VELOSEZON | MODEL CONSTRUCTION

The proposed design is the winner of one of the contests of velomobiles in the Lithuanian city of šiauliai.

My first recumbent I built in the 1980’s, a few times it was altered in search of the optimal ratio of seat design and arrangement of the pedals, steering wheel.

The final version is designed for wheels from bicycles brand MMVZ or “gum” though tested it on other wheels. Bigger diameter is possible only for rider height not less than 170 cm: this is due to the fact that the steering wheel is between my legs.

Low seat position and, therefore, the center of gravity even with a relatively small rear track and the small base makes the machine comfortable as the recliner, and unstable on steep turns tipping is virtually eliminated in the worst case begins to move on two wheels, like a conventional bike — front and one rear, while there is no fixed point of tipping over. The design fault is occurring the lateral torque on the steering wheel when pressing the pedals. But this is noticeable only when hill climbing; on a flat plot of land is not felt — even you can only manage the legs and the hands removed from the steering wheel. At turns, both feet of the rider lean into turns and stay on the pedals; turning radius is thus less than one and a half meters at the outdoor track.

Good value for the elements of the basic units of structure allowed us to create a velomobile with good dynamic characteristics, good aerodynamics and modern design. As shown by the operation of the machine in a few years, it is easy to operate, safe on the roads, does not interfere with the General flow of traffic, also suitable for business trips and for leisure. Especially fit this crew (with a roomy trunk) gardeners, cottagers, gardeners. The velomobile can be operated by people who, for one reason or another is not available a normal bike.

“Velotron”, so I named my car is a muscular three-wheeled vehicle (Fig. 1), comprising a frame with a seat type “chaise longue”, the two rear fixed wheels and front steering wheel located in the rotating frame with a pedal and chain transmission mounted on a turning fork.

Fig. 1. Recumbent “Velotron”:

1 — steering wheel, 2 — chain plug, 3 — rod, 4 — carriage, 5 — chain drive, 6 — tube carriage 7 swivel plug, 8 beam frame, 9 — connecting pipe 10 — bracket-seat, 11 — front frame 12 — column support seat 13 — seat 14 — baggage bag, 15 — rear wheels, 16 — trunk.

If the constructor has other parts, it needs to perform their own drawings in scale of 1:1, refer to below instructions. First, you need to determine the distance from the pedals to the so-called anthropometric points And the intersection lines of the back and bottom of seat (Fig. 2). For average height it is approximately equal to 950…1000 mm. the legs should be slightly bent at the knees and the feet to be level with the seat. The back is attached to a tilt of 30°…45°. To model this easily, if on a chair with a back to put an inclined metal plate or plywood sheet to rest against the edge of the filled box to the desired height.

Fig. 2. Definition schema anthropometric point A.

Fig. 3. The rear frame Assembly:

1 — connecting pipe, 2 — bracket of the seat 3 to the front frame, 4 — median bushings axle rear wheels, 5 — mounted shields, 6 — the rear of the frame.

(The position of the rider on the “Velotron” modeled home in the tub). Found distance to be the original when procenjivanja design.

The angle of the chain fork to the horizon depends on the diameter of the wheels and may be 30°±15°. Note, however, that the carriage of the actuator should not be below 350 mm from the road, as otherwise the heel will touch the bumps when pedaling.

Anthropometric point a, in turn, should not be above the carriage. It is also desirable that the distance from the center of the BB to the wheel axis was not more than 400-500 mm, and the clearance between the tire wheel and fork — not less than 5 mm.

One should dwell on the pose of a rider, providing the highest possible power transfer. The determining factor here was the optimization of the angle between the bent leg and the body: it is the same as that of the cyclist, only recumbent rider advantageously rotated in space. The position of the body, as we see from figure 2, nearly horizontal, aerodynamically justified. The angle of inclination of the spins to the horizontal preferable is less than 45° (in record velomobiles it may be even 15°). However, in all cases, the neck and the back rider should be approximately vertical, and the device seat is designed to provide. In addition, the response from the foot pedal moves the rider in the opposite direction — this movement is limited by a sharp curve of the seatback up and appropriate design of shoulders. While the seat has the headrest at the level of the neck, and it should not be higher than depicted in the figure, or on rough road a head will strike the headrest. The seat as a whole must be rigid, as this determines the efficiency of energy transfer from human to machine.

And now that set out the basic prerequisites, let us turn to the description of the device of the recumbent. The most important production machines are rotary frame drive the front wheel and the seat frame.

As the drive of the front wheel, used rear brake hub. Conversely, the rear wheels serve as the front; they are set on a makeshift axle, which is structurally similar to pedal. To use these wheels with regular axles under the console fixing is impossible due to the low strength of the regular axes of bending. It is also impossible to attach them to Bicycle handlebars welded to the frame, as the structure will not be rigid with respect to lateral loads of the roll and the wheel will no longer be parallel to each other.

Made rotatable frame of the rear fork chain bike MMVZ or “Desna” and the front forks of the same bike. Is separated from the frame chain fork bracket axis that with a hacksaw exempt from the strut tubes. Before mounting the front fork it is clamped in a vise and throw the feathers on the value of 110…115 mm, then remove them from the brackets.

In chain the plug is inserted the rear wheel, the axis of which should be in the center of the brackets and fitting the front fork, putting on her the cut ends of the feathers to the chain brackets of the plug. The correct alignment of the plug relative to the wheel must be achieved by fitting the ends of the feather of front fork, as well as to maintain a distance from the wheel axis to base of tail front fork, is approximately 275…280 mm. When alignment is ensured, and the angle between the straights forks is 90°…95°, serverlimit connection of the ends of the front forks and brackets, insert one steel pin Ø 2,5…3 mm (wire or nails) and clench them. Now the wheel can be removed and once again to check the connection. Then prepare two tubes of Ø 12…14 mm for the connection of the carriage with the base of the front fork. The pipe should have an oblique cut to be customized.

Front frame ready for welding and soldering works. First gas welding welded two pipes in its place, and then solder the brass connections zastepowane all. You should achieve careful soldering, to then file off the excess. If welding or soldering has been performed carefully, the paint coating the forks are very hurt, and picking up enamel, these places can tint. It should be mentioned that the steering tube of the front forks, the author has shortened to 140 mm for the best viewing between the front and rear frames, and also for reduction of mass.

The connection of the rear frame beam (Fig. 1) are adjustable, but rigid enough: this quality largely depends on the rigidity of the structure. Therefore, the connecting pipe must have a diameter not less than 36 mm and a wall thickness not less than 1.8 mm (the elements of the folding frame to use for this purpose should not).

Before starting to work on the elements of the rear frame, to its side view is drawn in scale of 1:1 and applied to this template is prepared for welding details. When items are customized, they are pre-connect arc welding, produce a visual alignment or measure the symmetry and produce a final gas welding rear frame, privaris median pre-sleeve halves to the frame. They provide alignment of the inserted rod Ø 14 mm. the Latter is welded a connecting pipe, and the bracket of the seat.

If assembled rear frame profile matches scale drawing, is pre-welded mounting plates. They have two holes for connecting with flaps and two coaxial holes for installation tick the manual brakes, if the conditions they need.

Tail section rear frame is raised, which is caused by the desire to eliminate a noticeable deflection of this part of the velomobile.

The seat frame (Fig. 4) are made of solid aluminum alloy sheet with thickness of 2…3 mm, having cut from it the contour of the workpiece from the surface. Then draw lateral (inner) profile of the seat frame in 1:1 scale, using the grid. Flex the blank frame on this profile and strong mallet blows make ochibka boards (the Central part up to a height of 20…25 mm, bottom and top to 10…15 mm).

Fig. 4. The calculation of the seat frame.

It should be mentioned that if the sheet is too brittle, that the edge of the workpiece must be carefully annealed without heating to a reflow edge. Work on the frame requires accuracy and careful execution, particularly of the head restraint. The sections of the framework with holes for the support struts (see figure 1) need to strengthen two planks, prilepov them to each limb. All sharp edges are trimmed and rounded. If the changes obtained form of seats not expected, then glued on its frame transverse strips of foam the length of 60…80 mm and a thickness of 30…40 mm, additional fixing them with a cord in areas of sharp bends through the drilled holes. On top of the foam adhesive qualities beautiful solid fabric. Better if it feels slippery: such a casing when planting allows comfortable posture and will not cause additional friction when riding.

The rear wheels, as stated above, have their own axle (see figure). Driveshaft — the part responsible and must be made of high quality steel and tempered HDTV with a deep vacation and thoroughly customized to the hub of the wheel.

Fig. 5. Half shaft of the rear wheel.

The trunk in the form of a lattice (in this design from the industrial refrigerator) aluminum alloy sheet thickness of 1…1.5 mm; mounted in any way from the bottom to the rear frame. A small carrier bag mounted on the seat back, is used for tool storage and pump, it also can carry small items or products. It is easy to do from the school portfolio and prilepite or screwing to the seat frame.

Those who are fit seem inconvenient, it is recommended to make a control flap on a hinge.

When tested in a velomobile, check the roll-forward follows: to disperse at horizontal section of level road to the maximum speed (35…40 km/h) and from the reference notes to measure the path of inertia. As practice shows, it needs to be 175…200 m.

Tire pressure: front wheel 3…3,5 kg/cm², rear 2,7…3 kg/cm²; these figures in the operation of the velomobile, it is desirable to monitor every two weeks. You should pay attention to the parallelism of the rear wheels by measuring the distance between their rims front and rear: the difference in the measurements should not exceed 1…3 mm.

The velomobile has a retro-reflector and lighting with battery pack. Signs, decals on the seat-back is performed by a sticker. They are cut from fluorescent foil applied in the design of traffic signs. It is also desirable to have a small box attached to the velomobile and visible from all sides. This is enough to attract the attention of other drivers to unusual crew.

To store bicycles in the apartment, as the dimensions allow it to raise the lift and to carry through a standard doorway door.

Technical characteristics of the velomobile

Type — road, for teenagers and adults

The number of places is one

Drive — pedal, chain drive on the front wheel

Number of teeth:

sprocket — 51

slave — 15

Brake — foot operated, front wheel drive

Tyre size, mm — 40 — 406 (20″X1³/₄“)

The height of the lower part of the seat above the road, mm — 40

Seat — polulezhachee, like chaise

Base, mm — 840 — 850

Track, mm — 630 — 640

Overall dimensions, mm — 1650X880X725

Weight, kg — 18 — 20

V. MAZURCHAK, engineer, master of sports of the USSR, Poltava

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