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Technical; Page 2. General Information                                                                             

Hydraulic hybrid vehicles share the same architecture and operate in much the same manner as an Electric Hybrid Vehicle. The outcome for all hybrid vehicles is to reduce fuel consumption and emission. This is achieved by using kinetic energy generated when slowing the vehicle. The method is called "regenerative braking". In an electric hybrid the motor/generator is used as a break to slow the vehicle, this generates electricity and charges the vehicles batteries. In a hydraulic hybrid the Pump/Motor generates energy by forcing a fluid into a hydro-pneumatic accumulator, where nitrogen gas is compressed to produced a high-energy output on demand. 

 The three most common categories of hydraulic hybrid vehicle
architectures are;

1.parallel hybrid vehicle

2.series hybrid vehicle

3.compound or power-split hybrid vehicle. 

1. Parallel Hydraulic Hybrid Vehicle

In a parallel hydraulic hybrid vehicle (HHV), the engine still provides power to the wheels through a standard transmission. The hydraulic components are attached to the drive shaft and assist in stopping and accelerating the vehicle. 


2. Series Hydraulic Hybrid Vehicle

Before the word hybrid was connected to motor vehicles, this system was referred to as a "Hydrostatic Transmission" the same as used on many ride on lawn mowers. Series hybrids are not mechanically connected to the drive axle. The power is transferred from hydraulic pump through hydraulic hoses to the hydraulic motor connected to the drive axle.

This allows the engine to operate at its most efficient level, the internal combustion engine's RPM increasing and decreasing depending on load or power demand. 


3. Compound or Split hybrid system

This hybrid system combines the best attributes of all the hybrid systems and that of a standard vehicle to produce the ultimate hybrid system.

 It could also be described as a multi-modal hybrid system.

Mode 1. Operating as a parallel hybrid vehicle.

Mode 2. Operating as a series hybrid vehicle.

Mode 3. Operating as a mechanical driven vehicle.


The sophisticated operating system blends all 3 modes to produce the most efficient environment for the internal combustion engine to operate in. The outcome being the least amount of fuel consumed and drastically reducing exhaust emissions. At low speeds the transmission operates as a series hybrid then at high speeds as a mechanical drive vehicle. In between the parallel hybrid mode assists in launching the vehicle and when high power is required.

This system can be enhanced further by adding a gearbox to the output side of the hybrid drive unit, which transforms it into a Hydro-Mechanical-Transmission (HMT).


 More information can be found on the US EPA site; http://www.epa.gov/otaq/technology/research/how-it-works-parallel.htm

Images below identify the placement of the introduced hybrid modules into the vehicles drive line.  Note these are typical rear wheel drive longitudinal mounted engines, the green sections represent the secondary power source placement. 


1. Typical placement for OEM new vehicles

2. A non invasive hybrid systems favored by most aftermarket manufacturers

3. Typical split hybrid system, also referred to as a hydro mechanical transmission

4. This is our original end-of-line hybrid system, ideal for heavy duty applications

5. Same as number 3 above, without incorporating a gearbox

6. Front-of-engine mounting,  used as a mild hybrid system


Additional info will be added soon.

Cliff Hall