12 Hydraulic Hybrids That Go Heavy Duty

From cars and vans to excavators and garbage trucks, here’s a peek at some of the most notable hydraulic hybrid efforts from the past few years.
  • The little-known hydraulic hybrid powertrain is alive and well, and slowly making in-roads in heavy-duty vehicles.

    The technology, which uses hydraulics instead of electrical components to aid an internal combustion engine, is said to offer big efficiency benefits.   

    To be sure, though, it’s taken the hydraulic hybrid many years to find its place in the world of transportation. Within the past decade, manufacturers have placed it in pickups, buses, garbage trucks, excavators, full-sized vans, and even cars. In general, the technology fared better in heavy-duty vehicles and commercial applications.

    In the following slides, we offer photos and schematics of hydraulic hybrid powertrains. From cars and vans to excavators and garbage trucks, here’s a peek at some of the most notable hydraulic hybrid efforts from the past few years.

  • This hydraulic hybrid configuration from Lightning Systems employs five main parts: a hydraulic pump/motor; hydraulic manifold, power transfer module; and two accumulators. During operation, the system uses braking energy to power the pump, which pressurizes nitrogen gas in the accumulator. The nitrogen gas then becomes a compressed “gas spring,” providing stored energy when needed.

    When the vehicle accelerates, the gas spring releases, driving the wheels through a gearbox in the power transfer module. In this way, the hybrid system essentially stores the braking energy and reuses it to launch the vehicle, resulting in better fuel efficiency. (Image source: Lightning Systems)

  • Lightning Systems’ hydraulic hybrid powertrains are available as an option on Ford Transit and E-Series vans and chassis. Application to vans, trucks and buses is making more sense as initial costs come down, say Lightning’s executives.

    Customers, they say, will pay about $500 for each percentage point boost in fuel efficiency. “If you can give a 20% mile-per-gallon improvement, then the customer will be willing to pay about $10,000 extra for it,” noted Tim Reeser, CEO of Lightning Systems. (Image source: Ford, Lightning Systems)

  • In 2015, Parker Hannifin targeted its RunWise hydraulic hybrid technology at heavy-duty vehicles, such as garbage trucks, that need to stop and start frequently.

    The fluid power giant was outfitting trucks in Florida, Colorado, California, Texas and Washington, as well as internationally. (Image source: Parker Hannifin)

  • In 2012, Caterpillar, Inc. unveiled a hydraulic hybrid excavator. Known as the Cat 336E H, the excavator is said to use 25% less fuel than predecessors, thanks to hydraulic hybrid technology. (Image source: Caterpillar, Inc.)

  • In 2013, PSA Group announced it was working on hydraulic hybrid technology for Peugeot vehicles. The company filed for 80 patents on its Hybrid Air system, which combined hydraulic power, compressed air energy storage, and a gasoline-burning engine.

    The company said the technology would yield a 45% fuel savings in urban driving and 35% overall. Subsequent news reports said that the company put the technology on hold. (Image source: PSA Group)

  • PSA’s system combined hydraulic power, compressed air energy storage, and a gasoline-burning engine. It had three modes: gasoline power alone; air power alone (where the hydraulic motor directly sends power to the wheels); or a combination of the two. (Image source: PSA Group)

  • In 2017, Ford Motor Co. announced its Advanced Fuel Qualified Vehicle Modifier program, which includes, among others, companies that install hydraulic hybrid powertrains for Ford trucks and vans.

    Lightning Systems will serve as a third-party installer for the Ford F-350, F-450, and F-550 Super Duty trucks, and the F-650 and F-750 medium-duty trucks, as well as E-series full-sized vans. Shown is the F-350. (Image source: Ford Motor Co.)

  • Chassis layout shows where accumulators, hydraulic pump/motor, valve manifold, controller, and power transfer module are located on Ford F-450 truck. The two accumulators include a low-pressure and high-pressure unit. The low-pressure accumulator operates at between 100-300 psi; high-pressure goes up to 6,000 psi. During operation, the low-pressure unit pushes hydraulic fluid to the pump, which pressurizes it and sends it to the high-pressure side. As the high-pressure accumulator fills, it pressurizes the nitrogen gas inside it, creating a “gas spring” type of effect. The gas spring then serves as a form of stored energy, much as a battery would in an electric hybrid. Hydraulic hybrids offer a 40% increase in fuel efficiency, according to the EPA, and their components are lighter than those of battery-based hybrids. (Source: Ford Motor Co.)

  • In 2011, Altair ProductDesign unveiled what it called “the world’s first hydraulic hybrid transit bus.” In a press release, the company said it would reduce total cost of ownership by $170,000 per bus. (Image source: Altair Engineering, Inc.)

  • A few years ago, Artemis Intelligent Power Ltd. fitted its Digital Displacement Hybrid Transmission to a BMW 530i to demonstrate the capabilities of the technology.

    Artemis claimed that the hybrid system doubled the car’s miles-per-gallon efficiency in city driving. (Image source: Artemis Intelligent Power, Ltd.)

  • In Artemis’ BMW set-up, the engine never directly drives the wheels. Instead, it generates power for the hydraulics, enabling a hydraulic motor to directly drive the wheels or charge the accumulator for later use. (Image source: Artemis Intelligent Power, Ltd.)

  • In October, 2016, United Parcel Service deployed 50 hydraulic hybrid box trucks in the Chicago area, using Lightning Systems technology. (Image source: Lightning Systems)




Senior technical editor Chuck Murray has been writing about technology for 33 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and auto.


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