Porsche’s Volkstraktor

Ferdinand Porsche’s technical vocabulary embraced the tugs and tractors that he built at Austro-Daimler during World War I. Although intended to pull field kitchens, artillery, and ammunition, his machines also had potential for agricultural service in peacetime. Indeed, many of Porsche’s military creations were put to just those uses when peace broke out.

After he established his own design office in Stuttgart in 1930-31, Porsche concentrated on the products for which he saw the greatest potential: passenger cars and racing cars. Soon he and his team were fully engaged with the Grand Prix Auto Unions and the massive task of creating the Volkswagen car and factory. But when Porsche and Adolf Hitler met, their discussions often touched on Germany’s need for tractors to accelerate the work of its farmers, not only at home but also in the conquered territories that would comprise the future Greater Germany.

When 1937 commenced the outlook for a tractor project improved at the three Porsche office floors in the seven-story Ulrichsbau at Kronenstrasse 24 in Stuttgart, the last major work of esteemed architect Philipp Jakob Manz. His Auto Union contract having expired, Porsche renewed his relationship of the 1920s with Daimler-Benz. With main design work finished on the VW, his team had time to address the tractor. Porsche set out his desiderata as follows:

“Inexpensive to buy and maintain, suitable for large-scale manufacture, adequate performance for all work concerning farming and agriculture, robust and simple to operate.” This was his clarion call for a true Volksschlepper or Volkstraktor (People’s Tractor).

Development

On November 24th, 1937 Porsche’s chief engineer Karl Rabe issued the first document on a tractor project, giving it the Type number 110. His engineers studied various aspects of the job including its materials needs. On June 2nd, 1938, a week after the cornerstone-laying ceremony at the VW factory, Rabe set out the activity plan for building three prototypes—the standard Porsche number. The first was to be ready on September 3rd, 1938—Porsche’s 63rd birthday—and the other two 10 days later.

Though the birthday may have been missed, one Type 110 tractor was ready before the year’s end and another in 1939. These were virtual “breadboard” studies with a new air-cooled vee-twin engine and the driver seated in front. Three more prototypes in 1939 seated the driver more conventionally in the rear, using the same engine. This left space in front for a boxed cargo platform.

Carrying a load in the cargo area was important for the tractor’s stability under power, suppressing dangerous nose-lifting. Boulders were used for this when ploughing for example. When the Allied military came to inspect these tractors after the war, they asked the resident Porsche man at VW, Josef Kales, why they had rocks in their cargo platforms. “Well,” said the bemused Kales, “they’re cheaper than iron!”

Karl Rabe’s project list indicates that Porsche’s work on this tractor and its refinements was financed by the Volkswagen project budget. Because this didn’t extend to building a factory, Robert Ley put his “Strength Through Joy” labor organization forward as he had for the VW works. Land was acquired at Waldbröl, east of Cologne and Bonn, where Ley was the Gauleiter—the local authority. Austrian architect Peter Koller, designer of the town of Wolfsburg, prepared a plan for four huge production halls. Though planning continued until the effort was abandoned in 1944, not a spadeful was turned to begin construction.

Ironically, just as the Waldbröl dream was dying the Porsche team were putting more hours into a much-improved tractor. “Against all the constraints on improvements to vehicles that were not decisive for the war effort,” said Ferry Porsche friend Albert Prinzing, “Porsche encouraged this child, which was dear to him, all the more because he was compelled to deal with military vehicles.”

How was Porsche managing to keep the now-Type 113 project alive? His team developed a relationship with the OM works in Brescia, Italy, a renowned truck maker. Although much was lost in the war-ending collapse, several examples of the 113 survived on the Porsche family estate at Zell am See in Austria. Some were powered by wood-fed gas-generator units built into their noses.

“During the last year of the war,” the Porsche people told Tore Franzen, Chrysler engineer who was investigating for the Allies, “a considerable quantity of the Porsche development capacity had been devoted to this vehicle.” This was the result of a June 1944 order from a “Standartenführer Hoffmann” for 50 tractor-type vehicles suitable for the transport of four people, to be available with wheel or tracked drive and propelled by gasoline or generator gas. For this Porsche created its Type 293 adaptation of the 113, which was to have been built by OM. Although the war ended before even one 293 was built, this was additional tractor experience for the Porsche team.

The Type 113 post-war survivor, Tore Franzen reported, “is claimed by the Professor to have a good performance and to incorporate all power takeoffs, draw-bar arrangements, etc. required by modern agricultural practice.” On a wheelbase of only 55.1 inches with a 49.2-inch track, the Type 113 was a spunky-looking number, now with fully enclosed power unit.

Engine, gearbox and drive axle were unified in a compact package at the driver’s feet, with the five-speed transmission overhung behind the differential as in the Auto Union racing car. Novel was a hydraulic coupling between engine and clutch that allowed the tractor to be started and driven in any gear and helped the engine keep running when any blockage occurred.

The power unit was an in-line air-cooled twin, introducing a concept that was to prevail in future Porsche tractors. Features were a single head covering both cylinders, three main bearings, pushrod and rocker valve gear and a scirocco cooling fan that ran at 4,900 rpm when the engine was at its power peak of 2,000 rpm. Output was 15 hp from 1,696 cc (100 × 108 mm). Giving a top speed of 10 mph, its five-speed transmission had a super-low ratio for harrowing.

A gear pump in the engine’s sump powered a built-in hydraulic system to operate lifting arms for mowers, cultivators and other equipment. A large frame tube extended forward from the power package to the front suspension and steering. Power-train housings had been built of both iron and aluminum. In the latter instance its curb weight was 2,425 pounds.

Here was a well-thought-out tractor ideal for the smaller landholder, suitable either for gasoline or gas-generator operation. It was, finally, the Volkstraktor. Ferdinand Porsche had no hope of winning Austrian interest in it. All the factories of the Steyr-Daimler-Puch group were in the Russian Zone of Occupation, from which the Soviets had taken 5,000 of the company’s 18,000 machine tools as reparations.

In 1945 Porsche turned to a company in Germany that he knew well, the Zahnradfabrik Friedrichshafen (ZF), which produced many components for vehicles but not yet complete ones. The highly esteemed company sent a man to Zell am Zee in August 1945 to assess the Type 113. He totted up 25 suggestions, albeit chiefly to do with the gas generator. ZF would not be a tractor-building candidate.

A contract signed with Cisitalia in Italy required—among racing and sports cars—a mini-tractor with a 43.3-inch wheelbase and a single-cylinder diesel engine of 895 cc giving 11 hp. Intended for vineyard workers and mountain farmers, it required special drives for mowing and a cable reel. Planned for production by Italian agricultural-equipment maker Poggi, this Type 323 tractor went west when Cisitalia went south.

Between 1945 and 1948 the Porsche engineers marooned at Gmünd designed and built yet another two-cylinder tractor iteration. This came in two flavors, the gasoline-fueled Type 312 and the diesel-engined Type 313. While the 312 was generally on Type 113 lines, with its transaxle overhung at the rear, the 313 adopted a more conventional layout with its transmission between the engine and final drive. In spite of its small size this had, in fact, been proposed for the Italian mini-tractor.

The new chassis of the 313 had better proportions with a 59.1-inch wheelbase and 57.1-inch track. The latter was adjustable, to suit farming conditions, down to a minimum of 49.2 inches. A prototype of this tractor family performed superbly as far away as Brazil, where Porsche man Emil Rupilius worked with government interests in an effort to launch production. Dreams of 12,000 being built yearly turned out to be just that. In tests of the Porsche designs against rivals, they never failed to come out ahead. Who would capitalize on this decade-long design and testing effort?

Enter Allgaier

The man who would seize the opportunity was known for his enthusiasm for new ideas and projects. This was Erwin Allgaier of the eponymous Georg Allgaier Presswerke, which he had headed since 1939. His family company specialized in the supply of pressings, press tools and other devices. At its works in Uhingen, south-east of Stuttgart, it had been making a small water-cooled tractor from the pen of Paul Strohhäcker since 1946.

Agricultural technician Wilhelm Gommel, who had good contacts with both Porsche and Allgaier, may have helped bring the companies together. But Erwin Allgaier had been in contact with the Porsche design office since the 1930s.

“I knew Porsche when he still had a design office in Kronenstrasse in Stuttgart,” he related. “We also pressed parts for them in our factory during the war. When I saw the Volkstraktor after the war I said: ‘That’s just the little tractor for me.’” Starting while much of the Porsche staff was still in Gmünd, they and Allgaier’s engineers worked jointly on the design of the first “Porsche System” Allgaier tractor.

To begin the work the Allgaier team drew up an 11-page list of suggested changes to be made in the series-built tractor, many posed as questions rather than demands. This provided the basis for a discussion at Gmünd in October 1949 in which the customer was represented by Erwin Allgaier and engineers Fritz Bauer and Robert Mack. Karl Rabe led the conversation on the Porsche side.

“The minutes recorded for this meeting served as the basis for creating the factory drawings,” said an Allgaier man. A subsequent internal Porsche memo warned, “Please do not leave any drawings lying exposed after office hours and cover drafting boards! Deadline for various engine drawings is 15 December 1949.”

In December the contract between the two companies was finalized and executed. Liaison engineer on the project was Porsche’s Leopold Schmid, who would spend some weeks at Uhingen with the Allgaier engineers, detailing the front suspension, steering, transmission, final drive, driver’s seat, fenders and toolbox.

Around this time the designation system was settled. It included “AP” for the two participants followed by a horsepower number—already an Allgaier tradition. They based the horsepower on results already obtained on the engine of the Type 313, for this was to be a diesel tractor. Its output was 17 hp so the tractor became the AP 17. In the end the engine developed 18 hp but the designation was left unchanged.

To reduce cost the Porsche engineers specified many parts of die-cast aluminum, using a strong high-silicon alloy. This necessitated recruitment of suppliers with this capability. They had to be able to cast the parts in such a way that further machining was unnecessary or only trivial. A pre-series of ten tractors was decided upon, made from parts that conformed entirely to those that would be mass-produced. Early in 1950 trials commenced to weed out problems and set the final specification.

Work was under intense time pressure, for Erwin Allgaier was determined to launch the AP 17 at the mid-1950 German Agricultural Exhibition in Frankfurt. Uhingen hosted a progress meeting on March 27th when Ferdinand Porsche, Ferry and engineers Rabe and Schmid attended a tour of the work to date. Ferdinand had a few suggestions for improvements. They saw a nearly completed engine, of which a telegram on April 25th reported the successful completion of a 30-hour test.

On June 9th, 1950 Ferdinand and Ferry Porsche were on deck when the all-new Porsche-designed Allgaier AP 17 tractor was presented to the press at Frankfurt’s Hotel Frankfurter Hof. The price was announced, which had blockbuster impact at a reasonable 4,450 Deutschmarks ($930 U.S. dollars then, or $10,300 in 2020 dollars). By the third day of the Exhibition some 15,000 orders had been booked. The first AP 17 left the factory on July 10th, 1950, followed by completion of the 500th AP 17 tractor on October 13th-14th. The end of the year saw 1,550 completed. Into 1951, almost 5,000 had been put into service.

The AP 17 offered many novel yet well-tried features. Integrated into its cast-aluminum structure was its air-cooled two-cylinder diesel engine with Bosch oil injection and individual cylinder heads. A feature was a gear-driven centrifugal oil filter. Its displacement was 1,374 cc (90 × 108 mm) delivering 18 hp at 2,000 rpm.

The engine drove a five-speed transmission and a hydraulic pump to power accessories. Between engine and clutch was the distinctive fluid coupling that avoided stalling and allowed starting in any gear ratio. A distinctive touch was its dashboard, which with all electrical controls and fuses was attached to the steering column.

For its new tractor Allgaier invested in a new factory. It found a suitable property in the Friedrichshafen enclave of Manzell where airplane-builder Dornier had a surplus works canteen. The L-shaped building needed clearing out and installation of separate assembly lines for engine and vehicles, much as Porsche’s type 356 production was evolving. A credit line of several million Deutschmarks from the Baden-Württemberg state soothed the financial pain of the transformation.

Porsche and Allgaier cooperated closely in the early 1950s to offer a tractor range that was as profitable as it was innovative. An important aim was to create engines of two, three, and four cylinders that shared as many components as possible. Introduced in 1952, the three-cylinder type A 133 was an important step in this process.

Resulting from decisions made in weekly design meetings in which Porsche’s Leopold Schmid and Wolfgang Eyb were active, the A 133 used major components from the AP 17 such as the transmission’s gearing, which was outsourced. Shared with the Allgaier twin-cylinder tractor were all the engine’s reciprocating parts, giving its swept volume of 2,061 cc and 33 horsepower at 2,000 rpm.

New features of the A 133 included a frontal power takeoff and a sprung front axle adjustable for height. Successfully proven, the hydraulic coupling in the driveline was kept to provide operating flexibility. Special care was needed in the design of the new hood, a complex injection molding giving the typical lively and grille-free appearance of the air-cooled Allgaier-Porsche tractor that was thought to be styled by Porsche’s Erwin Komenda.

Production of the A 133 began in September of 1952. In all some 4,000 of this three-cylinder model were made through mid-1956, including a follow-on version designated P 133. The A 133 had a gasoline version, the A 132, which had a single cylinder head serving both its cylinders. This was the basis of one of the most striking and unusual of the Allgaier-Porsche tractors. Called the P 132, it had fully enclosed bodywork.

Nicknamed the “Brazilian”, the P 132 was the result of contacts that began in 1948 when engineer Emil Rupilius took a Type 312 to Sao Paulo in search of a company to manufacture the Porsche creation. A trip two years later by Erwin and Oskar Allgaier discovered interest from Brazil’s coffee and fruit plantations in a machine that could mow down unwanted growth while not damaging their valuable plants. Gasoline rather than diesel was preferred for economic reasons.

To test the requirement an AP 17 chassis was given a longer wheelbase and smaller front wheels. At the rear its hydraulic system powered a rotary mower that trimmed a meter-wide path. Shaped around the machinery was steel skirting designed to slip through plant growth that would be left unmolested, ventilated where needed for the engine’s air cooling.

Sent to Sao Paulo in 1952, the prototype performed successfully but showed a need for more power. This was provided by a stroke increase from 108 to 116 mm, giving 1,820 cc. From an order of 1,000, the first 220 were made at Allgaier’s Friedrichshafen factory and shipped to the port of Santos.

Although the final P 312 proved its merit on the plantations, the contracted importer’s arrangements were so catastrophically inadequate that the first shipment to Brazil was also the last one. The small handful of survivors of these unusual tractors have since been show-stoppers throughout the world.

In the summer of 1952 the agricultural exhibition in Mannheim was the venue for the launch of the tiniest Allgaier-Porsche, the single-cylinder A 111. It had a conventional tractor’s long wheelbase with the engine over the front wheels, leaving a central gap in which its farming equipment was fitted and deployed. The A 111 and its two-cylinder sister the A 122 had large flywheels to give running stability over difficult terrain instead of the Voith hydraulic couplings previously favored.

Such couplings were optional on the A 122 and standard in the three-cylinder A 133 and four-cylinder A 144, the proud top of the all-diesel Allgaier-Porsche range. While the others had transmissions made by Allgaier, ZF supplied the gearbox for the 4,500-pound A 144. Introduced at the 1953 agricultural exhibition in Cologne, it displaced 3,289 cc and produced 44 hp at 2,000 rpm and, most importantly, 127 lb-ft of torque at 1,400 rpm. From top to bottom of the range the use of standard parts throughout was ruthlessly pursued. Most of the 200-odd A 144s produced were exported.

Mannesmann Replaces Allgaier

In 1955 the Allgaier family began to feel the stress of a growing business that was undercapitalized. Competition from Ferguson tractors in Britain was putting pressure on selling prices. At the same time Porsche’s business manager, Albert Prinzing, desired to maintain the benefits of the license and project fees that flowed to Porsche from tractor design and production.

Thus, Prinzing was midwife to a new relationship with industrial firm Mannesmann, which founded the Porsche-Diesel Motorenbau GmbH to take over all tractor production at the beginning of 1956. It moved the works to a newly equipped building in Friedrichshafen with an annual production potential of 16,000 tractors. Prinzing, the new company’s managing director, described the new arrangements as “having the shares taken over by Mannesmann and the management entrusted to a team from Porsche.”

Flagship of the new “Porsche-Diesel” range was the four-cylinder P 144, carried over from the Allgaier A 144. In 1958 this evolved into the more powerful Master 408. Its new double clutch required a longer chassis and wheelbase that did not aid agility. This handicap was overcome with the spring 1960 introduction of the Master 418, which had a new shorter ZF transmission allowing a reduced wheelbase and giving an optional faster top speed.

A powerful two-ton machine, the Master 418 was capable of coping with the most severe demands of its day with its front and rear power takeoffs. The Voith hydraulic clutch in its drive line aided maneuverability and flexibility, as it did in some of the smaller models, which were carried over from the Allgaier operation. This allowed 9,465 tractors to be produced in the transition year of 1956. Names also came into use, with the smallest the Junior, the twin the Standard, the triple the Super, and the Master at the top.

With Karl Rabe now devoting the bulk of his time to tractor development, Porsche brought a number of new ideas to the farming machines, such as infinitely variable transmissions using belts or hydraulics. It also schemed more advanced diesel engines with valves in a vee angle. Although many of these new ideas reached prototype status, none progressed to production in an increasingly cost-constrained environment.

Porsche Tractor Production Ends

Competition from larger rivals and changes in market demand led to the closing of Porsche-Diesel in mid-1963 after some 120,000 tractors were produced. The creation of Porsche-Diesel-Renault Sales GmbH in June 1963 provided a brief continuation, largely using existing components. Soon thereafter the business was dissolved, with Renault carrying on the provision of parts and service.

It had not been an easy road for the Volkstraktor, from its first stirrings in 1937 to a plethora of prototypes, production in 1950 and finally closure in 1963. But it was part and parcel of the Porsche saga, bringing to life a family of tractors of the highest quality. Many are still treasured throughout the world.