The traditional traveling device of construction machinery adopts mechanical transmission or hydro mechanical transmission. Mechanical transmission has the advantages of high transmission efficiency and high transmission precision. But it is inconvenient to shift gears and adjust speed, so it is difficult to realize intelligent control. The hydraulic mechanical transmission mode introduces the hydraulic torque converter on the basis of the mechanical transmission mode. The hydraulic torque converter has the advantages of adaptive transmission ratio and load, soft transmission, etc. However, the high efficiency area of the hydraulic torque converter is very narrow, and the low-speed stability is poor. For construction machinery with low driving speed and requiring frequent starting, braking and reversing, the total transmission efficiency is low, resulting in large heating of the system, poor operability and high labor intensity of the driver.
At present, the transmission modes of the driving system of engineering vehicles include mechanical transmission, hydro mechanical transmission, hydraulic transmission and motor drive. Each transmission mode has its own advantages and disadvantages. This article will introduce hydraulic transmission and its advantages and disadvantages.
Hydraulic transmission is a widely used transmission mode in recent years. The power of the engine finally drives the wheels through the hydraulic pump, hydraulic valve and hydraulic motor. Compared with mechanical transmission and hydro mechanical transmission, hydraulic transmission has the advantages of flexible layout, good operability and easy to realize intelligent control. Hydraulic transmission is divided into open system and closed system according to system form. The open system consists of one-way hydraulic pump, main control valve and two-way hydraulic motor. The hydraulic oil flows through the hydraulic pump, main control valve and hydraulic motor and returns to the hydraulic oil tank. The utility model has the advantages of good speed adjustment, good heat dissipation, etc. The closed system is composed of two-way hydraulic pump, two-way hydraulic motor and auxiliary hydraulic valve. The hydraulic oil enters the hydraulic pump again after the hydraulic pump and hydraulic motor do work. The utility model has the advantages of high pressure, compact structure, stable transmission, etc.
