Bearing socket connection mode.The function of the wheelbarrow is to connect the axle, the bearing, and the fork into one.Limited by the structure of the unicycle and the space of installation, the wheelbase can not adopt the standard bearing pedestal, which can only be specially designed.The wheelbase and fork connection modes have undergone three generations.The first generation of wheelbase has the worst connection and has been completely eliminated from the developed areas of the wheelbarrow, such as Europe and America.The second generation is a little bit better, and there are very few low-end cars abroad.The great wave of the sand, the survival of the fittest, the third generation of the bearing stands out.The low grade car of foreign high school basically adopts the third generation bearing seat.1;It is not easy to love you, and many of you are suffering from it.The first generation of bearings is made of ordinary steel sheet metal, which is actually an iron shell.Simple construction, low cost and only a few cents per cost.Low strength, easy to deform.The lateral stability is extremely poor, often causing the bearing to move in the direction of the crankshaft.Because of the vulnerability, the stress concentration in the root causes the metal fatigue and the cracking damage.(2) when the bearing is replaced, it is difficult to remove the bearing. The three hands of the bearing extractor are difficult to hold at the same time, and the individual can hardly change the bearing. (3) it belongs to disposable products, which can be deformed or damaged once.Only from the manufacturer or the seller's hand the whole package (bearing in the bearing pedestal already installed bearing) mail order.High replacement cost.It's almost impossible to change the good bearings you like.(4) because the first generation of the bearing seat and the car fork connection are flat, the corresponding position at the bottom of the fork is also compressed into a flat shape, which greatly reduces the stability of the vehicle fork.After the bottom of the fork is crushed, there are only a few rings of thread in the mounting screw hole.(5) the only advantage is that the screws on the bearing pedestal are rectangular and can be adjusted to the relative position of the wheel and fork center.The machining precision of the fork (length and width) can be greatly reduced.As long as the length of the tube is not more than 5 mm, the wheel can be transferred to the center of the fork.There are some deviations in the size of the flat bottom of the fork, which will not affect the installation. It is convenient for some enterprises with poor technical and production capacity.2;The second generation of bearing seats are not used at home and abroad, and are soon replaced by the third generation bearing pedestal.The second generation of the bearing block has solved some of the first generation's shortcomings. (1) the bearing pedestal can be used repeatedly, and it is convenient to remove the bearings. The bearings can be purchased individually or in place.   (2) it is not easy to deform, and it is greatly improved after installation.(3) installation and disassembly is also difficult, but it is more convenient than the generation.It is easy to wear on the inside and not suitable for long-term use.What is more, it is made of plastic and easily broken.There's no harm in it.3;Third generation bearing pedestal.The third generation bearing pedestal and car fork welding are one, high strength, good stability.Quick and convenient installation and disassembly, easy to replace the bearing, rugged and durable.It has been adopted by the developed regions of Europe and America.The only disadvantage of the third generation is that the machining precision of the fork is high, and the left and right sides of the car must be equal, otherwise the wheel deviation is not correct.For the producer processing equipment, the processing technology requirements are high.