During expansion, a vacuum is created, causing the air in the liquid to separate and bubbles to form! I will explain the issues.
The involute gear pump has a variable trapped volume at the meshing part as the gears rotate. During contraction (Figure A), it generates abnormally high pressure, which puts stress on the bearings and causes vibration and noise. Additionally, during expansion (Figure C), a vacuum is created, leading to the separation of air in the pumped liquid and the formation of bubbles. As clearly shown in the figures, the inter-tooth volume at the meshing part has a narrow inlet, which causes cavitation during the inflow of the pumped liquid, resulting in vibration, noise, pitting, and reduced efficiency. 【Issues (Partial)】 ■ The inter-tooth volume at the meshing part has a narrow inlet, causing cavitation during the inflow of the pumped liquid. ■ Causes vibration, noise, pitting, and reduces efficiency. ■ The slip rate of the gears is large, and there are significant fluctuations at the meshing point. ■ Promotes wear of the gears, leading to decreased capacity and power loss. *For more details, please refer to the PDF document or feel free to contact us.
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【Other Issues】 ■ Shrinkage: Causes excessive stress on bearings due to the occurrence of abnormally high pressure, leading to vibration and noise. ■ Expansion: Creates a vacuum, causing air in the liquid to separate and form bubbles. ■ There is a limitation on the minimum number of teeth, so the number of teeth cannot be reduced below a certain limit, resulting in increased weight and volume. *For more details, please refer to the PDF document or feel free to contact us.
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For more details, please refer to the PDF document or feel free to contact us.
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Nihon Kuroido Kogyo Co., Ltd. is a manufacturer specializing in liquid transport pumps. Our Eri Kuroido gear pumps and Kuroi rotary pumps have been adopted by many manufacturers across Japan, earning long-standing trust in liquid transport technology. Please feel free to contact us if you have any inquiries.