10 Questions per Day in the Moving Equipment Technology Exchange Area – Issue 7

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This post was last edited by yxmqh on 2009-10-14 17:04. Please hide your replies; otherwise, no rewards will be given! Those who answer all questions correctly in the sixth round can receive a maximum reward of 20 wealth points. The hidden method can be viewed by linking to http://bbs.hcbbs.com/thread-492556-1-1.html. The standard format for answering questions is: after using hidden replies, respond sequentially as follows: 1、A 2、A 3、A. 1. Among the following options, which one is not a cause of tap damage? ( ) A. When the hole cannot be drilled, the tap has reached the bottom yet the tap wrench is still being forced. B. Materials with high toughness, combined with the absence of lubricant, cause the workpiece to stick to the tap. C. The tap wears down and becomes dull; moreover, since the material is hard, the stress on the tap increases. D. Excessive amount of lubricant is used. 2. In practical production, the appropriate tension for a V-belt is such that it can be pressed down by about ( ) mm using the thumb. A、5 B、15 C、25 D、35 3、As shown in the figure, the projection of line ab on the horizontal plane reflects its actual length; this property is called ( ). A. Similarity B. Parallelism C. Authenticity D. Accumulation 4. The bolt GB897-87-M10*50 indicates that the threads at both ends of this bolt are ( ). A. Coarse-thread regular threads B. Fine-thread regular threads C. Imperial pipe threads D. Serrated threads 5. A mechanical seal relies on ( ) to ensure a tight fit between the end faces of the moving and stationary rings. A Sealing ring B Cover C Medium D Elastic element 6. The closed impellers of centrifugal pumps come in single-suction and double-suction types; the flow rate of a double-suction impeller compared to that of a single-suction impeller is ( ). A. The double-suction impeller is larger. B. The single-suction impeller is larger. C. They are basically the same. D. It’s impossible to compare. 7. Before starting a hot oil centrifugal pump, it is necessary to perform ( ) on the pump. A. Rapid preheating B. Heat retention C. Preheating D. Cooling 8. A blockage in the balance pipe of a centrifugal pump will cause ( ) harm. A. The outlet pressure increases. B. The inlet pressure increases. C. The load on the thrust bearings increases. D. The pump gets clogged. 9. The main reason for blockage in the cooling water of a centrifugal pump is ( ). A. Many bends in the water pipes. B. Long cooling pipelines. C. High water pressure. D. Water containing dirt. 10. When the air valves of a reciprocating compressor are first installed in their respective chambers, they should be able to ( ) within those chambers. A Free rotation B Free swinging C Back and forth swinging D Up and down swinging