General Information

Serial #

N/A

Part Number

1

Total Parts

2

AKA

N/A

Patents

N/A

General Description

Unknown

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

N/A

Width

N/A

Height

N/A

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Motorized Ground Transportation

Category

Automotive parts

Sub-Category

N/A

Manufacturer

AKA

OLDSMOBILE

Country

Unknown

State/Province

Unknown

City

Unknown

Context

Country

Unknown

State/Province

Unknown

Period

Unknown

Canada

Unknown

Function

A device that indicates the speed an automobile is traveling in miles per hour, kilometers per hour, or both (Harris, "How Speedometers Work").

Technical

In 1902, Otto Schulze filed the first patent for the mechanical speedometer, also known as eddy-current speedometer. At the turn of the 20th century, automobiles became more popular and faster, resulting in more accidents. Mechanical speedometers became an essential dashboard instrument to enforce early speed limits and to prevent accidents because they allowed motorists to see and adjust how fast they were traveling. Speedometers are a standard feature in contemporary vehicles and the first electrical speedometer emerged in 1993 (Harris, "How Speedometers Work"). A mechanical speedometer measures speed using a drive cable; one end is attached to gears in the automobile's transmission, while the other end is attached to a permanent magnet, which rests inside a speedcup within the speedometer assembly. The speedcup is attached to the needle, which is held in place by a hairspring; the needle is visible in the cockpit along with the face of the speedometer, which displays a range of numbers from zero to an upper limit that can vary by make and model (Harris, "How Speedometers Work"). As the automobile moves, the magnet spins at a rate consistent to the speed of the vehicle, rotating the drive cable. A rotating magnetic field is created as the magnet spins and these forces affect the speedcup, causing an electrical current to flow into the cup in small rotating eddies, called eddy currents. A drag torque is created from the eddy currents that affect the speedcup. Since the cup and the needle are attached, they turn in the same direction as the magnetic field but only as far as the hairspring will allow. The force created by the revolving magnet is balanced by the opposing force of the hairspring, allowing the needle to rest on the face of the speedometer to indicate the current speed of the vehicle (Harris, "How Speedometers Work").

Area Notes

Unknown

Details

Markings

Numbers on face of speedometer start from 0 – 200 and increases in increments of 10; text on the back of the frame: “Made in U.S.A.” (Supp.Info)

Missing

4 buttons on the back of heater on the right side; missing screws on the top right and left sides (Supp. Info.

Finish

Unknown

Decoration

N/A