In October, 2013, Regina Weidenfeller, the President of the Hill Country Antique Tractor & Engine Club in Fredericksburg, Texas, was contacted by Jim Smith of Brackettville, Texas. Mr. Smith indicated that he wished to give the club five Gibson tractors. Two club members--Troy Rhodes and Will Weidenfeller--drove to Brackettville with a large flatbed trailer and brought the tractors back to the club's area on the grounds of the Gillespie County Fair Association. The five tractors included:
  • A 1945 Gibson Model A. Tractor Seattle Serial # SS180, Tractor Longmont Serial # 782, Engine Serial # 597212 (January, 1945)
  • A 1946 Gibson Model D. Tractor Serial # D523, Engine Serial # 661319 (May, 1946)
  • A 1947 Gibson Model D, Tractor Serial # D7224, Engine Serial # 825110 ()February, 1947)
  • A 1948 Gibson Model E. Tractor Serial # 331. Engine Serial # 1037517 (February, 1948) 
  • A 1959 Harvey Powerflex 10. Tractor Serial # 1134, Engine Serial # 7462013.
The 1945 Gibson Model A is thought to have  been built in Seattle, Washington, prior to the move to Longmont, Colorado. The transmission is from a Chevrolet truck and the differential/axles from a Chrysler automobile. Mr. Smith found this tractor in Western Idaho.

The 1946 Gibson Model D has 22-inch rear tires on Ford rims, a Chevrolet truck transmission, and a Chrysler differential/axles. Mr. Smith assembled this tractor from a pile of parts he purchased.

The 1947 Gibson Model D has 24-inch rear tires on International-Harvester Cub rims, a Borg-Warner T-96 transmission, and a Chrysler differential/axles. Mr. Smith purchased this tractor at an auction in Western Nebraska.

The 1948 Gibson Model E has a two-cylinder Wisconsin engine and a Borg-Warner T-96 transmission. Mr. Smith acquired this tractor from a salvage yard near Casper, Wyoming.

The 1959 Harvey PowerFlex 10 has a Clinton engine, a Ford truck clutch and differential/axles, and a Ford four-speed transmission from a World War II staff car.

To view a slideshow of photos, please click on Gibson/Harvey Photos

Gibson Logo Harvey Powerflex 10
Harvey PowerFlex 10

Gibson Model E
Gibson Model E

Gibson Model A
Gibson Model A

Gibson Model D
Gibson Model D

Gibson Model D
Gibson Model D


Harry A. Gibson founded the Gibson Manufacturing Corporation in Seattle, Washington, in 1933, to build railroad cars to transport loggers and supplies to and from logging camps. The company decided to capitalize on the demand for tractors after World War II, and it began to build small tractors as a sideline during slack periods. The Gibson trademark was registered in 1943.

When workers threatened to unionize, Harry’s son Wilber F. Gibson moved tractor production to a new factory in Longmont, Colorado, in 1945. The move may also have been motivated by the need for a more centralized location for sales and distribution. Longmont is located forty miles northwest of Denver. The company's arrival was touted as "the first new heavy industry to locate in Longmont in over forty years." The first Gibson tractors rolled off the assembly line in Longmont on March 2, 1946. Tractor production continued in Seattle for a period after the plant was opened in Colorado.

The Gibson Corporation produced farm implements for its tractors; these included plows, cultivators, disc harrows, spring-tooth harrows, angle dozers, and sickle-bar mowers A new building was added in 1948 to allow the company to increase its production of implements. The company also began to produce full-size tractors at this time. By 1948, the company employed over 200 workers, and  Gibson tractors were sold throughout the United States and in over two dozen foreign countries.

A Gibson tractor was advertised as the "Master of 1000 Chores. The Gibson tractor is outstanding in development design. The tractor is ideally adapted for use on the small general farm, truck farm, orchards or as a auxiliary tractor for large farms, ranches, country estates and municipalities, along with park systems."

The Gibson Company manufactured forklifts for the Navy during the late 1940's and early 1950's. During the 1950's, the company also entered into contracts to produce practice bombs for the Navy and rocket assemblies and artillery shells for the Army.

Tractor production ended on February 15, 1952, when the company closed, probably from a variety of reasons such as competition from other brands, overextension due to military contracts, inability to meet production quotas of tractors and implements, and the lack of a strong dealer network..  An announcement in May, 1952, indicated that the company had been sold to Helene Curtis Industries.  The Gibson Manufacturing Company then was reorganized as a division of  the Fox Metal Company of Denver, Colorado--a firm owned by Helene Curtis. No tractors were produced by the Fox Company; it only sold parts for a period of seven months during 1953.

In July, 1954, the Gibson facilities were leased to Western American Industries, and that company resumed tractor production and built approximately 1,000 tractors before production was discontinued in 1958. At that time, the Gibson brand name ceased to exist. Information regarding Gibson Company production is scare and often based on hearsay, as the firm's records were burned in the parking lot after the company closed.

After Wilber Gibson severed ties with the Gibson Company, he started building PowerFlex 10 tractors in 1958 in Berthoud, Colorado--a small community north of Longmont. PowerFlex 10 tractors were built from left-over Gibson parts and Ford truck parts. In 1959, Wilber Gibson had a heart attack while working on the Harvey assembly line and he died shortly thereafter; he was 44 years old. 
After Wilber Gibson's death, the Chicago entrepreneur who had financed the venture took over the enterprise and added his name to the tractor. The PowerFlex 10 became the Harvey PowerFlex 10.


The Gibson Manufacturing Corporation produced a variety of tractor models from 1946 to 1952, including the Model A, the D Series (D, SD, Super D and Super D2), the E Series (E, EF, EW and EWF), the Super G (only one built), the H Series (H, HFS and HFA), the I Series (I, IFS and IFA),  and the M (only one known--possibly a prototype).

Harry A. Gibson founded the Gibson Manufacturing Corporation in Seattle, Washington, in 1933, to build railroad cars to transport loggers and supplies to and from logging camps. The company decided to capitalize on the demand for tractors after World War II, and it began to build small tractors as a sideline during slack periods. The Gibson trademark was registered in 1943.

When workers threatened to unionize, Harry’s son Wilber F. Gibson moved tractor production to a new factory in Longmont, Colorado, in 1945. The move may also have been motivated by the need for a more centralized location for sales and distribution. Tractor production continued in Seattle for a period after the plant was opened in Colorado.

On March 2, 1946, The Longmont Times-Call reported: "Fifty-two small farm tractors went off the assembly line at the Gibson Manufacturing Corporation this week as the company went into production. The first 16 tractors left by truck and trailer for Denver, where they were consigned to tractor dealers. Distribution of the remaining 36 will be: ten to Boise, Idaho, ten to Salt Lake City, Utah, and a rail carload to Phoenix, Arizona." These tractors were Model A tractors--the first model produced by the Gibson Corporation.

The Model A had a 42-inch wheelbase and weighed 875 pounds. The tractor was powered by a one-cylinder, 5.9 hp., air-cooled, AEH Wisconsin industrial engine, which was started with a rope-start.  The tractor had 4.00 x 12 front tires mounted on cast-iron hubs and 7.50 x 16 rear tires on one-piece wheels. The tractor had a three-speed automobile transmission and an automobile differential with shortened axles and independent, external, rear-wheel brakes. Company representatives scavenged transmissions and differentials from salvage yards in the Seattle area and refurbished them for reuse in the tractors. A number of tractors were issued with Chevrolet transmissions and Plymouth differentials; however, others were used as available, including Borg-Warner T-96 transmissions--the same as those used in Willys Jeeps, AMC, Crosley, Ford-Falcon, and Studebaker automobiles, and Economy Power-King garden tractors, amongst others. 

Incorporating used automobile parts was a practice adopted by a number of garden tractor manufacturers at that time, and it usually resulted in durable and reliable tractors which were often overbuilt. At one point, Harry Gibson was sued over a company claim that Gibson tractors were built with all-new parts. The end result was that Gibson tractors varied one from another, depending on what parts were available at the time.

Tractors built in the Colorado plant continued to have automobile transmissions, but differential housings were specifically cast for the tractors. The Longmont housings had "Seattle, Washington," cast in raised letters on one side of the axle tube and "Longmont, Colorado," on the other. The clutch consisted of a V-belt-tightening mechanism (4 A-belts), with a chain-drive to the transmission. The Gibson Company claimed that the Model A could pull a 13 1/2-inch plow and plow two to three acres in a 10-hour day, with fuel consumption of 1 1/2 quarts per hour. The Model A had neither hood (engine cover) nor fenders; it was steered with a tiller (lever) on the right side. Early Model A's were painted Ford gray, with yellow trim. Later Model A's were painted Wisconsin gray. Standard equipment on a Model A was a front blade raised and lowered by means of a lever on the left side, towards the front, and an adjustable hitch, raised and lowered with a second lever on the left side, near the rear. Approximately 500 Model A's were built in 1946.

The Model D was the second tractor produced by the Gibson Corporation. It was four inches longer than the Model A, with a wheelbase of 46-inches; it weighed 955 pounds. The Model D had 4.00 x 12 front tires. Early tractors had 22-inch rear tires mounted on one-piece rims and centers. Later Model D's had 24-inch rear tires mounted on detachable rims--the same size rims and tires as those on Farmall Cubs. The rear wheels were adjustable from a minimum tread width of 33-inches to a maximum width of 54 1/4-inches.

Some early Model D's were powered by one-cylinder, 9 hp., air-cooled, AHH engines started with hand cranks; most Model D's utilized the same 5.9 hp. AEH Wisconsin engines used on the Model A. The Model AEH engine was started by wrapping a rope around a pulley mounted on the end of the crankshaft and pulling. The Model D also had the same lever (tiller) steering, V-belt-based clutch, and automotive transmission as the Model A. The three-speed transmission produced forward speeds of 2, 4, and 7 mph.; reverse moved the tractor at 2.5 mph.

The differential housing on the Model D was cast iron and produced specifically for the tractor; like those on the Model A, each axle-housing had "Seattle, Washington," in raised letters on one side and "Longmont, Colorado," on the other. It has been reported that the differential gears were the same as those in a Chrysler automobile, but this has not been confirmed. Like the Model A, the Model D did not have a engine cover (hood); however, fenders were optional. Although rope-start was standard; a starter-generator system was optional. The Model D was outfitted with the same front blade and adjustable hitch as the Model A.

Early Model D's were painted Ford gray; later ones were Wisconsin gray. Front and rear wheels were red; the rear rims were steel colored. The Model D sold for $545, and it was produced from 1947 to 1949. Implements available from the Gibson Corporation for its tractors included a plow, cultivator, disc harrow, snow plow, angle dozer-blade, spring-tooth harrow, and sickle-bar mower.

The Model SD was basically the Model D, with the addition of hood, grill, and fenders. The Model SD retained the lever steering used on Models A and D. The Model SD weighed 1,065 pounds. Electrical and hydraulic systems were options.

Not all owners/operators of Models A, D, and SD were pleased with lever steering. It was not unusual to have these tractors modified locally with automobile steering wheels and gear boxes; those from Volkswagens were popular. 

The Super D retained the features and options of the Model SD, including the single-cylinder Wisconsin AEH 5.9 hp. engine. It was the first Gibson tractor factory-equipped with a steering wheel. It weighed 1,105 pounds.

The Super D2 continued many of the features of the Super D; however, it was the first Gibson tractor powered with a two-cylinder engine--the 12 hp., Model TF Wisconsin, L-head, air-cooled engine. The Super D2 had a 52-inch wheelbase and weighed 1,375 pounds.
The Gibson Corporation touted Models Super D and Super D2 as having "...simplicity of design and construction--your assurance of long-lasting and trouble-free operation."

The Model E was larger than the Model A or any of the Model D Series tractors. It was powered by the same two-cylinder Model TF Wisconsin engine used in the Super D2 tractor. Early Model E tractors had tiller (lever) steering; most were issued with steering wheels. The steering wheel was offset to the right side, and it  reduced the operator's visibility on that side. The Model E was available in four versions; the basic Model E, a row-crop (tricycle) configuration; the Model EW, a row-crop (tricycle) configuration with wide rear-wheel adjustment; the Model EF, a standard four-wheel configuration with front-wheel adjustment from 40 to 60 inches and standard rear-wheel width; and the Model EWF, a wide-tread (84-inch) cultivating tractor. The Model EWF could straddle two corn rows.
The Model E was the only Gibson tractor with rear drop axles (chain-driven). Tractors in the E Series each weighed 1,905 pounds. Model E tractors had a rear hydraulic lift and both splined and keyed PTO shafts on a transfer case mounted in front of the transmission. The keyed shaft was for a pulley.  Although an electrical system was standard on most Model E's, some early tractors were issued with magnetos and were started with a hand crank. Also on early Model E's, a pedestal supported the rear of the hood and the gas tank; this pedestal was initially replaced on later tractors with a sheet-metal dashboard/firewall and finally with a cast-iron dashboard/firewall. With the addition of side panels and decals, Model E tractors were similar to the larger H and I models which came later.

Tractors from Model I on were full-sized tractors with four and six-cylinder engines. Row-crop models, adjustable front axles, tire options, and electrical and hydraulic systems were available in later tractors.

The Model I Series was made up of the Model I, a row-crop (tricycle) tractor; the Model IFS, with a standard fixed front axle, and the Model IFA with an adjustable front axle. A six-cylinder ZXD Hercules engine powered Series I tractors. The tractors had a 94-inch wheelbase, 5.50 x 16 front tires, and 10 x 38 rear tires; they weighed 4,000 pounds each. A Model I was texted at the Nebraska Test Laboratory in May, 1949 (Test # 408), and it was rated at 39.5 hp. (belt-hp.).  

A photograph of a Gibson Model M exists. However, nobody has gone on record as owning such a tractor, so it might have been a prototype which never made it into production.

The Model G was believed to be the last Gibson tractor built by the Gibson Corporation. Only one Model G tractor is known to exist, and it was Wilbur Gibson's personal tractor. Mechanically, the Model G was identical to the Model I. It weighed 4,512 pounds and was priced at $2,170. The Model G varied from the Model I in that it had a higher driver's seat, a steering wheel that was angled rather than vertical, chrome trim, and a hood that could be raised to facilitate service.
The Model H Series consisted of the Model H, a row-crop (tricycle) tractor; the Model HFS, with a standard fixed front axle; and the Model HFA, with an adjustable wide-front axle. Model H Series tractors were powered with four-cylinder Hercules 1XB engines. They had an 86-inch wheel base,  5.00 x 15 front tires, and 10 x 38 rear tires; they weighed 3,650 pounds. The Model H was tested at the University of Nebraska Test Laboratory in May, 1949 (Test # 407), and the tractor was rated as a 25 hp (belt-hp.), two-plow tractor.

Approximately 50,000 Models A, D-Series, and E-Series tractors were built; less than 500 each of Models H and I were produced.

Early Gibson Model A and Model D tractors were painted Ford gray; later tractors were painted Wisconsin gray. Model A tractors had yellow wheels; Model D tractors had red wheels. All other models were red with steel-colored rims (some Super D tractors had yellow inner rims).

The two longest-lived Gibson models were the Super D and Super D2--both being built from 1948 to 1952 by the Gibson Corporation, and then again during the mid-1950's to 1958 by Western American Industries.

During the final years of the Gibson Corporation, there were also attempts to produce a small Model 365 mower/tractor powered by a 2 1/2 hp. Briggs & Stratton engine, and a Gibson Country Clubber--a two-seat golf cart powered by a two-cylinder, electric-start, air-cooled engine. There is no indication that either vehicle was actually produced.

Production of Gibson tractors was suspended in February, 1952, and the factory closed in June, 1952.

The Gibson Manufacturing Corporation was sold to Helene Curtis Industries in 1952, and production ceased for seven months. During that time, only parts were available from a Helene Curtis subsidiary--the Fox Metal Company. Production interests were eventually leased to Western American Industries, and that firm built approximately 1,000 Models D, SD, and Super D tractors. An advertisement dated March 25, 1957, priced the Model D at $760, the Model SD at $810, and the Model Super D at $845.

Locating a serial number on a Gibson tractor can be an adventure in itself. Many tractors had serial numbers stamped on the right frame rail--sometimes on the end of the rail itself.  However, there were exceptions, and some owners assert that their tractors lack serial numbers. Also, a rumor has circulated  that blocks of serial numbers were skipped, so that the company could cite larger production figures for publicity purposes. Serial numbers usually consist of the model letter, followed by the production number.

Due to a lack of company records, many questions have been raised about the production of Gibson tractors. These include: Did any of the tractors produced in Seattle have the cast-iron differentials made specifically for Gibson tractors? And, conversely, did any of the tractors produced in Longmont have automobile differentials? How many Model A's were built in Seattle and how many in Longmont? Why were both the Longmont and Seattle locations cited on the cast-iron differentials? How long did tractor production continue in Seattle after the Longmont plant was up and running?

After disassociating himself from the Gibson Manufacturing Company, Wilbur Gibson designed and produced the PowerFlex 10 Tractor in Berthoud, Colorado, in 1958 and 1959.  After Wilber Gibson died in 1959, the entrepreneur who had financed the  enterprise took over production and added his name to the tractor. The PowerFlex 10 became the Harvey PowerFlex 10. PowerFlex 10 and Harvey PowerFlex 10 tractors were assembled from used Ford truck parts and left-over Gibson parts. The tractors had 9.6 hp. single-cylinder Clinton Red-Horse engines, and Ford truck clutches, transmissions, and differentials. Most tractors had three-speed transmissions with shifting levers on the steering columns; a few were made with four-speed transmissions and transmission-mounted shifting levers. Apparently, the only implement made for the Harvey tractor was a front blade. It is estimated that between 50 and 60 PowerFlex 10 and Harvey PowerFlex 10 tractors were built in 1958 and 1959.