Lawn Mower Parts Names & Functions

Although lawn mowers are pretty simple, especially if you know a thing or two about engines and vehicles, there are several components you won’t find on your motorcycle or car. Moreover, even those that bear the same name may not have the same function.

Some of the lawn mower part names include the fuel primer bulb, recoil starter, cutting blade, grass catcher, grass deflector, bail arms, choke lever, fuel shut off, and height adjustment. The parts commonly found on other vehicles include the engine, deck and wheels, throttle, and belts and pulleys.

lawn mower parts diagram

Lawn Mower Parts Name and Short Descriptions

Before we jump into all the different lawn mower parts’ names and their functions, we should mention that we won’t go into much detail about every single component. Instead, we will count major systems as one, like the engine, and briefly explain their purpose and everything that may be important for you to know as an owner.

Grass Cutting Blade

The cutting blade of a lawn mower sits under the deck and is attached directly to the engine’s crankshaft. The blade is two-sided with a center bolt and can be sharpened if it wears out. However, these blades are made of steel and are pretty cheap and easy to replace as well.

The average lawn mower blade is around 20 inches long, but it can be anywhere between 6 and 40 inches. It’s also worth mentioning that the blade has the biggest impact on how fast it can cut grass because a bigger bade equals a bigger cutting surface area.

Recoil Starter

The recoil starter is the complete assembly of the cord you pull when you want to start the engine. The recoil starter is attached directly to the crankshaft and can only turn it in one direction.

The rope is connected to the recoil starter hub and rewound back into place by a leaf coil. Also, there is usually a cooling fan integrated into the recoil starter assembly, so removing it can and will cause the engine to overheat.

Height Adjustment

The wheels on a lawn mower are attached to an eccentric hub which is why turning the height adjustment lever raises the mower deck. This system is pretty simple, but lawn mowers can raise all four wheels at once, and they do it with the help of additional lever systems connected to the main one.

Grass Cacher

The grass catcher is the mesh bucket that sits on the back of the lawn mower and does just that, catches the grass you are cutting. You can remove the grass catcher, and the mower will work just fine, but all the cut grass will disperse on your lawn and will look really ugly once it dries.

Grass Deflector

A grass deflector is something you will find on lawn mowers without a grass catcher. The grass deflector sits on the side of the lawn mower and deflects grass in a certain direction, usually away from your legs and face. Removing the deflector can be extremely dangerous because small rocks will likely hit you in the face or eyes at extremely high speeds.

Deck and Wheels

The deck of a lawn mower is what we would call a chassis on other vehicles. The deck can be metal or plastic, with the latter being longer lasting and cheaper but more brittle. As for the wheels, they are made of hard plastic in the vast majority of cases and rarely ever break. Still, the wheels have bearings that can fail and make it more difficult to push.

Shut-Off Bail Arm

The shut-off bail arm is the front lever on the handlebars that you pull when you want to start the mower and release to shut it down. The reason you have to keep the bail arm pulled in the entire time the engine is running is that it shuts down in case of an emergency. For example, if you trip and fall, your leg or hand could end up in the blade, but with a bail arm, nothing will happen because the blade will stop spinning by the time you reach the ground.

Self-Propulsion Bail Arm

The propulsion bail arm is something you will find only on self-propelled lawn mowers. When you pull the self-propulsion bail arm, you engage the clutch, and the lawn mower starts moving. And just like it’s the case with the shut-off bail arm, once you release it, the lawn mower will stop. However, the engine will keep running until you release the shut-off bail arm because the two systems are independent of each other.

Propulsion Belts and Pulleys

The propulsion belts and pulleys transfer engine power to the wheels. The first pulley sits between the engine and the cutting blade, and the second sits on the axle. And, of course, a belt connects the two pulleys and transfers power to the wheels. Also, a hand-operated clutch sits on the axle, and that’s what you operate using the self-propulsion bail arm.


All lawn mower engines are small, single-cylinder four strokes. That’s pretty much the same type of engine you will find in motorcycles and older cars, only smaller and with fewer cylinders. That means the lawn mower engine parts’ names are also the same. A lawn mower engine has a gas tank, a carburetor, fuel lines, a piston, valves, a crankshaft, a camshaft, an air filter, spark plugs, oil, etc.

The only thing that sets lawn mower engines apart is the cooling system or lack thereof. A lawn mower engine doesn’t have a radiator, coolant, expansion tank, or anything else other than a cooling fan that’s directly attached to the crankshaft.

Throttle Adjustment Lever

The throttle adjustment lever is on the handlebars, and you use it to increase or decrease engine speed. Once you set it to a certain position, another mechanical system that has to do with engine speed regulate the throttle in order to keep the engine speed constant regardless of outside conditions.

Choke Lever

Pulling the choke lever restricts the air intake of the engine, which in turn enriches the air/fuel mixture. That makes it much easier to start the engine when the outside temperatures are cold or when the engine itself is cold. But once the engine fires up and warms up a little, return the choke lever to its original position to void engine stalling and poor performance.

Fuel Shut Off

Most lawn mowers have a fuel shut-off lever which cuts the fuel supply to the carburetor. The system isn’t in place to shut the engine down but to avoid carburetor overflow when the lawn mower is stored and isn’t being used. Always, make sure to engage the fuel shut off once you are done with the lawn mower to prevent the fuel from spilling in your garage because it can be a major fire hazard.

Fuel Primer Bulb

The fuel primer bulb isn’t actually a bulb, but it does resemble one. A fuel primer is the red rubber button on the side of the carburetor and is used to fill up the carburetor with fuel after the lawn mower has been sitting for a few weeks.

When you push the primer bulb in, the air inside escapes into the atmosphere, but when you release it, it creates a vacuum in the fuel system and pulls fuel into the carburetor. Also, the primer bulb should only be pushed in two to three times; otherwise, you could overfill the carburetor.

check before using your lawn mower

What are the parts of a lawn mower called?

The parts exclusive to lawnmowers are called bail arm, grass deflector, grass catcher, choke, cutting blade, recoil starter, primer bulb, and deck. Other parts include the engine, belts, wheels, spark plugs, carburetor, etc.

How many parts does a lawn mower have?

According to, a standard lawn mower has up to 270 individual components. That includes different engine parts, chassis, drivetrain, controls, etc.

What is the part called that you pull on to start a lawn mower?

The part you pull on to start a lawn mower is called a recoil starter assembly or a pull-start mechanism. The reason it’s called a recoil starter is it uses a recoil spring to wind the rope.

What is the flap on the back of a lawn mower called?

The flap on the back of a lawn mower is called a grass deflector. A grass deflector keeps the cut grass and other debris from hitting your legs or even your face if it’s sitting on the side of the mower.

What is a mower belt called?

A mower belt is typically called a blade belt or a drive belt. However, people may call them V-belts because that’s the type of belt used to transfer power from the engine to the wheels.

What parts of a lawn mower are simple machines?

The simplest parts of a lawn mower are the deck, wheels, different levers, and handlebars. The deck is the chassis to which all other components attach, and the rest of the mentioned parts are all solid pieces of metal or plastic.


In the end, the components exclusive to lawnmowers include the deck, the grass catcher, the grass deflector, the cutting blade, and the height adjustment mechanism. The components you will find on other vehicles and tools in a similar shape are the recoil starter, the primer bulb, bail arms, the choke lever, the throttle mechanism, and the fuel shut-off. And lastly, the components of a lawn mower that are the same as on other vehicles are the engine, wheels, belts, and pulleys.

Ibro Cehic

Ever since I was bitten by the automotive bug during early childhood I was obsessed with cars. My first driving experience came when I was ten and I already started tinkering with cars and motorcycles at thirteen. So, right from the beginning, I knew my life would revolve around cars, even if I wasn’t sure how that would happen. And today, thanks to my second passion, writing, I get to share my love for automobiles with other enthusiasts through my articles.

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