Rear chassis, possibly of a Napier,with torque reaction taken by a longgirder alongside the jointed driveshaft

Torque reaction effects on a leafspring in a Hotchkiss drive system

Hotchkiss driveFrom Wikipedia, the free encyclopedia

The Hotchkiss drive is a system of power transmission. It was the dominant form of power transmission forfront­engine, rear­wheel drive layout cars in the 20th century. The name comes from the French automobile firmof 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 shaft­drive and chain­drive configurations. The Hotchkiss drive is a shaft­drive system (another type of direct­drivetransmission system is the torque tube, which was also popular until the 1950s).

All shaft­drive systems consist of a driveshaft (also called a "propeller shaft" or Cardan shaft) extending from thetransmission in front to the differential in the rear. The differentiating characteristic of the Hotchkiss drive is thefact that it uses universal joints at both ends of the driveshaft, which is not enclosed. The use of two universaljoints, properly phased and with parallel alignment of the drive and driven shafts, allows the use of simple cross­type universals. (In a torque­tube arrangement only a single universal is used at the end of the transmissiontailshaft, and this universal should be a constant velocity joint.) In the Hotchkiss drive, slip­splines or a plunge­type (ball and trunnion u­joint) eliminate thrust transmitted back up the driveshaft from the axle, allowing simplerear­axle positioning using parallel leaf springs. (In the torque­tube type this thrust is taken by the torque tube tothe transmission and thence to the transmission and motor mounts to the frame. While the torque­tube typerequires 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 greaterflexibility, typically in trucks and specialty vehicles built on truck frames. Some installations use rubber mountsto isolate noise and vibration. The 1984–1987 RWD Toyota Corolla (i.e., Corolla SR5 and GT­S) coupe isanother example of a car that uses a 2­part Hotchkiss driveshaft with a rubber­mounted center bearing.[1]

This design was the main form of power transmission for most cars from the 1920s through the 1970s. Presently (circa 2012), it remains common inpick­up trucks, and sport utility vehicles.

There is no connection between The Hotchkiss drive and the modern suspension­modification company Hotchkis.

References

1. Toyota 1984­1987 RWD Corolla mechanical service manual

Automobile Engineering: A General Reference Work (http://books.google.com/books?id=­7M3AAAAMAAJ&pg=RA2­PA515&dq=%22Hotchkiss+drive%22&as_brr=1&ie=ISO­8859­1)

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Categories: Automotive transmission technologies Hotchkiss

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