The windshield wiper motor is the engine behind your car wipers. Together with other parts of the wiper system, it ensures a clean windshield when driving. Read on for detailed information about car wiper motors. By the end of the article, you will be familiar with how a wiper motor works, how manufacturers design it, and more. More importantly, we will help you estimate the cost to replace your car wiper motor by looking at the price range.
Wiper Motor Definition: What is Wiper Motor?
The wiper motor is the part that moves windshield wiper linkages. It enables the wipers to accelerate across the windshield, and is one of the wiper system components. The wiper motor assembly typically consists of a DC motor to provide motion, a gear reduction mechanism to multiply torque, and small arm to transfer motion to the wiper linkages.
Car wiper motors are mostly used in the front windshield where they mount on the firewall, just below the windshield cowl. The wiper motor location on the firewall is necessary. It makes connecting it to the wiper linkages easy, and the transfer of motion to the wiper linkages direct.
Some vehicles feature wipers both in the front and rear windshield. These include hatchbacks and similar cars. In such cases, there will usually be two separate motors; one for the front wipers and another rear wiper.
Just like the front windshield wiper motor, the rear wiper motor comprises an electric motor and gear mechanism to multiply toque. However, the assemblies of the two motors differ slightly in their design, with the front motor having a more elaborate transmission.
Let us now see how wiper motor manufacturers design the component and the parts that make a typical wiper motor. This will help you understand the working of car wiper motors when we get to that.
Parts of a Wiper Motor Assembly
The wiper motor mechanism, as already stated, contains more than an electric motor. There’s usually the part that transmits motion to the wipers attached to the main motor assembly. And although wiper motor specifications such as torque and current draw may differ, the general design does not. In that regard, a typical wiper motor is divided into these two sections.
- Motor Assembly
Let’s see the function of each.
This is the cylindrical (or rectangular) section- and the main part of a wiper motor mechanism. It contains all the components found in a conventional electric motor. These parts are enclosed inside a housing made from metal for strength and often coated to prevent rusting or corrosion.
The motor assembly components include brushes, commutator, armature, and magnet. The wiper motor brushes convey current alternately, causing a reversal of polarity and continuous motion. To enable a two-speed operation, most wiper motors come equipped with three brushes.
The function of the commutator is to distribute current to the armature coil as it spins. The armature, on the other hand, is copper wire around a magnetic core. Its purpose is to generate the magnetic field that causes rotation.
The motor’s magnets serve to provide the magnetic flux that works against that of the armature coil to enable the armature to rotate. Most car wiper motors use permanent magnets that are glued to the housing.
Wiper Motor Gearbox
The wiper motor gearbox is the transmission part of the assembly. It connects to the motor by means of long bolts and contains parts necessary to the operation of the wipers. Unlike the motor assembly housing that’s all metal, the gearbox features a plastic cover on the upper side.
Wiper motor gearbox mechanisms vary in terms of gear arrangement and a few other features. The most common is a worm gear and park switch combination. This setup essential consists of spiral and wheel gears. The spiral gear is formed on the end of the motor shaft and arranged to drive the wheel gear.
The worm gear serves several purposes. It multiplies the motor’s torque, enabling it to operate the heavy rods that make the windshield wiper linkages. It also reduces the speed of rotation to match that of the wipers.
As already indicated, the gearbox assembly also integrates a home or park switch. The switch is usually in the form of a round wheel with a conductive ring on the inner surface. The wheel rotates when the motor is in operation.
As the wheel rotates, three arms make contact with the conductive surface on the ring, forming what is commonly called the park limit switch. The wiper park switch serves to ensure that windshield wipers return to the home position when the driver switches them off. Without the switch, the wipers would stop anywhere on the windshield and obstruct a driver’s view.
To transmit motion, the wiper motor gearbox contains a shaft that attaches to the main output gear on one end and protrudes out of the housing on the other. The shaft also usually has a small arm attached to it. The wiper motor arm function is to transfer motion from the shaft to the wiper linkages.
How does a Wiper Motor Work?
The wiper motor function is to power the windshield wipers. It converts electric energy into mechanical energy, and transmits the resulting motion to the wiper mechanism. How does that happen? Below is a step by step explanation of the wiper motor operation.
- The wiper motor is activated by the flow of current through the motor assembly. This is usually initiated by the driver by turning the wiper switch located on the steering column or by pushing a button on the dash. The switching of power is also normally controlled by a relay within the wiper motor wiring system or the motor itself.
- Upon receiving voltage, the motor will start to spin. The end of the motor shaft is a spiral gear that connects to a wheel gear. This offers gear reduction and reduces the speed of spin by up to 50 times. The wheel connects to and rotates an output shaft. In some wiper motors, the worm gear does not rotate the output shaft directly but through an additional gear mechanism
- The output shaft attaches to a crank or small arm that, in turn, connects the wiper motor assembly to the wiper linkages. As the wiper motor arm turns, it transfers the motion to the rest of the wiper system by oscillating the linkages. This results in the wiper blades moving across the windshield in a back and forth motion.
The wiper motor working principle explained above is the simple sequence of events that follow the activation of the wipers by the wiper switch. In reality, though, the operation is a complex process that involves many different parts.
Car, wipers for example, mostly use two different speed settings, low and the high. This is often made possible by using a third brush in the motor assembly and low current for the low setting and high current for the high setting.
Car windshield wipers also utilize an intermittent wiping feature. This allows the wipers to come on at set intervals. This feature is useful during times when you’re driving in a light drizzle or to remove occasional splashes from the windshield.
Modern car wiper systems integrate automation features such as rain sensing systems. These use sensors behind the windshield to measure the refractive properties of raindrops. The signals then activate the wiper action and at the appropriate setting.
All these features are governed by an electronic control module, or wiper motor control module is usual. Other important components of the wiper system, and which control the wiper motor operation, include the relay, fuse, and connectors.
The wiper motor relay function is to switch on power to the motor assembly and is usually part of the switch wiring. The wiper motor fuse shields the motor and other parts from shorting or current overloads, while the wires and connectors transmit power and electric signals.
Types of Wiper Motors
There are several types of the windshield wiper motor. These are classified according to location, design, and voltage rating, among other criteria. The type of wiper motor matters when out shopping for one. A front wiper motor, for example, cannot be installed in the rear window, and vice versa. The wiper motor types include the following.
12V Wiper Motor
As the name suggests, the 12V windshield wiper motor runs off a 12 volt power source. These wiper motor types are the most common and suit many different cars. The image above shows a typical 12 volt wiper motor.
24V Wiper Motor
This is the type of wiper motor that uses a 24 volt power source. It’s commonly used in large vehicles that have to power heavy wiper linkages. The 24V wiper motor uses less current to move heavy loads, and can be said to be more efficient than the 12 volt version.
Front Wiper Motor
The front windshield wiper motor operates the front wipers and is normally located in the engine bay, on the firewall. In terms of design, it features a motor assemble, gearbox, and output shaft connected to a crank arm. The arm purpose is to move the wiper linkages back and forth.
Rear Wiper Motor
The rear windshield wiper motor, as the name suggests, is used to power the rear wipers in a car. It’s generally a different design from the front one both in terms of parts and features. Because the rear wiper is usually a single blade, the motor does not need a complex gear mechanism and drives the arm directly.
Permanent Magnet Wiper Motor
A wiper motor can use permanent magnets or electromagnets in the motor assembly. Most car wiper motors today are the permanent magnet type. There are several reasons for that. Permanent magnets offer the advantages of quiet and reliable operation, low cost, and minimal power consumption, among other benefits.
Field Coil Wiper Motor
A few versions of the windshield wiper motor use field coils or electromagnets instead of permanent magnets. What this means is that the armature is surrounded by coils of wire wound to a magnetic core. The field coil wiper motor is an old design, and often found in older vehicles.
Universal Wiper Motor
The universal windshield wiper motor is the type that is built to suit a broad range of cars. They are usually aftermarket versions and preferred by buyers who own older cars. These are cars whose wiper motor models may have been discontinued. A universal windshield wiper motor kit contains parts to enable Installation in different cars.
Car Wiper Motor Price
How much is a windshield wiper motor? Different wiper motor manufactures quote different prices for their products. Upon reaching the auto parts market, the wiper motor is again priced differently. To help you compare these prices, we will look at the cost of the components for different cars. These are the prices offered by wiper motor suppliers and which also depend on your geographical location.
Generally, the cost of a windshield wiper motor varies from $30 lowest to $350. There are models that cost higher, of course, depending on the type of car and its make, among other factors. Overall, the price is influenced by:
- Type of car
- Type of wiper motor
- Whether OEM or aftermarket
- If new or reconditioned
Luxury cars use costly parts, including the wiper motor, while a front windshield wiper motor will generally cost more than a rear one. On the other hand, the manufacturer set price will dictate the wiper motor cost and you can expect popular brands to be more expensive.
When buying your cars wiper motor, you will find that the price varies between OEM and aftermarket types, with aftermarket wiper motor costing less most of the time. A new windshield wiper motor cost will also be higher than if you go for a rebuilt unit.
Your car’s wiper motor, especially the front windshield wiper motor, plays a crucial role in ensuring safety when on the road. You may not realize that until you’re caught up in a drizzle or other situation that obstructs your windshield view. That’s why the motor should be working at all times. Having looked at the wiper motor information regarding its working and design, you now understand the mechanism in detail. Read the next section know how a wiper motor fails end what to do when the one on your car goes bad.