1. Put damage:

 This is the biggest characteristic of ductile iron manhole covers, ductile iron manhole covers can be heavy pressure 36T/60T, light can be confined 21T. Even if the load pressure exceeds its limit, ductile iron manhole cover cast iron manhole cover is not as common as broken, but a slight deformation of the car and pedestrians has a certain security.

2. Anti-shock:

 only through the mouth of the Manhole set to U-shaped, with a T-type synthetic rubber, U-shaped slot embedded in the contact Manhole covers and the process in order to cushion and reduce the vibration force.

3. Anti-slip:

 3mm tread covers convex surface, and thus play a good non-slip effect.

4. Anti-impact:

 Manhole covers the contact with the colossal surface, directly on the T-rubber, and dealt with gently, to eliminate noise.