As a P series planetary reducer, the sealing principle of P3SA19's sealing protection components is consistent with the sealing logic of the same series of models and general planetary reducers. The core is designed around the shaft end, box joint surface, screw plug and breathable parts, and prevents leakage and impurity intrusion through contact sealing, gap sealing, etc. The specific sealing principles of each component are as follows:
Input/output shaft skeleton oil seal : This component is the core seal at the shaft end, and it usually adopts a double-lip structure with a dust-proof lip. The sealing principle is to rely on the spring ring that comes with the oil seal to tighten the journal, so that the lip of the oil seal closely fits the surface of the shaft, forming a contact sealing surface to prevent the lubricating oil in the box from leaking out. At the same time, the outer dust-proof lip can form secondary protection with the shaft surface, reducing external dust from entering the lip and avoiding lip wear; the grease applied on the lip not only reduces friction during rotation, but also further enhances the sealing effect. After the lip is worn, it can also achieve a certain amount of automatic compensation through the pre-tightening force of the spring to maintain sealing performance.
O-ring and sealant on the joint surface of the box : The joint surfaces of the box, end cover, flange, etc. will be equipped with O-rings and oil-resistant sealant will be applied. The O-ring relies on its own elasticity to deform, filling the tiny gaps on the joint surface, forming an elastic sealing barrier to prevent oil from leaking from the gap; the matching silicone or polysulfide sealant will fill the tiny gaps not covered by the O-ring, and after solidification, it will fit closely with the joint surface. The two work together to form a double seal. At the same time, some joint surfaces will also have an oil return ditch, so that even a small amount of infiltrated oil can flow back to the tank through the oil return ditch, improving sealing reliability.
Oil drain/oil level screw plug sealing gasket : The sealing gasket at the screw plug is mostly made of elastic material. During installation, it is squeezed between the screw plug and the end face of the threaded hole of the box as the screw plug is tightened. It fills the uneven spots on the end face through elastic deformation, fills the gap in the threaded connection, cuts off the channel for oil leakage along the thread gap, achieves static sealing, and prevents lubricating oil from leaking from the screw plug connection.
Breathing cap (breathing valve) : Although it does not directly block oil, it is a key component to ensure overall sealing. When the reducer is running, the internal oil temperature rises, and the expansion of air will cause the air pressure in the box to rise. Excessive air pressure can easily open oil seals and other seals, causing leakage. The filter structure inside the breathable cap can prevent external dust from entering the box when the air pressure is balanced. At the same time, when the internal air pressure increases, the valve plate of the breathable cap will automatically open to discharge excess gas; when the air pressure decreases, air will be sucked in, thereby maintaining the air pressure balance inside and outside the box, and indirectly protecting the sealing effect of other sealing components.
Auxiliary sealing components (if configured) : If P3SA19 is used in severe working conditions such as high dust, auxiliary components such as labyrinth seals or oil slingers may be installed. The labyrinth seal forms a sawtooth-shaped narrow gap through the fixed parts and the rotating parts. The gap is filled with grease, and the throttling effect of the fluid in the narrow gap is used to prevent oil leakage and dust intrusion. The oil thrower uses centrifugal force to throw the oil flowing outward along the shaft surface back into the box. It is often used in conjunction with other seals to further improve the shaft end sealing performance.
