Methods to move the boom when pressurized fluid from the source is not approachable to and to lower the boom during an abnormal operation condition

摘要

"Methods to move the boom when pressurized fluid from the source is not approachable to and to lower the boom during an abnormal operation condition.An elevator load industrial has a boom which is raised and lowered by a first hydraulic actuator and a load carrier is pivoted with respect to the boom by a secondHydraulic actuator.In the case of the supply of hydraulic fluid to actuate the actuator fails, the boom can be lowered by gravity by draining the fluid from the first hydraulic actuator.To prevent a load slide carrier load as the boom descends, the load carrier is pivoted to maintain a substantially constant angular relationship with the floor.This is accomplished by selective transport of fluid drained under pressure from the first hydraulic actuator into the second hydraulic actuator.Changes in the position of the boom are sensoreadas and, in response,The flow of hydraulic fluid to the second hydraulic actuator is controlled to produce corresponding changes in the position of the carrying load.