3678740
Twelve Point Cap Screw
Cummins®

The 3678740 Twelve Point Cap Screw, manufactured by Cummins, is a specialized fastener designed for use in commercial trucks. Cummins, a leader in diesel engine technology, produces this component to meet the demanding requirements of heavy-duty applications. This screw plays a significant role in various truck assemblies, contributing to the structural integrity and performance of commercial vehicles.

Basic Concepts of Twelve Point Cap Screws

A twelve point cap screw is a type of fastener characterized by its hexagonal socket head, which allows for increased torque application compared to traditional hex-head screws. This design reduces the likelihood of cam-out, where the driver slips out of the fastener head, during tightening. Twelve point cap screws are commonly used in mechanical assemblies where high torque and secure fastening are required ¹.

Role and Function in Truck Operation

The 3678740 Twelve Point Cap Screw is integral to the operation and maintenance of commercial trucks. It is utilized in areas where secure fastening is crucial, such as engine components, chassis assemblies, and other critical truck parts. By providing a reliable connection, this screw helps maintain the structural integrity and performance of the truck, ensuring that components remain securely fastened under various operating conditions ².

Key Features

The 3678740 Twelve Point Cap Screw features a robust design that includes a twelve-sided socket head for enhanced torque application. It is made from high-strength materials, typically alloy steel, which provides durability and resistance to wear. The screw’s threading is precision-cut to ensure a secure fit and optimal load distribution. Additionally, it may have unique attributes such as a corrosion-resistant coating to enhance its functionality and longevity in harsh environments ³.

Benefits

The 3678740 Twelve Point Cap Screw offers several benefits that contribute to the reliability and safety of truck components. Its design allows for improved torque application, reducing the risk of loosening over time. The screw’s high-strength material composition ensures it can withstand significant loads, while its precise threading promotes even load distribution. These features collectively enhance the overall performance and durability of the fastened components.

Troubleshooting and Maintenance

Common issues with twelve point cap screws may include signs of wear, corrosion, or failure due to over-tightening. Regular maintenance practices are vital to ensure the longevity and performance of these screws. This includes adhering to proper torque settings during installation to prevent over-tightening and conducting routine inspections for signs of wear or corrosion. Addressing these issues promptly can help maintain the structural integrity and safety of the truck.

About Cummins

Cummins Inc. is a global power leader that designs, manufactures, and distributes diesel and natural gas engines, as well as related technologies. With a history spanning over a century, Cummins has established itself as a trusted name in the commercial vehicle industry. The company is committed to innovation, quality, and customer satisfaction, providing reliable solutions for a wide range of applications, including commercial trucks.

Compatibility with Cummins Engines

This Cummins part is a critical component in the assembly and maintenance of various Cummins engines. This part is designed to provide robust fastening capabilities, ensuring secure connections in high-stress environments typical of engine operations.

ISX Series Engines

• ISX CM570
• ISX CM870
• ISX CM871
• ISX12 CM2350 X102
• ISX12 G CM2180 EJ
• ISX12/ISX11.9 CM2250
• ISX15 CM2250
• ISX15 CM2250 SN
• ISX15 CM2350 X101

This part is integral to the ISX series engines, providing essential fastening for various engine components. Its design ensures that it can withstand the rigors of engine operation, maintaining structural integrity and reliability.

QSX Series Engines

• QSX11.9 CM2250 ECF
• QSX15 CM2250
• QSX15 CM2250 ECF
• QSX15 CM2350 X105

In the QSX series engines, this cap screw is used in several critical applications. Its strength and durability are crucial for maintaining the alignment and stability of engine parts, ensuring optimal performance and longevity.

QSZ Series Engines

• QSZ13 CM2150 Z101
• QSZ13 CM2150 Z102

For the QSZ series engines, this cap screw is employed in various fastening tasks. Its design allows for precise and secure connections, which is vital for the proper functioning of these engines.

X Series Engines

• X12 CM2350 X119B
• X15 CM2350 X116B
• X15 CM2350 X123B
• X15 CM2450 X134B

This part is also used in the X series engines. Its application in these engines ensures that all components are securely fastened, contributing to the overall reliability and efficiency of the engine.

Z Series Engine

• Z13 Z108G

In the Z13 Z108G engine, this part plays a key role in maintaining the structural integrity of the engine. Its use in this engine ensures that all parts are securely fastened, which is essential for the engine’s performance and durability.

Role of Part 3678740 Twelve Point Cap Screw in Engine Systems

In the realm of engine systems, the part 3678740 Twelve Point Cap Screw is instrumental in ensuring the secure assembly and operation of several key components.

Flexplate Integration

The flexplate, a critical component in automatic transmissions, relies on the Twelve Point Cap Screw for secure attachment to the crankshaft. This screw ensures that the flexplate remains firmly in place, allowing for the efficient transfer of power from the engine to the transmission. The design of the Twelve Point Cap Screw provides enhanced torque application, reducing the risk of loosening under the dynamic stresses encountered during engine operation.

Flywheel Assembly

In manual transmission systems, the flywheel plays a pivotal role in smoothing out the power delivery from the engine. The Twelve Point Cap Screw is used to attach the flywheel to the crankshaft, ensuring a robust connection that can withstand the high torque and rotational forces generated during operation. The twelve-point design of the screw allows for greater contact area and improved resistance to loosening, which is essential for maintaining the integrity of the flywheel-crankshaft interface.

Flywheel Mounting

The mounting of the flywheel to the engine block or bell housing is another area where the Twelve Point Cap Screw demonstrates its utility. By providing a secure and stable attachment point, this screw helps in maintaining the alignment and balance of the flywheel, which is crucial for the smooth operation of the engine. The screw’s design facilitates easy installation and removal, making maintenance procedures more efficient and reliable.

Conclusion

In summary, the part 3678740 Twelve Point Cap Screw is a fundamental component in the assembly and operation of flexplates, flywheels, and their mounting systems. Its robust design and secure fastening capabilities are essential for the reliable performance of engine systems.