Petrol–electric transmission (UK English) or gasoline–electric transmission or gas–electric transmission (US English) is a

transmission system In telecommunications, a transmission system is a communication system that transmits a signal from one place to another. The signal can be an signal (electrical engineering), electrical, fiber-optic communication, optical or radio wave, radio s ...

for

vehicles A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered vehicles (e.g. bicycles, tricycles, velomobiles), animal-powered tr ...

petrol engine A petrol engine (gasoline engine in American and Canadian English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends ...

s. Petrol–electric transmission was used for a variety of applications in

road A road is a thoroughfare used primarily for movement of traffic. Roads differ from streets, whose primary use is local access. They also differ from stroads, which combine the features of streets and roads. Most modern roads are paved. Th ...

, rail, and marine transport, in the early 20th century. After

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

, it was largely superseded by diesel–electric transmission, a similar transmission system used for

diesel engine The diesel engine, named after the German engineer Rudolf Diesel, is an internal combustion engine in which Combustion, ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to Mechanics, mechanical Compr ...

s; but petrol–electric has become popular again in modern

hybrid electric vehicle A hybrid electric vehicle (HEV) is a type of hybrid vehicle that couples a conventional internal combustion engine (ICE) with one or more electric engines into a hybrid vehicle drivetrain, combined propulsion system. The presence of the electri ...

s. Petrol–electric transmission was used in certain niche markets in the early 20th century, such as in the petrol–electric railway locomotives produced in Britain for use on the War Department Light Railways during

or for privately owned Arad & Csanad United Railways. In France, the Crochat petrol–electric transmission system was used for standard gauge locomotives (up to 240 kW of electrical power).

Description

Petrol–electric vehicles follow a series hybrid architecture. A

spark ignition A spark-ignition engine (SI engine) is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, ...

internal combustion (IC) engine acts as the prime mover, powering a generator which converts the rotational energy into electrical energy. The generator charges a battery pack and drives a

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, or electric multiple unit trains. Traction (engineering), Traction motors are used in electrically powe ...

that provides

tractive effort In railway engineering, the term tractive effort describes the pulling or pushing capability of a locomotive. The published tractive force value for any vehicle may be theoretical—that is, calculated from known or implied mechanical proper ...

for the vehicle to move. Hybridpeak

The engine is usually smaller than what would be required for powering a conventional petrol vehicle of the same size. The engine usually runs at its optimum high efficiency

RPM Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min−1) is a unit of rotational speed (or rotational frequency) for rotating machines. One revolution per minute is equivalent to hertz. Standards ISO 80000-3:2019 def ...

, powering the generator. When extra power is needed for acceleration or for climbing gradients, both the engine and the battery pack powers the motor. When the engine produces more power than is required at the road wheels, the surplus is used to charge the battery. Petrol–electric vehicles typically doesn't require any stepping up or transmission as electric traction motors can operate at a wide rpm range at peak efficiency. The Engine generator pair is a compact unit that isn't connected mechanically to the road wheels. The connection is purely electrical.

Advantages

* Electric traction motors are more efficient than IC engines in stop-and-go driving, typically the case in urban and suburban routes. * The IC engine can be made smaller than what is usually required to move a similar sized pure gas-powered vehicle. IC engines are their own

air pump An air pump is a pump for pushing air. Examples include a bicycle pump, pumps that are used to aerate an aquarium or a pond via an airstone; a gas compressor used to power a pneumatic tool, air horn or pipe organ; a bellows used to encoura ...

s and have poor efficiency at low speeds. So IC engines have to be made larger than what is required for conventional gas-powered vehicles. This is not the case for petrol-hybrid vehicles where an electric motor provides traction. Electric motors can deliver peak torque at a wide range of RPMs. Small engines result in a compact design and more space. * IC engines can operate at their peak RPM range throughout and improve mileage. IC engines operate at peak efficiency at higher RPMs, In petrol–electric vehicles, the engine can keep running at these speeds as the motor is the one delivering traction. This results in lesser fuel usage and harmful emissions. This isn't the case with conventional vehicles where the engine has to slow down when the vehicle brakes. * Petrol–electric vehicles have an idle-stop function where the engine can be shut off during idling or during long deceleration. *

Regenerative braking Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy or potential energy into a form that can be either used immediately or stored until needed. Typically, regenerativ ...

is possible with petrol–electric vehicles. When the brakes are applied, the traction motor can be switched to act as a generator and charge the battery pack. A magnetic resistance force acts on the wheels to slow them, while the battery is charged. Conventional brakes use frictional braking force only, which dissipate and waste rotational energy as heat. Regenerative braking saves energy, they are used in combination with friction brakes for anti lock braking (ABS). * Petrol–electric vehicles can deliver additional power when it is demanded by the driver, like during hard acceleration or climbing a gradient. They also have

automatic transmission An automatic transmission (AT) or automatic gearbox is a multi-speed transmission (mechanics), transmission used in motor vehicles that does not require any input from the driver to change forward gears under normal driving conditions. The 1904 ...

and can deliver step-less power.

Disadvantages

* Petrol–electric vehicles have many energy-conversion steps, which can result in reduced efficiency due to energy loss at each stage of the transition. * Petrol–electric vehicles, and typically most series hybrid vehicles need two electric machines, a generator coupled to the engine and a motor/generator coupled to the wheels. * They need larger electric traction motors. * Having two types of motor adds weight and complexity

Historical applications

Road

Examples of

using petrol–electric transmission include the

Tilling-Stevens Tilling-Stevens was a British manufacturer of buses and other commercial vehicles, based in Maidstone, Kent. Originally established in 1897, it became a specialist in petrol-electric vehicles. It continued as an independent manufacturer until ...

bus (UK) and the

Owen Magnetic file:1920 Owen Magnetic Touring Car ad.jpg, 1920 Owen Magnetic Touring Car ad, from ''House Beautiful'' magazine The Owen Magnetic was a pioneering American brand of Hybrid electric vehicle, hybrid electric luxury automobile manufactured between 19 ...

touring car (USA). File:1914 Tilling-Stevens double-decker bus.jpg, Tilling-Stevens petrol–electric bus File:1920 Owen Magnetic Touring Car ad.jpg, Owen Magnetic touring car 1920 advertisement File:St. Chamond.jpg, St. Chamond tank

Rail

Examples of petrol–electric rail vehicles include the North Eastern Railway 1903 Petrol Electric Autocar, Doodlebug (rail car), GE 57-ton gas–electric boxcab, Weitzer railmotor and the petrol–electric locomotives built for the War Department Light Railways by Dick, Kerr & Co. and

British Westinghouse British Westinghouse Electrical and Manufacturing Company was a subsidiary of the Pittsburgh, US-based Westinghouse Electric and Manufacturing Company. British Westinghouse would become a subsidiary of Metropolitan-Vickers in 1919; and after Metr ...

. In France, the '' Crochat-Colardeau'' system of Henry Crochat and Emmanuel Colardeau was used in some petrol–electric railcars. File:Autocar at Filey Station.jpg, North Eastern Railway Autocar at Filey Station File:Doodlebug ebt m1.jpg, Gas–electric "Doodlebug" railcar File:Dick Kerr & Co Petrol Electric Locomotive.jpg, Dick, Kerr & Co. petrol electric locomotive under construction File:AMTP 020 Crochat.jpg, Crochat petrol electric railcar preserved at Pithiviers File:Weitzer ACSEV hybrid railmotor.jpg, Weitzer railmotor produced for

ACsEV The ACsEV (Aradi és Csanádi Egyesült Vasutak, English language, En.: Arad & Csanad United Railways) were a Lands of the Crown of Saint Stephen, Hungarian joint-stock railway company. Till 1920, the network had a length of 391 Kilometre, km. ...

Marine

Most

submarines A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or info ...

that served in

were diesel–electric. However, some petrol–electric submarines had been built before the war. Examples include:

Plunger-class submarine The ''Plunger'' class was an early class of United States Navy submarines. In the first years of their service, they were used primarily as training and experimental vessels for the newly formed "silent service" to familiarize naval personnel w ...

(USA), A-class submarine (1903) (UK), SM U-1 (Austria-Hungary), Russian submarine Krab (1912). File:USS Plunger - NH 42620 - cropped.jpg, USS Plunger S2-1 File:Russian submarine Krab.jpg, Russian submarine Krab

Military vehicles

Petrol–electric systems were tested on the British Mark II tank, American Holt gas–electric tank and French Saint Chamont in 1917. The latter used the Crochat-Colardeau system of Henry Crochat and Emmanuel Colardeau. This allowed the left and right traction motors to run at different speeds for steering and is detailed in patent US1416611. The 1936 prototype Char G1P was also designed with a petrol–electric drive.

Ferdinand Porsche Ferdinand Porsche (3 September 1875 – 30 January 1951) was a German automotive engineering, automotive engineer and founder of the Porsche, Porsche AG. He is best known for creating the first Petrol engine, gasoline–Electric motor, el ...

was the main developer of these drive trains for military vehicles in

Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...

. He created the VK 3001 (P) prototype and VK 4501, of which 91 units were produced as the Porsche Tiger. They were later converted into Ferdinand, and subsequently

Elefant Elefant ( German for "elephant") was a heavy tank destroyer (self propelled anti-tank gun) used by German ''Panzerjäger'' (anti-tank units) during World War II. Ninety-one units were built in 1943 under the name Ferdinand (after its designer F ...

, tank destroyers. Another noteworthy design was the 188-tonne Porsche type 205 prototypes, commonly known as the Maus

super-heavy tank A super-heavy tank is any tank that is notably beyond the standard of the class heavy tank in either size or weight relative to contemporary vehicles. Programs have been initiated on several occasions with the aim of creating an extremely resi ...

Modern applications

In the 21st century, petrol–electric transmission has gained a new lease of life in hybrid electric vehicles. Examples include: Ford Fusion Hybrid; Honda Civic Hybrid;

Toyota Prius The is a Compact car, compact/small family car, small family liftback (supermini/subcompact sedan (car), sedan until 2003) produced by Toyota. The Prius has a Hybrid vehicle drivetrain, hybrid drivetrain, combined with an internal combustion ...

References

{{DEFAULTSORT:Petrol-electric transmission Gasoline engines Automotive transmission technologies