Crane Development origin: history. 10 BC, Roman architect Victor Ruwais was in its construction manual describes a lifting machinery. This machine has a mast of cranes, mast mounted pulley by guyed mast position, using a winch to pull cable through pulleys to lift heavy loads. Some overweight machinery available two masts, constitute herringbone, the lift was traversing crane manufacturer, but only slightly, operation is very difficult. Crane safety devices: the height limit device. After starting to rise to a predetermined height hook crane manufacturers, touch the limit weight, open limit switch, 'had about' indicator light that is bright, and cut off the hook lifting, arm extended, the boom volts to such action and to ensure safe operation. Then just manipulate the hook down boom boom retracted or lifted up (ie safe side operation), etc. When the handle so that the limit weight lifting constraints, normal operation is restored. Large cranes | Yongchang Machinery (certified) | crane provided by the Henan Yongchang Engineering Machinery Co., Henan Yongchang Engineering Machinery Co., Ltd. (www.tadanocrane.net) is Anyang, other leaders, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. In Yongchang machinery leadership with the staff warmly welcome all inquiries negotiations to create a better future Yongchang machinery.