You can break down lawn mower belts by design or function. The types of lawn mower belt designs are Standard V-belts, Cogged V-belts, and Serpentine belts. These designs may be deck, drive, or PTO belts.
Belts are the blood running through a lawn mower’s veins. They transfer power from the engine to the mower’s moving parts. With the help of our in-house engine expert, we take a deep dive into the different types of lawn mower belts.
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Types of lawn mower belts by belt design
Mechanical belts are lax, looping material that link rotating shafts. They come in a variety of types. However, when it comes to lawn mowers, I’ve only seen V-belts, Cogged V-belts, and Serpentine belts.
Standard V-belts
V-belts are, by far, the most common kind of lawn mower belt. They get their name from their trapezoidal shape. Many types of them exist, but about 90% of mower belts are Standard V-belts. They’re an affordable solution that stands strong against harsh mowing conditions.
Cogged V-belts
Cogged V-belts have a tighter radius than standard V-belts. The term “cogged” refers to slots across the belt’s length, so they’re sometimes called toothed belts.
When comparing cogged vs. standard V-belts, cogged have the following advantages:
- Slightly more efficient
- Run cooler
- Rumored to improve cut quality
Serpentine belts
Serpentine belts are sometimes seen on fancy riding mowers but are more common in automotive applications. Although most mowers don’t use serpentine belts, when they do, it’s likely a PTO or fan belt.
These ribbed belts are thicker than V-belts. They also have an excellent belt to pulley contact ratio. When comparing serpentine vs. V-belts, serpentine belts have the following advantages:
- Quieter
- More efficient
- Easier to maintain
- Less likely to slip
Types of lawn mower belt functions
Deck belts spin the mower blades, and drive belts spin the tires. A few mowers have PTO belts to transfer power to additional equipment.
Deck Belts
Deck belts make riding lawn mowers capable of cutting. Without them, the crankshaft couldn’t control the mower blades.
The deck belt loops around the engine pulley and deck spindles. Guided by the pulley, the belt transfers power from the engine to the mower blades. Consequently, the mower blades spin and the turf gets trimmed.
The table below describes most lawn mower deck belts.
| Length | 42 – 160 in. |
| Belt designs | Standard V-belt, Cogged V-belt |
| Type of mowers | Riding lawn mowers |
Drive Belts (aka Transmission Belts)
Drive belts invigorate mowers with the momentum to move by connecting the crankshaft to the wheels. They loop from the engine pulley to the transmission pulley. From self-propelled to hydrostatic, drive belts are the blood running through the veins of lawn mower drive systems.
| Length | 14 – 90 in. |
| Belt designs | Standard V-belt |
| Types of mowers | Self-propelled, riding lawn mowers |
PTO Belts
PTO (Power Take-Off) systems transfer power from the mower engine to attached hydraulic equipment. Some riding lawn mowers have an electric PTO system, and others have mechanical PTO. The latter uses PTO belts.
| Length | 80 – 115 in. |
| Belt designs | Standard V-belt, Cogged V-belt, Serpentine |
| Types of mowers | Riding lawn mowers |
How to select the right size lawn mower belt
According to engine expert Jeff Yochum, belts come in infinite sizes. To choose the right belt for your mower:
- Look for the belt’s OE number in your mower’s user manual.
- Google the OE number.
- You’ll find an assortment of same size belts, including the manufacturer’s official replacement part and cheap Chinese replicas.
If you can’t find your mower manual:
- Try googling it. Many manuals are available online.
- The OE number is on the mower’s old belt
Lawn Mower Belt Materials
Rubber is standard. The flexible material keeps a tight grip on pulleys while withstanding damage. You’ll often see rubber V-belts reinforced with poly or steel tension cord. However, Kevlar is the toughest reinforcer.
Kevlar is a highly durable synthetic material. With higher tensile and rim strength, Kevlar lawn mower belts have the longest average lifespan.
V-belt Type Codes and Profiles
Manufacturers mark standard v-belts with type codes that tell:
- Profile letter: Top-width—Z, A, B
- Length number: Inner circumference in inches
For example, if a V-belt’s type code is A38, its profile is A and its length is 38 inches. Profile A has a top-width of ½ inch, as shown in the table below.
| V-belt Profile | Top-width (inches) |
| Z | 0.375 |
| A | 0.5 |
| B | 0.656 |
| C | 0.875 |
| D | 1.25 |
| E | 1.5 |
Lawn mower V-belts have a Z, A, or B profile.
Lawn Mower Belt Prices
The average lawn mower belt costs about $40, but the average drive belt costs much less than the average deck belt.
| Type of belt | Typical cost |
| Deck | $20 – $110 |
| Drive – Self-propelled | $6 – $40 |
| Drive – Riding Mower | $25 – $60 |
| PTO | $55 – $110 |
FAQ: Types of Lawn Mower Belt
1. How many belts does a lawn mower have?
The number of belts a lawn mower has depends on the type of lawn mower:
- Riding lawn mowers: Most have two belts, one for the deck and another for the transmission. However, some also have PTO belts.
- Self-propelled mowers: Most have one belt for the drive system.
2. Can my lawn mower belt have different applications?
Yes. Yochum says, “There are some belts that are used on cars, mowers, and industrial applications.” For example, standard V-belts are popular agricultural, industrial, and HVAC parts.
3. Which belt is the primary mower belt?
The deck belt is the lawn mower’s primary mower belt.
4. What’s the difference between a drive belt and a deck belt?
The drive belt transfers engine power to the transmission and wheels, while the deck belt spins the mower blades.