The utility model is composed of a fuel tank, an oil pipeline, a check valve, a hydraulic pump, a leg fixing plate and a fixing pin, a rotating latch, an oil cylinder, a plunger, a support leg shell, a leg seat, an oil return pipe, etc., the top of the cylinder is a fixedly connected leg fixing plate, fixing plate 1 There are steering latches and fixing pins on the side, the cylinder is connected to the plunger rod and the ball head and plunger spring, the ball head is live connected to the steering leg seat, the cylinder is also connected to the fuel tank through the oil return switch on the oil inlet, pipeline and return pipe, it has novel concept, scientific design, specification, reasonable, labor saving, labor saving, large support load, light and dexterity, sturdy and durable, simplicity of production and applicability