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Based on Otos’ over a decade of experience in repairing various hydraulic pumps, it has been found that wear and tear of the internal components of the pump can lead to internal leakage. Among them, the large leakage area between the floating bushing and the gear end face is the main location causing internal leakage. This portion of the leakage accounts for about 50% to 70% of the total internal leakage. In a gear pump with internal wear and leakage, its volumetric efficiency decreases, resulting in the pump’s output power being **lower than its input power**. All of its losses are converted into heat energy, which can cause the oil pump to overheat. 1. Wear of internal components in the oil pump: Wear of the internal components of the oil pump can cause internal leakage. Among them, the large leakage area between the floating bushing and the gear end face is the main location causing internal leakage. This portion of the leakage accounts for about 50% to 70% of the total internal leakage. In a gear pump with internal wear and leakage, its volumetric efficiency decreases, resulting in the pump’s output power being **lower than its input power**. All of its losses are converted into heat energy, which can cause the oil pump to overheat. If the bonding plane is compressed, wear will occur due to the slight movement of the floating bushing during operation, resulting in slow lifting or inability to lift the agricultural tool; such a floating bushing must be replaced or repaired. 2. The wear of the oil pump housing is mainly due to the wear of the floating bushing hole (the normal clearance between the gear shaft and the bushing is 0.09~0.175 mm, with a maximum of 0.20 mm). The gears operate under the action of pressurized oil; the tips of the gears are close to the oil pump housing, causing wear on the low-pressure chamber of the pump body. Another type of wear is the circumferential wear on the working surface inside the housing; this wear is mainly caused by impure oil, so it is necessary to use oil free from impurities. 3. Wear of the oil seal, aging of the rubber seal: The rubber oil seal in the unloading plate ages and deteriorates, losing its elasticity; as a result, it can no longer provide a sealing barrier between the high-pressure oil chamber and the low-pressure oil chamber. This allows the oil pressure from the high-pressure chamber to leak into the low-pressure chamber, a phenomenon known as \"internal leakage\". It reduces the operating pressure and flow rate of the oil pump. The normal operating pressure of the CB46 gear pump is 100~110 kg/cm², its normal oil delivery rate is 46 L/min, and the standard rubber seal for the unloading plate is 57×43. The self-tightening oil seal is a skeleton-type oil seal of PG25×42×10; when it is damaged or becomes ineffective over time, air is drawn into the oil pump through the gaps between the oil seal and the spindle journal, or from the junction between the oil inlet flange and the oil pump housing. This air then enters the oil tank via the return pipe, where it causes numerous bubbles to form. This will cause a decrease in the amount of oil in the tank, while the amount of oil in the engine’s oil pan increases, resulting in slow lifting of the agricultural equipment or even an inability to lift it at all. The oil seal must be replaced to eliminate this fault. 4. Insufficient oil supply from the oil pump or no oil pressure: The working device lifts slowly, trembles while lifting, or fails to lift at all ； Bubbles in the fuel tank or fuel lines ； The hydraulic system makes a \"hiss, hiss\" sound during lifting ； When the tractor is first started, the working device can be raised; however, after operating for a while and the oil temperature rises, it raises slowly or cannot be raised at all ； It can be raised under light load, but not under heavy load; the telescopic stage cannot be raised. Cause of the fault: (1) The oil level in the hydraulic tank is too low ； (2) Hydraulic oil not used according to the season ； (3) The oil inlet pipe is severely blocked by debris ； (4) The oil seal of the drive gear of the oil pump is damaged, allowing air to enter the hydraulic system ； (5) The \"O\"-ring seals at the inlet and outlet connections of the oil pump, or those on the elbow fittings, are damaged; the fastening bolts of the elbow fittings or the nuts on the inlet and outlet pipes are not tightened properly, allowing air to enter the hydraulic system ； (6) Internal leakage in the oil pump, aging of the sealing ring ； (7) Wear or scratches on the end face of the oil pump or on the end faces of the shaft sleeves of the driving and driven gears; the unevenness of the end faces of these two shaft sleeves is out of tolerance ； (8) Internal leakage caused by incorrect assembly of internal parts of the oil pump ； (9) Installing a “right-handed” oil pump in a “left-handed” setup, resulting in damage to the skeleton oil seal ； (10) The hydraulic oil is too dirty.