When new user just uses heavy-duty truck with Fast gearbox, user usually reflects that it is not easy for vehicle to put into gear when starting. The reason is that user does not read instruction manual or is not trained so that user does not understand operating features of Fast gearbox. As we know the main box of old Fast gearbox has no synchronizer so that starting shift shall have clutch and the brake to coordinate the work. When the vehicle starts, if only the clutch pedal is stepped on but the switch valve of clutch and the brake is not turned on, and then the brake cannot work. Therefore, it is difficult to put into gear. Some users know the requirements for starting operation, but they still reflect that it is difficult to put into gear. Generally speaking, driver is too short and leg is too short, moreover, the seat is too high, therefore, the leg cannot touch the operational position of the brake when starting. As a result, the seat height shall be adjusted to meet the requirements. If the clutch really makes the brake switch valve turn on but it is still difficult to put into gear when starting. And it seems that the clutch is not released completely, and then it indicates that the clutch brake system has fault. Now please inspect braking gas circuit firstly, put the brake valve on the left lower of gear box, loosen the gas type fitting of brake cylinder and then step on the clutch pedal to turn on the clutch brake valve. Please observe whether gas type fitting exhausts gas to the outside. If it is not smooth to exhaust, then it indicates that there is fault for the switch valve of the brake. Please disassemble it or replace it. If it is normal to exhaust, and then it indicates that there is no problem in the switch valve and maybe the fault is on the brake cylinder. The treatment is to disassemble the clutch brake cylinder. Please observe whether the brake cylinder piston seal ring is wore or leaks gas, whether the piston can move smoothly and is not clamped. If it leaks gas, and then replace seal ring. Finally, please inspect whether the piston brake arc concave surface is worn seriously. If it is worn seriously, please replace the brake cylinder piston. Most importantly, many heavy-duty trucks are not equipped with “clutch braking device” for the moment. When the vehicle puts into gear when starting, the clutch pedal shall be stepped on and then put into gear later, which is the same with other types. If it is difficult to shift gear when the vehicle drives normally, then please inspect whether the reason is remote operation of shift level. Fast gearbox adopts remote shift mechanism on the heavy-duty trucks. If shift level is adjusted inappropriately or the jointing and bushing are too tight or excessively worn, the resistance of shift gear will be increased so that it is difficult to shift gear. In particular, some gears are difficult to shift. The screw can be adjusted by adjusting gear shift arm of gearbox to make joystick in appropriate position. For gearbox with double-lever double-shift mechanism, when lever of controlling selector lever or flexible shaft are not adjusted appropriately, the gear on the edge cannot put into reserve gear, creeper gear, and 7th and 8th gear. At this moment, please remove the operating lever or flexible shaft from the operating lever and then put the selector lever on the gear selection position of edge gears, adjust the length of operating lever or flexible shaft to reach the gear selection position of the limit and to connect joystick or flexible shaft with selector lever. At present, various series of gearboxes are equipped with all synchronizer. It is so convenient for these types of gearboxes to shift gear. When a gear is not easy to shift, please inspect whether the synchronizer of this gear is damaged. When gearbox with all synchronizer is operated, please shift gear with rational shift gear speed, which can reduce the abrasion of synchronizer and lengthen the service life of synchronizer. When shift gear is performed between two adjacent high gear and low gear (e.g. fourth and fifth gear), appropriate interval shall be needed for prodding high and low gears and pushing in gear. When the action of gear shift is too coherent, it is easy to burn and damage synchronizer of secondary gearbox. If remote operating lever is separated from gear shift arm of gearbox, it is still difficult to shift some gears with the method of directly operating gear shift arm, and it indicates that the inside of gearbox has fault. At this moment, repair with disassembly is needed. Generally speaking, the reason is that shift shaft of gearbox cover is deformed, sliding sleeve and two shafts are deformed or excessively worn or the shift shaft or lockpin of lifting level is loosened.