Door lifter for coke oven

摘要

An door lifter for coke ovens is provided with a door lifting or lowering power actuator consisting of two hydraulic cylinders connected in series and in back-to-back relationship. In the case of the door removal, first one of the two hydraulic cylinders is actuated so that the hooks are made into engagement with the corresponding lug pieces of the door and when they have engaged, said one hydraulic cylinder is stopped and locked. Thereafter the other hydraulic cylinder is actuated so that the door is lifted to be removed from the oven. In order to reengage the door, the other hydraulic cylinder is reversely actuated so that the door is lowered by the same stroke as the lift stroke and then said one hydraulic cylinder is reversely actuated so that the hooks are disengaged from the lug pieces of the door. In the case of the prior art door lifter of the type having a single hydraulic cylinder for lifting or lowering the door in two steps or strokes, there must be provided a hydraulic control circuit which is very complex in construction and expensive, but the use of two hydraulic cylinders can considerably simplify the hydraulic control circuit.