Rear axle with torque rod (Manual of Driving and Maintenance)

The Hotchkiss drive is a shaft drive form of

power transmission Power transmission is the movement of energy from its place of generation to a location where it is applied to perform useful work. Power is defined formally as units of energy per unit time. In SI units: :\text = \frac = \frac Since the develo ...

. It was the dominant means for

front-engine, rear-wheel drive layout In automotive design, a FR, or front-engine, rear-wheel-drive layout is one where the Internal combustion engine, engine is Front-engine design, located at the front of the vehicle and rear-wheel-drive, driven wheels are located at the rear via a ...

cars A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded as t ...

in the 20th century. The name comes from the French automobile manufacturer Hotchkiss, although other makers, such as

Peerless Peerless may refer to: Companies and organizations * Peerless Motor Company, an American automobile manufacturer. * Peerless Brewing Company, in Birkenhead, UK * Peerless Group, an insurance and financial services company in India * Peerless R ...

, used similar systems before Hotchkiss. During the early part of the 20th century chain-drive power transmission was the main direct drive competitor of the Hotchkiss system, with the

torque tube A torque tube system is a power transmission and braking technology that involves a stationary housing around the drive shaft, often used in automobiles with a front engine and rear drive. The torque tube consists of a large diameter stationary h ...

also popular until the 1950s. Leaf spring, showing torque reaction effects (Manual of Driving and Maintenance)

Most shaft-drive systems consist of a

drive shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power and torque and rotation, usually ...

(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 the axle housing is firmly attached to the leaf springs to transfer the axle torque through them to the car body. Also, it uses

universal joint A universal joint (also called a universal coupling or U-joint) is a joint or coupling connecting rigid shafts whose axes are inclined to each other. It is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges lo ...

s 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 contrast, a

arrangement uses only a single universal at the end of the transmission tailshaft, typically a

constant velocity joint Constant-velocity joints (also known as homokinetic or CV joints) are mechanical joints which allow a drive shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play. They ...

, and the axle housing is held fast by the torque tube, which anchors the differential housing to the transmission. 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 spring A leaf spring is a simple form of spring commonly used for the suspension in wheeled vehicles. Originally called a ''laminated'' or ''carriage spring'', and sometimes referred to as a semi-elliptical spring, elliptical spring, or cart spring, it ...

s. 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, when combined with rear coil springs (1938-62 Buick), requires additional locating elements, such as a

Panhard rod A Panhard rod (also called Panhard bar, track bar, or track rod) is a suspension link that provides lateral location of the axle. Originally invented by the Panhard automobile company of France in the early twentieth century, this device has been ...

, this is not needed with a torque tube/leaf spring combination (1906-1937 Buick, early Ford, etc.). Some Hotchkiss driveshafts are made in two pieces with another universal joint in the center for greater flexibility, typically in

truck A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...

s and specialty vehicles built on firetruck frames. Some installations use

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...

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.Toyota 1984-1987 RWD Corolla mechanical service manual This design was the main form of power transmission for most cars from the 1920s through the 1970s. As of 2016 it remains common in

pick-up truck A pickup truck or pickup is a light-duty truck that has an enclosed cabin, and a back end made up of a cargo bed that is enclosed by three low walls with no roof (this cargo bed back end sometimes consists of a tailgate and removable covering) ...

s, and

sport utility vehicle A sport utility vehicle (SUV) is a car classification that combines elements of road-going passenger cars with features from off-road vehicles, such as raised ground clearance and four-wheel drive. There is no commonly agreed-upon definitio ...

s. Just as important as power transmission is braking. In power transmission, the torque applied to the wheels is countered by an equal and opposite reaction in the axle housing, but in braking, the torque of braking the wheels is equal but in the same direction. In a rear wheel drive car, the braking applied by the rear brakes is just as important as the power transmission, and the problem is the same and is solved in the same manner. Firmly anchoring the axle housing to the leaf springs transfers both directions of torque, (both acceleration and braking), to the car body. There is no connection between the Hotchkiss drive and the modern US suspension-modification company called Hotchkis.

References

Automobile Engineering: A General Reference Work
{{DEFAULTSORT:Hotchkiss Drive Automotive transmission technologies Hotchkiss et Cie Shaft drives