The Mechanics Behind Screw-Drive Vehicles

Imagine life without the reliable wheel. It has enabled us to traverse hard surfaces such as dirt trails and paved roads effortlessly and swiftly, serving us well for millennia.

However, the wheel struggles in mud, snow, or water, as these surfaces lack the firmness needed for effective traction. The absence of resistance in such environments makes movement challenging.

Over time, innovative vehicle designers have devised a seemingly unconventional solution. These unique machines navigate through semi-fluid terrains like snow and mud using a mechanism similar to how a screw moves through wood.

This article delves into the workings of screw-drive vehicles, their historical background, and their performance in off-road conditions that would challenge even a Humvee.

For dedicated Mytour.com readers, the next step is clear: proceed to the following page to discover the intricacies of screw-drive vehicle design.

Screw-Drive Vehicles Design

The most distinctive feature of screw-drive vehicles is their unusual design. Instead of traditional wheels, they are equipped with two large, elongated cylinders, each adorned with screw-like threads along their entire length.

The driver's and passenger seating area, along with an engine, is positioned atop the cylinders. The engine is connected to the screw cylinders via shafts, chains, or other mechanical systems, enabling them to rotate in opposite directions. This counter-rotation allows the vehicle to move forward or backward. If both screws rotate in the same direction, the vehicle moves sideways.

These vehicles operate on the Archimedes Screw principle. This concept involves wrapping a flat surface around a pole on an incline and rotating it to move liquids or loose materials, known as "suspended solids," upward against gravity. Historically, such devices may have been used to irrigate Babylon's hanging gardens. Today, they are employed for irrigation, land reclamation, and transporting semi-solids like grain or sewage.

Screw-drive vehicles don’t need to be fully submerged in mud, snow, or water to function. They displace enough material to generate motion, essentially operating like a reverse Archimedes Screw. Additionally, the hollow cylinders can serve as flotation devices.

To steer a screw-drive vehicle, the operator adjusts power distribution between the left and right screws, determining the direction of movement. These vehicles can even move sideways, mimicking the motion of a crab.

Despite their engineering brilliance, screw-drive vehicles are unlikely to win any awards for aesthetics. From the practical Armstead Snow Motor, derived from a Fordson tractor, to the Soviet ZiL-29061, these machines were designed to conquer wet, sticky, and otherwise impassable terrains. Their designers prioritized durability over appearance, resulting in uniquely rugged vehicles.

Continue reading to explore some of the most notable screw-drive vehicles developed over the past century.

Screw-Drive Vehicles History

The origins of these machines are somewhat unclear, but one of the earliest documented designs was by Jacob Morath, a Swiss immigrant to the U.S., who patented a twin-screw ploughing machine in 1899.

One of the most widely recognized screw-propelled machines is the Armstead Snow Machine, also called the Snow Devil. A popular online video showcases its ability to navigate deep snow with ease, outperforming other forms of transport, including a struggling horse.

Despite its prowess in wet snow, the Armstead, a modified Fordson tractor, struggled in the harsh, dry snow of Alaska. The Fountainhead Antique Auto Museum, which houses several of these machines and their histories, notes this limitation [source: Fountainhead Antique Auto Museum].

Military forces have occasionally explored screw-driven locomotion. Nazi Germany experimented with a screw-propelled vehicle to navigate the snowy Eastern Front, where tanks often became stuck. Johannes Raedel's invention never reached production. Similarly, the U.S. military considered a screw-drive design for its Special Forces transport, the "Weasel," during World War II before opting for a tracked vehicle.

During the Cold War, the Soviet Union's ZiL automotive company created one of the most formidable screw-drive vehicles, the ZiL-29061. With its sharp angles and massive twin screws, it resembled a post-apocalyptic machine. Online videos showcase its ability to retrieve cosmonauts from remote, inhospitable regions like Siberia.

Screw-drive vehicles are still in use today, particularly in industrial and mining settings. They excel in traversing muddy terrain and breaking up clay to accelerate drying.

To learn more about the capabilities and limitations of screw-drive vehicles, proceed to the next page.

Screw-Drive Vehicles Performance

As you might have guessed, screw-drive vehicles are highly specialized. They excel in specific environments but are impractical for everyday tasks like grocery shopping—unless your store is located in a swamp or snowy wilderness.

In their ideal environments of mud and slush, some screw-driven machines can achieve speeds of 7.5 to 10 miles per hour (12 to 16 kilometers per hour). For instance, the Armstead/Fordson performed well in deep, heavy snow but faltered in powdery conditions. It was also known for its high fuel consumption. On the positive side, it could reportedly tow 20 tons (18,144 kilograms) of cargo, such as logs, using sleds. These vehicles thrive in heavy snow, mud, ice, and marshland but perform poorly on regular roads, disqualifying them as true all-terrain vehicles.

One of the most notable modern uses of a screw-driven vehicle was the 2002 crossing of the Bering Strait by two British adventurers. Their "Ice Challenger" expedition marked the first land-based crossing of this perilous route between the United States and Russia.

The crossing is fraught with dangers, including ice floes capable of damaging ships, unstable ice that may give way under a vehicle's weight, and even polar bears. Despite these risks, Steve Brooks and Graham Stratford successfully navigated the Bering Strait in their Snowbird 6. This amphibious vehicle utilized tracks for snow and solid ice, while its outrigger-style screws enabled it to float and move through water. The screws also assisted in transitioning the vehicle from water back onto the ice.