Roller drive, aka Robson’s drive - an extraordinary technical solution, used by vehicle developers even though not too often, however very widely. It is found on all-terrain vehicles., and on trucks, and even great.
How torque is transmitted from the engine to the drive wheels of the car? Average car enthusiast, more or less tech savvy, will say - on a rear-wheel drive machine, the torque is usually transmitted by the driveshaft, front-wheel drive — collapses, and on the bike — chain (and sometimes a belt). More advanced will remember the hydraulic motors, often used there, where it is not possible to lay a hard shaft, but you can stretch a hydraulic line - for example, on complex construction equipment. And the young generation will say, that the most modern technology is a motor wheel, in which in general there is no such superfluous part as a drive shaft! Все они, certainly, are right, but with these options the list of technical solutions is not limited. One of the curious inventions is the wheel drive., often referred to as the Robson drive.
Roller wheel drive is very easy to understand, and in manufacturing. In its simplest form, the roller rotating from the engine is simply pressed against the close pair of wheels on its own side (with the opposite - similarly), and twists them both. This is a friction version of Robson’s drive.. A more complicated and more correct option is a gear. In it, the rollers and tire wheels are compatible pairs - the protrusions of the rollers are in gearing with a suitable tire tread shape. Toothed "robson" is widely used in the harsh "cutlet", when all-terrain vehicles are designed for extreme criteria. An important nuance of the gear scheme is the need to use special tires of a special type, whose protector is initially designed to rotate with an outer roller.
The friction option is not bad as an auxiliary — it is convenient for retrofitting with a "robson" serial multiaxial machines of a classic design, type of three-axle truck tractors on ordinary wheels. For example, on 6x2 triaxial trucks (three bridges, one of them leading) "Robson" is used as a passive mechanism. In this case, the roller is not connected with the engine - at the touch of a button from the driver’s cab, it simply presses against the wheels of the driving and driven axles and, as an intermediary, transfers the torque from the tires of the driving axle to the tires of the “idle” adjacent to it. As a result, two bridges out of 3 become active, and the original 6x4 box layout turns into 6x4!
So do, if the machine is intended for use on paved roads, but occasionally forced to move to weak soils, where the risk of stalling. Instead of expensive all-wheel drive and toothy rubber, Robson rollers are used in conjunction with typical road tires. This option, true, limited in torque transmission due to the risk of slippage and is suitable only for occasional use, not to kill tires.
Yes, of course, that "robson" — specific thing. For example, for cars it is completely useless. However, in special situations it is indispensable and allows you to solve a number of fundamental problems..
Firstly, the above trucks. Now this drive is used in commercial technology - as an auxiliary (passive) in tractors (in driver's jargon called "bear"), as well as the main (active, with hydraulic motors) in special equipment, working in logging - for example, in trailers with driving axles, forwarderah and harvesterah. Finnish truck manufacturer Sisu produces tractors with Robson installed at the factory, offers it and Volvo as a function, and for Scania or DAF tractors, a number of third-party European companies make rollers with clamping hydraulic cylinders. Robson’s passive drive allows the tractor to give two main axles with “little blood” — without an expensive second drive axle, transfer case, additional cardans and the rest. Plus, you get a fair amount of fuel economy - the second drive axle is connected only when slipping off-road, and on the pavement it just turns off.
Another very wide area of application for the Robson drive — all-terrain vehicle construction, cars for damn off-road - swamps, snow in human height, deserts and the like. There, the roller drive is already used in its active form - the gear roller spins from the engine and spins the running wheels. "Robson" allows you to dramatically reduce the mass of the car by reducing the number of bridges and driveshafts, which is very important for all-terrain vehicles, and when using low-pressure pneumatics as wheels, it’s also practically possible to abandon the suspension. Roller driven machines are very reliable - no suspension, and break the axles, cardan or razdatku on them is almost impossible, because the connection of the wheels with the engine is “soft”. disadvantages, of course, also present, where without them! A lot of fuel is wasted on overcoming friction, and the torque is limited by the gearing properties at the “roller-tire” point.
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In general, experiments with roller drive wheels - the story is quite old. For example, the British company Armstrong-Siddeley developed and even rolled out small-series vehicles in the first quarter of the 20th century. However, this type of drive has not received mass distribution, since at the dawn of development it was only frictional, and as a main mover of little use. Roller spinning wheels due to friction, being very pressed to the tire surface and suffering from severe slippage in mud and clay.
However, in the second half of the twentieth century, Robson's drive again became fascinating to auto designers - as the passive auxiliary on trucks has already mentioned, and as an active main. The population of the land gradually began to reconsider their attitude to the development of the northern regions, where is the tracked vehicle, before that, the tundra ironed with might and main and leaving ugly ruts that had not been overgrown for decades on their soils, began to be uniformly superseded by "humane machines". The latter use the so-called "low pressure pneumatics" — extra large (with a diameter of one and a half meters or more) large contact area wheels, allowing you to ride on the moss, leaving no trace. And the roller drive with its low weight, simplicity and highest reliability turned out to be very useful here. In addition to high mechanical fault tolerance, the advantage was the absence of gearboxes outside, oil-filled - wheel gears and final drives in axles. As a rule, these nodes require increased attention after any contact with water, and on machines with roller drive wheels all the elements, afraid of water, hidden inside a sealed enclosure - "boat". Thanks to this arrangement, most of the "roller" all-terrain vehicles swim perfectly and do not require maintenance after overcoming each swamp or other reservoir.
Now in our country with a dozen companies make serial (although the series are small) ATVs based on a roller drive - cars under the Berkut brands, Three, Wanderer, Guard and others. These all-terrain vehicles are used by oil industry workers., gas, geologists, environmentalists, on a small shoulder (before 100 km) often with success replacing the famous northern "flying truck" Mi-8, whose flights are excessively expensive in depreciation and fuel. A roller pneumatic passage with a diesel engine for one and a half to two liters crawls with the same load even cheaper!
Often use "robson drive" and garage do-it-yourselfers, who make such all-terrain vehicles for themselves, living in countless harsh and remote regions of the country. By the way, implied, that in the very near future, the law “On the Development of the Arctic Zone of the Russian Federation” will spell out a complete ban on the movement of mechanized transport along the tundra and forest-tundra, disturbing land cover, which will definitely displace tracked vehicles from the Arctic.
Well, one can’t but mention the “small forms” of the roller drive. Well known, eg, famous french motorized bike VeloSolex, produced for decades, with 1946 years to 1988, and revived in the 2000s as Chinese clones.
Designed by VeloSolex, as well as its countless factory copies and makeshift makeshift 30-50 cc two-stroke gasoline engine mounted on the front fork is large and pressed with a rubber roller on the shaft to the surface of the tire - “Robson” in its purest form! Notched contact not used — ordinary serial tire is used, but in asphalt, purely frictional contact is quite sufficient.