Ramp Control Systems

On ramp ascent, Rokion trucks can navigate a 20% grade at full GVWR at its maximum programmed speed over a distance of 13 km*, for a total vertical rise of 2500 m.

 

Down ramp, our battery powered trucks take full advantage of regenerative braking — descending ramps of up to 20% grade.

 

RAMP DESCENT

 

Regenerative Braking System

 

When driving down grade, the regenerative braking system uses the electric motor as both a motor brake and as a generator that transfers energy into the battery modules. Regenerative braking is activated by simply releasing the accelerator pedal while in motion, allowing the electric motor to slow the vehicle down while simultaneously charging its batteries.

 

Regenerative braking allows our battery powered trucks to descend ramps of up to 20% grade without the strain on braking and drive components.

 

Integrated Brake Resistor

 

During ramp descent, the regenerative braking system remains active even when the batteries are fully charged. The integrated brake resistor allows for this by bleeding energy from the battery modules in advance of incoming regenerative energy. The energy that the brake resistor bleeds off is converted to heat, which is either dissipated by the vehicle cooling system, or vented inside the vehicle.

 

Adaptive Speed Control

 

Adaptive Speed Control ensures that regenerative braking is available at all times. The speed of the vehicle is varied to maintain equilibrium between battery charge levels and the rate of energy discharge.

 

There is a limit to the amount of heat energy that the brake resistor can reasonably dissipate from fully charged batteries on a continuous ramp descent. As a safeguard, our vehicle control system uses sophisticated algorithms to limit vehicle speed in response to battery state of charge and vehicle temperature.

 

When the batteries are at a lower state of charge, they can absorb more regenerative energy. When the batteries are at a higher state of charge, Adaptive Speed Control takes over and gradually lowers vehicle speed. This action, in tandem with the brake resistor, ensures regenerative braking is maintained for the duration of ramp descent. Once the brake resister and cooling system are able to dissipate heat at a rate faster than incoming regenerative energy, Adaptive Speed Control gradually allows the vehicle to return to its pre-programmed max speed limit.

 

As the vehicle decelerates, the amount of regenerative energy produced by the electric motor is reduced, lowering the amount of energy the batteries must absorb. This action reduces the amount of energy the brake resistor must withdraw from the fully charged batteries in anticipation of incoming regenerative energy.

 

In addition to the regenerative braking system, standard service brakes and emergency brakes ensure operational safety on ramp descent.

 

RAMP ASCENT

 

Intelligent Power Delivery

 

On ramp ascent, Rokion trucks can navigate a 20% grade at full GVWR at its maximum programmed speed over a distance of 13 km*, for a total vertical rise of 2500 m.

 

Although these capabilities surpass the grade, distance, and depth found in typical ramp access mines, our goal was to engineer a truck that could climb any ramp in any mine. Rokion trucks have enough power to climb a 100% grade (45 degrees).

 

*Approximated — this distance would be sufficient for all but the longest ramps in the world.

 

Drawbar Force

 

Rokion trucks use electric motors and gearboxes designed for lower speeds and higher torque, which are ideal for mine application and ramp use. Conventional all-wheel drive trucks designed for pulling still compromise on torque and drawbar force to preserve speed and acceleration for legal road use.

 

Our trucks not only have a higher drawbar force, our power control systems provide intelligent power delivery and traction control for unmatched ramp navigation.