Starter Motor Armatures Manufacturer

Every MZW armature uses ISO 16949 certified Enameled Copper Wire, it can stand high temperature and produce high torque as required.

MZW strictly tests starter armatures from future electricity failures before release. Thus to ensure a 100% accurate performance.

MZW manufactured starter armatures are dynamically balanced, they run steadly at a high speed.

The armature shaft is engineered under CNC machinery, for a longer life and an excellent Precision balance.

Splines of shafts are rolled perfectly to provide high accuracy, as well as ground bearing surfaces.

MZW is a brand providing high-performance starter armatures which you can always put trust in.

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MZW Starter Motor Armature Guide

starter motor armature

The starter motor armature is an internal component of a starter motor. Although hidden from view, it plays a big role in the working of vehicle starting systems. This article is an overview of the car stater armature. It includes information about its meaning, design, and operation. Also, a FAQs section to answer common questions related to the component.

Starter Motor Armature Definition

An armature in a starter motor is the part that rotates. It consists of windings, an iron core supported on a shaft, and a commutator. You cannot see the armature without disassembling the motor. However, you can feel its working when the motor spins to crank your car’s engine.

The armature is one of the main starter motor parts- and an important one for that matter. It contains the parts that move to set the starter drive gears or any other mechanism in motion. That way, it forms an essential part of the process to start an engine.

Let’s now see how the armature for starter motor functions to bring about rotation. Also, why the motor cannot operate without a working armature.

starter motor armature parts

What is the Function of Armature in a Starter Motor?

Vehicle starter motors contain a moving coil and another stationary one. The stationary coil is often technically called a stator and comprises either an electromagnet or permanent magnet. Most modern starters use permanent magnet motors, which are stronger and energy-efficient.

The moving or turning coil is the starter motor armature. It only becomes a magnet when the motor receives an electric current. The armature assembly, being the moving part, provides the force to spin the motor’s shaft. This constitutes the motor rotation that does useful work to start the engine.

We can, therefore, define the starter motor armature as the part that converts electric current into the needed rotary motion. It enables the motor to overcome external force and crank the engine.

A lot more happens than the simple explanation given here, as you will find out the next.

starter motor armature function

How a Starter Motor Armature Works

Starter motor armatures exist in a wide range of sizes. It depends on the intended application, which can be low-power or heavy-duty. They all operate identically, though, by using an electric current to cause rotation.

The starter motor armature contains a slotted iron core around which many loops of conductor wire are wound. When current flows through these windings, a magnetic flux is generated.

The coils on the armature end in a part called a commutator. The commutator itself is made up of segments. Each segment is a conducting surface, and insulated from the others. The segments allow different sections of the coil to receive current at different times during rotation.

Surrounding the starter armature assembly is a magnetic field from the stator. The motor stator can be coil windings on a magnetic core or a permanent magnet. When the field is from an electromagnet, the wires connect to the battery.

Here is what happens when the ignition key is turned, and what culminates in the starter armature rotation.

  • A turn of the ignition key or pressing a button to start the engine results in the flow of current to the starter solenoid. In some cars, a remote relay closes the solenoid circuit. The activated solenoid, in turn, operates the starter motor circuit, switching its connection with the battery.
  • Current flows through the starter motor brushes to the commutator and starter armature windings. The part of the coil receiving the current energizes, producing a magnetic field around it.
  • This magnetic flux interacts with that of the stator or field coils, resulting in a push/pull or what is known as starter armature winding reaction. The armature moves in the magnetic field, usually from a higher to a lower field intensity.
  • As the armature turns, the commutator also turns with it, causing the sections in contact with the brush to change. That results in the next section conveying current to the armature windings. The adjacent part of the coil energizes, and the process repeats.
  • The changing commutator contact causes a continuous rotation of the armature until it turns past haft the commutator surface.
  • After a half turn, the other part of the commutator now conveys current to the armature windings. This causes a change of polarity, ensuring rotation continuity. The armature, therefore, spins non-stop for as long as current flows into the motor.
  • The many segments or contact bars of the commutator offer two benefits. One, they help to produce a smooth rotation of the armature. Two, the segments increase the force of rotation by ensuring a magnetic force for every small turn of the armature assembly.

The happenings described here are made possible by various components of the armature. Here is a look at each part and the part it plays.

parts and functions of armature

Starter Motor Armature Parts and their Functions

Looking at a starter armature assembly, one can easily pick out four parts: a cylindrical slotted section, wire windings, a segmented ring, and a central shaft.

Starter Armature Core

The core of the starter motor armature is its largest part. It consists of thin circular and slotted layers of iron, also called laminations. The pieces are insulated from each other to reduce eddy currents. If it were a continuous block of metal, eddy currents would occur and waste electrical energy in the form of heat.

starter motor armature core

Iron is used for the armature core due to its excellent magnetic properties. It produces a strong magnet, which is necessary for the amount of torque required to start an engine. All around the core are slots to secure the coil windings. The slots run the length of the armature assembly.

Starter Armature Coil Windings

Looped around the core are the starter motor armature windings. These are fairly thick copper wires that conduct current with the least resistance. To prevent shorting and other problems, the starter armature coil wires feature a thin layer of insulation.

The coil windings of a starter motor armature end in the commutator where they attach to specific segments. This enables the changing of electrical connections with the windings. It also allows the reversal of polarity and, therefore, the continuity of armature rotation.

starter armature coil windings

As we have seen, the coils, together with the iron core, have to produce a strong rotational force. For that reason, several different loops are used, which can be as many as 30 in a single core. Each coil also features many turns of the wire to help increase the strength of the magnetic field and, therefore, torque.

Starter Armature Commutator

The commutator is found in the back of the motor’s housing and forms part of the armature assembly. Usually round and segmented, its main function is to transfer current to the armature in the required sequence. That is made possible by the segments or copper bars on which the motor brushes slide.

Each segment or bar on the commutator conveys current to a particular coil. To enhance efficiency, the contact surfaces are made from a conductive material, usually copper. The bars are also separated from each other using a non-conductive material such as mica. This helps prevent shorting.

Armature Commutator

Brushes supply current to the commutator. The brushes are spring-loaded, ensuring constant contact with the commutator and minimizing the possibility of failure. The arrangement of the brushes may vary from one motor to another. In some motors, they are on the sides of the shaft, and the end-plate in others.

Starter Armature Shaft

This is the central rod that runs through the starter motor armature assembly. It holds the parts that make the armature, from the core, windings, to the commutator. Bearings at either end support the shaft, allowing it to rotate freely.

armature shaft

To start the engine, the shaft spins the starter drive mechanism either directly or indirectly. It can be a pinion gear at the end of the shaft or a set of reduction gears and other parts. For strength, the shaft is usually steel. It is normally insulated from the commutator copper bars.

Starter Motor Armature Torque

The starter armature assembly converts electrical energy into rotary motion. The force of rotation must be large enough for the engine to come to life. To ensure that, several design characteristics are necessary. These include increasing the number of armature or field windings, using permanent magnets, and utilizing a specific wiring pattern.

Most starter motor armatures contain as many as 30 coil segments. That is usually high enough to ensure smooth rotation and high torque. Many motors also employ permanent magnets, which can be multiple to improve torque further. Electromagnets depend on the battery for current. Apart from draining the battery, that also means reduced power.

Another way to increase torque is by using specific coil configurations. For the circuity or starter armature windings, different patterns can be used. Each has its up and downsides. The next part is a description of each, including the benefits and disadvantages.

Starter Armature Windings Pattern

Electric motor manufacturers use three different ways to wind armature wires: Shunt, Series, and Compound.

Series Wound

The field or stator coils are in series with those of the armature. Current follows a continuous path from the field wires, brush, commutator, to the armature windings and back to the brush on the other side.

Series wound motors produce a strong rotational force immediately after starting. That drops considerably as the speed of rotation picks up. This arrangement suits the requirements of car starting systems where initial torque matters the most. Most automotive starter motor armatures are, therefore, shunt wound.

Other configurations include the following.

Shunt Wound

The armature coil features parallel connections with the field coils. This type of winding pattern does not produce a high enough torque. However, an increase in the speed of rotation does not cause the torque to reduce. Because of the low force generated by the armature, shunt wound motors are not suited for starting systems. Instead, they are mostly used in vehicle accessories.

Compound Wound

In this armature wiring pattern, a section of the armature coils are connected with those of the stator (or field coils) in series. The other section is connected in parallel. The pattern allows the motor to have the benefits of both shunt and series patterns. As a result, the armature torque remains high enough and constant throughout the motor operation.

starter motor armature problem

Starter Motor Armature FAQs

We went out looking for questions that many vehicle owners and car enthusiasts ask about the starter armature. Here are their answers.

Q1. What materials are used on the starter armature?

A. Most of the starter armature construction is copper. These include the wire or coil windings. The commutator plates or bars, too. Copper is used due to its exceptional ability to conduct electricity, among other reasons. The armature core is usually laminations of soft iron material.

Insulation is found all over the components, from the surfaces between iron laminations of the core to the wires of the armature. The commutator segments also feature an insulating material. The shaft that supports the armature components is made of steel.

Q2. What is starter armature resistance?

A. It is the specified resistance of the armature circuitry or the windings on the core. You can use a volt or ohmmeter to measure the resistance. Changes in the readings can be used to troubleshoot the armature, especially the coils.

A high resistance indicates a burned coil or broken parts of the circuitry. It could also show dirty contacts and commutator when measured at the terminals. A considerable drop of resistance, on the other hand, would be due to shorting.

Q3. What are the causes of starter armature problems?

A. Starter armature malfunction can result from worn, corroded, or shorted conductors and burned wires. Friction between moving parts causes surfaces to wear out. Insulation can break down and short components, while current overloads cause burnt-out coils. If oil or water finds way into the motor, corrosion occurs.

In most cases, it is the commutator that is the problem. It could be worn or covered by dirt and not transferring current efficiently. When that is the reason for failure, you can choose to clean the dirty parts. Some faults require you to buy a new armature assembly or change the bad components using a starter armature kit

Q4. What signs show a faulty starter armature?

A. Armature failure is also starter motor failure. Signs include a motor that will not spin or spins with a low torque. Noisy starting also shows bad starter motor parts, among them the armature. The signs of failure should point you to the problem. You could test the armature for circuitry problems or use visual observation to find worn or corroded parts.

When carrying out a starter motor armature test to determine resistance, the use of the right tools is highly recommended. Knowledge about the component’s amp draw and other parameters is also advised.

Q5. What are the starter motor armature repair options?

A. You can replace individual parts or change the entire armature assembly. Many car owners opt for starter motor armature rewinding to fix burned coils. It can save you money, especially when the motor in question is a costly one.

In the case of a dirty commutator, cleaning it is one way to restore efficiency. We would recommend identifying the problem first before commencing repairs, though. Here is a video explaining how to check a starter motor armature.

Q6. How is a starter motor armature test done?

A. There are several starter armature testing methods. The most common involves checking for current or amp draw. If the electrical pathways or circuitry is faulty, that will come out as high resistance.

The car manual contains the specifications for starter armature wire resistance values. You should find it useful when carrying out the test as well as other diagnostic actions on various armature parts.

Q7. Can you replace the armature for a starter motor?

A. You can. In fact, replacing the assembly is usually one of the ways to save your car’s starter motor. That is unless you want to replace the motor itself. Many DIY enthusiasts opt to do it themselves (it is a fairly simple process). However, seeking a mechanic’s services is always more convenient and safer.

Q8. What is the starter armature price?

A. The cost ranges from as low as $20 to as high as $100 or more. A lot depends on the type of engine the armature is built for. Also, its quality and whether it is an aftermarket product or OE. Other factors come into play, too, such as the manufacturer. Different auto parts makers can set different prices for similar starter armatures.


A starter motor armature, although unseen, performs an important function in the action of the starter motor. It ensures the current from the ignition system circuit converts to torque without fail. Unfortunately, the component is one of the most prone to damage and failure. With the information contained in this guide, you now understand the working and usefulness of the armature in a car starter motor.

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