The hydraulic winch uses oil as the working medium, transmits the movement through the change of the sealing volume, and transmits the power through the pressure inside the oil.

(1) Power part - converts the mechanical energy of the prime mover into the pressure energy (hydraulic energy) of the oil, for example: a hydraulic pump.

(2) Execution part - converts the hydraulic pressure energy input from the hydraulic pump into the mechanical energy that drives the working mechanism. For example: hydraulic cylinders, hydraulic motors.

(3) Control section - used to control and regulate the pressure, flow and flow direction of the oil, for example: pressure control valve, flow control valve and direction
Control valve.

(4) Auxiliary part - The first three parts are connected together to form a system for oil storage, filtration, measurement and sealing. For example: piping and fittings, fuel tanks, filters, accumulators, seals and control instruments.

The pressure exerted at any point on a volume of liquid can be transmitted equally in all directions. This means that when multiple hydraulic cylinders are used, each cylinder will be pulled or pushed at a respective speed depending on the moving load. The required pressure will first move the hydraulic cylinder carrying the minimum load with the same range of hydraulic cylinder load capacity, and the hydraulic cylinder carrying the maximum load will eventually move. In the hoisting machinery, the mechanism for lifting or lowering the cargo is called a hoisting mechanism, and generally adopts a winch type, and such a machine is called a winch or a winch. The hoisting mechanism of the hoist is generally composed of a driving device, a wire rope winding system, a take-up device, and a safety protection device. The drive unit includes components such as an electric motor, a coupling, a brake, a speed reducer, and a reel. The wire rope winding system includes a wire rope, a reel, a fixed pulley and a movable pulley. The pick-up device has various forms such as a hook, a lifting ring, a grab bucket, an electromagnetic chuck, and a hanging beam. The safety protection device has an overload limiter, a lifting height limiter, a descending depth limiter, an overspeed protection switch, etc., and is used according to actual needs. There are three driving methods for the winch, namely internal combustion engine drive, electric motor drive and hydraulic drive. The hoisting mechanism driven by the internal combustion engine is mainly transmitted from the internal combustion engine to the various working mechanisms including the hoisting mechanism via the mechanical transmission device. The advantage of this driving mode is that it has its own independent energy source, is flexible and suitable for mobile work. In order to ensure the independent movement of the various institutions, the transmission system of the whole machine is complicated and cumbersome. Since the internal combustion engine cannot be reversed and cannot be loaded, it is necessary to rely on the clutch of the transmission link to realize starting and reversing. This driving mode is difficult to adjust the speed and the operation is troublesome. There are currently only a few places to apply. The motor drive is the main drive of the winch. The mechanical characteristics of the DC motor are suitable for the working requirements of the lifting mechanism, and the speed regulation performance is good, but it is difficult to obtain the DC power supply. In large hoists, internal combustion engines and DC generators are often used for DC drive. The AC motor drive can directly obtain power from the grid, which is easy to operate, easy to maintain, light in weight and reliable in operation, and widely used in electric winches. The hydraulically driven hoisting machine drives the hydraulic pump by the prime mover, inputs the working oil into the actuator (hydraulic cylinder or hydraulic motor) to actuate the mechanism, and realizes the speed regulation by controlling the liquid flow of the input actuator. The advantage of the hydraulic drive is that the transmission ratio is large, and a wide range of stepless speed regulation can be realized, the structure is compact, the operation is stable, the operation is convenient, and the overload protection performance is good. The disadvantage is that the hydraulic transmission components are required to have high manufacturing precision and the liquid is easily leaked. At present, hydraulic drives are increasingly used in marine winches.