The Hotchkiss drive is a system of power transmission. It was the dominant form of power transmission for front-engine, rear-wheel drive layout cars in the 20th century. The name comes from the French automobile firm of Hotchkiss, although it is clear that other makers (such as Peerless) used similar systems before Hotchkiss.

During the early part of the 20th century the two major competing systems of power transmission were the shaft-drive and chain-drive configurations. The Hotchkiss drive is a shaft-drive system (another type of direct-drive transmission system is the torque tube, which was also popular until the 1950s).

All shaft-drive systems consist of a driveshaft (also called a "propeller shaft" or Cardan shaft) extending from the transmission in front to the differential in the rear. The differentiating characteristic of the Hotchkiss drive is the fact that it uses universal joints at both ends of the driveshaft, which is not enclosed. The use of two universal joints, properly phased and with parallel alignment of the drive and driven shafts, allows the use of simple cross-type universals. (In a torque-tube arrangement only a single universal is used at the end of the transmission tailshaft, and this universal should be a constant velocity joint.) In the Hotchkiss drive, slip-splines or a plunge-type (ball and trunnion u-joint) eliminate thrust transmitted back up the driveshaft from the axle, allowing simple rear-axle positioning using parallel leaf springs. (In the torque-tube type this thrust is taken by the torque tube to the transmission and thence to the transmission and motor mounts to the frame. While the torque-tube type requires additional locating elements, such as a Panhard rod, this allows the use of coil springs.)

Some Hotchkiss driveshafts are made in two pieces with another universal joint in the center for greater flexibility, typically in trucks and specialty vehicles built on truck frames. Some installations use rubber mounts to isolate noise and vibration. The 1984–1987 RWD Toyota Corolla (i.e., Corolla SR5 and GT-S) coupe is another example of a car that uses a 2-part Hotchkiss driveshaft with a rubber-mounted center bearing.

This design was the main form of power transmission for most cars from the 1920s through the 1970s. Presently (circa 2012), it remains common in pick-up trucks, sport utility vehicles, and vehicles intended to have better than poor performance.

Note that there is no connection between Hotchkiss drive and the modern suspension-modification company of a similar name (Hotchkis).

A torque tube system is a driveshaft technology, often used in automobiles with a front engine and rear drive. It is not as widespread as the Hotchkiss drive, but is still occasionally used to this day. Driveshafts are sometimes also used for other vehicles and machinery.

 Construction

The "torque" that is referred to in the name is not that of the driveshaft, along the axis of the car, but that applied by the wheels. The design problem that the torque tube solves is how to get the traction forces generated by the wheels to the car frame. The "torque tube" transmits this force by directly coupling the axle differential to the transmission and therefore propels the car forward by pushing on the engine/transmission and then through the engine mounts to the car frame

In contrast, the Hotchkiss drive has the traction forces transmitted to the car frame by using other suspension components such as leaf springs or trailing arms. A ball and socket type of joint called a "torque ball" is used at one end of the torque tube to allow relative motion between the axle and transmission due to suspension travel. Since the torque tube does not constrain the axle in the lateral (side-to-side) direction a panhard rod is often used for this purpose. The combination of the panhard rod and the torque tube allows the easy implementation of soft coil springs in the rear to give good ride quality

In addition to transmitting the traction forces, the torque tube is hollow and contains the rotating driveshaft. Inside the hollow torque ball is the universal joint of the driveshaft that allows relative motion between the two ends of the driveshaft. In most applications the drive shaft uses a single universal joint which has the disadvantage that it causes speed fluctuations in the driveshaft when the shaft is not straight. The Hotchkiss drive uses two universal joints which has the effect of canceling the speed fluctuations and gives a constant speed even when the shaft is no longer straight

Application

Examples of the torque tube were the American cars of the Ford brand up through 1948, which used the less expensive transverse springs that could not take the thrus

Buick started using coil springs in the 1930s, as did Nash's 1941 '600' model; these also necessitated using a torque tube. American Motors (AMC) also continued to use a coil spring rear suspension design with a torque tube on their large-sized cars (Rambler Classic and Ambassador) through the 1966 model year. The 1961-1963 Pontiac Tempest incorporated an unusual curved “torque-tube” with a 4-inch drop (about 10 centimeters) that housed a 3/4 inch (2 cm) solid steel driveshaft (nicknamed the "rope shaft") without universal joints on each end. The main purpose was to make the floor lower, thus increasing the car's interior room. The Peugeot 504, Peugeot 505, (except estate/station wagons) and the Volvo 300 Series also used a torque tube.

The torque tube driveline is also used in Sprintcars and Midget cars. The C5 and C6 Chevrolet Corvette, Lexus LF-A, Porsche 924, Porsche 928, Porsche 944, Aston Martin DBR9, Aston Martin DBS, Aston Martin DB7, Maserati Quattroporte V, Maserati GranTurismo and the Mercedes-Benz SLS AMG also use variations on this design, mostly with rear-mounted transaxles.

The Czech made Tatra truck is the only full size truck using a torque tube and independent suspension on all wheels.

A drive shaft, driveshaft, driving shaft, propeller shaft (prop shaft), or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement between them.

Drive shafts are carriers of torque: they are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress, whilst avoiding too much additional weight as that would in turn increase their inertia.

To allow for variations in the alignment and distance between the driving and driven components, drive shafts frequently incorporate one or more universal joints, jaw couplings, or rag joints, and sometimes a splined joint or prismatic joint.

History

The term drive shaft first appeared during the mid 19th century. In Storer's 1861 patent reissue for a planing and matching machine, the term is used to refer to the belt-driven shaft by which the machine is driven. The term is not used in his original patent. Another early use of the term occurs in the 1861 patent reissue for the Watkins and Bryson horse-drawn mowing machine.Here, the term refers to the shaft transmitting power from the machine's wheels to the gear train that works the cutting mechanism.

In the 1890s, the term began to be used in a manner closer to the modern sense. In 1891, for example, Battles referred to the shaft between the transmission and driving trucks of his Climax locomotive as the drive shaft, and Stillman referred to the shaft linking the crankshaft to the rear axle of his shaft-driven bicycle as a drive shaft.In 1899, Bukey used the term to describe the shaft transmitting power from the wheel to the driven machinery by a universal joint in his Horse-Power. In the same year, Clark described his Marine Velocipede using the term to refer to the gear-driven shaft transmitting power through a universal joint to the propeller shaft. Crompton used the term to refer to the shaft between the transmission of his steam-powered Motor Vehicle of 1903 and the driven axle.

Automotive drive shafts

 Vehicles

An automobile may use a longitudinal shaft to deliver power from an engine/transmission to the other end of the vehicle before it goes to the wheels. A pair of short drive shafts is commonly used to send power from a central differential, transmission, or transaxle to the wheels.

Front-engine, rear-wheel drive

In front-engined, rear-drive vehicles, a longer drive shaft is also required to send power the length of the vehicle. Two forms dominate: The torque tube with a single universal joint and the more common Hotchkiss drive with two or more joints. This system became known as Système Panhard after the automobile company Panhard et Levassor patented it.

Most of these vehicles have a clutch and gearbox (or transmission) mounted directly on the engine with a drive shaft leading to a final drive in the rear axle. When the vehicle is stationary, the drive shaft does not rotate. A few, mostly sports, cars seeking improved weight balance between front and rear, and most commonly Alfa Romeos or Porsche 924s, have instead used a rear-mounted transaxle. This places the clutch and transmission at the rear of the car and the drive shaft between them and the engine. In this case the drive shaft rotates continuously as long as the engine does, even when the car is stationary and out of gear.

Early automobiles often used chain drive or belt drive mechanisms rather than a drive shaft. Some used electrical generators and motors to transmit power to the wheels.

Front-wheel drive

In British English, the term "drive shaft" is restricted to a transverse shaft that transmits power to the wheels, especially the front wheels. A drive shaft connecting the gearbox to a rear differential is called a propeller shaft, or prop-shaft. A prop-shaft assembly consists of a propeller shaft, a slip joint and one or more universal joints. Where the engine and axles are separated from each other, as on four-wheel drive and rear-wheel drive vehicles, it is the propeller shaft that serves to transmit the drive force generated by the engine to the axles.

A drive shaft connecting a rear differential to a rear wheel may be called a half shaft. The name derives from the fact that two such shafts are required to form one rear axle.

Several different types of drive shaft are used in the automotive industry:

• One-piece drive shaft
• Two-piece drive shaft
• Slip-in-tube drive shaft

The slip-in-tube drive shaft is a new type that also helps in crash energy management. It can be compressed in the event of a crash, so is also known as a collapsible drive shaft.

 Four wheel and all-wheel drive

These evolved from the front-engine rear-wheel drive layout. A new form of transmission called the transfer case was placed between transmission and final drives in both axles. This split the drive to the two axles and may also have included reduction gears, a dog clutch or differential. At least two drive shafts were used, one from the transfer case to each axle. In some larger vehicles, the transfer box was centrally mounted and was itself driven by a short drive shaft. In vehicles the size of a Land Rover, the drive shaft to the front axle is noticeably shorter and more steeply articulated than the rear shaft, making it a more difficult engineering problem to build a reliable drive shaft, and which may involve a more sophisticated form of universal joint.

Modern light cars with all-wheel drive (notably Audi or the Fiat Panda) may use a system that more closely resembles a front-wheel drive layout. The transmission and final drive for the front axle are combined into one housing alongside the engine, and a single drive shaft runs the length of the car to the rear axle. This is a favoured design where the torque is biased to the front wheels to give car-like handling, or where the maker wishes to produce both four-wheel drive and front-wheel drive cars with many shared components.

Drive shaft for Research and Development (R&D)

The automotive industry also uses drive shafts at testing plants. At an engine test stand a drive shaft is used to transfer a certain speed / torque from the Internal combustion engine to a dynamometer. A "shaft guard" is used at a shaft connection to protect against contact with the drive shaft and for detection of a shaft failure. At a transmission test stand a drive shaft connects the prime mover with the transmission.

In the automotive field, a transaxle is a major mechanical component that combines the functionality of the transmission, the differential, and associated components of the driven axle into one integrated assembly.

Transaxles are near universal in all automobile configurations that have the engine placed at the same end of the car as the driven wheels: the front-engine, front-wheel drive layout, rear-engine, rear-wheel drive layout and rear mid-engine, rear-wheel drive layout arrangements.

Many mid- and rear-engined vehicles use a transverse engine and transaxle, similar to a front wheel drive unit. Others use a longitudinal engine and transaxle like Ferrari's 1989 Mondial t which used a "t" arrangement with a longitudinal engine connected to a transverse transaxle, a design the company continues to this day. Front-wheel drive versions of modern Audis, from the A4 upwards, along with their related marques from the Volkswagen Group (which share the same automobile layout) also use a similar layout, but with the transaxle also mounted longitudinally.

 Front-engine, rear-wheel drive transaxles

Front-engine, rear-wheel drive vehicles tend to have the transmission up front just after the engine, but sometimes a front engine drives a rear-mounted transaxle. This is generally done for reasons of weight distribution, and is therefore common on sports cars. Another advantage is that as the driveshaft spins at engine speed it only has to endure the torque of the engine, instead of that torque multiplied by the 1st gear ratio. This design was pioneered in the 1934 Škoda Popular, and then in the 1950 Lancia Aurelia, designed by the legendary Vittorio Jano.

Since this placement of the gearbox is unsuitable for a live axle (due to excessive unsprung weight), the rear suspension is either independent, or uses a de Dion tube (notably in the Alfa Romeos). Rare exceptions to this rule were the Bugatti T46 and T50 which had a three speed gearbox on a live axle.

The Nissan GT-R is unique in that it uses a rear transaxle with an AWD layout, the transaxle in this case also contains the differential sending power back to the front wheels via a separate driveshaft.

Notable Front-engine, rear-wheel drive layout vehicles with a transaxle design include:

• 1898-1910 De Dion Bouton
• 1914–1939 Stutz Bearcat
• 1929–1936 Bugatti Type 46
• 1934–1944 Škoda Popular and Škoda Rapid
• 1950–1958 Lancia Aurelia
• 1951–1956 Pegaso Z-102
• 1957–1970 Lancia Flaminia
• 1961–1963 Pontiac Tempest
• 1964–1968 Ferrari 275
• 1963-1968 Ferrari 330
• 1968–1973 Ferrari Daytona
• 1972–1987 Alfa Romeo Alfetta
• 1974–1987 Alfa Romeo GTV/Alfa Romeo GTV6
• 1976–1988 Porsche 924
• 1976–1991 Volvo 300 series
• 1977–1985 Alfa Romeo Giulietta
• 1978–1995 Porsche 928
• 1982–1995 Porsche 944 and Porsche 968
• 1984–1987 Alfa Romeo 90
• 1985–1992 Alfa Romeo 75
• 1989–1991 Alfa Romeo SZ
• 1992–2003 Ferrari 456
• 1996–2005 Ferrari 550/575M
• 1997–up Chevrolet Corvette
• 1997–1999 Panoz Esperante GTR-1
• 1997-2002 Plymouth Prowler
• 1998-2005 Shelby Series 1
• 2003-2006 Chevrolet SSR
• 2003–on Aston Martin DB9
• 2004-2009 Cadillac XLR
• 2004–on Ferrari 612 Scaglietti
• 2004–on Maserati Quattroporte
• 2005–up Aston Martin V8 Vantage
• 2006–up Ferrari 599 GTB Fiorano
• 2008-up Alfa Romeo 8C Competizione
• 2009–up Lexus LF-A
• 2010-up Mercedes-Benz SLS AMG

 Rear-engine, rear-wheel drive transaxles

Volkswagen and later Porsche made extensive use of transaxles in their rear (and mid) engined vehicles, including:

• 1938–2003 Volkswagen Beetle
• 1940–1945 Volkswagen Kubelwagen (Type 82)
• 1941–1944 Volkswagen Schwimmwagen (Type 166)
• 1948–1965 Porsche 356
• 1950–present Volkswagen Type 2
• 1955–1974 Volkswagen Karmann Ghia
• 1961–1973 Volkswagen Type 3
• 1963–present Porsche 911
• 1965–1969, 1976 Porsche 912
• 1967–1969 Alfa Romeo 33 Stradale (mid-engined)
• 1968–1974 Volkswagen Type 4
• 1969–1976 Porsche 914 (mid-engined)
• 1975–1989 Porsche 930

 Four-wheel drive

All Audi cars with longitudinal engines and their 'trademark' quattro four-wheel drive (4WD) system, along with their related marques from the Volkswagen Group which share the same layout, utilise a transaxle. This is mounted immediately behind the front-mounted engine (again, longitudinally) and contains the 'gearbox' (manual, automatic, DSG, or CVT), along with both the centre differential, and the front differential and final drive unit.

Other 4WD applications include:

• 1984–1986 Ford RS200 – mid-engined, with the gearbox in the front;
• 2007–on Nissan GT-R – front-engined, with the gearbox in the rear.