Do you know? There are many factors that affect the crawler chassis of engineering drilling rigs. If the design is not well considered and the design is unreasonable, there will be problems such as walking and steering difficulties, and poor acceleration performance. The following factors generally affect the performance of the crawler chassis of engineering drilling rigs.
1. The running resistance of the ground to the track
The running resistance of the ground to the track refers to the running resistance caused by ground deformation, and its size is related to the grounding pressure of the track, the location of the center of mass of the vehicle, and the ground conditions. Because the crawler chassis of engineering drilling rigs are generally constructed on relatively harsh grounds, when selecting the specific drag coefficient for operation, various working environments should be fully considered to select a suitable drag coefficient.
2. Internal resistance
Internal resistance mainly refers to the walking resistance caused by the frictional force inside the walking mechanism. The general track chassis is composed of drive mechanism, track, track roller, guide wheel, support chain wheel or drag chain plate. When walking, the friction between these mechanisms must produce a certain internal resistance. This resistance generally consists of five parts: 1) When the track shoe bypasses the guide wheel and the drive wheel, the track pin and the track pin sleeve rotate relatively Friction resistance at the time. This resistance is related to the diameter of the track pin and the coefficient of friction between the track pin and the pin sleeve. 2) Friction resistance at the roller. This resistance is related to the outer diameter of the roller, the diameter of the roller, the gravity of the roller to the track shoe, and the coefficient of friction between the axles of the rollers. 3) Friction resistance at the guide wheel. This resistance is related to the friction coefficient between the guide wheel and the bearing, the diameter of the guide wheel shaft and the diameter of the guide wheel raceway. 4) Friction resistance at the drive wheel. This resistance is related to the friction coefficient of the driving wheel bearing, the diameter of the driving wheel shaft, the diameter of the pitch circle of the driving wheel, and the pulling force of the tight side of the track. 5) Friction resistance at the carrier chain or carrier chain plate. This resistance is mainly related to the weight, contact area and friction coefficient of the track shoes supported by the chain wheel or drag chain. The internal resistance generally accounts for about 16% of the walking resistance, so full consideration should be given to the design.
3. Slope resistance
The slope resistance refers to the walking resistance caused by the self-weight component when the vehicle climbs the slope. The general construction site is uneven, which requires that the crawler chassis of the engineering drilling rig must have a certain climbing ability. The slope resistance formula is F=mgsina. It can be seen that the magnitude of the slope resistance is mainly determined by the vehicle's climbing degree and its own weight, and is proportional to the two. This resistance generally accounts for about 60% of the entire driving resistance, which is the main factor affecting the driving performance of the crawler chassis of the engineering drilling rig.
4. Turning resistance
Turning resistance mainly has the following two situations: 1) Turning resistance in situ. The in-situ turning resistance refers to the resistance generated when the tracks on both sides turn at the same time. This resistance is mainly related to the proportional coefficient of vertical load and friction resistance, the length of track contact and the track gauge. 2) Steering resistance of one side track. Unilateral track steering resistance refers to the resistance generated when one side of the track brakes and the other side unilaterally turns. This resistance is mainly related to the flow resistance coefficient, steering resistance coefficient, track ground length and track gauge. In addition, the magnitude of these two resistances is also related to the center of mass of the vehicle. If the mechanical center of mass falls on the center of the track frame (that is, the track ground pressure is evenly distributed), the turning resistance at this time is more uneven than the track ground pressure. Smaller, so you should try to make the center of mass of the vehicle fall in the center of the track frame when turning.
5. Wind resistance
The size of the wind resistance is mainly related to the windward area of the vehicle, the filling rate of the structure and the wind speed. For medium and large-scale crawler engineering drilling rig vehicles, due to their relatively large traction force, the wind resistance is generally very small, accounting for only about 0.1% of the traction force, so the wind resistance can only be used as a reference factor.
Inertial resistance is the walking resistance caused by the acceleration when the vehicle is started. Its magnitude is mainly related to its own weight and starting acceleration, and is proportional to it. For some engineering rig vehicles that travel slowly and do not require quick start, this factor can also be used as a reference factor only.
Therefore, when designing the crawler chassis of engineering drilling rigs, all kinds of resistance should be fully considered according to specific working conditions, and detailed and careful calculations should be made in order to design a reasonable transmission mechanism and select a suitable walking reducer.
