Aluminum Tube,Aluminum Making Production Line,Steel Tube Production Line,Welding Production Line Yangzhou Donglun Industrial Equipment Co., Ltd , https://www.dltubemill.com
At present, the CB-B gear pump is widely used in dump trucks and construction machinery. This article outlines common causes of vibration and noise, along with troubleshooting methods for reference.
**1. Causes of Vibration and Noise and Their Solutions**
**(1) Air Ingestion**
①The CB-B gear pump body and its side covers are sealed using rigid seals. If the contact surface flatness does not meet specifications, air can be drawn into the system during operation. Similarly, if the pump cover and pressure plate make direct contact, air may also enter. If the gland is made of plastic, it may become loose or damaged due to temperature changes, leading to air leakage. To fix this, if the pump body or cover’s flatness is out of tolerance, they should be ground on a flat steel plate using an "8" shaped pattern with fine sand, or on a surface grinder to ensure flatness is less than 5μm. Additionally, the plane and hole perpendicularity must be maintained. For leaks between the pump cover and gland, epoxy adhesive can be applied for sealing.
â‘¡ The shaft is typically sealed with a skeleton oil seal. If the lip spring becomes detached, the seal is improperly installed, or the lip is damaged or aged, negative pressure at the back of the seal may cause air ingestion. Replacing the seal usually resolves this issue.
â‘¢ A low oil level in the tank or an improperly submerged suction nozzle can cause the pump to draw in air. In such cases, the fuel tank should be refilled, and the suction nozzle should be positioned below the oil surface. If the return pipe is exposed above the oil level, negative pressure within the system might pull air back in, so the return pipe should generally be submerged below the oil level.
④ If the pump is installed too high relative to the oil surface, especially when the pump speed is reduced, insufficient suction may occur, causing air to be drawn in. Adjusting the pump’s height to meet the required clearance will resolve this issue.
⑤ A clogged or undersized oil filter can increase suction resistance and allow air to enter. Additionally, a larger port diameter may also introduce air. Cleaning the filter or replacing it with a larger capacity one of appropriate size can prevent both air ingestion and noise.
**(2) Mechanical Issues**
â‘ Misalignment between the pump and coupling can cause vibration and noise. Ensuring proper coupling alignment is essential.
â‘¡ Contamination in the oil can lead to wear on the gears and other components, resulting in noise. Replacing the oil, improving filtration, and cleaning the pump can help. If the gears are severely worn, they should be repaired or replaced.
â‘¢ Damaged or excessively worn internal parts can cause vibration and noise. Examples include large tooth profile errors, poor meshing between gears, rough tooth surfaces, incorrect overhang length, excessive tooth backlash, or improper contact area. In such cases, replacing the gears or regrinding them may be necessary. Damage to the needle cage in the bearings, or excessive wear on the shaft journal and needles, can also cause mechanical noise. Disassembling the pump and replacing the needle roller bearings is often required.
â‘£ An overly small gear assembly gap or unremoved burrs from the gear end faces can damage the mating surfaces, leading to internal leakage and reduced flow. Dirt entering the pump can also wedge between the gear end face and the front/back covers, causing communication between high and low-pressure chambers. To address this, disassemble the pump, grind the gear end faces to increase the axial gap, polish the front and rear cover end faces with a surface grinder, and remove any burrs (without chamfering). The depth and width of the unloading grooves on the end caps should also be adjusted accordingly.