What are the solutions for oil leakage at the observation window of NMRV040-10-F-71B5 reducer

Aging, deformation, and hardening are the most common causes of oil leakage, so replacing the gasket or O-ring with a fresh, oil-resistant rubber component will resolve the majority of issues.

 Before reassembly, it is crucial to clean the mating surfaces between the window and the gearbox housing, as residual oil, metal shavings, or paint can compromise the seal. 

Once clean, reassemble the components and tighten the screws evenly to prevent warping the window or distorting the sealing surface; always use a crisscross tightening pattern and avoid over-torquing any single fastener.

Because the NMRV040 has a compact oil capacity, overfilling can cause excessive internal pressure during operation, forcing oil out through the inspection window. The oil level should be maintained at the center of the sight glass and must not exceed the upper limit. Additionally, inspect the breather plug, as a clogged vent traps pressure inside the gearbox and pushes oil out through weak points like the inspection window and shaft seals; clean or replace the breather to ensure proper ventilation.