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Old 12-14-2005, 03:22 PM   #1
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Default How To Build A Karakat

I'm trying to rebuild this post. This is not the final version. Come back later.

-----------------------------

What is a “karakat”???

This concept for the first karakat's was conceived in the northern area of Russia. They acheived their off-road travel by means of innertube used as a low pressure chamber. These cross-country vehicles are extraordinarily popular in the northern snowy cities, for example Arkhangelsk. The advantages of these machines are obvious. They freely navigate any snowy obstacles, swamp, mud, etc, and some are capable of even floating. One additional prime advantage - their relative cheapness. This makes karakaty irreplaceable transportation for fishermen, winter adventures, and off-road enthusiasts. If this enthusiasm is shared by you, this will probably be interesting.

What are they made of?

As the basis of karakata, as a rule, lies a motorcycle engine. Sometimes, to simplify construction the origional motorcycle frame is used. For the most simple units, construction is limtited to 3 frames for inflated innertubes (on the back are two wheels with either the usual live axle or automotive axle). Such “karakaty” have speed disadvantages, but fairly fail on impassable terrain. Sometimes, preserving motorcycle frame, karakats are made with four wheels. In this case two steering wheels and steering gear box replace the motorcycle fork. However, many builders replace the motorcycle frame and make their own. Naturally, such modifications allow the cross-country vehicle to be more spacious, comfortable, and convenient. “Cuttles” are custom built with four or six wheels, optional additions include roofs, and car seats. Due to car seats and the rest of the modifications the undercarriage is also as a rule more complicated. Steering control is provided either by the a steering box or articulating frame.
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:22 PM   #2
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Default Re: How To Build A Karakat

If you decided to build a “cuttle” yourself, pay attention to this material on construction and calculation for building a cross-country vehicle with low-pressure tires.

v. [SHALYAGIN], Candidate in Technical Sciences.

There are 6 sections:

* Selection of diagram and the calculation of the cross-country vehicle
* Secrets of the layout
* Engine and transmission
* The undercarriage
* Control system
* Design


P.S. Remember! When building karakata, first of all be creative, but to over build it - is impossible!

[Thats what they say erik, only trying to be accurate. :P ]
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Bobby after seeing pictures of "the tires"
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Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:28 PM   #3
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Default Re: How To Build A Karakat

Selection of diagram and the calculation of the cross-country vehicle


When planning the creation of a cross-country vehicle on low-pressure tires, you must first of all, solve the chief problem: what machine do I want/need? It is important from the very beginning to clearly determine its purpose, capacity (number of seats, size/mass of the luggage), and its operating conditions.

After visualizing the planned cross-country vehicle as a whole, then move on to the selection of engine, transmission, running gear, brake systems, steering control, cab and formula for ground pressure. The final consideration must start only after the you compare your desires and possibilities.

Following the design stage - determine the basic parameters of the cross-country vehicle: its own weight (equipped), useful and total mass, the sizes of the tires, the power of the engine, and the gear ratios of the transmission.

For the tentative calculation of its weight, it is possible to use data of table 1. The precise weight must be calculated from the weight of all your components.

The payload (useful mass) of the cross-country vehicle of is calculated by the formula:

Payload = Seats * (Person Weight + Luggage Mass)
Where:
  • Seats - Number of places for people to sit
  • Person weight - the average mass of an adult, (75kgf)
  • Luggae Mass - Mass of Luggage (kg)


The total mass of the cross-country vehicle is determined from the formula:
Total Mass = Vehicle Mass (unloaded) + Payload

After calculating the total mass it is necessary to figure out the weight distribution over the separate axles and wheels, and to find those with the most load. For an approximation, you can consider that the rear wheels of motorcycle based cross-country vehicle is 70-75% of the "Total Mass". For automobile based cross-country vehicles assume the total mass is distributed evenly along the axles and the wheels.

The dimensions for tire innertube are selected based on the load. It is possible to use data of table 2 or formula:

Continous Load ~ 0.7 Peak Load ~ 0.25 (Pressure+1) (D2-d2) B,

Where:
  • Continous Load - The operational load of the innertube, kG
  • Peak Load - The peak load of the innertube, kG
  • Pressure - Air pressure in the innertube, kgf/cm 2
  • D - Outer diameter of the innertube, dm;
  • d - Rim diameter, dm;
  • C - Width of the innertube, in.

(Some help for us Americans)
psi = kg/cm^2 * 14.223
kg/cm^2 = psi * .070309



In [ekologichnykh?] cross-country vehicles, the air pressure in the innertubes must not be more than 0.2-0.3 [kgs]/[cm]2. (2.8-4.3psi)

The maximum power of the engine (in hp) should be calculated from the formula:

HP=10-3SP * Total Mass
Where:[LIST][*]HP - Horsie Power, hp[*]SP - 20-35, The specific power (energy saturation) of the machine[*]Total Mass - The total mass of the cross-country vehicle


The high values of specific power are applied to calculations for motorcycles and lower ones for micro-automobiles.

From the maximum power of engine it is possible to approximately find its working volume VP in [sm]3 using table 3.


When selecting an engine, it is necessary to consider that it might need forced cooling. The engines from motor s******s are supplied with the intent of forced cooling. But a motorcycle engine installed in the cross-country vehicles must be equipped either with a fan driven from the crankshaft or with a turbo. A turbo uses exhaust to generate air flow, and with a jacket to guide airflow to critical areas the engine will stay cool.

The calculation of the minimum and maximum gear ratios for the transmission should be carried out according to the formulas:

Minimum Gear Ratio =0.377*Radius* MaxRPM / MaxSpeed
Maximum Gear Ratio = Minimum Gear Ratio * Gmin * Gmax


Where:
  • Radius - Radius of the innertube rolling surface, equal to 0,475D
  • For above, D - Outer diameter of the innertube
  • MaxRPM - Maximum RPM of the engine
  • MaxSpeed - The maximum speed of cross-country vehicle, km/h (45 km/h)
  • Gmin/max - Minimum and maximum gear ratios of the gearbox.

The standard functional diagrams of power transfers are shown below:


Simplest are the transmissions of cross-country motorcycles (A) and cross-country motorized wheelchairs (D), made either 3x2 or 1+2x2. Power is transfered from the power unit (engine), to the gear box, to the interwheel differential, and further to the semiaxes, and finally the driven wheels. Steering wheel - not driving.

The power transfer of micro-automobile cross-country vehicles has a more complex construction.

The transmission of all-wheel-drive 2 axle cross-country vehicle with the hinged frame (B) contains a reverse gear box, intermediate chain transmissions, and an interaxle gimbal drive .

In an all-wheel-drive 2 axle cross-country vehicle with the front steering wheels (E) power transmission includes the connecting shafts, the chain transmissions, and the steering u-joints.

The power transfer of the 3 axle micro-automobile cross-country vehicle, according to the diagram (c), is close in the construction to the power transfer of 2 axle cross-country vehicle with the steering wheels (E).

Some amature designers use locking differentials that substantially increases the passability of the vehicles on slippery surfaces.

Comparing the diagrams shown in the picture, it is possible to isolate the repetitive structural elements of the cross-country vehicles: power units, intermediate and onboard chain transmissions, main drives with the interwheel differentials and the reverse reductors, wheels with the innertubes.

After determining the general appearance of the constructed machine, formula of the running system, and diagram of transmission you can move to the next section.
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:32 PM   #4
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Default Re: How To Build A Karakat

Secrets of the layout

In the previous section we examined the selection of overall diagram and the methods to calculate the basic parameters of your cross-country vehicle on innertubes. The following stage of the design is developing the assembly diagrams and drawings, on which the constructed machine is depicted as the technical system. This drawing includes structural elements (component parts): engine, power transfer (transmission), running system, brake and steering control, body, the control linkages, electrical and other equipment.

First make a sketch - layout diagram. It determines arrangement in the machine of the driver, passengers, baggage carrier, and the machine as a whole. Having a diagram considerably simplifies the construction machine. The layout diagram gives initial information for constructing the missing parts of the machine.

When deciding the layout of the machine the designer must consider the large number of different factors (number of seats, the capacity of baggage carrier, the formula of running system, its maneuverability) and find the optimal solution. This decision can be made via the comparison of the alternatives. When studing the intermediate and final versions it is necessary to compromise, to find the golden mean in each specific case. The study of already completed vehicles can aid the developer.

All variations of the were was represented at the All-Union inspection competition of home-made cross-country vehicles on innertubes.

To analize of the constructions of all these machines is difficult, and there is no need for this. All the designs can be classified as one of the following: motorcycles, motorized wheelchair, micro-automobiles and microbuses.

The application of innertubes as a low pressure tire provides a large contact patch with the ground compared with normal tires. Such tires make the cross-country vehicles practically harmless for thawed and remoistened ground, turf and covered with small plants surfaces; a similar transport is capable of working on the floodland meadows and the swamps, in the tundra and the forest-tundra transition area. (Basically, the thing is tread lightly compatible...obviously)

Cross-country motorcycles are constructed with, as a rule, one or two seats and with either running systems 1(ski)+2x2 and 3x2. Ski-wheel motorcycles relate to the snow, and wheel - to the snow and swamp buggies.

Cross-country motorized wheelchairs are equipped with either running systems 1(skii)+2x2, 3x2 and with an engine from a motor s****** behind the axle. Motorized wheelchairs have an open or closed one or two seat cab.

Micro-automobile cross-country vehicles can have one, two, three, or four seats with the 2 axle (4x2, 4x4) and 3 axle (6x4, 6x6) running systems, and with the engine mounted in front or rear. Steering is accomplished either by turning the front steering wheels or through the hinged articulated frame. To decrease the turning radius the slight braking to internal wheels is done.

Cross-country microbuses for the first time appeared at the inspection competition of 1989. 5 - 2 axle (4x4) with the hinged frame; 8 - 2 axle (4x4) with steering wheels; 6 - 3 axle (6x6) with steering wheels.

It is evident from the brief survey of home-made cross-country vehicles that the greatest variety of technical and assembly solutions are characterized by the micro-automobiles. Therefore it is expedient to examine the technology, development, and layout diagram of cross-country vehicle on innertubes based on the example of micro-automobiles.

First select a scale for the future diagram. Practice shows that preliminary layout it is nest to make the scale 1:10 or 1:5. This scale simplifies the tracing of the machine and its structural elements. Final layout it is better to scale 1:1 or 1:2; this increases the accuracy.

It saves time to develop the layout diagram of the constructed cross-country vehicle in this sequence:
  1. Draw body taking into account the arrangement of the seats.
  2. Apply to the schematic wheels of the selected standard size. The number and arrangement of wheels must correspond to the formula of running system and to the method of turning.
  3. Arrange on the layout diagram engine, units of power transfer, control elements of machine (steering wheel, pedal and levers), and baggage carrier.
  4. Apply to the diagram the outlines of body and machine as a whole, windows, doors, wings, etc
  5. Select the construction of frame and suspension and to depict them in the diagram.
  6. Estimate weight of the machine - distribution of its own and total mass over the axles.
  7. Determine with the aid of the geometric constructions the minimum turning radius of machine.

When developing the layout diagram it is necessary to ensure compactness of its construction - minimum overall sizes and volume, and consequently, the minimum of its own and total mass: on it all the most important performance properties depend (dynamicity and fuel efficiency, passability and ecology (enviornment impact)).

The mass distribution of a 2 axle machine can be calculated from the formulas:

Front Axle = (m1*b1 + m2*b2 + … + mn*bn) /L
Rear Axle = (m1*a1 + m2*a2 + … + mn*an) /L


Where:
  • Front/Rear Axle = weights on axle
  • m1, m2, mn - mass of the compartment parts of the machine, driver, passengers, load
  • a1, a2, an - distance horizontal from the center of the masses to the front axle
  • b1, b2, bn - distance horizontal from the center of the masses to the rear axle
  • L - Wheel base of the machine

For the 3 axle machine the masses fall to front axle and to the bob carts. In this case by wheel base of machine is understood as the distance between the front axle of machine and the midpoint between the two rear wheel centers. The mass which falls to the bob carts, is distributed between the rear axles equally.

Two simplified (without details) layout diagrams are shown as an example in the figures: triaxlel (6x4) and biaxle (4x4). With the development of layout diagrams following specs were accepted:
  • Number of seats - 2
  • Mass of the luggage - 50 kgf
  • Mass of the machine in the equipped state - 500 kgf (not more)
  • Air pressure in the tires - 0.25[kgs]/[cm]2 (not more) (3.5psi)
  • Maximum speed - 45 km/h
  • Automobile must possess the ability swim through small water obstacles.


Layout diagrams of triaxle (I) and biaxle (II) micro-automobile cross-country vehicle on innertubes:
1- power unit, is 2nd fuel tank, 3- drive axle with the reverse reductor, 4- intermediate drive. And department for the driver and the passenger; B motor- transmission department; In, G front and rear caps.

Tires for biaxle cross-country vehicles - innertubes the size of 14.00-20 (1300X400-508), triaxle - 1065X420-457, supplied with protector and [gruntozatsepnymi?] tapes. Smooth turning of automobile cross-country vehicles is achieved with the aid of front steering wheels. The possibility to slightly brake the internal lagging wheels when turning sharp will reduce the turning radius. Bodies of both automobile cross-country vehicles have airtight bases, which consist of the nose and stern sheets, boards and bottom. Seats for driver and passenger can be shifted sideways.

Both automobile cross-country vehicles are practically identical with respect to design parameters performance properties. Therefore an amateurish designer can accept any of the proposed layout diagrams for the basis for further development.
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:36 PM   #5
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Default Re: How To Build A Karakat

Engine and transmission
[characters fixed] [cohesion means clutch]

The home-made cross-country vehicles most often use engines from motorized wheelchairs or motor s******s, but as a rule, they frequently come from motorcycles. The first thing they are equipped with are fans for forced cooling, required because of the slower speeds. The engines have power acceptable for the majority of amateurish machines; and also are small in overall size and mass. However at the same time there is little standardization between engine models and this limits the possibilities for a standard vehicle design because of known technical solutions with a specific engine. (mounting, gear box design/mounting, etc)

There are plenty of engines from motorcycles to choose from. However, it is necessary to remember that this engine be equipped with forced cooling - by a fan with a jacket, which moves air to the components which have a high temperature.

The engines from motorcycles, motor s******s and motorized wheelchairs have air cooling, which substantially simplifies their construction and decreases their mass. It also increases reliability (air-cooled engines are easier to start at low, something about not fearing thawing out). The bad characteristic is the increased noise. However, its possible to compensate for this with the installation of soundproofing.

These engines do not have completely balanced pistons or crank gear and are characterized by nonuniform torque output, which is caused by the small number of cylinders. With devolping power such engines vibrate. The basic method of reducing the intensity of vibrations transferred from the engine to the chassis is the application of spring suspension of the engine. Elastic suspension must also prevent shock transfer from frame to the engine which occur during the travel along uneven road.

It works well to use rubber to support the engine. The suspension must have the characteristic of allowing the engine to be rigid in the longitudinal and transverse directions and elastic on the vertical line. It is important to consider that rubber has a low fatigue tensile strength. Therefore the engine supports should be projected so that the rubber would undergo only compression and shift.

Mechanical geared transmissions, transfer case (with locked differential), and a differential wheel dive are used on the home-made cross-country vehicles.

Many amateurish designers use locked differentials in the transfer case of cross-country vehicles which substantially improves the passability of machines.

Lets examine some examples. The drivetrain of motorcycles and motorized wheelchairs on innertubes is comparatively simple (Fig. 1). From the power unit (CA), which contains engine, primary chain, clutch and gearbox, the rotation is transferred by the chain main drive (ГП) to interwheel differential (Д), while from it - to the semiaxles (ПО) of driven wheels (ВК). Controlled wheels (УК) - not driven.


Fig. 1. The functional diagrams of the drivetrain of motorcycle (а) and motorized wheelchair (б) on the low-pressure tires.

Such cross-country vehicles are created on the base of engines and chain transmissions from motorcycles or the motor s******s. Tank and interwheel differentials are borrowed from the drive axles of passenger automobiles.

The drivetrain of cross-country micro-automobiles and microbuses are complex, which is caused by the need for the large number of the driven wheels.

In figures 2 and 3 is the drivetrain of the biaxle 4x4 and triaxle 6x4. In these transmissions chains are commpnly used, which is combinedm with an engine and drive axle with the reverse gear box from a motorized wheelchair. These applications in figures 2 and 3 have the advantage of one axle for driving 4 wheels. The disadvantage is the large number of chains which require frequent adjustments and constant monitoring.

The drivetrain of biaxle 4x4 cross-country vehicle (Fig. 2) contains the intermediate chain transmission (ПП), which connects the power unit (CA) with the reverse reductor (PP), drive axle (BM), onboard chain transmissions (БПп1 and БПп2, БПл1 and БПл2), transverse cardan shafts (КВп and КВл), the semiaxes (ПО) of driven wheels - controlled (УВК) and unguided (BK). Index 1 in the drawing refers to the front, 2 to the rear. Index П indicates the right side, and Л indicates the left side.


Fig. 2. The functional diagram of the drivetrain of the 4x4 chain drive biaxle micro-automobile cross-country vehicle

In the triaxle 6x4 cross-country vehicle (Fig. 3) the leading wheels (УК) are used to steer. The driven wheels (ВК) do not steer, but spread the load out for a lower contact pressure; therefore transverse cardan shafts in the power transfer be absent (front wheel drive). However, in other respects the transmission is practically the same as in biaxle micro-automobile.


Fig. 3. The functional diagram of the drivetrain of the triaxle 6x4 chain drive micro-automobile cross-country vehicle

Shaft transmissions are more complicated in comparison with the chain drive (Fig. 4).

The drivetrain of biaxle all-wheel-drive machine with the steeringwheels (Fig. of 4(a-top)) includes clutch and gearbox integrated with the engine in the power unit (CA), the primary cardan shaft (ПКВ), the torque divider (РК), the longitudinal cardan shafts (КВ1 and КВ2), drive axles (ВМ1 and ВМ2) with main drives and the differentials, transverse cardan shafts (КВп and КВл), the semiaxis (ПО) of driven wheels.

In the drivetrain of the cross-country vehicle with the hinged frame (Fig. 4(6-bottom)) transverse cardan shafts be absent, instead in the longitudinal cardan shaft (KB) there are additional universal joints (ДКШ), placed in the hinged device of the frame.


Fig. 4. The functional diagrams of the shaft transmissions of micro-automobile cross-countrys vehicle with steering wheels (а) and with a hinged frame (б)

For building cross-country vehicles with shaft transmissions it is best to use engines from heavy motorcycles, cardan shafts and drive axles from passenger automobiles.

The drivetrain of the vehicles with driven steering wheels deserves special examination.

Driving the steering wheels (УВК) causes the need for universal joints. Common automobiles use a single cardian joint on and double cardian u-joint on the semiaxles, with the double cardian at the wheel. This creats a constant angular velocity. The simpler shafts used with these cross-country vehicles have only 2 single cardian joints. The high elasticity of innertubes makes it possible to use single universal couplings both on the internal and on the external the ends of the semiaxles.

These examples examined are far from covering the entire variety of engines and transmissions of cross-country vehicles. At the same time they contain some standard technical solutions, which are repeatedly repeated in the amateurish machines.
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:39 PM   #6
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The undercarriage

Next we're going to cover some of the aspects of running gear. These aspects have been developed from several determinations.

The running system (undercarriage) of cross-country vehicle is the cart, formed by frame, by suspension, by wheels and/or by pair of wheelss. Pair of wheels is understood as the parallel or consecutive arangement of wheels, connected together by axles or by links, beams, and leaf springs.

The frame (carrier system) of the machine is served as the base, on which are established the engine with the operating systems; the mechanisms of power transfer (transmission), brake system, steering control, and body.

Suspension holds all of these devices, with the aid of which the frame rests on wheels and pair of wheelss.

The main element of the drivetrain are the ballon tires. The transmit the load by the force of gravity to the ground. This can cause forward motion to start or stop (obviously). The ballon tires decrease the impact transferred to the machine which appear with the passage through uneven terrain.

The wheels of the cross-country vehicle, besides the low (more precise - ultralow) pressure pneumatic tire, consists of the outer rim, the wheel lug pattern, the spokes or disc center (Fig. 1). Rim, spokes or disc together form the base of wheel.


Fig. 1. Wheels for cross-country vehicles on low-pressure tires:
А - with two flat disks, Б - with two rings and flat disk, В - with two rings spokes, Г - with two formed disks (А, Г - with innertubes, supplied with the protector and tightening straps, Б, В - with the "naked" innertubes).

Ror amateurish cross-country vehicles innertubes are used the pressure bags (tires) from conventional vehicles (trucks, automobile and tractor trailers) - "naked" or with the light tread strips from the nylon or rubberized cloth plotted over the external surface of innertubes. Air pressure in pneumatic tires 0.2-0.3 kgs/cm2 (2.8 - 4.3psi), which enables the cross-country vehicle to pass over soils with low weight bearing capacity (and ecology), and their large volume creates buoyancy.

The pneumatic tubes, tighten to the rims by the transversely located cord, nylon or rubber belts. Bulges form in the zones where the bands are absent which play the role of cleats.

Its worth noting that the application of "naked" tires decreases the level of harmful actions on the soil, but at the same time worsens the cohesion of pneumatic tires with the road and will make them those by more subjected to wear and punctures.

Proven with long distance Transarctic trips of home-made cross-country vehicles and the many-year experience of operation by their amateurs, low-pressure tires have proven reliability and long lasting for traveling impassable road. Because of this, Voz'metsya Industry will develop higher quality pressure bags for intensive races, then reliability and longevity of such tires can be increased substantially.

An important part of the running system is the suspension. It transmits to wheels (or pair of wheels) the weight of the machine, passengers, and cargo. Springs and shocks connect from the axles to the frame to handle longitudinal and lateral forces, which appear as it travels down the road. It deadens the shocks and (rapid) impacts, received by wheels unevennesses of theroad.

Elastic supports (springs) from the automobile can be adapted to these cross-country vehicles; leaf springs, coil springs, torsion shafts. For the elimination of fluctuations; friction and hydraulic dampers (shock absorbers). However, elastic elements are all ready on many home-made cross-country vehicles, since the low-pressure tires are not bad shock absorbers.

When not using springs it is necessary to use beams (in the four- and six-wheel running systems). They allow rocking movement relative to the frame, which allows wheels in parallel or sequential pair of wheelss (6x6) to copy the unevennesses of the terrain (Fig. 2). (basically, articulation).


Fig. 2. Bob elements of suspensions (A - front axle, Б - rear onboard beam):
1 - longitudinal horizontal hinge, 2 - transverse horizontal hinge.

The most comfortable conditions for the driver and the passengers are created by building suspensions with springs (elastic elements) (Fig. 3). Their application gives possibility it increased failure-free related to fatigue, performance, and increased longevity (life) of the cross-country vehicles.


Fig. 3. Suspensions with springs (elastic elements):
А, Б - solid axle
В, Г - independent axle
Д, Е - solid axle
Ж, 3 - independent axle
(А, В, Д, Ж - steering; Б, Г, Е, 3 - non-steering)

The leaf spring can serve two purposes, as links in the suspensions (to locate the axle) and as an elastic element (spring). Leafs can also be used in a manner that requires links, or guides, to keep the axle located under the vehicle. Coil spring and other suspension methods will almost all ways require these links.

The possible suspensions of cross-country vehicles is divided into the following forms: group (dependent, solid axle), in which the movement of one wheel is transmitted to another via the beam or bridge; individual (independent), in which there is no or little interaction between the wheels. Independent is the best for smoothness of motion, however it is more complex to construct.

The parameters for suspension of cross-country vehicles are selected so that its spring-loaded part (the sprung weight) fluctuates with the frequency of normal walking (0.8 - 1.2 Hz). The free fluctuations sprung weight must be rapidly attenuated (for 2 - 3 seconds). Such fluctuations are transfered to the human organism comparatively easily.

As the frame for some cross-country vehicles they use base of the body (unibody). A frame (or unibody) must posses a sufficient stiffness so that under the action of the loads, which appear during the motion of machine, the alignment of the mechanisms fastened to it remain practically constant.

Using the body as a frame allows its mass to be somewhat decreased. However, with a separate frame and body it is possible to simplify construction of the body, reduce the level of internally-produced noise by using rubber body mounts, simplified assembling and dismantling the vehicle, and the replacement of damaged parts and pieces.

Automobile cross-country vehicles can be made with one or two sections, which predetermines by the construction of their frame. The single-section (monoblock) frames are continuous, while on the two-section (two-unit type) hinged (articulated) frames are two pieces (Fig. 4). The continuous frames (Fig.4(A-top)) are similar in construction to the frames of usual passenger automobiles. Hinged (Fig. 4(б-bottom)) - have much in common with the frames of hinged articulated tractors.


Fig. 4. Frames of cross-country vehicles (A - continuous, б - hinged):
1 - vertical hinge, 2 - flapping hinge.

Hinged frames consist of two half-frames, connected between themselves with vertical and horizontal hinges. The vertical hinge is for changing the direction of the machine (steering). The flapping hinge allows the machine to adapt to the terrain.

A disadvantage to the articulated design is the increased tendency to tip sideways while steering. Another concern is the horizontal hinge. When designing the frame an elastic element can be added to prevent the half frames from turning in relation to each other with the ability progressively adjust hardness.
__________________
Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:41 PM   #7
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Default Re: How To Build A Karakat

Control system


Among the parts of the cross-country vehicle special are controls like brake and steering systems. Quality and reliability of these these systems is a very important part of safety and the motion of the vehicle. They allow the driver to smoothly and sharply reduced the speed of machine up to a total standstill. The brakes also hold the machine an unlimited time in the fixed state both on the horizontal and on inclines. The brakes can also assist the machine in turning sharper by breaking the inside lagging tires.

On the automobile cross-country vehicle it has two independent brake systems: working (with vehicle in motion, using a peddle) and parking brake also performing as a spare (from the lever). Assemblies can use the same system for the working and parking brake (Fig. 5).


Fig. 5. Brake control for the cross-country vehicle:
1 - brake pedal, 2 - brake arm, 3, 4 - central thrusts, 5 - idler lever, 6 - equalizing yoke, 7 - onboard thrusts, 8 - lever of expansion cam, 9 - expansion cam, 10 - brake shoe.

Turning the cross-country vehicles is achieved by two methods: by changing the position of the steering wheels, like a regular automobile, or by the hinged articulated frame. The most commen method for steering is by turning the front wheels. (Fig. 6).


Fig. 6. Steering control for the cross-country vehicle:
1 - steering wheel, 2 - control shaft, 3 - steering gear, 4 - drop arm, 5 - longitudinal thrusts, 6 - transitional bridge, 7 - lever of slewing journal, 8 - lever of steering trapezoid, 9 - transverse pulled, 10 - controlled wheels.

When turning the vehicle with the the front wheels only it is difficult to obtain a small turning radius because of the large outer diameter of the low-pressure tires. Machines with the hinged frame are free from this deficiency.

Some amateurish designers decrease the turning radius of machines with front steering wheels by the slight braking of internal wheels. This is commonly done on agricultural tractors. In this case control of right and left brake assemblies must be separate (by two pedals or levers). Under the simultaneous operation of both pedals or levers normal braking of machine occurs. The application of manual control of the brakes to sharply turn the machine is preferable. This will help prevent driver mistakes.

For smooth braking and for maintaining safe speed on descents it may be necessary use the engine as brake. It can also be used on slippery roads independently and in combination with the service brake to prevent lateral drifts. Basically this converts the engine into the brake, just let go of the throttle peddle and leave the engine clutched.

An important performance property of the vehicle is its ability to drive in a straight line without the interference of the driver (and independently return to the center after the end of turning). With poor stabilization control of the machine it becomes tiresome to drive.

The stabilization of steering is reached due to the transverse inclination of the axis of the pins of slewing journals, and in machines with the hinged frames due to the longitudinal inclination of the axis of vertical hinge.

Such constructive solutions help a little, however the task of stabilizing the vehicles can be solved with the aid of elastic elements, which return the controlled wheels or hinged frame to the neutral position.
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


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Old 12-14-2005, 03:45 PM   #8
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Default Re: How To Build A Karakat

[Note: This last section is kind of dry. The translation was full of describing adjectives and modifiers that really ruined the english generated from the russian. I left a bunch of stuff out that made me scratch my head...and honestly I can't see how much design there is in a square box. I guess I'm not an artist]

Design


The main difference in cross-country compared to regular vehicles lies in the fact that the wheels with the tires are of an increased overall size. Moreover the machines are intended predominantly for use in many conditions such as tundra, forest-tundra, snow, ice, water, etc. Snow and swamp buggies must also posses the ability to overcome obstacles by fording or swimming.

After figuring out all of the technical details its time to make your vehicle beautiful. Designers today strive to create of beautiful, and convenient devices useful to man and society. A point which deserves consideration is the artistic construction of the cross-country vehicle: the guarantee of convenient operation and the aesthetical expressiveness of machine.

Ergonomic requirements for the machine are developed by investigating the activity of the human operator in the vehicle; the gauges, placement of controls, temperature, noise, vibration, illumination, etc.

The seat direction, their dimensional parameters are determined with the layout of machine with the use of representations of "standard" person, templates and mannequins. Basic data, necessary for designing the places for the driver and the passengers to sit in the automobile- cross-country vehicle are cited in figures 1 and 2.


Fig. 1. The place for the driver to sit in the cross-country vehicle


Fig. 2. Arrangement for driver and passengers seating

The pedal and lever operation of the vehicle must be located in reach respectively of arms and legs of driver. The movement of controls must be coordinated with the natural motion of arms and legs of driver, and also corresponded to the change in course (for example, the steering wheel rotating to the right turns the vehicle right, and left to left). Mechanical effort on the control elements must be reflected in the behavior of the object (for example, pedal force on the brake must it was associated with the vehicles breaking effort).

The shape of physical elements of the cross-country vehicle create the impression of integrity, the perfection of the machine, can be achieved two basic ways: by creating a layout diagram from one or two centers (Fig. 3) and by creating of a layout diagram on single or dual grid, formed by intersecting (at straight or oblique angle) lines (Fig. 4). Changing the position of the center (or centers), leading additional slants, it is possible to visually strengthened these or other operational special features of the cross-country vehicle: its tractive power, high-speed possibilities etcetera. The drawing allows attention to the increased passenger and cargo capacity of cross-country vehicle as the form is changed.


Fig. 3. Creating a diagram of the cross-country vehicle from two centers (О1 and О2):
а - the balanced diagram; б - the diagram which emphasizes traction; в - the diagram which emphasizes the high-speed possibilities


Fig. 4. Creating a diagram of the cross-country vehicle on a rectangular grid
(а, б, в - the same as in Fig. 3).

The goal is a form in harmony. Proportionality of vehicle and its component parts that give the visual perception of the object as whole. 0.618, which corresponds to the relation of the dimensions of human body, obtained by geometric construction. With the artistic construction of cross-country vehicles K was accepted as 0.4 - 0.6.

Examples shown in figures 5 and 6 are diagrams of two and three axle vehicles. The values of the constant of proportionality of their sizes is within the recommended interval:



Where:
  • Lгаб, Bгаб, Hгаб - Overall dimensions (length, width, height)
  • Lбаз - Wheel base
  • D - Outer diameter of wheel
  • X1 and Х2, У1 and У2 - Coordinate of the point O, which belongs to the greatest sections of machine on the vertical line and to horizontal.

The lines, which form the outline (silhouette) of the vehicle and its basic parts are shown in Fig. 5 and 6. The embodiment of united aesthetical looks means they stand out in a group of machines in the same class.

Mastery of the methods of artistic construction has allowed amateurish designers to create machines which correspond to the requirements of ergonomics and technical aesthetics. Artistic construction must become part of the process of designing the new and promising cross-country vehicles. Amateurish cross-country vehicles must be designed with the look of the industrial production models developed by professional designers and designers.


Fig. 5. Harmonious design of a 2 axle cross-country vehicle on innertubes


Fig. 6. Harmonious design of a 3 axle cross-country vehicle on innertubes

Thats it folks!
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Bobby after seeing pictures of "the tires"
Quote:
Originally Posted by Longfield
After seeing these tires I think that the 30 splines would get scared and go limp and not go in the housing! I think these tires have rockwells writen all over them!


www.brokenyoke.com
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Old 01-04-2006, 10:02 AM   #9
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Default Re: How To Build A Karakat

You planning on building one?
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Old 03-01-2007, 10:11 PM   #10
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Default Re: How To Build A Karakat

gee done any reaserch yet. jk
well that is detail.
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Old 08-08-2007, 04:15 AM   #11
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Default Re: How To Build A Karakat

Thought this site might be of interest; LITVINA
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