In addition to its mountain driving capability, a small self-propelled agricultural crawler needs to work under high load conditions, so its overall design should require a reasonable layout and compact structure. In terms of dynamics, it is important to ensure that there is sufficient drive power for good acceleration, hill climbing and obstacle-crossing performance, as well as improving the safety and stability of the small agricultural crawler. Because of the relatively small size of the vehicle and the limited size of the tracked chassis, it is easier to roll over than medium and large tracked vehicles when driving on uneven roads in mountainous and hilly areas.
According to the design requirements, the following design principles were adopted for the overall arrangement of the vehicle in order to improve the rollover resistance of the self-propelled small agricultural tracked transporters:
(1) The travel system is designed with a simplified travel system consisting of integral rubber tracks, drive wheels, supporting wheels, tensioning wheels and tensioning mechanism. The rubber tracks are light in weight and the sag above the tracks is small when driving, so they can be used without a carrier wheel. Due to the low design speed and the fact that it only carries goods, the suspension devices necessary for medium and large tracked vehicles can be omitted from the design, in order to reduce the overall vehicle mass and facilitate resistance to skidding and overturning.
(2) The ultra-low-speed gear train design, consisting of a two-shaft transmission with a central gear main reducer, gives the tracked transport vehicle a sufficiently large driving force and ultra-low-speed output performance, which is conducive to improved passability and also to improved roll-over resistance.
(3) In order to make the mass of the vehicle evenly distributed and reasonable, suitable for driving on complex road surfaces in undulating mountainous terrain and to improve anti-rollover performance, the height of the transport vehicle off the ground and the position of the vehicle's centre of gravity must be taken into account. The chassis frame is H-shaped, with the engine and transmission placed near the drive wheels, i.e. on the same platform at the rear of the frame. The main gearbox housing is fixed to the frame and placed under the engine and transmission. The engine transmits the power to the transmission via the belt drive, the transmission output shaft transmits the power to the central gear of the main reducer via the gear drive and then, via the normally engaged steering clutch, the power is transmitted to the half-axle and the track drive wheels, enabling the tracked transport vehicle to be driven. The carriage for transporting goods is located in the middle and front of the frame, so that the front and rear weights of the transport vehicle are more evenly distributed when fully loaded, which is conducive to improving the anti-rollover performance.
(4) The handrails, gearshift handle, clutch and throttle are designed according to ergonomic arrangements to make handling more comfortable and convenient. The dimensions of the wagon are based on the standard basket size for fruit transport. In order to increase the loading volume, the carriage is designed with telescopic panels to extend the dimensions to different degrees in the left, right, front and rear directions in order to increase the loading capacity of the fruit, while the position of the centre of mass under different loading loads is conducive to improving the anti-rollover performance.