BS428
Product Description
Transmission system
Description of transmission
BS428 transmission is a fixed shaft, constant mesh and power gearshift transmission, which is mainly used for LG933L and LG936L loader. In the transmission system of LG933L and LG936L, the engine is directly connected to the torque converter via an elastic plate so as to realize output power, and torque converter is connected via the propeller shaft to front input flange of the transmission where speed change and torque increase happens such that the power can be transmitted to front and rear drive axles via front and rear propeller shafts respectively.
BS428 transmission mainly consists of input shaft assembly, countershaft assembly, and reverse gear shaft assembly, high-low gear sliding sleeve as well as its control mechanism and many pairs of constant mesh gear, etc.
Fig. 2-1 | 1.Breather 2.Transmission control valve 3.Reverse gear shaft 4. Input shaft 5.Countershaft 6.Oil drain plug 7.High-low gearshift fork 8.Output shaft 9.Filter 10.Oil filler pipe 11.Parking brake |
Basic parameters of transmission & torque converter assembly
| Item | Parameters/description | |
| Torque converter | Type | Single-stage three-element turbine hydraulic torque converter |
Torque ratio | 3.25 | |
Oil pressure at torque converter inlet (MPa) | 0.5~0.6 | |
Oil pressure at torque converter outlet (MPa) | 0.2~0.3 | |
| Transmission | Type | Fixed-shaft power shift |
Gears | 4 gears in front and 2 in the rear | |
| Transmission working pressure (MPa) | 1.1~ 1.5 | |
Structure and principle of transmission
Structure of transmission
BS428 transmission includes three sets of normally opened clutches, which are closed by hydraulic fluid, and they control the 1st gear, 2nd gear, 1st reverse gear respectively, or the 3rd gear, 4th gear and 2nd reverse gear when the shift fork is set to a higher gear. The one installed on the input shaft is the 1st gear clutch; the power from torque converter is transmitted to input shaft via a connecting flange and the input shaft is the total input of transmission. The one installed on the countershaft is the 2nd gear clutch, and the countershaft can transmit the power from the 1st gear and the reverse gear to the output gear. The one installed on the reverse gear shaft is the reverse gear clutch which can make the loader drive backwards when it is engaged.
Fig. 2-2 | 1. Reverse gear shaft clutch 2. Input shaft clutch 3. Intermediate gear shaft clutch |
Shifting principle of transmission
The transmission’s gearshift mechanism is a mechanically-operated one, with the gear controller of BS428 transmission shown in Fig.2-3. This gear controller includes two gearshift levers: 1. direction control handle (see Fig. on the left), which connects to the gearshift control valve stem on the transmission via a flexible shaft; 2. high/low speed control handle (see Fig. on the right), which connects to the shift fork on the transmission via a flexible shaft. The gear controller operates the clutches of different gears by controlling the speed change valve. The working conditions of clutches are shown in table 2-2.
Fig. 2-3 Gear selector