Starter (engine) - Electric

Electric

The electric starter motor or starting motor is the most common type used on gasoline engines and small Diesel engines. The modern starter motor is either a permanent-magnet or a series-parallel wound direct current electric motor with a starter solenoid (similar to a relay) mounted on it. When current from the starting battery is applied to the solenoid, usually through a key-operated switch, the solenoid engages a lever that pushes out the drive pinion on the starter driveshaft and meshes the pinion with the starter ring gear on the flywheel of the engine.

The solenoid also closes high-current contacts for the starter motor, which begins to turn. Once the engine starts, the key-operated switch is opened, a spring in the solenoid assembly pulls the pinion gear away from the ring gear, and the starter motor stops. The starter's pinion is clutched to its drive shaft through an overrunning sprag clutch which permits the pinion to transmit drive in only one direction. In this manner, drive is transmitted through the pinion to the flywheel ring gear, but if the pinion remains engaged (as for example because the operator fails to release the key as soon as the engine starts, or if there is a short and the solenoid remains engaged), the pinion will spin independently of its drive shaft. This prevents the engine driving the starter, for such backdrive would cause the starter to spin so fast as to fly apart. However, this sprag clutch arrangement would preclude the use of the starter as a generator if employed in hybrid scheme mentioned above, unless modifications were made. Also, a standard starter motor is only designed for intermittent use which would preclude its use as a generator; the electrical components are designed only to operate for typically under 30 seconds before overheating (by too-slow dissipation of heat from ohmic losses), to save weight and cost. This is the same reason why most automobile owner's manuals instruct the operator to pause for at least ten seconds after each ten or fifteen seconds of cranking the engine, when trying to start an engine that does not start immediately.

This overrunning-clutch pinion arrangement was phased into use beginning in the early 1960s; before that time, a Bendix drive was used. The Bendix system places the starter drive pinion on a helically cut drive haft. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to ride forward on the helix and thus engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back down the helical shaft and thus out of mesh with the ring gear.

An intermediate development between the Bendix drive developed in the 1930s and the overrunning-clutch designs introduced in the 1960s was the Bendix Folo-Thru drive. The standard Bendix drive would disengage from the ring gear as soon as the engine fired, even if it did not continue to run. The Folo-Thru drive contains a latching mechanism and a set of flyweights in the body of the drive unit. When the starter motor begins turning and the drive unit is forced forward on the helical shaft by inertia, it is latched into the engaged position. Only once the drive unit is spun at a speed higher than that attained by the starter motor itself (i.e., it is backdriven by the running engine) will the flyweights pull radially outward, releasing the latch and permitting the overdriven drive unit to be spun out of engagement. In this manner, unwanted starter disengagement is avoided before a successful engine start.

Read more about this topic:  Starter (engine)

Other articles related to "electric":

Folk Rock - Subgenres - Electric Folk
... Electric folk (aka British folk rock) is the name given to the form of folk rock pioneered in Britain during the late 1960s by the bands Sweeney's Men, Fairport Convention, and Pentangle ... of traditional British folk music influences gives electric folk its distinctly British character and flavour ... Electric folk was at its most significant and popular during the late 1960s and 1970s, when, in addition to Fairport and Pentangle, it was also taken ...
Index Of Engineering Articles - E
... Earthquake engineering -- Elasticity -- Electric charge -- Electric current -- Electric field -- Electric motor -- Electric potential -- Electrical ...
East Lancashire Railway - Locomotives - Electric
... Electric Multiple Units BR Class 504 unit 65451+77172 (stored at Buckley Wells, being restored as hauled coaching stock) ...
USS Flier (SS-250)
... Career Builder Electric Boat Company, Groton, Connecticut Laid down 30 October 1942 Launched 11 July 1943 Sponsored by Mrs ... Balabac Strait, 13 August 1944 General characteristics Class type Gato-class diesel-electric submarine Displacement 1,525 long tons (1,549 t) surfaced 2,424 long tons (2,463 t) submerged Length ... Her keel was laid down 30 October 1942 by Electric Boat Company of Groton, Connecticut ...
Gaston (comics) - Props, Inventions and Other Running Gags - Other Inventions
... duffle coat A rotating Christmas tree A pneumatic ashtray An electric scarecrow A folding bicycle A remote-controlled electric iron A mini-lawnmower (to ...

Famous quotes containing the word electric:

    Remember dancing in
    those electric shoes?
    Remember?
    Remember music
    and beware.
    Anne Sexton (1928–1974)

    The family circle has widened. The worldpool of information fathered by the electric media—movies, Telstar, flight—far surpasses any possible influence mom and dad can now bring to bear. Character no longer is shaped by only two earnest, fumbling experts. Now all the world’s a sage.
    Marshall McLuhan (1911–1980)

    Persons grouped around a fire or candle for warmth or light are less able to pursue independent thoughts, or even tasks, than people supplied with electric light. In the same way, the social and educational patterns latent in automation are those of self- employment and artistic autonomy.
    Marshall McLuhan (1911–1980)