Hydraulic dump tops are common in trucks

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Hydraulic dump tops are common in trucks

Dump trucks in road transportation in our country has a long history, after years of development, people constantly improve its weaknesses, eventually spawned many versions, but the way of lifting the same principle, only by the design of the different species, on the top of the dump to adapt to a variety of different operating conditions and load, Next, let’s dig the bottom of the dump top.

1、Trucks dump hydraulic roof classification

1.1Trucks front mounted hydraulic roof

In our life, known colloquially as “former top dump” trucks, is the assembly of superposed hydraulic roof, found in the trucks capacity big, the using big dump of the single oil cylinder, will explain from the principle, the vehicle in the same lifting load, due to the law of lever principle, superposed on the top of the hydraulic lifting position, thus it is involved in the principle of leverage and energy saving.

From the perspective of bearing capacity, the superposed on the top of the hydraulic lifting strength small, the top box seat and trucks girder base position of impact is reduced, can not only take more weight, but also to ensure the stability of the roof, the vehicle at the top of the bad road conditions when unloading, packing case also can maintain a higher lateral rigidity.

However, the front hydraulic top also has a lot of design defects, such as its cylinder piston stroke is long, for unloading site height is limited, compared with the common specifications of the middle hydraulic top, when the carriage lifts the same height, the front hydraulic top due to the installation position is in front, so the length of the piston is longer than the middle hydraulic top.


Before as well as the hydraulic tubing length is limited, the general placed at the top of the hydraulic oil tank is placed behind the cab, which is the front of the trucks, placed next to front hydraulic roof, occupy a part of the vehicle chassis space, many mountain road transport heavy dump truck is the need to install the tank, the position of the general design is also at the top of the front of the hydraulic position, both will need to choose each other, From the point of view of design.
Common assembly models: the above mentioned the superposed hydraulic roof are generally load large vehicle assembly, for road transport trucks, the vehicle weight is particularly important, only the superposed on the top of the hydraulic design major, since its bearing surface for the crate before the board, if the pursuit of light, only from the perspective of reducing container plate and end plate on hand.

In order to cooperate with the assembly of the front-mounted hydraulic top, the front plate of the container is tightly locked with a thickened iron plate to the hydraulic top fixed point, which is the main fulcrum to support the “lever principle”. There can be no jerry-cutting. In order to pursue excellent hydraulic capacity, the load capacity is 25-30 tons and above, Common rear eight wheels, four rear eight, four rear four dump trucks are more assembly front top dump

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1.2Middle mounted hydraulic roof

The front-mounted hydraulic top is suitable for heavy-duty trucks, so what are the common areas of the middle-mounted hydraulic top? Early coal single bridge car, four after four four after four four after six models are loaded with mid-mounted hydraulic top, their net weight is mostly between 20-30 tons, which is also divided into the mid-mounted hydraulic top: double cylinder hydraulic top and horizontal single cylinder hydraulic top, here we first introduce the double cylinder hydraulic top.

No dead weight, center of gravity, flexibility, the type of hydraulic roof is more suitable for road transport vehicle, because it is assembled in a relatively short dump trucks containers, can effectively reduce the vehicle’s center of gravity, raise up the roof stability, many pull coal, brick, lassa dump truck, unloading in the specific field, field road surface roughness is limited, The middle hydraulic roof can greatly avoid the case of side down.

Compared with the front hydraulic top is arranged in the front of the container support surface, the support surface of the middle hydraulic top is directly arranged in the front of the container, using the same “lever principle”, after careful analysis will find that the position of the hydraulic top is set in the front, the force of the roof is smaller.


Type hydraulic installation location is on the top of the girders of the inside, so its overall weight distribution on the girder section, the hydraulic oil cylinder can also be set in the inner side of the girder, good use of the girder space area, the overall weight is reduced gravity, is beneficial to improve the stability of the vehicle, the center of gravity will be much lower than superposed hydraulic roof.
Like road dump truck is also often need to walk bumpy road, on the top of the type of hydraulic advantages will play out, but it also has a fatal flaw, is in order to improve the piston stroke, type hydraulic top to the bottom of the distance of the ground space is not high, should notice when some bad road conditions, sometimes the site in the trucks, is at the bottom of the hydraulic pressure on the top of the first to the top in the mud on the surface, Form a great driving resistance.

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2、How to maintain the trucks dump hydraulic top

Hydraulic system is the most important is the hydraulic oil, hydraulic oil 46 #, 32 # and when winter is usually loaded with 32 # hydraulic oil viscosity is low, the summer is loaded with 46 # hydraulic oil of high viscosity, winter in the south, of course, can also use 46 # hydraulic oil, pay attention to the different brand, label is prohibited hydraulic oil mix.

Oil cleanliness of hydraulic system is very important, must guarantee the oil cleanliness and replacement cycle, if there are impurities mixed with the hydraulic oil, will with the hydraulic pipe into the valve group and oil cylinder, cylinder seals for valve group caton or damage caused, regular check good hydraulic line at the same time, to check whether there is crack, leakage phenomenon, interface can find fault in time, timely replacement of damaged parts, Because of the sudden increase in hydraulic oil pressure, if there is a dark disease of the pipeline will not hold and burst.


Many sand transport dump trucks will add protective sleeve in the hydraulic cylinder shell, to avoid impurities into the oil, and pay attention to whether the surface of the hydraulic piston rod is abnormal wear and scratch, if there is a need to professional repair department for maintenance, correction or replacement, otherwise it will affect the efficiency and safety of lifting.
General self-discharging hydraulic roof are long service life, failure rate is low, only the top car to pay attention to the flatness of the road, if the Angle is too large, do not force the dump, and observe the crate back plate of the lock is on, to avoid the top after the accumulation of goods can’t unload in container inside, add pressure to the hydraulic roof at the same time, also easy to cause head light foot heavy vehicles