Prevention of the Engineering Mechanical Failure(Ⅱ)

2) Reduce the influence of temperature
In operation, each component has its own normal temperature range. As the cooling water temperature is generally 80-90 ℃, and the temperature of hydraulic oil of the hydraulic drive system is 30-60 ℃. If it is less than or greater than this range, the wear of the parts will be accelerated, causing deterioration of the lubricating oil and the changes in material properties, and so on. For this reason, in the course of using the construction machinery:
(1)The machinery should not work with overload at low temperature to ensure the normal low-speed operation in the pre-heating stage so that the machinery can reach the required temperature before traveling or working, which should not be neglected because it was not a problem at that time;
(2) The machinery should not operate at high temperatures, the value of the operation on a variety of thermometers should be checked in the mechanical process and if any problem is found, the machinery should be immediately shut down for inspection to find and remove the fault. The machinery with reasons not found, should not continue to work without being checked.In the usual work, the working conditions of the cooling system should be checked. The water-cooled machines must be checked daily before work with cooling water added; as for air-cooled machines, the dust on the air cooling system should be regularly cleaned up to ensure the smooth flow of cooling air.

Prevention of the Engineering Mechanical Failure(Ⅴ)

Timely maintenance:
In the course of use, a variety of mechanical failures happen inevitably. In these failures, the effect of some failures on the mechanical device may be very small, some are more serious, and some even cause a big crash accident. Experience shows that serious mechanical failure is often caused by a number of minor faults. The reason lies in the neglect of timely disposal of small faults. Therefore, mechanical failures, regardless of seriousness, should be ruled out in a timely manner, so as to maintain normal mechanical performance, reducing the likelihood of leading to greater failure. In a sense, the timely treatment of mechanical failure is an effective measure to reduce and prevent failures. The so-called timely treatment referring to:
1. In accordance with the maintenance procedures for machinery, the machine should be maintained and repaired regularly. And other groups of various maintenance and repair must be carried out according to the requirements. A variety of maintenance and repair of existing specifications are summarized referring to years of practical experience, which is a scientific and rational. In the absence of significant technological progress and innovation, these procedures to guide construction machinery repair and maintenance is absolutely nature, and must be complied with.
2.The construction machinery should be checked regularly and irregularly to timely know the operating situations of the machine. Once the temporary faults occur, they should be promptly treated. We should not pay no attention to those faults because they are small and do not influence the use so that they lead to greater failure.

Ensure reasonable lubrication of machinery:
The surface wear, corrosion and material aging of the components are the three major exchange-efficient mechanical forms under normal conditions of use, and the failure of parts caused by wear face takes up the largest proportion. That is, the mechanical wear is one of the main factors making the various components in the technical state to the limit. So, to solve the problem of wear of mechanical parts, we can use superior materials, advanced manufacturing technology and reasonable mechanical structures. What’s more, one of the important work is to ensure the reasonable lubrication of machinery. According to statistics, more than half of the engineering machinery failures,are caused by poor lubrication. Due to the precision of the parts of the mechanical construction, good lubricity can keep the normal working gap and a suitable operating temperature, thereby reducing the wear of parts and the mechanical failure. Normal and reasonable lubrication is one of the effective measures to reduce mechanical failure.
1. The lubricant should be reasonably chosen in accordance with the different types and applicable structures of lubricants. Besides, according to the mechanical requirements, the appropriate choice of quality group and quality level should be chosen. And according to the mechanical requirements, the right lubricant grades should be used in the machine work environment and different seasons. Neither the use of low grade lubricants, nor the replaced lubricants is allowed, including the inferior products.
2. The quantity and quality of the lubricants should be checked regularly. The lubricants should be supplied if there are not enough. And the quality of them should be guaranteed. Different types and grades of lubricants are used under emergency conditions. Therefore, after that, some of the lubrication system should be cleaned.

Prevention of the Engineering Mechanical Failure(Ⅰ)

Due to the influence of materials, technique, the aging components, human factors and other factors, the various engineering mechanical failures often happen, which is unavoidable. However, if the reasons of the failures can be analyzed correctly and the effective and key protective measures are employed, those failures can be effectively avoided and extend the life of the machinery.

1. Reduce the impact of the harmful factors
1) Reduce the impact of the mechanical impurities
The mechanical impurities usually refers to the non-metal materials including the dust as well as the soil and some metal filing and wear debris in the process of the machinery being used. Once those mechanical impurities enter the inner machinery or reach the surface of the connected parts, the harms are great such as stopping the relative movement, increasing the wearing speed and temperature of components, breaking the fluid oil and so on. Therefore, as for the engineering machinery working in the bad state or on the complex fields:
(1) The high-quality and matching parts, lubricants and greases should be used to block the source of harmful impurities;
(2) The mechanical protection work in the work site should be done to ensure that the appropriate agency can work properly, preventing all kinds of impurities into the machinery inside. The broken machinery should be repaired as much as possible in the regular place. In the course of the on-site repair, appropriate precautions should be taken to prevent the pollution of impurities before the replaced parts entering the machinery.

The Possible Dangers in the Course of Bridge Building And the Corresponding Measures

Dangers
1.The bridge building crane collides with the box girder.
2.The auxiliary legs and guide beam bear stresses when the machine builds the bridge.
3.The hydraulic system fails to work.
4.The box girder produces horizontal attack on the bridge building crane.
5.There are drawings in the steel wire rope of the hoist.
The box girder is placed directly on the jack.

Preventive measures
1.In the whole process of the bridge building crane feeding the girder, there should be professional staff to supervise and check the operating situations of the truss car of hanging beam and the work place of the box girder to prevent the collision between the box girder and the bridge building crane.
2.The continuous actions of stop and start of the bridge building crane are not allowable to lessen the longitudinal attack on the bridge building crane. And the machine should be tested before it starts to lift objects.
3.The hydraulic cylinder and drum should not bear any stress when the bridge building crane feeds the girder.
4.There should be professional staff to supervise and check the work situations of hoist and brake of the truss car hanging girders.
5.The steel wire rope of the hoist should be highly safe and firm.
6.The girder being placed downwards should not collide with the front leg of the bridge building crane and the box girder that has been erected.
7.The box girder should not be directly fell on the jack, and when the box girder is near the jack, the 4 jacks around begin jacking off work and should not stop until all the weight is born by the jacks.

The Types and Characteristics of the Bridge Building Crane(Ⅱ)

1.The downstroke movable support system

Compared with the upstroke movable system, the main characteristics of the downstroke movable system lie in:

Advantages:The width of the girder is not limited. It adopts the method of supporting directly for the convenience of adjusting the alignment of the base mould; the horizontal frontal area of the downstroke movable support system  is smaller than the upstroke movable support system, bearing smaller wind stress. It is of high safety if it constructs in the typhoon.

Disadvantages: It needs to take up the net height and the large bracket must be installed on the bridge pier; the movable support system must be spread horizontally.

2.The movable-supported bridge-building equipment

Compared with the prestressed concrete box girder of entire hole manufacture, the main advantage of the segment assemble is that the beam shape is the same, featuring the appropriateness of using industrial prefabrication of high quality. Put the prefabrication and assemble into  parallel operation, characterized by short construction period; its main drawback is to require a certain field of girder prefabricating and storing. The segment transport is limited by the transport equipment, assembly equipment, transportation channels (such as tunnels),  control of linear and other technical aspects.

The Types and Characteristics of the Bridge Building Crane(Ⅰ)

1.The types of the bridge building crane
1)According to the construction method: casting and segment assembling in the same place.
2)According to the template: the mobile mould frame and the movable support system. The mobile mould frame casts the concrete girder on the field whereas the movable support system assemble
3)According to the position of the bridge pier: upstroke movable support system and the down stroke movable support system.
Nowadays, the upstroke movable support system is the most common one.
2.Upstroke movable support system
Compared with the down stroke movable support system, the advantages of the upstroke movable support system lies in:
Advantages: the main structure is above the bridge pier and the support of the main beam is on the top of the pier or on the precast pier segment. Therefore, there is no need to take up the place under the bridge and the bracket beside the pier. It is especially used in the construction of the overpass, the urban elevated bridge, the elevated bridge in the deep ravine or on the soft base.
Disadvantages: Its body is too large, huge size. The support point must be on the body of the newly made girder when it fabricates beam, and therefore we need to wait before pouring the next hole when a new cast beam can withstand greater loads. The numerous boom and boom bring in the inconvenience of construction; when the bottom die is in the open in the way of the next turn, thus requiring greater clearance under the bridge,whose use is restricted.

The Differences Between the Honeycomb Girder and the Box Girder

The main beams of gantry crane produced by Zhengzhou Huazhong Construction Co,.Ltd employ the structure of isosceles triangle, which has applied for national patent.The structure features light weight, stiffness, small deflection, strong resistance of wind and other advantages. The design of the main longitudinal girder retains the load-bearing steel plate on both sides of the box girder, and removes the upper and lower non-load-bearing steel plate with the top direct welded together and the lower instead by channel steel, designed to be triangular cellular beams, which retains the advantages of box girders, but also overcomes the shortcomings of box girder.
Compared with the box girder, the honeycomb girder is characterized by light weight, high safety and strong resistance of wind;
Compared with the trussed girder, the honeycomb girder has a large welded contact surface. Therefore, the honeycomb girder has a low deflection and high rigidness. The two main longitudinal beams are connected with six steel pins.
The main longitudinal beam of the honeycomb girder uses the load-bearing plants, which are more expansive than these used by the trussed girder.Therefore, under the premise of the same configuration and weight, the cost of gantry crane produced by Zhengzhou Huazhong Construction Co,.Ltd are more expansive than the truss girder. The reason why we have adopted this structure is that the cellular beam crane has three advantages over the truss girder crane: a.more durable main beam; b. Smaller deflection and c.higher safety.

Along with the need of the construction of railway passenger special line, the movable support system, a kind of mature construction tech and equipment, is widely used on the construction field of railway and bridge. MZ900S is one of the representative products of Zhengzhou Huazhong Construction Machinery Co., Ltd.

MZ900S movable support system is specially used in the construction of railway passenger special line of 32m. The quality protective measures and safe work in the air of the movable support system attain the purpose of safe production, improved construction quality, fast processing speed and low cost.

In the constructing process of the movable support system, the incomplete inspection of one step may influence the whole schedule, even may cause the accidents of overturn of the support system or people injuries. In the following are several tips regarding the inspection of the movable support system.

The personnel should comply with the law and rules. All the construction machinery should be tested before they are being put into operation. Also, all the staff should get some certificates before being enrolled. The walking rails and the working site should be even and smooth. In addition, the lifting speed should be slow and the operators are not allowed to conduct two operation in the same time.

Inspect the Bridge Erecting Crane before It Starts to Work

To prevent the occurrence of emergent accidents and control and deal with the accidents timely, to minimize the losses caused by the accidents and to protect the benefits of the society and the enterprise, some effective measures should be employed.

The accidents including the crane injury, staff falling and machine overturn may easily happen on the bridge erecting crane. We conclude some points for you to refer to with the hope that they can help to protect the benefits casino online of the society and the enterprise and decrease the accident rate.

The type of the bridge erecting crane should confirm to the requirements of structure; the operators and staff must be well trained and in position with certain certificates;the bearing parts of the assembled bridging equipment should be inspected and confirmed by the professionals before they are used in the construction; the command and the contacting signals should be correct.

Before the machine starts to work, the front and back legs should be placed properly with good lighting in the evening; the previous work should be well done before the machine goes through the holes and the rails must be clear; the machine must cooperate with the transport girder well.

After the work, whether all the devices are in the safe place and the power is off should be inspected. The doors of the driver’s cab and the windows of the electrical box are closed well.