Car Windscreen Wiper Assembly: How It All Works Together

Have you ever wondered how your car wipers work? Sitting in the driver’s seat, it might seem like a simple flick of the wiper stalk is enough to get your wiper blades to swing into action and clear your windshield. However, behind the curtain (or under the bonnet in this case), there is a complex system at play that keeps your windshield clean, come rain, snow or any other kind of debris.

It is important to understand the functioning of your wipers as it not only helps you use the system better, but it also helps you troubleshoot different parts of the car windscreen wiper assembly. Maintaining the system in good health can be the difference between getting home safely, or being stranded by the side of the road when the weather gets bad.

Different Parts Of A Car Windscreen Wiper Assembly

The different parts required for the proper functioning of your wiper blades are collectively called the wiper assembly. The same parts are used for the rear windshield wiper as well. Here’s a look at each part individually.

1. Wiper Motor

A wiper motor is the heart of the entire wiper assembly. It runs off your car’s battery to create the rotational motion which is used to turn your wipers. Now, motors spin at high speeds, and therefore wiper motors use a method called gear reduction to convert gear reduction to convert the high speed rotational motion to a lower speed, which can then be applied to oscillate your wiper blades.

Common Problems: A wiper motor is often the most heavy duty part of a wiper assembly, and in most cases, it lasts the lifespan of a vehicle. However, motors can sometimes overhear or wear out, and the most obvious common fix is to replace it. Some motors can also suffer from a reduced output over time, which results in a poorer wiping performance. Again, the best way to fix it is to replace the motor.

2. Linkage Mechanism

The linkage mechanism ensures that the effort being made by the wiper motor is converted into the oscillating motion so that the wipers can clear the windshield. Also known as wiper transmission, it is made up of metal arms and joints. 

Common Problems: The linkage mechanism is also well built and meant to last the entirety of a vehicle’s lifespan. However, improper use such as dry wiping can wear out the linkage mechanism and even cause it to fail. A failing linkage mechanism will cause the wipers to move in an uncoordinated system, and can cause damage to the windshield. It is best to replace the linkage mechanism if it has been damaged.

3. Wiper Arms

The wiper arms are connected to the linkage mechanism at one end and the wiper blade at the other. Wiper arms are spring loaded and this is how they ensure that the wiper blades maintain enough pressure on the windscreen to clear the rain water or wipe off the debris.

Common Problems: Wiper arms can bend over time due to an improperly functioning wiper system or because of external damage. An expert mechanic can repair minor damage by reversing the bend, otherwise it will need to be replaced. Wiper arms are also exposed to the elements and can rust over time. Rust affected wiper blades need to be replaced as they can break off while the wiper arm is in motion, causing damage to the windscreen.

4. Wiper Blades

Wiper blades connect to the wiper arms and house the rubber blade that glides on the windscreen to clear off the water or debris. Wiper blades can be of different types. Older car models used to come fitted with conventional wiper blades which featured a metal bracket that held the rubber blade in place. Modern cars feature frameless wipers that are made mostly of rubber and connect to the wiper arm using a small adapter mechanism placed in the centre.

Common Problems: Wiper blades are meant to be replaced at periodic intervals as they wear out. You should look out for signs such as streak marks, squeaking noises or the rubber blades skipping on the glass surface, all of which point to the fact that it needs to be replaced.

5. Control Switch and Relay

This is the control lever or switch that is located inside the cabin and brings the wipers into action. The control switch has different settings that can run the wiper at different speeds and intervals. It is also used to activate the washer fluid system.

Common Problems: A blown fuse is the most common issue with a control switch. Fuses can easily be replaced by a mechanic or by consulting your owner's manual. Sometimes, the wiper stalks can wear out over time and not function properly and in such an instance, they need to be replaced.

6. Windshield Washer System

The windshield washer system is a subsystem in itself. It consists of spray nozzles, pipes, fluid reservoir and pump. When activated, the pump pushes the windshield wiper fluid from the reservoir into the fluid lines, which then carry it to spray nozzles. The spray nozzles convert the water into thin jets and spray it onto the windshield, which is then wiped by the wiper blades to clean the glass surface.

Common Problems: The most common issue with the windshield washer system is a clogged nozzle. This happens when the system has not been used in a long time, and the salt deposits solidify in the nozzle, obstructing the flow of water. Your local mechanic can easily clear the obstruction using fine metal pins. The fluid lines or water reservoir can develop a leak due to external damage, in which case they will need to be replaced.

Conclusion

A car windscreen wiper assembly is a complex system that works together to ultimately cater to the simple task of keeping your windscreen clear of water and debris. Having a working knowledge of the system will help you in diagnosing small problems, and help you make informed decisions when replacing different parts of the system and in conducting small maintenance activities to keep your wiper assembly in a healthy state.