【Mechanical Equipment Technology Edition】Daily Question 201804014: Common Faults of Screw Refrigeration Compressors (3)
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This post was last edited by YORK Industrial Refrigeration on 2018-4-28 at 16:55. This year’s 【Daily Question】 is divided into three categories: screw refrigeration compressors, refrigeration systems, and oil circuits, aiming to provide a comprehensive understanding of refrigeration technology. (If you encounter something you don’t know or can’t answer, please actively look up information; as you do so, your skills will improve!) ) All participants in the comments on this post will receive 1-3 wealth points; those who give complete answers will get 10-15 points, with the validity period being two days. ============================== Common faults of screw refrigeration compressors (3): What are the reasons for a screw compressor to lock up? Most cases of lock-up are related to the oil; oil quality, oil temperature, oil pressure, and oil level are all very important parameters! If there is a problem with just one of these four parameters, it can cause the compressor to lock up! The bearings of the compressor itself are damaged, and the axial and radial displacements of the screw exceed the designed limits, which leads to wear of the internal mechanical components of the compressor. Over time, these gaps become larger and more metal shavings end up in the oil! This ultimately leads to wheel lockup at the front! ============================== High-quality promotions: Mechanical equipment——Videos on the repair and calibration of York compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1806833 Mechanical equipment——Maintenance procedures for York screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1806833 Mechanical equipment——Upgrading of York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs of GEA Grasox screw compressors https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese Maekawa MYCOM screw compressors https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
1. The piston of the master brake cylinder does not return (all four wheels lock up); 2. The piston of the slave brake cylinders does not return; 3. The return spring for the wear plates is defective; 4. The push rod of the master brake cylinder is not adjusted properly, resulting in no free movement (all four wheels lock up); 5. The gap between the wear plates is too small; 6. The check valve of the vacuum booster is defective.
1. If the air compressor has been left unused for an extended period of time, it is essential to ensure that there is sufficient oil inside the compressor head when it is started up again. If there isn’t enough oil, a sudden shortage of oil during operation can cause the compressor head to get stuck. Therefore, for equipment that has been shut down for a long time, enough oil should be added to the compressor head before it is restarted. 2. Failure to replace or add lubricant in a timely manner leads to a lack of oil supply. Or, blockages or leaks in the oil circuit can cause a lack of oil in the engine head, leading to jamming. 3. There are too many impurities: carbon deposits and coking. Therefore, it is crucial to choose the right lubricant and to replace it regularly; when using air compressor oil, it is essential to use the original product from the manufacturer. Using cheap and inferior lubricants, or failing to replace the lubricant over time, can both result in jamming of the engine head.
Reasons for screw compressor seizure: quality of lubricating oil； Leakage in the evaporator and condenser.
1. Poor clearance at the exhaust end of the machine head, resulting in jamming； 2. Poor clearance at the air intake end of the machine head, causing jamming ； 3. Reverse jammed ； 4. Lubricant-related issues, such as: prolonged idling, insufficient oil volume inside the compressor components, resulting in an immediate oil shortage ； The machine in operation has insufficient oil supply ； An excessively low oil level causes the bearings at both ends of the screw rotor to lose lubrication during operation ； There are too many impurities in the lubricating oil. 5. The compressor bearings are severely aged and worn out ； 6. Foreign object has entered and caused jamming ； 7. Gear jammed.
1. The piston of the master brake cylinder does not return (all four wheels lock up);? 2. The piston of the slave brake cylinders does not return;? 3. The return spring for the wear plates is faulty;? 4. The push rod of the master brake cylinder is not adjusted properly, resulting in no free movement (all four wheels lock up);? 5. The gap between the wear plates is too small;? 6. The valve in the vacuum booster is faulty.
1. Damaged bearings. 2. Inappropriate clearance between the male and female rotors. 3. Presence of foreign objects inside the compressor, which causes the male and female rotors to stick together. 4. Overheating or overpressure in the compressor, as well as a sudden increase in load, leading to changes in the clearance between the rotors and between the rotors and the compressor cylinder walls, thereby causing the compressor to stick. 5. Oil supply interruption.
1. The piston of the master brake cylinder does not return (all four wheels lock up); 2. The piston of the slave brake cylinders does not return; 3. The return spring for the wear pad has failed; 4. The rod of the master brake cylinder is not adjusted properly, resulting in no free movement (all four wheels lock up); 5. The gap between the wear pads is too small; 6. The check valve of the vacuum booster has failed.
1. The piston of the master brake cylinder does not return (all four wheels lock up); 2. The piston of the slave brake cylinders does not return; 3. The return spring for the wear pad has failed; 4. The rod of the master brake cylinder is not adjusted properly, resulting in no free movement (all four wheels lock up); 5. The gap between the wear pads is too small; 6. The check valve of the vacuum booster has failed.
1. Firstly, there may not be enough lubricating oil in the air compressor. There are several possible reasons for this lack of lubrication: 1. Prolonged idling (including during transportation) can result in insufficient oil inside the compressor’s motor, leading to a sudden shortage of oil and subsequent jamming. Therefore, equipment that has been idle for a long time needs to have an adequate amount of oil added to its motor before it can be restarted ； 2 The machine in operation does not receive sufficient oil supply; this may be due to delayed replacement or addition of lubricant, or blockages and leaks in the oil circuit, resulting in a lack of oil in the engine head and subsequent jamming ； 3. An excessively low oil level causes the bearings at both ends of the screw rotor to lose lubrication during operation, leading to severe wear of these bearings and resulting in friction that causes the male and female screws to stick together. The bearings of the air compressor are aged and severely worn. To determine the degree of wear, it is possible to do so without removing the bearings: try to move the needle rollers or balls on the lower side of the bearings. If they can be moved easily, it indicates that they need to be replaced ； As the air compressor operates for an extended period of time, the main bearings inevitably experience wear, which leads to an increase in the axial and radial movement of the screws. This change results in alterations in the gaps between the screws, as well as between the screws and the main housing and its front and rear end surfaces. Such variations in the gap are normal and acceptable throughout the bearing’s service life, and the resulting decline in the air compressor’s output volume as well as the increased load on the drive motor are also normal and acceptable. However, when the bearing wear and the clearance between the main components exceed the allowable limits, serious consequences may occur. For example: if a piece of iron scrap that is 1 millimeter thick gets in, it might cause a jam. Firstly, friction occurs between the screw inside the host and its front and rear end surfaces, as well as between the screw and the host housing. This leads to a sharp increase in the motor’s load; the most severe consequence is that the screw gets stuck, and in some cases, friction between the screw’s end surfaces and those of the assembly can result in the destruction of the host (the machine head). If the motor protection system does not respond properly or fails, it may even lead to damage to the motor itself. Three. There are too many impurities, including those in the oil, carbon deposits, and coking. Therefore, choosing the right lubricant is crucial, as is replacing it ；
1. The unit has not been rotated. 2. The rotor is bent. 3. High level of impurities in the lubricating oil. 4. No calibration was performed during installation (for the coupling and internal components of the unit). 5. Bearings are worn out