The Technology

What is the Regenerative Drive System (RDSTM)?

Permo-Drive has created an intelligent hybrid hydraulic system for urban commercial vehicles which saves fuel and therefore reduces carbon emissions and other pollutants. These vehicles are significant fuel users and polluters in every country.

The RDS technology captures energy normally wasted as heat during braking and re-uses the same energy to accelerate the vehicle, thereby reducing fuel and emissions.

The RDS comprises a hydraulic pump/motor connected to the driveline, accumulators, reservoir, sensors, hydraulic control manifold and a programmed software controller. The components are existing mature technology, consolidated into a system by sophisticated software and controls.

The pump/motor can be connected anywhere in the driveline but generally it is connected to the driveshaft between gearbox and differential. The gear box ratio and the size of the pump and accumulator are determined by the mass of the vehicle and its drive cycle. The sensors and electro-hydraulic control system are independent of vehicle size.

The RDS technology can be installed into any suitable vehicle regardless of the type of fuel the vehicle uses (diesel, natural gas, LPG or petrol).

When will the RDS be available?

The development of the base RDS technology is complete. Future progress is concentrated on the application of the RDS into specific vehicle makes and models.

The RDS is targeted to be available as series production in 2008.

How the RDS Technology Works

The operation of the RDS is remarkably simple. It is operated from the vehicle throttle pedal and is seamlessly managed by the intelligent control system.


The RDS technology works by controlling a hydraulic pump which moves hydraulic oil under high pressure into an accumulator to compress nitrogen gas. The energy to compress the gas comes from the vehicle, thus slowing it down without the need to use the normal brakes.

The driver slows the vehicle by relaxing the throttle pedal (there is no need to use the brake pedal). Whenever the vehicle is required to slow the RDS provides the normal braking and stores the otherwise wasted energy.


When the vehicle subsequently accelerates the energy previously stored during braking is released back to the vehicle. The pressurised nitrogen moves the accumulated oil through back through the pump, thus providing the power to accelerate the vehicle. During this process the power requirement from the engine is reduced, therefore reducing fuel consumption and consequent pollutant emissions.

Intelligent Control System

In response to driver demand via the throttle pedal, the RDS control system manages the storage and delivery of energy. The control system thinks for itself by adapting to both operator demand and driving conditions. It does so in a manner that is unobtrusive to the driver.

As the RDS operates in parallel with the vehicle driveline, should any problem occur, the control system turns the RDS off and allows the vehicle to continue working.