Manhole cover balancers must ensure safety during manhole opening and closing

2025-07-23 13:45:55

Manhole cover balancers must be easy to operate and ensure safety during manhole opening and closing.

The manhole cover balancer comprises a combined frame, a spiral spring, a shaft, a sleeve, and a spring box. The inner end of the spiral spring is inserted into a groove on the outer periphery of the sleeve for fixation, while the outer end of the spiral spring extends into a flat straight slot in the spring box. One end of the shaft has a shoulder with a hexagonal head and a pin hole on the shoulder side. The outer frame's boss also has a pin hole. The other end of the shaft has a groove for a circlip. A pin is inserted into a pin hole aligned with the outer frame's boss, positioning it. The outer frame provides a position limit for the middle frame and spring box. The inner frame is connected to the middle frame at one end via a small shaft. A short cylinder on the inner frame inserts into an oblong hole in the middle frame's connecting plate, with an adjustment screw at the top end of the oblong hole. The spring box's flat straight slot is positioned against the upper end surface of the outer frame's connecting plate, and the spring box's boss is positioned against the lower end surface of the connecting plate.