Application brief: Gearboxes in electric adventure vehicles (EAVs)

Electric adventure vehicles (EAVs) need light transmission components but lots of torque. So EAV maker Outrider USA recently sourced a Neugart planetary gearbox to solve the design problem. Outrider makes several versions of the Alpha (for everyday use on gravel and streets) and the Horizon for offroad cycling.

Each model has a drive to output 1 to 4 kWh. For high-speed road applications, Outrider chose a single-stage Neugart PLQE 60-mm gearbox with a 5:1 gear ratio. EAVs for lower-speed applications have a two-stage version with a 15:1 gear ratio.

Outrider briefly considered a two-stage belt drive, but this didn’t provide necessary reduction — and a three-stage belt drive would’ve taken up almost triple the space of the PLQE planetary gearbox.

One of the biggest challenges Outrider engineers faced was finding a gearbox with enough torque density to handle 13,000 rpm. EAVs use performance motors, so the gearbox had to meet output rpm and torque requirements. Smaller gearboxes can handle high speeds but not torque. In contrast, the PLQE 60 has up to six planets for higher torque density in a given frame size than comparable gearboxes. The gearbox also accepts overloading to boost speeds and torque. Gearboxes in this size have a regular torque rating of 40 Nm.

The PLQE 60 gearbox weighs only about two pounds, so keeps drive weight low. In fact, the Outrider’s power-dense drive system puts out about five and a half horsepower out of a 7-lb package. Plus the PLQE 60 doesn’t need an adaptor, as it comes with a direct motor attachment or connecting to the EAV motor. That keeps weight and design footprint to a minimum. PLQE 60 millimeter gearboxes are (in a single stage) 97% efficient; double-stage versions are 94% efficient.