How to choose the rear axle speed ratio for operating tractor in mountainous areas

How to choose the rear axle speed ratio when operating a tractor in mountainous areas. Many overseas fleets tend to fall into the trap of simply pursuing high horsepower when purchasing tractors, neglecting the matching of rear axle speed ratios. After the vehicles are put into operation in mountainous areas, they frequently downshift and have difficulty climbing, accelerating the wear and tear of the gearbox and engine, directly increasing maintenance costs. Simply put, with the engine and gearbox unchanged, the larger the rear axle speed ratio, the stronger the wheel torque, and the better the climbing ability, but the cruising speed is lower; The smaller the speed ratio, the more fuel-efficient it is when driving on flat roads, but when encountering long and steep slopes, it is easy to have insufficient power. Selection cannot be based solely on speed ratio numbers, it needs to be comprehensively judged based on slope, load capacity, and gearbox type. If it is a hilly area with short slopes and small gradients, the vehicle can choose a speed ratio of 3.7 to 3.9 for standard load transportation, paired with an overdrive gearbox. The uphill power is sufficient, and the reasonable cruising speed can also be maintained on flat roads, balancing power and fuel economy. It is suitable for mixed routes in mountainous and plain areas. If there are many steep slopes and heavy loads during transportation, it is common for building materials and ore transportation in mountainous mining areas. High speed ratio rear axles such as 4.11 and 4.33 are preferred to amplify wheel torque. When climbing, the engine can be stably maintained in the optimal torque range, reducing frequent gear shifting operations, lowering gearbox and clutch losses, and improving the reliability of the vehicle on continuous uphill sections. For extreme mountainous heavy load conditions with a slope of over 6%, a speed ratio of 4.875 can be considered. Low speed traction is stronger, but the engine speed is higher during daily driving, resulting in an increase in fuel consumption. When selecting a gearbox, it is also necessary to match it. An overdrive gearbox is suitable for alternating between uphill and flat roads, while a direct transmission is more suitable for continuous steep slopes to avoid gear and speed ratio mismatches. In addition, the selection of speed ratio should be considered in conjunction with engine braking and hydraulic retarder. In mountainous areas, not only should the uphill traction force be taken into account, but the braking load on long downhill slopes is also crucial. When vehicles with high speed ratios go downhill, the engine braking effect is better, reducing the burden on the brake pads. Many customers, driven by the desire for high speed and fuel efficiency, choose low speed ratio models to operate in mountainous areas. When driving uphill with low torque and high load, the engine runs at overload for a long time, resulting in a significant increase in failure rates. Long term operation is not worth the loss. When selecting export vehicles, it is necessary to confirm the target market road slope, conventional load capacity, and transportation distance in advance, and not apply the speed ratio scheme of plain trunk lines. When purchasing the fleet, priority should be given to providing the manufacturer with route information, and the factory will match the entire powertrain to ensure stable operation of the vehicle in mountainous areas, reduce maintenance downtime in the later stage, and improve the operational efficiency of the fleet.