Editing Starter (engine) (section)

==Electric==
[[File:Automobile starter 2.JPG|right|thumb|{{Ordered list
|Main housing (yoke)
|[[Freewheel]] and [[pinion]] gear assembly
|[[Armature (electrical engineering)|Armature]]
|[[Field coils]] with [[Brush (electric)|brushes]] attached
|[[Brush (electric)|Brush-carrier]]
|[[Starter solenoid|Solenoid]]
}}]]
[[File:Starter motor diagram.png|thumb|350px|right|Starter motor diagram]]

The electric '''starter motor''' or '''cranking 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 and parallel circuits|series]]-parallel wound [[direct current]] [[electric motor]] with a [[starter solenoid]] (similar to a [[relay]]) mounted on it. When DC power from the [[lead–acid battery|starting battery]] is applied to the solenoid, usually through a [[Key (lock)|key]]-operated switch (the "ignition 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.<ref>{{cite news |last1=R. Howell |first1=Benito |title=Permanent Magnet Generators for Diesel Engines |url=http://www.pmgenerators.com/products/diesel-generators/dc-generator/ |access-date=14 January 2021 |agency=PM Generators|date=17 August 2017}}</ref>

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.

The sprag clutch arrangement would preclude the use of the starter as a generator if employed in the hybrid scheme mentioned above, unless modifications were made. The standard starter motor is typically designed for intermittent use, which would preclude its use as a generator. The starter's electrical components are designed only to operate for typically under 30 seconds before overheating (by too-slow dissipation of heat from [[Joule heating|ohmic losses]]), to save weight and cost. Most automobile owner 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 shaft. 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.<ref>{{cite journal|url= https://books.google.com/books?id=XNwDAAAAMBAJ&pg=PA186 |title=Know Your Car's Nervous System - Starters |journal=Popular Mechanics |date=June 1952 |pages=186–189 |volume=96 |issue=6 |access-date=25 May 2015}}</ref>  This has the disadvantage that the gears will disengage if the engine fires briefly but does not continue to run.

{{Listen
 |filename = Prestolite DD FT 225.ogg
 |description = A starter motor with Bendix Folo-Thru drive cranks a [[Chrysler Slant-6 engine]]. The Folo-Thru drive pinion stays engaged through a cylinder firing but not causing the engine to start
 |type = sound
 |pos = right
 |title= Hear a Folo-Thru starter
}}

===Folo-Thru drive===
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.

===Gear reduction===
{{Listen
 |filename = Chry_1.5OSGR_Starter.ogg
 |description = A Chrysler gear-reduction starter cranks a V8 engine
 |type = sound
 |pos = right
 |title= Hear a gear-reduction starter
}}

In 1962, [[Chrysler]] introduced a starter incorporating a [[gear]]train between the motor and the drive shaft. The motor shaft included integrally cut gear teeth forming a pinion that meshes with a larger adjacent driven gear to provide a [[gear reduction]] ratio of 3.75:1. This permitted the use of a higher-speed, lower-current, lighter and more compact motor assembly while increasing cranking torque.<ref>{{citation|title=The 1962 Starting Motor and Alternator |publisher=Chrysler Corporation |date=November 1961}}</ref> Variants of this starter design were used on most rear- and four-wheel-drive vehicles produced by Chrysler Corporation from 1962 through 1987. It makes a unique, distinct sound when cranking the engine, which led to it being nicknamed the "Highland Park Hummingbird"—a reference to Chrysler's headquarters in [[Highland Park, Michigan]].<ref>{{cite journal |title=Memorable Mirada |journal=Hemmings Classic Car |date=June 2007 |first=David |last=LaChance |url= http://www.hemmings.com/hcc/stories/2007/06/01/hmn_feature7.html |quote=...the twitterings of the Highland Park hummingbird, Mopar's famous gear-reduction starter... |access-date=25 May 2015}}</ref>

The Chrysler gear-reduction starter formed the conceptual basis for the gear-reduction starters that now predominate in vehicles on the road. Many Japanese automakers phased in gear reduction starters in the 1970s and 1980s.{{Citation needed|date=November 2011}} Light aircraft engines also made extensive use of this kind of starter, because its light weight offered an advantage.

Those starters not employing offset gear trains like the Chrysler unit generally employ planetary [[epicyclic gearing|epicyclic gear trains]] instead. Direct-drive starters are almost entirely obsolete owing to their larger size, heavier weight and higher current requirements.{{Citation needed|date=November 2011}}

===Movable pole shoe===
[[Ford Motor Company|Ford]] issued a nonstandard starter, a direct-drive "movable [[pole shoe]]" design that provided cost reduction rather than electrical or mechanical benefits. This type of starter eliminated the solenoid, replacing it with a movable pole shoe and a separate starter relay. This starter operates as follows: The driver turns the key, activating the starter switch. A small electric current flows through the solenoid actuated starter [[relay]], closing the contacts and sending large battery current to the starter motor. One of the pole shoes, hinged at the front, linked to the starter drive, and spring-loaded away from its normal operating position, is swung into position by the magnetic field created by electricity flowing through its field coil. This moves the starter drive forward to engage the flywheel ring gear, and simultaneously closes a pair of contacts supplying current to the rest of the starter motor winding. Once the engine starts and the driver releases the starter switch, a spring retracts the pole shoe, which pulls the starter drive out of engagement with the ring gear.

This starter was used on Ford vehicles from 1973 through 1990, when a gear-reduction unit conceptually similar to the Chrysler unit replaced it.

===Inertia starter===
{{unreferenced section|date=July 2018}}
A variant on the electric starter motor is the inertia starter (not to be confused with the Bendix-type starter described above). Here the starter motor does not turn the engine directly. Instead, when energized, the motor turns a heavy [[flywheel]] built into its casing (not the main flywheel of the engine). Once the flywheel/motor unit has reached a constant speed the current to the motor is turned off and the drive between the motor and flywheel is disengaged by a freewheel mechanism. The spinning flywheel is then connected to the main engine and its inertia turns it over to start it. These stages are commonly automated by [[solenoid]] switches, with the machine operator using a two-position control switch, which is held in one position to spin the motor and then moved to the other to cut the current to the motor and engage the flywheel to the engine.

The advantage of the inertia starter is that, because the motor is not driving the engine directly, it can be of much lower power than the standard starter for an engine of the same size. This allows for a motor of much lower weight and smaller size, as well as lighter cables and smaller batteries to power the motor. This made the inertia starter a common choice for aircraft with large [[radial engine|radial]] piston engines. The disadvantage is the increased time required to start the engine - spinning up the flywheel to the required speed can take between 10 and 20 seconds. If the engine does not start by the time the flywheel has lost its inertia then the process must be repeated for the next attempt.