vành đai đàn hồi có xu hướng đẩy nhanh tiến độ mài mòn và tỷ lệ thất bại của cả hai lái xe và đơn vị điều khiển. Tần số lỗi tần số lỗi ổ đĩa vành đai các tần số của người lái xe, đơn vị điều khiển, và vành đai. Đặc biệt, tần số tại một thời gian, tốc độ trục tương ứng chỉ ra lỗi lầm với sự cân bằng, | 84 An Introduction to Predictive Maintenance Table 5-1 Belt-Drive Failure Symptoms Causes and Corrective Actions Symptom Cause Corrective Action High 1X rotational frequency in radial direction. Unbalanced or eccentric sheave. Balance or replace sheave. High 1X belt frequency with harmonics. Impacting at belt frequency in waveform. Defects in belt. Replace belt. High 1X belt frequency. Sinusoidal waveform with period of belt frequency. Unbalanced belt. Replace belt. High 1X rotational frequency in Loose misaligned or Align sheaves retension or axial plane. 1X and possibly 2X radial. mismatched belts. replace belts as needed. Source Integrated Systems Inc. belt elasticity tends to accelerate wear and the failure rate of both the driver and driven unit. Fault Frequencies Belt-drive fault frequencies are the frequencies of the driver the driven unit and the belt. In particular frequencies at one times the respective shaft speeds indicate faults with the balance concentricity and alignment of the sheaves. The belt frequency and its harmonics indicate problems with the belt. Table 5-1 summarizes the symptoms and causes of belt-drive failures as well as corrective actions. Running Speeds Belt-drive ratios may be calculated if the pitch diameters see Figure 5-5 of the sheaves are known. This coefficient which is used to determine the driven speed given the drive speed is obtained by dividing the pitch diameter of the drive sheave by the pitch diameter of the driven sheave. These relationships are expressed by the following equations Drive Sheave Diameter Drive Reduction ------ -------------- Driven Sheave Diameter Ê Driven Sheave Diameter Drive Speed rpm Driven Speed rpm X -------- ----- k Drive Sheave Diameter Using these relationships the sheave rotational speeds can be determined however obtaining the other component speeds requires a bit more effort. The rotational speed of the belt cannot directly be determined using the information presented so far. To Machine-Train
