At the beginning of the last century, engineers from leading countries of the world worked on the creation of promising propulsion systems for technology that could improve its performance. The wheels showed insufficient maneuverability on rough terrain, while the tracks, having the required mobility characteristics, were too complex and unreliable. Because of this, new options for a propulsion device that could solve all the tasks were regularly appeared and were proposed. One of the authors of the original developments was the British inventor Bramah Joseph Diplock. At the turn of the 19th and 20th centuries, he proposed an original propulsion device called Pedrail.
One of the main problems with the "traditional" wheel design is the small footprint, which increases ground pressure and reduces flotation. The original goal of the pedrail project was to increase the footprint with some technical means. Later B. J. Diplock has improved its propulsion unit by adding a number of new units to its composition. The result of this was the emergence of several versions of the undercarriage, suitable for use on vehicles for various purposes. Some of the original ideas were tested in practice using prototypes. Moreover, after the outbreak of the First World War, equipment with a Pedrail chassis almost reached the point of being used by the troops.
Demonstration tests of a tractor equipped with Pedrail wheels, 1911. Photo by Wikimedia Commons
The undoubted advantage of the tracked mover was the use of tracks with a relatively large area. Thus, with the correct connection of the caterpillar and wheel, it became possible to create a relatively simple and effective propulsion device. It was on this idea that B. J. Diplock. In the future, the original proposal was developed, during which the design of the undercarriage of promising technology became noticeably more complicated.
Wheel Pedrail
The most obvious solution to this problem was to install swing platforms on the wheel rim. Nevertheless, in this case, the issue of overcoming some obstacles remained unresolved. Because of this, some new units had to be added to the propulsion system. At the cost of complicating the design, it was possible to significantly increase the throughput of the equipment.
B. J. system wheel design Diplock. Drawing from patent US658004
The finished version of the wheel of the Pedrail system looked like this. The basis of the product was a horseshoe-shaped support piece, the outer surface of which was a rail. With the help of hinges, springs and guide rods, the support piece had to be suspended from the machine body. Also, the wheel received a cylindrical casing with holes on the side surface. Supporting devices were to be placed in them, which were able to move to and from the center of the wheel. The supporting device was a platform of the required size, hinged to the arm. The second end of the arm was equipped with a roller that was supposed to be between the casing and the rail.
When the machine was moving with a "pedrail" undercarriage, the support platforms had to move in a circle. At the bottom of the trajectory, they were able to descend to the ground. The curved lower part of the rail allowed multiple platforms to touch the ground at the same time. Then further rotation of the wheel made the platforms rise upward, starting a new revolution. This design, as conceived by B. J. Diplock, made it possible to provide a significant increase in the area of the supporting surface, but at the same time it was simpler than a tracked mover.
Tractor with pedrail wheels overcomes an obstacle. Photo Cyberneticzoo.com
The main elements of the original propulsion device were the legs and the rail along which they moved. For this reason, the project was named Pedrail - from the Latin word for "foot" and the English word "rail". The development was widely known under this name. However, in the 1900 patent, the invention was designated differently and much more modestly - Wheel ("wheel").
Already in 1903, the designer began to test the original design in practice. To continue the work, Pedrail Transport Company was founded, whose employees were engaged in the assembly of unusual propellers. Soon, the first prototype of a machine with a chassis using Pedrail devices appeared. The first experiments were carried out using modified steam tractors of existing models. Over the next few years, prototypes appeared with one or two axles equipped with Pedrail systems. The propulsion device designed by B. J. Diplock was mounted on both the front and rear axles of the tractor, while the second axle retained the standard wheels. In addition, there were carried out checks of cars with a full set of "pedrails".
A clear demonstration of the characteristics of the equipment: the tractor pulls two trailers with trailers on board. Photo Cyberneticzoo.com
The modified tractors performed well on various tracks and terrains. They differed from the basic version of the vehicle with wheels equipped with simple wide rims in improved cross-country ability. It was also possible to overcome various obstacles. In particular, photographs have survived depicting one of the wheels crossing a stack of boards, while the other remained on the ground.
Tests of experienced tractors with Pedrail propulsion showed all the advantages of the new system over existing developments. The new "wheel" differed from the caterpillar in a lesser design complexity and a large resource. At the same time, the use of a wheel-like system still did not allow for an increase in the support surface, allowing it to compete with the track. From "traditional" wheels, the development of B. J. Diplock was more difficult, but gave a higher cross-country ability. Thus, in a number of cases, the pedrail proved to be a more effective mover, although in other situations it was necessary to use the existing models.
Hitting an obstacle from a different angle. Photo Douglas-self.com
At the end of the first decade of the 20th century, B. J. Diplock brought his project to the stage of demonstrating prototypes to a potential customer. For several years, Pedrail Transport Company has conducted a series of demonstration tests, the purpose of which was to demonstrate the capabilities of the technology. During these events, tractors with an unusual chassis moved along highways and off-road, overcame various obstacles, etc. However, despite the successful completion of the assigned tasks, the prototypes did not achieve the expected success. The military showed interest in the original development, but did not express a desire to get equipment with such propellers.
Caterpillar Pedrail
The Pedrail propeller, which was a modified wheel, had certain advantages over existing systems, but there were also some disadvantages. For this reason, the author of the project continued to work on the further development of the chassis for promising technology. The main goal of the following works was to further increase the support surface. For this, the design of the "pedrail" was proposed to be changed using developments on tracked movers.
Tractor with full set of Diplock wheels. Drawing from The New York Times, Febrary 7, 1904
In 1911, Pedrail Transport Company brought the first track prototype to trial, based on the original ideas of B. J. Diplock. In terms of general design features, the tracked propulsion unit was similar to the existing wheeled one. At the same time, there were some notable differences. So, the authors of the project abandoned the cylindrical casing, and also changed the shape of the main frame. Now all the units had to be placed on an increased length openwork truss. It had rails for the rollers of the supporting devices and other parts. The frame had a straight top surface and a curved bottom rail. Due to this, the support platforms were sequentially lowered to the ground, before taking the optimal position. Possible skewing of the platform during lowering was practically excluded. For correct movement along the perimeter of the frame, the support platforms now had two rollers in tandem arrangement.
The prototype of the new propeller was made in the form of a single frame with a pedrail track. For reliable holding in an upright position, a side beam with a stabilizing wheel of a simple design was attached to the product. The prototype did not have its own power plant. During the checks at the test site, it was planned to tow it using the existing equipment. In particular, a tractor with wheels of the Pedrail type could serve as a tug.
Pedrail system track diagram. Drawing from patent US1014132
The proposed version of a tracked engine with support platforms instead of traditional tracks was of some interest. It should be noted that a few years later, this idea was applied in one of the new projects, which had a certain chance of reaching operation in the army. Nevertheless, immediately after the appearance of the pedrail caterpillar, it was decided to develop the new project in a different way. The proposal that appeared implied a noticeable revision of the existing design, which made it possible to simplify the production and operation of equipment. The development of this version of the Pedrail propulsion unit was completed by the mid-tenths.
New technology projects
In February 1915, B. J. Diplock presented the British military and political leadership with a prototype of a new technology based on a modified tracked propulsion system. Military leaders and high-ranking officials were shown a relatively compact crawler truck, distinguished by increased cross-country characteristics. Such a product, as conceived by the creators, could be used by the army for transport purposes. The battles of the First World War have already shown the importance of logistics and highlighted the complexity of transport on rough terrain.
Prototype pedrail caterpillar. In the background is one of the prototype tractors with a wheeled chassis. Photo Practicalmachinist.com
The basis of the transport cart was a tracked platform of a fairly simple design. Its main element was the frame, the profile of which followed the outlines of the prototype of the 1911 model. At the same time, the frame included two curved rails for the track rollers. Rollers installed on chain links were supposed to move along the rails. The latter, one after another, were completed with support platforms. A characteristic feature of the 1915 bogie was the equipping of two tracks with common platforms. Thus, two chains with their own guide rails were actually part of a single track. This did not allow to control the movement of the chains separately, but gave the maximum possible dimensions of the supporting surface.
Brackets for body mounting were attached to the sides of the bogie frame. It was proposed to transport goods on a long platform with drop sides. Also, devices for interaction with the tug were to be placed on the body.
At the beginning of 1915, an experimental tracked trolley was shown to the leaders of the country. During this demonstration, stones with a total weight of about 500 kg were in the body of the product. Among the representatives of the country's leadership, who were shown the new development, was the first lord of the Admiralty, Winston Churchill. The official volunteered to personally check the vehicle. Despite half a ton of stones, W. Churchill was able to independently move the cart from its place and roll it a little on the lawn.
Cargo trolley sample 1915 Photo Practicalmachinist.com
Also, at the beginning of 1915, specialists from Pedrail Transport Company created a sample of military equipment on a chassis of their own design. On a bogie with one track, equipped with wide supporting devices, it was proposed to mount a frame with mounts for an armored shield. Thus, a polygonal shield was located above the central part of the cart, behind which a pair of beams with handles for moving were provided. It was assumed that the soldiers would be able to push a shield on a tracked chassis in front of them, protecting themselves and their comrades from enemy fire.
The project of the movable shield was brought to the stage of construction of a prototype. This product was tested at the test site and shown to representatives of the military department. The military reviews were not positive, which is why an interesting proposal did not even lead to the construction of a full-fledged prototype with a shield made of armor steel.
Demonstration of the original mover to the representatives of the command had a positive effect on the further fate of the project, since now there was an opportunity to receive state support. In addition, specialists from the military department became interested in the development, who could help Pedrail Transport Company in creating new projects. It should be noted that the designers of the military department were interested in both developments of B. J. Diplock. Soon, the first proposals appeared concerning the creation of a full-fledged military equipment with propellers of the Pedrail type.
A prototype of a mobile armored shield for the infantry. Photo Practicalmachinist.com
One of the first to come up with a new idea was Major T. J. Heatherington. His proposal concerned the construction of a wheeled armored vehicle equipped with Pedrail wheels of the Diplock system. Due to such a propulsion device, which is distinguished by its large size, it was proposed to overcome various obstacles inherent in the battlefield of the First World War. This project was not implemented, but remained in the history of British tank building. A promising armored vehicle was called Big Wheel Landship ("Land ship on large wheels").
Another proposal came from Colonel R. E. B. Crompton. This officer intended to build an armored vehicle using two tracked propellers. In accordance with the first version of the project, the machine called Pedrail Landship ("Land ship with a" Pedrail "propulsion) was supposed to have a long hull with the longitudinal placement of two tracks designed by B. J. Diplock. Subsequently, the design was finalized, after which the machine was built according to an articulated scheme.
Illustrations for H. Wells' story "Land Battleships". Drawings On-island.net
Interestingly, the Pedrail project left its mark not only in the history of technology. Back in 1903, when B. J. Diplock and his colleagues worked on the creation of an experimental technique, their development became the "character" of a literary work. HG Wells' story "Land Battleships" was dedicated to unusual combat vehicles with cannon and machine-gun armament, powerful armor and a non-standard chassis. In just a couple of hours, 14 armored vehicles managed to defeat an entire enemy army. The main character, a war correspondent, during the battle managed to examine the chassis of the enemy equipment and remember its creator. The enemy's "land battleship" had ten wheels of the "pedrail" system with individual suspension and its own drive on each. High mobility and fighting qualities allowed the crews of armored vehicles to determine the outcome of the entire war in the shortest possible time.
The Brahma project of Joseph Diplock made it possible to solve some of the problems of the existing propellers and to some extent contributed to the further development of technology for various purposes. The first results of the original project were several prototypes based on existing tractors, as well as light equipment for various purposes. Later, on the basis of developments on the Pedrail theme, British designers created new equipment projects. Already in 1915, they tried to adapt the development of an enthusiastic engineer for use in the army. The following projects, based on the invention of B. J. Diplock are worthy of separate consideration.
