Our primary product, the PUP AgRover is designed as a low-cost mobile utility platform suitable for off-road conditions, able to carry a payload of 1000 kg (2,000 lbs), pull implements, and power attachments with an on-board engine. The PUP AgRover is targeted towards entrepreneurs and small-holder farmers. The Purdue team is focused on providing products locally owned, manufactured, and maintained for Sub-Saharan Africa (SSA) and similar regions. These products are designed to help communities meet the challenges of transportation, water scarcity, crop production, harvest, energy needs and more.
Weighing less than 500 kg, and able to carry a payload of double the empty weight, the base version of the PUP AgRover has a clutched transmission, 4-8 kw engine and a top speed (configurable) of 30-50km/hr. The lightweight truss frame is made entirely from 30x30mm angle iron, all locally sourced. No custom tooling is required as it is constructed simply by cutting and welding angle iron. Each wheel has a hydraulic break and coil spring suspension for safe and comfortable operation. A torsion bar has been incorporated into the design to improve the vehicle stability (increased roll stiffness), an important addition since the single front wheel does not contribute to roll stability and the roll stiffness without a torsion bar is approximately one-half that of a 4-wheel vehicle.
The three wheel design has several advantages. Cost is reduced since there are fewer components and the steering mechanism is a simple mechanical tiller. The frame design is also simpler since the frame experiences very little twisting, even under heavy loads, as opposed to 4-wheel vehicles where one wheel can lose contact with the ground on uneven road or trails. Performance off-road is improved for 2WD vehicles as well, since the rear traction forces are nearly constant, a result of the single front tire not contributing to the roll stiffness of the suspension. As with all designs there are trade offs, and in this case the primary disadvantage of a three wheel vehicle is that the roll (tipping) axis is a line between the front and rear tires and high speed sharp turns can lead to roll-over tendencies. With reasonable speeds (the PUP is limited to 50km/hr, and typically set up for 30km/hr max), maneuvers, and load placements this risk is avoidable.