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(R) Connections for Fluid Power and General Use - Hydraulic Couplings - Diagnostic

2nd Edition, May 1, 2013

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Product Details:

  • Revision: 2nd Edition, May 1, 2013
  • Published Date: September 1, 1996
  • Status: Active, Most Current
  • Document Language: English
  • Published By: SAE International (SAE)
  • Page Count: 642
  • ANSI Approved: No
  • DoD Adopted: No

Description / Abstract:

Introduction and History

The automobile, or horseless carriage, as it was originally known, appeared at the end of the 19th Century, approximately one hundred years ago, a direct consequence of the availability of suitable internal-combustion engines.

The design of automobiles evolved from that of the horse-drawn carriage, itself the culmination of several thousand years of slow evolution from early carts and chariots. At the time of arrival of the automobile, carriages already had suspension systems, very desirable in view of the poor roads at the time. There was therefore already a body of knowledge regarding ride quality and suspension systems. However, virtually no published material existed concerning investigation of handling qualities.

It is interesting to speculate what sort of concept of handling the earliest chariot engineers may have had. Perhaps the most obvious requirement of a high-performance chariot is a small mass. Certainly, the importance of this was appreciated at least 2000 years ago. The wheels were so light that they were removed when not in use (e.g., overnight) to obviate eccentricity and lack of roundness due to creep.

Early carts had steering in which the entire front axle pivoted about a vertical central pivot. Lightweight chariots were two-wheeled, so yawing could be achieved by relative rotation of the wheels, and the need for steering as such did not arise. The traditional horse-drawn carriage of the 18th and 19th Centuries had rigid axles front and rear; steering of the complete front axle about its central pivot naturally left the wheels perpendicular to radii from a notional center of the path arc. However, steering by movement of the complete axle was inconvenient, requiring large clearance around the wheels, so steering by pivoting the wheels separately on stub axles was introduced. In 1816 Georges Langensperger stated the geometric condition required for stub-axle steering to maintain the wheels perpendicular to their arc of motion. Such an arrangement was highly desirable to minimize friction at the wheels during low-speed maneuvering on small radii. This is still the case, although conditions are different at higher speeds. Ackermann recognized the importance of this invention; by agreement with Langensperger, acting as his agent in London, he took out British patents in 1817, and hence this arrangement is widely known as Ackermann steering. Some sixty years later, Amadée Bollée, in designs of 1873 and 1878, achieved a similar effect, possibly independently. From 1878 to 1881 Jeantaud arrived at the same arrangement, and performed some more scientific assessments. As a result, Langensperger's principle is known in France as the Jeantaud diagram. In 1893 Benz was granted a German patent for another arrangement, similar to Bollée's later type. By the time of the introduction of the automobile, then, stub axle steering was well established, and cars adopted this system from the beginning.

AIA/NAS Aerospace Standards