The track of the hoisting machinery is the operating route of the hoisting machinery laid by steel rails, which can ensure that the hoisting machinery runs along the specified line and transmits wheel pressure to the foundation.
Tracks usually consist of two steel rails. When the lifting machinery is operating, the track must not move horizontally or vertically, and the track must be easy to adjust. The metal fixed parts of the track rails should be free of cracks, looseness and corrosion; if there are cracks, they should be replaced in time, and other defects should also be dealt with in time.
When a large vehicle or trolley brakes, longitudinal or transverse force is generated. If the large and small cars brake at the same time, a combined braking force will be generated, causing the track to bear an oblique thrust. If the track is installed so that one side is generally higher than the other, the crane will move entirely to the lower side, thereby increasing the lateral force on the track. For this reason, effective measures should be taken to reliably fix the track. Especially for outdoor cranes, in order to prevent them from being blown away and tipped over by the wind, the rail clamps are clamped on the track when they are not in working condition. The reliability of such track laying is even more important.
In addition to reliability, track installation must also consider ease of replacement. Especially in places with continuous production, this point cannot be ignored. For this reason, it is recommended not to use permanent connections such as riveting or welding.
There are currently two commonly used rail-bearing beams for installing tracks, one is a steel structure beam and the other is a concrete prefabricated beam. Precast concrete beams must have pre-embedded openings for anchor bolts during installation.
1. Fixing method with pressure plate: In order to adjust in the horizontal direction, the holes on the pressure plate must be made into long holes. For vertical adjustment, pads can be added under the rails. This method is relatively simple and reliable. When designing the track pressure plate, it must have sufficient rigidity. Each pressure plate can be made with single or double holes according to the magnitude of the force.
2. Hook bolt fixing method: When fixed on a steel rail beam, the width of the flange plate should not be greater than 400mm, otherwise the hook screw will need to be very long, thus reducing the firmness of the fixation.
3. Welding and bolting method: first weld the pad with long holes on the ground to the bottom of the rail or square rail, and then lift it to the anchor bolts of the rail-bearing beam to fix it. This type of connection requires precise installation of anchor bolts and welding of backing plates, otherwise the holes and bolts will be misaligned, causing installation difficulties.
How cranes are suitable for curved tracks
The traveling mechanism of the crane runs on an arc-shaped track and must be adaptable and stable. It must be able to meet the radius and curvature requirements of the arc track and be able to drive smoothly on the arc track to ensure the safety and accuracy of the crane’s operation. In order to increase the stability and balance of the crane on the curved track, the traveling mechanism usually adopts a multi-wheel design, and effective measures are taken to reduce wear on the track. For example, the traveling mechanism usually uses guide devices, which may include rollers, guide wheels, etc., whose function is to guide the crane to travel along the correct arc track to prevent steering deviation or friction on the track.
In addition, the power of the driving device must consider the additional load to meet the operating requirements of the crane on the arc track. For cranes running on curved tracks, it is necessary to reconsider the applicability of safety devices, anti-collision devices, limiters and alarm systems, because there may be deviations in position at this time and the response will not be timely.
Here are a few temporarily listed
1. Under large curvature radius, rely entirely on horizontal roller guidance; if there is a possibility of rail rubbing, add a rail side lubrication device.
2. When the curvature radius is small and the track is circular, it can be arranged similar to the slewing mechanism of a large floating crane (or the circular track of a nuclear power plant bridge crane).
Different types of tracks, different values of the radius of curvature, different types of cranes (such as suspension cranes, bridge cranes, gantry cranes, gantry cranes, etc.) may have different requirements, so in practical applications, should follow the customer’s specific requirements and standards for the crane.