Study On Optimal Design Of Power-Shift Transmission For Three Ton Backhoe Loader

Backhoe Loader compact structure, a device can be used to realize the excavation and loading operations. Used for highway maintenance, municipal engineering, cable laying, irrigation and water conservancy construction, etc.The TLB1-4WB transmission which used for most of backhoe loaders in the market is made by Carraro Italian. The transmission has four forward gears and four reverse gears. The shift forward and backward is by electro-hydraulic control. Speed gear shift using synchronizer. The shift mode has a characteristic of simple, compact and low cost.However, the special working condition of backhoe loader machine need frequent shifting.TLB1-4WD transmission is a special operation mode which leads to heavy workload, poor operating comfort and low shift efficiency when the driver is in operation. The transmission would release the front axle automatically when it's in high-speed gear (4th gear). The backhoe by a four-wheel drive would tune into a two-wheel drive. It is achieved by the interruption of the power transmission line of the mechanical gear to the output shaft controlled by electro-hydraulic. The torque converter of the transmission is a riveting single-stage single-phase three-element torque converter. It had a simple structure and stable performance but lower transmission efficiency. The backhoe loader often needs to high speed walking. Traditional single-stage single-phase torque converter has lower transmission efficiency when at high speed, resulting in larger fuel consumption.This paper aims to improve the structure of TLB1-4WD transmission which gear power transmission is controlled by an electromagnetic valve through a joint separation control of multi disc wet clutch. Power is transmitted to the output shaft rear axle by respective range gear to form individual speed stage instead of synchronous mechanical shifting. Lifting gear can be performed without cutting power by electro-hydraulic control power shift with comfortable operation and high efficiency shift. Released the axle wound be achieved by combination and separated of the wet multi-plate clutch which controlled by electromagnetic proportional control valve. When at low speed, the clutch engagement at the disc spring pressure and power through the gears meshing transmission to front axle. At high speed, the wet clutch is separated and the power is cut off, the front output shaft loses the output. Application of floating guide wheel structure with a one-way clutch in the torque converter.The flow impact positive of stator blades and the stator is fixed when the turbine output speed is low and the torque increases. The flow impact the back of the stator blades when the turbine output speed is high and the stator rotates with the turbine and efficiency of power transmission torque converter increases and converter into the coupling conditions. It can be achieve that better shift comfortable, higher shift efficiency and higher transmission efficiency of transmission by the way that speed gear and released axle agencies controlled by power shift and while using a single-stage two-phase three-element integrated hydraulic torque converter.