Crane safety devices: the height limit device. After a predetermined height from the hook raised 50 tons of truck crane price, touch the limit weight, open limit switch, 'had about' indicator light that is bright 50 tons truck crane, and cut off the hook lifting, arm stretched out , crane and other movements of volts to ensure safe operation. Then just manipulate the hook down boom boom retracted or lifted up (ie safe side operation), etc. When the handle 50 tons of second-hand truck crane, so that weight lifting constraints limit the operation returned to normal. Crane use and maintenance: Note frequently check the oil, hydraulic oil, coolant, brake fluid and fuel oil (water) bit and quality, and pay attention to check the tightness of the machine. Inspection found a lack of excessive water, we should analyze the reasons. Meanwhile cranes, lubricate all lubrication points should be strengthened, it is recommended run-in period, the class must be on the lubrication point lubrication (except for special request).