Wiring Diagrams and Repair Information for Tractor Starters

Published: 21st July 2010
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How to Repair a Tractor Starter.

The repair of a tractor starter can be a simple matter if the workings of the starter can be understood. This article features the typical starter. Various manufactures of starters all utilizes the same principle, and thus, the workings of the starter is similar, with the only differences is the size of the starter, the amperage used in starting, and the required voltage to operate.

Principle One: A Starter is two (2) devices connected to the other. The large cylindrical part is basically the starter. The other smaller connecting cylindrical device is called a Starter Solenoid. If these two (2) parts are understood, then the workings of the entire starter can be easily comprehended.

The larger cylindrical device is a simple electrical motor. It has an armature, which are the winding copper wires around the inner circumference of the motor body. It also has a stator, which is set of metal bars placed in a circular fashion on a shaft.

Principle Two: The way the motor moves, is that current from the battery is applied to the armature. This induces magnetism in the stator. By Flemings' Left Hand Rule, the stator will then produce a motion in one direction. This motion is what is referred to as "starting" in tractors.

Principle Three: There are two (2) sets of current that are supplied to any starter. One is a heavy gauge red live wire, and that typically is wired from the positive battery lead straight to the starter motor. However, a moving spring mechanism from the solenoid prevents it from grounding through the armature.

Principle Four: The second live red wire leads from the ignition switch straight to the solenoid. The solenoid is a piece of cylindrical magnetic metal device that has conducting copper wire wound around it. The copper windings are separate from the metal. The metal device is free to move up and down in the copper windings, but is pushed to one side by a spring device.

When energized, the solenoid moved forward rapidly. One end of the solenoid has a arm attachment that flicks a switch. This switch then connects the heavy gauge wire from the battery to the motor armature, producing the desired turning motion.

Principle Five: One end of the motor has attached to it, the starter drive gear that meshes with the engine flywheel, to turn the engine, thus, initialing the starting process.

Now that the basic understanding of the motor is understood, you are a better situation to understand how to repair a starter. When the ignition is turned, and no motion is achieved from the starter, there are several possibilities.

1.0 Check that current is being delivered to the starter thru the heavy gauge wire from the battery (and of course the battery should be fully charged), and the smaller gauge red wire from the ignition switch to the solenoid (some circuits has a relay). If there is current delivered to these two locations, then check and clean all grounding wires (typically the back or brown wires)

2.0 Assuming that point #1 is OK, and to further repair the starter, remove the starter for further investigation. With a multi meter, (or an external power source as a substitute for the battery) check that the wire windings for the solenoid is not broken. Ground one end of the solenoid to the battery and apply positive current to the other end, and the solenoid should flick. If it doesn't, then the solenoid needs to be changed as the windings are broken somewhere.

3.0 Perform the same procedure to the starter. Be careful, as large starters can be erratic when not held in place. If there is spinning of the starter when the external current is applied, then its armature and stator windings are working. If not, then the starter needs to be send to be rebuilt, as re-windings are best left to those are specialist in that field.

4.0 Sometimes these are in working order, however, the starter drive gears are broken, stuck, or the starter bearings are defective. Change as necessary.

Sometimes to save time and money, it's just best to change the starter altogether, as this is faster. A good mechanic can have a starter removed and replaced on an engine within 15-20 minutes.

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