The oil leakage problem of the reducer of the lever type chain crane is mainly caused by design defects, insufficient manufacturing technology, improper maintenance, and sealing failure. The core reasons and targeted treatment methods are as follows:

1、 Analysis of the core causes of oil leakage

design flaw

Breathable hole issue: Failure to design breathable holes or too small aperture can cause the internal pressure of the reducer to be unbalanced with the external environment, resulting in lubricant leakage. For example, after prolonged operation, the connection surface between the two boxes may leak oil due to poor sealing.

Missing oil return groove: The box body is not equipped with an oil return groove, and lubricating oil accumulates at the shaft seal, joint surface, etc., leaking under pressure difference.

Unreasonable shaft seal structure: Early designs often used oil groove and felt ring shaft seals, which have poor compensation performance and are prone to failure due to poor contact between the shaft neck and the seal.

Insufficient manufacturing process

Processing accuracy does not meet the standard: the roughness, flatness, and positional accuracy of the joint surface of the box body do not meet the design requirements, resulting in gaps and oil leakage. For example, insufficient roughness of the bearing hole can cause oil leakage during high-speed rotation.

Material and processing defects: The castings have not undergone annealing or aging treatment, and the internal stress has not been eliminated, resulting in deformation and gaps.

Improper maintenance

Ventilation hole blockage: Lubricating oil residue accumulates at the ventilation hole, causing poor exhaust and an increase in internal pressure.

Excessive oil volume: During operation, the oil pool is stirred violently, causing lubricating oil to splash and accumulate at the shaft seal, joint surface, etc., leading to leakage.

Loose bolts: Long term vibration or insufficient tightening torque can increase the gap between the joint surfaces.

seal failure

Oil seal aging: The oil seal material is not resistant to high temperatures or corrosion, with lip cracks, hardening, and loss of elasticity.

Installation issue: The oil seal is pressed too deep/too shallow, skewed, resulting in lip deformation or uneven contact.

Neck damage: Neck wear, scratches, or excessive surface roughness, resulting in increased sealing clearance.

2、 Targeted processing methods

Design optimization

Add ventilation device: Install ventilation caps on the observation hole cover and refueling hole cover to ensure balanced pressure inside and outside the box. For example, using an oil cup style breathable cap with a breathable hole diameter of 6mm for easy ventilation.

Improve the oil return system: A tilted oil return groove is opened at the center of the bearing seat tile towards the inside of the machine, and a notch is opened at the straight mouth of the end cover facing the oil return groove, allowing excess lubricating oil to flow back into the oil pool.

Improve the shaft seal structure: choose rubber sealing rings with good toughness and sealing effect (such as O-rings for soft tooth surface reducers and V-rings for hard tooth surfaces); For reducers with half shaft output, skeleton oil seals or separable end caps can be installed.

Manufacturing process improvement

Improve machining accuracy: Ensure that the roughness, flatness, and positional accuracy of the box joint surface and bearing hole meet the standards to prevent deformation.

Strengthening material treatment: Annealing or aging treatment of castings to eliminate internal stress and avoid deformation.

Maintain standards

Regularly check the ventilation holes: clean residue and keep them unobstructed; The oil level should be controlled within the range of the oil dipstick scale to avoid excess.

Tighten bolts: Tighten them diagonally in stages, increasing the torque by 30%, and finally meet the manual requirements; Install anti loosening devices (such as spring washers, stop washers) or apply thread locking adhesive.

Wipe and clean: After the equipment stops running, wipe the oil stains on the shaft to prevent dust from adhering.

Sealing repair and replacement

Oil seal replacement: Select the material according to the working conditions (such as nitrile rubber NBR for ordinary working conditions, fluorine rubber FKM for high temperature/corrosion working conditions); Apply lubricating grease to the lips before installation to avoid dry friction.

Neck repair: repair minor wear with electric brush plating or installation of shaft sleeves; Replace the shaft directly if it is severely worn/scratched.

Joint surface treatment: Use a flat grinding or milling machine to flatten the joint surface, ensuring that the flatness is ≤ 0.05mm/m; Thoroughly clean before applying adhesive, use anaerobic sealant (such as Loctite 510) with a thickness of 0.3-0.5mm, and assemble after curing for 24 hours.

Emergency response and material application

Polymer composite materials: For leakage at static sealing points, polymer composite materials (such as emergency repair agents for oil surfaces) are used for sealing without disassembly, saving time and effort.

Surface engineering technology: For oil leakage at static sealing points during operation, surface engineering technology is used to repair and eliminate the oil leakage.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment