SF-202A PRICE SACLE ADVANTAGE:
2.Automatic zero adjustment,automatic shutdown in 180 seconds,power saving function.
3.With counting function.
4.With overload, low voltage battery prompt function.
5.Unique front design, more convenient reading.
Price Scale,Digital Price Scale,Electronic Price Scale,Price Computing Scale Jiangyin Suofei Electronic Technology Co.,Ltd. , https://www.suofeiscales.com
Crane rotary reducer bearing seat repairing method
After prolonged use of a LTM1180 truck-type crane, issues such as excessive heat, abnormal noise, and oil leakage were observed in the bearing areas of the rotary pinion within the rotary reducer. Upon inspection, it was determined that the bearing had suffered from severe wear and damage, with the outer ring of the bearing having completely fallen off. The housing of the rotary reducer is constructed from cast steel, which presents challenges in terms of weldability due to its tendency to develop white joint structures, porosity, and cracks during welding. The two bearing housing holes are designed for 3524 and 3526 type bearings, respectively, with tight tolerances: one has a diameter of (215+0.01)mm, and the other is (260+0.01)mm.
When the crane operates, the bearing housing is subjected to vibration and shock, which necessitates that the material used for the seat hole possess moderate hardness, along with sufficient impact and vibration resistance. To address the failure of the bearing housing, three repair methods were considered: welding, nesting, and partial replacement.
The welding method involves cleaning the housing, boring the seat hole to increase its diameter, preheating the housing to around 400°C, and then heating the seat hole to a red-hot state (approximately 900–950°C). A copper alloy electrode is used to weld the area to the desired thickness, followed by slow cooling in an oven or using an infrared heater. Finally, the surface is machined back to the original design size. This approach offers good impact and vibration resistance, along with stable quality and a long service life. However, it is complex, time-consuming, expensive, and may result in peeling after repair.
The nesting method involves enlarging the bearing hole by 8–10 mm using a boring machine, inserting a cast steel liner with an interference fit, and securing it in place before machining it to the correct size. This method is simpler, cheaper, and faster, but can lead to issues with the clearance between the insert and the bearing, potentially causing overheating or slippage if not properly adjusted.
The partial replacement method entails mapping the damaged bearing area, fabricating a new bearing housing from a stronger material, removing the old housing using a lathe, and attaching the new housing via threading. The original housing’s reinforcing ribs are then repaired through welding, and the final bore is machined to the required dimensions. Although the first two methods have their advantages, they are not ideal for this specific application. Therefore, the partial replacement method was chosen. The new housing is made from high manganese steel, such as Mn13, 40Mn18Cr3, or 50Mn18Cr4, which, while not initially very hard, exhibits excellent plasticity and toughness. After machining, the hardness can reach up to HBW500.
Following the partial replacement repair, the bearing was reinstalled, and the rotary reducer operated normally during testing.
1.The use of high-precision tension sensor system,weighing accurate,error rate of 1/1000.