FOLDING Bike “Tourist” lives up to its name. He’s not heavy, quite durable, easy to move, has a good ergonomic proportions, fitted with four-chain transmission; it may be two racks, generator with headlight, speedometer, rear view mirror, audible signal, reflectors and stand. The best rating is a big demand for it, which, unfortunately, is not satisfied the domestic industry.
However, there is this bike and disadvantages, and the main — the awkwardness, the inability to fold the machine, as, for example, “Cama”. And without that try to enter with a bike in city traffic, or place it in the trunk of the car (which would have greatly increased the range of travel). And in the apartment folding bike post would be much easier — it would take almost two times less space than usual. In General, it was something to try to remake his “Tourist”.
The plane of the connector frame bike I chose vertical and did it for two reasons. First, during the folding wheels do not rise one above the other, therefore, the Bicycle can be folded without taking the wheels off the floor – just roll front to back. Second, because the top tube of the frame of a “Tourist” horizontal, and the bottom is with it an angle of 45°, was easier to make only one lower junction at an angle and the top straight, although the device they are similar.
That bike had the shortest length in the folded position, the plane of the joints should be placed in the middle of its base; however, this folding will not interfere with each other the axles of the wheels. Therefore, it is better that plane to be offset from the middle of 20-30 mm.
Now more about the design of the hinge connectors of the frame.
To the pipes of the bike frame welded pipes, and the flanges with eyelets connected to each other by bolts with wing heads (each of them passes through a smooth hole of the eyelet is welded to one flange, and screwed into the threaded hole of the other flange of the hinge node). In addition, another two bolts directly connect in the same way the flanges together. Experience has shown that it is desirable for this use appears now on folding bikes samoshvatyvayuscheysya bolts with swivel heads: and the key for them is required and they do not stick out (fixed head).
The process of folding is carried out so: at first completely turn the four bolts from the flanges and bolts are weakened in the eyes; then the frame is drawn in the direction of the folding — wheels will ride on a platform a meter and a half, and the bike will be folded. Not to lose inside-out bolts, it is better to tightly screw in the same holes, and weakened again tighten, then part of the bike will not spontaneously unfold. Well, for a full guarantee against accidental unfolding them can tie a rope or rubber cord. Unfolding in reverse order.
Flanges, bolts, lugs and lugs is desirably made of quality grade steel “45” or even more robust, otherwise fine thread on these details for the best tightening of the flanges and prevent loosening, quick work.
Geometry of a folding bike.
Geometry folding bike.
Lower swivel.
Bottom turning unit:
1 — the frame of the bike, 2 — nozzle, 3 — eye, 4 — bolt with wing head, 5 — lug, 6 — front lower flange, 7 — bottom rear flange.
Turning the upper node.
Top swivel:
1 — the frame of the bike, 2 — nozzle, 3 — eye, 4 — bolt with wing head, 5 — lug, 6 — front upper flange, 7 — rear upper flange, 8, 9 — bolt with a swivel head.
Semicircular cutouts at the free end of the branch pipe and the oblique cuts on the lower tubes it makes sense to treat after collapsing shells. Ready the pipes should slide into the frame tube with some effort.
The holes in the flanges were severely misaligned, it is necessary to cut them together, cementing the flanges in pairs. Hole Ø 29 mm Ø 32 mm are better to make first a little lower and then be put on the frame tubes.
Ball lock Ø 4 mm socket with swivel head — from any bearing, such as Cycling. Retainer spring wound from spring steel wire (string). The parameters of the spring: outer diameter of 3.9—4 mm, wire diameter 0.5—0.6 mm, spring free length 20-25 mm, number of turns 12-15.
Bolt with a swivel head.
Bolt with swivel head:
1 — housing bolts, 2 — swivel head, 3 — axis head, 4 — ball retainer, 5 retainer spring.
Scheme of Assembly of the upper flange.
Scheme of the Assembly of the upper flange:
1 — eyes, 2 boss, 3 — rear flange 4 — back upper flange, 5 — bolt technology, 6 — technology nut, 7 — pin technology for fixing the lugs of the upper flange, 8 — remote sleeve.
Scheme of Assembly of bottom flange.
Scheme of Assembly of bottom flange:
1 — eyes, 2 boss, 3 — front lower flange, 4 — rear lower flange, 5— bolt technology, 6 — technology nut, 7 technology pin 8 — remote sleeve.
Scheme of Assembly of joints.
The circuit Assembly hinges:
1 — the frame of the bike, 2 — a branch pipe of the upper joint 3 — rear top flange, 4 front upper flange, 5 — lug, 6 — technology nut, 7 — bolt technology, an 8 — eyelet, 9 — technological rod, 10 — remote washer upper hinge 11 — the remote washer lower ball joint, 12 — a branch pipe of the lower hinge, 13 — rear lower flange 14 — of the front lower flange.
Docking stations are going for gas welding (welding is no good here: the tube with millimeter wall easy to burn through). The welds have a side of 2.5—3 mm.
When welding, you must fulfill two conditions: to ensure the alignment of all the hinges swivel blocks (otherwise the folding and unfolding of the bike will happen to the resistance and deformation of the frame), and to prevent warping of the welded parts.
So Assembly is best done in two steps. First, the flanges are welded lugs and lugs; details are connected to each other with technological bolts and nuts with M6 thread so that all the holes matched. Eyes are collected in sets with pins (or bolts) and nuts with the same thread. Between each pair of lugs are mounted standoffs. These tight sets are placed on the flanges and hold them by friction.
Then do gas welding chiseled pot holders (at least two for each part), then all adjusted, boil the seams. To prevent warping, you should not perform stitches for the entire length — better to do it in sections no longer than 10-15 mm each. Adjacent to the welding section seam can be started only after previous cooling to a temperature not higher than 40-50° C. in Order not to lose time, yet cools down one area, you can cook the other located as far as possible from the cooling (better another pair of flanges). After welding, the node is disconnected and cleaned.
The next operation is the mounting of pivot nodes. Primarily on the bike frame carefully is tokenized common plane dock. On both sides at a distance of 2 mm from it, make four cut, that is cut from the frame sections with a length of 4 mm. It is necessary that the welds of the joints do not protrude beyond the plane of the flanges.
Then put on a frame and installed in accordance with the drawings nozzles and flanges. Between the tubes of the frame remote install washers and both pieces tightly pull together (with rope or rubber strap). To ensure that the alignment holes of the mating nodes, inserted in them the technological pin, and flanges tightened by bolts with M6 thread.
Checking the proper placement of the parts on the frame (especially the location of the docking platforms, they should be strictly in one plane), as well as the alignment of its pipes, parts sticking, and then finally weld the above-described manner: first, the outside of the joints, and then removing the bolts and adding the frame from the inside. After that part of the frame separated, the seams are sanded and the holes in the flanges and the lugs modify the connector bolts. Followed by final finishing and painting of the joints of the frame.
B. DOROFEEV, Kharkov

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