tractor Is Freaking Huge

The Big Bud 747 V16 doesn't need acoustic guitar or gruff narration from Sam Elliott to make its point. Such tricks are for 600-horsepower pickup trucks.

A turn of the ignition says all the machine needs to say. Sixteen pistons vibrate a body that weighs over 100,000 pounds. Twin plumes of black diesel smoke flee silver exhaust pipes above the cab. When linked with a cultivator, the machine can deep rip 36 inches deep at a rate of 20 acres per hour. This thing eats name-brand farm equipment for breakfast.

Ron Harman never intended to build the biggest farm tractor in the world. “It was really built because of a need,” says Harman, who still makes a living building and refurbishing custom tractors. The Rossi Brothers, cotton farmers from Old River, Calif., came to Harman’s Northern Manufacturing Co. (now Big Equipment L.L.C.) for a machine that would let them quickly deep rip a third of their ground once a year. Whatever the company came up with would have to haul an 35,000-pound, 80-foot cultivator through tough western soil without a hiccup.

The final product stood as a testament to the late 1970s farm boom. Rising commodity prices and increased farm sizes pushed farmers to invest in bigger, more efficient pieces of equipment. When John Deere or Massey Ferguson couldn’t meet the requirements, farmers looked to Harman for custom-built machines.

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Since no one in the agricultural industry made parts for a tractor that big, the 85,000-pound Clark axles picked for the order, along with just about every other part on the tractor, came from either the mining or construction industries. Even then, parts had to be beefed up. Unlike a coal loader, the torque and stress on the machine would be continuous.

747 crew

The crew that built the tractor. Image courtesy of Big Equipment LLC.

Realizing the Big Bud was something of a test bed for larger-scale tractors, Northern Manufacturing built a frame that could handle available parts from a range of manufacturers. “The best thing about the tractor was that if any of those components wouldn’t have worked, we hadn’t painted our self into a corner,” says Harman. Versatile engineering, not the ridiculous claim of 950 horsepower, has always been the main point of Harman’s pride for the Big Bud 747.

The craftsmanship helped the tractor keep running — save a few pit spots — from 1977 until its recent retirement. After serving at farms in California and Florida, Randy and Robert Williams brought the tractor to their farm in Big Sandy, Montana and restored it to near-mint condition. They only agreed to lend the tractor to the Heartland Museum in Clarion, Iowa after opting for no-till farming.

“We are tickled to death to own it,” says Randy Williams. Some are tickled to death just to drive it. John Harvey, a tractor aficionado, found the experience so compelling he wrote a coffee table book full of facts, stories and pictures on the Williams Brothers’ tractor.

For the gear heads out there, here are the stats on the tractor.


Torque Converter: Twin Disc 8FLW-1801

Type: 18in. (45.72 cm) circuit with lock-up clutch

Blading: MS-380

Forward speeds: 6

Reverse speeds: 1

Axles: Clark D-85840

Brakes: 26 in x 8in (66.04 cm x 20.32 cm) airbrakes, all wheels

Hydraulic system type: Load-sensing system allowing maximum pump flow to steering and implement valve.

Maximum flow: 65 gal/min (245.96 liters/min)

Tank Capacity: 150 Gallons (567.64 liters)

Relief pressure: 2000 psi

Implement valve: 4-spool open center, 60 gal/min (227.05 liters/min)

Steering: Orbital motor with 100 cubic inch (1.64 liters) displacement per steering wheel revolution

Steering cylinders: Double action dual cylinders, 4.5 inch (11.43 cm) bore


95,000 lb (38,636 jg) estimated shipping weight

130,000 lb (49,895 kg) ballasted weight


Wheelbase: 16 feet, 3 inches (4.95 meters)

Height (top of cab): 14 feet (4.27 meters)

Length (frame): 27 feet (8.23 meters)

Length (end of drawbar): 28 feet, 6 inches (8.69 meters)

Width (over fenders): 13 feet, 4 inches (4.06 meters)

Width (over duals): 20 feet, 10 inches (6.35 meters)

This Tractor Is Freaking Huge