3909689
Round Head Cap Screw
Cummins®

This article provides an overview of the Round Head Cap Screw, part #3909689, manufactured by Cummins. It covers the basic concepts, purpose, key features, benefits, and maintenance suggestions for this component.

Basic Concepts

A Round Head Cap Screw is a type of fastener characterized by a rounded head and a threaded shank. It is designed to provide secure fastening in various applications. The screw is typically made from metal and is used to join components together by threading into a pre-drilled hole ¹.

Purpose of the 3909689 Round Head Cap Screw

The 3909689 Round Head Cap Screw by Cummins is utilized in commercial trucks to secure various components. It plays a role in ensuring that parts remain firmly attached, contributing to the overall structural integrity and performance of the truck ².

Key Features

• Round head design for easy installation and removal using common tools.
• High-quality material construction for durability and resistance to wear.
• Precision threading to ensure a secure fit and minimize the risk of loosening.
• Compatible with a variety of truck components requiring secure fastening.

Benefits

• Provides a strong and reliable fastening solution.
• Enhances the structural integrity of truck components.
• Easy to install and remove, facilitating maintenance and repairs.
• Designed to withstand the rigors of heavy-duty truck operations ³.

Troubleshooting and Maintenance

• Regularly inspect the Round Head Cap Screw for signs of wear or damage.
• Ensure that the screw is properly tightened to maintain a secure fit.
• Replace the screw if it shows signs of corrosion, stripping, or other forms of degradation.
• Use the appropriate tools to avoid damaging the screw head during installation or removal.

About Cummins

Cummins Inc. is a global power leader that designs, manufactures, and distributes engines, filtration, and power generation products. The company is known for its high-quality and reliable components, which are used in a wide range of industries, including transportation, construction, and agriculture.

Cummins Round Head Cap Screw 3909689 Compatibility

The Cummins Round Head Cap Screw part number 3909689 is a versatile component designed to fit a variety of Cummins engines. This screw is essential for securing various parts within the engine assembly, ensuring structural integrity and operational efficiency. Below is a detailed breakdown of its compatibility across different engine models:

6 Series Engines

• 6B5.9
• 6C8.3
• C8.3 G

The 6 Series engines, including the 6B5.9, 6C8.3, and C8.3 G, utilize the 3909689 screw in several applications. This screw is often used for fastening components that require a robust and reliable connection, such as securing valve covers or other critical engine parts.

C Series Engines

• C GAS PLUS CM556

The C GAS PLUS CM556 engine also incorporates the 3909689 screw. This engine, known for its gas-powered capabilities, relies on this screw to maintain the integrity of its components under operational stress.

ISB Series Engines

• ISB CM2150
• ISB6.7 CM2250
• ISB6.7 CM2350 B101

The ISB series engines, including the ISB CM2150, ISB6.7 CM2250, and ISB6.7 CM2350 B101, use the 3909689 screw in multiple locations. These engines, known for their durability and performance, benefit from the screw’s strength and reliability in securing various engine components.

ISC Series Engines

• ISC CM554
• ISC CM850

The ISC series engines, such as the ISC CM554 and ISC CM850, also feature the 3909689 screw. This screw is critical in maintaining the structural integrity of these engines, ensuring that all fastened parts remain securely in place.

ISL Series Engines

• ISL CM554
• ISL9 CM2150 SN

The ISL series engines, including the ISL CM554 and ISL9 CM2150 SN, utilize the 3909689 screw in various applications. This screw is essential for securing components that require a high level of reliability and strength.

QSC and QSL Series Engines

• QSC8.3 CM554
• QSC8.3 CM850 (CM2850)
• QSL8.9 CM2150 L141
• QSL9 CM554
• QSL9 CM850 (CM2850)

The QSC and QSL series engines, such as the QSC8.3 CM554, QSC8.3 CM850 (CM2850), QSL8.9 CM2150 L141, QSL9 CM554, and QSL9 CM850 (CM2850), also incorporate the 3909689 screw. This screw is used in various applications within these engines, ensuring that all critical components are securely fastened.

Role of Part 3909689 Round Head Cap Screw in Engine Systems

In the context of engine systems, the part 3909689 Round Head Cap Screw is instrumental in securing and maintaining the integrity of various components.

Flexplate

The flexplate is a vital component in automatic transmission vehicles, serving as the connection between the engine and transmission. The Round Head Cap Screw, specifically part 3909689, is used to fasten the flexplate to the crankshaft. This secure attachment ensures that the rotational force generated by the engine is efficiently transferred to the transmission, enabling smooth operation of the vehicle. The screw’s design helps in withstanding the dynamic loads and vibrations inherent in the engine’s operation, thus maintaining a stable connection.

Flywheel

In manual transmission vehicles, the flywheel plays a similar role to the flexplate, acting as the interface between the engine and the transmission. The Round Head Cap Screw, part 3909689, is employed to attach the flywheel to the crankshaft. This connection is essential for the proper functioning of the clutch system. When the clutch is engaged, the flywheel transmits the engine’s power to the transmission, allowing the vehicle to move. The screw’s robust construction ensures that this connection remains firm under the high torque and cyclic stresses experienced during gear changes and acceleration.

Conclusion

The 3909689 Round Head Cap Screw by Cummins is a critical component in ensuring the structural integrity and performance of various engine systems. Its robust design, precision threading, and compatibility with a wide range of Cummins engines make it an essential part for securing critical components in both automatic and manual transmission vehicles.