在液压传动系统中,为了使液压缸在上端或者中途位置能与自重等平衡而停住,一般使用平衡阀。但是,这种平衡回路(图1)有以下不足之处。那就是由于各平衡阀的特性不同,使多个液压缸同步工作困难。另外,液压缸与平衡阀之间的元件因破损等产生漏油时,液压缸急速动作,就很危险。 In the hydraulic transmission system, in order to make the hydraulic cylinder at the upper end or half-way position with the deadweight balance and stop, the general use of balancing valve. However, this balance circuit (Figure 1) has the following deficiencies. That is because of the different characteristics of the balance valve, so that more than one hydraulic cylinder difficult to work simultaneously. In addition, the hydraulic cylinder and balance valve between the components due to damage such as oil leakage, the hydraulic cylinder rapid action, it is very dangerous.