1. Characteristics of walking device of crawler bulldozer
Crawler bulldozer driving system includes three parts: frame (or frame), walking device and suspension. The frame is the skeleton of the whole vehicle, used to install all the assemblies and components, so that the whole vehicle becomes a whole. The walking device is used to support the body and convert the driving torque and rotational motion transmitted by the power device to the driving wheels into the driving force and speed required for the vehicle to work and travel. Suspension is a connection device that transmits force between the vehicle frame and the walking device. ---Meizhou track chain assembly manufacturer
Compared with the wheeled driving system, the crawler bulldozer has the following characteristics: First, the support area is large, and the ground contact pressure is small. Therefore, the tracked vehicle is suitable for operation in a soft or muddy field, the sag is small, the rolling resistance is also small, and the passing performance is better. Second, there are crawler teeth on the supporting surface of the track, which is not easy to slip and has good traction adhesion performance, which is conducive to exerting a large traction force. Third, the structure is complicated, the weight is large, the motion inertia is large, the cushioning performance is poor, the 'four-wheel belt' wears seriously, the cost is high, and the life is short. Therefore, the running speed of the tracked vehicle cannot be too high, and the maneuverability is also poor. Fourth, tracked vehicles can also work in high-temperature fields, and the outstanding advantages of 'low specific pressure' and 'large traction' cannot be replaced by wheeled vehicles.
Second, the composition and function of the crawler bulldozer walking device
The walking device of the crawler bulldozer is composed of a walking frame, a guide wheel, a crawler tensioning device, a supporting sprocket, a roller, a crawler assembly, and a driving wheel. The left and right crawlers are wrapped around the above four wheels and are tensioned. The device is tensioned and directly in contact with the ground. The driving wheels drive the crawler to rotate around the four wheels and do not roll directly on the ground. The guide wheel is to tension the track and guide it to wind properly. Several rollers roll on the track surface of the track to transfer vertical loads to the track. The supporting sprocket supports the upper half of the track so that it does not sag, and can reduce its up and down vibration. The above four wheels and tensioning devices, except for the driving wheels, are assembled on a wheel frame (that is, a trolley frame, also called a track frame), thereby forming a trolley. Each tracked vehicle has two left and right trolleys. The weight of the whole vehicle is transmitted to the lower crawler through the trolley frame and rollers, so that the lower crawler is pressed tightly on the ground. When the drive wheel is driven by the final transmission gear (driven gear), the gear teeth pull the crawler, and the ground immediately produces a reaction force on the crawler, which causes the carriage to move forward or backward relative to the ground, and the vehicle Follow it. 1. Track assembly. The track assembly includes track shoes, chain links, track pins and pin sleeves. Each track is composed of dozens of track assemblies. Because it is in direct contact with the ground and bears the full weight and driving force of the body, it must have sufficient strength, rigidity and wear resistance. The track shoes used in the track assembly are generally provided with track thorns, which is to increase the adhesion of the track running and make it less slippery. There are 3 types of single ribs, double ribs and three ribs. The loader uses double ribs.
2. Rollers. The track roller is one of the worst working conditions of the crawler walking device. Therefore, there must be a reliable sealing device and lubrication device. There are many structural types of rollers. The structural types of rollers commonly used are composed of main parts such as shafts, wheel bodies, iron sleeves and floating oil seals. The roller axle adopts the middle shoulder type, and the remaining parts are symmetrically arranged on both sides of the shoulder. Although this structure is more complicated and less manufacturable than the straight shaft type, it can withstand larger axial forces and impact loads. Especially after the use of floating oil seals and bimetallic sleeves, the service life is greatly improved and the maintenance workload is simplified.
3. Guide wheel. The function of the guide wheel is to guide the running direction of the crawler running device, so as to reduce the impact received when the crawler moves forward. The guide wheel, like the roller, also adopts a shaft with a middle shoulder type, a bimetal sleeve and a floating oil seal. ---Meizhou track chain assembly manufacturer
4. Support sprocket. The support sprocket is used to prevent the sagging of the upper part of the track and the fall off when the track is running. The carrier chain wheel of the loader is usually cantilever mounted on the track frame. The structure of the supporting sprocket is composed of main parts such as shaft, end cover, floating oil seal, supporting wheel body and rolling bearing. The carrier chain wheel is located on the upper part of the crawler frame and bears less load than the track roller. The dirt is not easy to invade and wear is less. ---Meizhou track chain assembly manufacturer
5. Drive wheel. The function of the driving wheel is to wind the crawler and make the loader run. The driving wheel is installed at the rear of the crawler frame, and the working conditions are extremely heavy. There are many types of driving wheels, commonly used are integral type, ring gear type and tooth block type, each with advantages and disadvantages in use. In order to make the driving wheels exchange and save raw materials as much as possible after wear, it is generally appropriate to use the insert ring type. The number of teeth is mostly odd, which can increase the service life.
6. Track tensioning device. For example, when the crawler loader is walking and working, the hinge joints of the crawler sections will be lengthened due to wear, which reduces the tension, the upper sag of the crawler will increase, the running will jump, and even the crawler will fall off, so the crawler is required. The tensioning device is tensioned. However, if the track tension is too tight, it will cause the pin shaft and the pin sleeve to be excessively stressed and quickly wear out. For this reason, an appropriate tension must be adjusted. The track tensioning device is connected with the guide wheel and moves forward and backward on the guide wheel guide. There are many types of track tensioning devices, and the adjustment screw type and hydraulic type are more commonly used. The hydraulic track tensioning device is composed of a guide bracket, a guide fork head, a piston and a buffer mechanism. This device is installed on the track frame behind the guide wheel. Use a grease gun to inject butter into the hydraulic cylinder at the oil nozzle. The piston is pushed to move, and the guide wheel is displaced on the track frame to achieve the purpose of tensioning the track. If the track is too tight, you can open the oil screw. Put a portion of butter to achieve proper tension. The buffer mechanism is composed of a large tension spring, which absorbs vibration during walking and provides sufficient tension to the crawler track.
3. Common wear of crawler bulldozer 'four wheels and one belt'
The walking mechanism of the crawler bulldozer carries the entire weight of the bulldozer. It is responsible for driving the bulldozer. The main form of damage is wear. This form of damage is concentrated in the following contact parts: the outer surface of the drive wheel gear and the track pin sleeve; the guide wheel and the track surface of the track link; the track roller and the track track of the track link Surface; supporting roller and track link track surface; track pin and pin sleeve contact surface; track plate and ground, etc.
1. Track wear
In the running mechanism of dry crawlers (compared to lubricated crawlers and sealed crawlers), the crawlers are not lubricated, which causes wear between the crawler pins and the pin sleeve due to relative movement during work. The wear between the pin and the pin sleeve in the crawler is inevitable and normal, but this wear will extend the pitch of the crawler and make the crawler too large. This wear situation continues. The track will move sideways, causing the wear of the guide wheels, rollers, carrier sprockets, driving gear teeth and other components, and also the wear of the track pins and sleeves. Track wear is also reflected in the decrease in the height of the track spurs due to the contact of the track shoes with the ground, and the track link caused by the contact of the track surface of the track link with the guide wheel, carrier chain wheel, and roller. The height is reduced. When the track shoe is worn seriously, it will cause a loss of bulldozer traction. ---Meizhou track chain assembly manufacturer
2. Drive wheel wear
The wear of the driving wheel gear teeth often occurs at the root of the gear teeth, the front and rear sides, the left and right sides, and the top of the gear teeth. When the bulldozer runs forward and the gear teeth lift the track pin sleeve, wear occurs on the front side of the gear teeth; conversely, when the bulldozer travels backward, the wear occurs on the rear side of the gear teeth. When the track is too loose, track deflection will occur, and the gear teeth will impact the side of the chain link, which will cause the wear of the side of the drive wheel. Another form of wear of the drive wheel teeth is top wear. Top wear occurs when the crawler and drive wheel teeth are filled with a viscous substance, and the meshing relationship between the drive wheel teeth and the track pin sleeve is changed. When the bulldozer is moving forward, it will mark the apex of the back of the tooth on the drive side of the drive wheel and the side of the pin sleeve.
3. Guide wheel wear
The wear of the guide wheel is caused by contact with the raceway surface of the chain link, and the wear of the protrusion width of the guide wheel body is caused by contact with the side of the chain link. The performance is as follows: the reduction of the convex width of the guide wheel body; the reduction of the diameter of the raceway surface of the guide wheel body; the reduction of the diameter of the guide wheel body.
4. Wear of the support sprocket
The wear of the carrier sprocket is caused by contact with the raceway surface of the chain link. The performance is as follows: the width of the flange of the support chain wheel is reduced; the outside diameter of the raceway surface of the support chain wheel is reduced; the outside diameter of the flange of the support chain wheel is reduced. ---Meizhou track chain assembly manufacturer
5. Roller wear
The wear of the track roller is the same as the wear of the support sprocket and guide wheel, which is also caused by contact with the raceway surface of the chain link. The specific performance is as follows: reduction of outer flange diameter; reduction of raceway surface diameter; reduction of bilateral inner flange diameter; reduction of bilateral inner flange width; reduction of outer flange width.
4. Preventive measures for the wear of 'four wheels and one belt' of crawler bulldozers
In view of the wear of the crawler walking mechanism, the following measures can be taken: if the bulldozer walking mechanism has obvious wear in the early stage, the operation should be stopped immediately. Check the coincidence of the center of the guide wheel, carrier chain wheel, supporting wheel, driving wheel and the longitudinal centerline of the walking frame; In order to extend the service life, the position of the front and rear rollers can be changed, but the original position of the single and bilateral rollers on the walking frame must be kept unchanged; after the components of the walking mechanism wear to the limit of use, , Track rollers, driving wheel teeth, crawlers, and chain track joints can be repaired or replaced by surfacing; for the situation where the track chain track pitch becomes longer due to wear, reverse chain track joints can be used to remedy or Replace with a new chain link.