Common hydraulic dump jack classification

Classification of hydraulic dump jacks

(1) Front hydraulic jack

Front hydraulic jack, commonly used in vehicles with a large load capacity, from the aspect of gravity, front hydraulic jack lifting force is small, the impact of the jack seat position of the cargo box and the vehicle beam base position is reduced, not only to withstand greater weight, but also to protect the stability of the lifting, so that the vehicle in bad road conditions when lifting the cargo box, the cargo box can also maintain a high lateral rigidity.

However, the front hydraulic jack also has many design defects. For example, its cylinder piston has a long stroke, which limits the height of the unloading site. Compared with the commonly used central hydraulic jack, when the carriage is lifted to the same height, the front hydraulic jack, Because the front hydraulic jack is installed in the front, the piston length is longer than that of the middle hydraulic jack.  

And the length of the hydraulic oil pipe is limited. Generally, the hydraulic oil tank of the front top is placed behind the cab, that is, at the front of the carriage, close to the front hydraulic jack, occupying part of the space of the vehicle chassis. Many heavy-duty dump trucks for mountain road transportation need to install water tanks, and the general design position is also the position of the front hydraulic top, so only one of the two can be installed.

Commonly assembled models: As mentioned above, front-mounted hydraulic jacks are generally assembled only by vehicles with large carrying capacity. For road transport vehicles, vehicle weight is also particularly important, but the front hydraulic jack design weight is large, its support surface is the front plate of the cargo box, if you pursue lightweight, you can only reduce the weight of the side and tail plates of the cargo box.

(2) Mid-mounted hydraulic jack

Mid-mounted hydraulic jacks are divided into: double-cylinder hydraulic jacks and horizontal single-cylinder hydraulic jacks.

In terms of self-weight, center of gravity, and flexibility, the center-mounted hydraulic jack is more suitable for road transport vehicles, because it can effectively lower the center of gravity of the vehicle when mounted on a shorter dump truck cargo box. This can improve the stability during lifting. Many dump trucks that transport coal, bricks and sand have limited smoothness of the road surface when unloading in a specific site. The mid-mounted hydraulic jack can greatly avoid the situation that the cargo box falls sideways.

Compared with the front hydraulic jack set in the front of the support surface of the cargo tank, the middle hydraulic jack support surface is set directly in the front of the middle of the cargo tank, the more forward the hydraulic jack is set, the smaller the force when lifting.

Mid-mounted hydraulic jacks are installed on the inside of the beam, so its overall weight is distributed in the beam part, the hydraulic cylinder can also be set on the inside of the beam, a good use of the beam gap area, the overall weight center of gravity are reduced, which is conducive to improving the stability of the vehicle driving, the center of gravity will also be much lower than the front hydraulic jacks.

However, it also has a fatal flaw, in order to improve the piston stroke, the center-mounted hydraulic jack ground clearance is not high, driving in some bad road conditions, the bottom of the hydraulic jack will first against the mud surface, forming a great driving resistance.

(3) Horizontal single-cylinder hydraulic jack

The horizontal single-cylinder hydraulic jack is more similar to the applicable models of the mid-mounted hydraulic jack, which also has the advantage of simple design, practicality, cost-effective, good durability and stability, and can also be assembled on the engineering dump truck.

So called horizontal hydraulic jack, because it is contracted state is lying in the interior of the beam, compared to the double jack, it saves a lot of space. However, in terms of self-weight, the middle-mounted double jack is better. Because of its own weight, the horizontal hydraulic jack was basically replaced by the middle-mounted double jack.

There are also some vehicles with super heavy load requirements, which use combined hydraulic jacks. Using the combined capabilities of front hydraulic jacks, mid-mounted hydraulic jacks and single-cylinder horizontal hydraulic jacks, a group of hydraulic jacks are strong and powerful. To improve the vehicle's top-lifting ability and stability. Of course, this combination is only used under specific working conditions, and this kind of assembly is not seen in general road transport vehicles.

(4) Rollover hydraulic dump jack

In the transportation fields of sand, coal, clinker, etc., many transporters are equipped with rollover semi-trailers, while the length of the dump jack of the rollover dump truck is much shorter, and the overall length is less than half of the central hydraulic double jack , installed in a line at the bottom of the cargo box.

Although its appearance looks very small, its bearing capacity is worthy of recognition. For some 11.5-meter, 13-meter and other long trailers, the rollover hydraulic jack is more secure for the rigidity of the cargo box.

How to maintain the hydraulic dump jack

The most important part of the hydraulic system is the hydraulic oil, of which the hydraulic oil is divided into 32# and 46#. In winter, it is generally filled with 32# hydraulic oil with lower viscosity, and in summer, it is filled with 46# viscous oil. High-grade hydraulic oil, of course, 46# hydraulic oil can also be used in winter in the south. It should be noted that it is strictly forbidden to mix hydraulic oils of different brands and labels.

The cleanliness of the oil in the hydraulic system is very important. The cleanliness of the oil and the replacement cycle must be guaranteed. If impurities are mixed into the hydraulic oil, it will enter the valve group and the oil cylinder with the hydraulic pipe, causing the valve group to become stuck or damage the oil cylinder seal. At the same time, check the hydraulic pipeline regularly, check whether there are cracks and leakage at the interface, so that the fault can be found in time and the damaged parts can be replaced in time.

Many dump trucks that transport sand and gravel will add a protective cover to the casing of the hydraulic cylinder to prevent impurities from entering the oil. At the same time, pay attention to whether there is abnormal wear and scratches on the surface of the hydraulic piston rod. If there is any, it needs to be repaired by a professional repair department, otherwise it will affect the lifting efficiency and safety.