Loaders are familiar to everyone. In addition to common wheel loaders, there are track loaders, backhoe loaders, skid steer loaders, and so on. The main task of the loader is to use its own movement to load and tilt bulk materials. This requirement creates its unique working device. Here is a brief introduction to the form of the working device of the loader. Due to the relative speciality of the skid loader, this article will not discuss it.
The working device of the loader is about performance and efficiency
When it comes to the form of the working device of the loader, in addition to the overall arrangement, the form of the bucket mechanism is mainly discussed. This is because the loader relies on the kinetic energy given to the loader by the walking mechanism to cause the bucket to be inserted into the material pile. The arms and the lifting mechanism are similar, and there is not much to discuss.
Early track loaders with long connecting rods and short swing arms
The bucket mechanism has a lot of knowledge. Although the common Z-link mechanism is also known as the reverse six-link mechanism, there are many other forms. We know that the early loaders that used hydraulic working devices were actually crawler loaders. At that time, due to the use of crawler tractors as the chassis, they were subject to many restrictions, usually in the form of 7-link forward rotation. The so-called forward rotation means that the rotation direction of the swing arm is the same as that of the bucket, and the reverse rotation is the opposite.
The same is the forward rotation of 7 connecting rods, and there are many differences in the layout of the cylinder.
After the emergence of the wheel loader, due to the rear of the engine, the front-end working device is not restricted, and various forms of link mechanisms have appeared. The most common is the forward rotation 8 link. There are some shortcomings in the form of forward rotation. When the boom is raised and lowered, the linkage mechanism is difficult to make the bucket move up and down. It requires the bucket cylinder to cooperate properly, and the mechanism is too complicated. Some machines require the bucket cylinder to feed oil when the bucket is digging up, and the power is obviously not as good as that of the big cavity.
Early wheel loaders mostly used forward 8-link
Therefore, later, the simpler and more efficient reverse six-link mechanism, that is, the Z-shaped link mechanism, became popular. The Z-shaped link mechanism digs up the bucket when the bucket cylinder is feeding oil in a large cavity, and has a large force. At the same time, it can also keep the bucket moving up and down while the boom is lifting. These advantages make Z-shaped connecting rods used in most loaders in the world, and even later track loaders also use this form after the engine is rear-mounted.
The same is the forward rotation of 8 connecting rods, and the cylinder arrangement is different.
Of course, everything is not absolute. For example, Carter introduced the 992G loader with a single boom structure in 1999. Due to the unusual boom form, the bucket mechanism also adopts the form of forward rotation six links. To avoid layout problems, of course, this form has been optimized to enhance the ability of the bucket to move in parallel. At the same time, a larger bucket cylinder is also used to ensure the bucket breakout force.
Including track loaders, Z-linkages are currently widely used in loaders
As for the backhoe loader, because the engine needs to be arranged at the front end, the working device of the loader is greatly limited. Some use the forward rotation six links, and some directly arrange the bucket cylinder on the rocker arm and the connecting rod. between. However, the backhoe loader is not the main earthmoving machine, and people's requirements for productivity and efficiency are not high, so the form itself is not very important.
Six-link forward type used by single boom loader
A special case of mainstream loaders now is Volvo. Except for the largest model, its loaders use the form of eight-link forward rotation, similar to some early structural forms. The oil cylinder is arranged below the boom and is also a bucket. The bucket is dug up when the oil is injected into the large cavity. By the way, the term "X-to-Y link" is no longer used abroad, because it is clear that this expression cannot well summarize various structural forms.
The front end of the backhoe loader is subject to the engine, and the structure is different from the ordinary loader
Volvo loaders mostly use special forms, which Volvo calls TP connecting rods
