3901221
Hexagon Head Cap Screw
Cummins®

A Hexagon Head Cap Screw is a type of fastener commonly used in various applications, including commercial trucks. Its primary function is to securely join components together, ensuring structural integrity and proper operation. This screw is particularly valued in the automotive and heavy-duty truck industries for its reliability and ease of use.

Basic Concepts of Hexagon Head Cap Screw

A Hexagon Head Cap Screw is characterized by its hexagonal head, which facilitates efficient tightening and loosening using a wrench or socket. The screw’s design includes a threaded shaft that engages with the internal threads of a nut or directly into a tapped hole, providing a strong and secure fastening. The hexagonal shape of the head allows for a firm grip, reducing the risk of slippage during installation or removal ¹.

Role of 3901221 Hexagon Head Cap Screw in Truck Operation

The 3901221 Hexagon Head Cap Screw by Cummins plays a significant role in the operation of trucks. It is used to secure various components and assemblies, ensuring that they remain firmly in place under the demanding conditions encountered in commercial trucking. This screw helps maintain the structural integrity of the truck and ensures that all parts function as intended, contributing to the overall reliability of the vehicle ².

Key Features

The 3901221 Hexagon Head Cap Screw is crafted from high-quality materials, ensuring durability and performance. Its thread pitch is designed to provide optimal engagement and holding power. Additionally, the screw may feature special coatings or treatments that enhance its resistance to corrosion and wear, further extending its service life. These features make it suitable for the harsh environments often encountered in commercial trucking ³.

Benefits

The 3901221 Hexagon Head Cap Screw offers several benefits that contribute to the reliability and maintenance of trucks. Its strength ensures that fastened components remain secure, even under significant stress. The screw’s resistance to loosening helps prevent unexpected failures. Furthermore, its compatibility with standard tools makes it easy to install and remove, facilitating routine maintenance and repairs.

Troubleshooting and Maintenance

To ensure the longevity and performance of the 3901221 Hexagon Head Cap Screw, it is important to address common issues such as loosening or corrosion. Regular inspections can help identify screws that may need tightening or replacement. Following proper torque specifications during installation is crucial to avoid over-tightening, which can damage threads, or under-tightening, which can lead to loosening. Additionally, keeping the screw clean and free of debris can prevent corrosion and extend its service life.

About Cummins

Cummins Inc. is a global power leader that designs, manufactures, and distributes a wide range of power solutions, including diesel and natural gas engines, as well as related technologies. With a history of innovation and a commitment to quality, Cummins provides high-performance components for the commercial truck industry. Their expertise in engine and powertrain systems ensures that their products, like the 3901221 Hexagon Head Cap Screw, meet the rigorous demands of heavy-duty applications.

Hexagon Head Cap Screw 3901221 in Cummins Engines

The Cummins part number 3901221, a Hexagon Head Cap Screw, is a critical component used in various Cummins engine models. This screw is essential for securing different parts within the engine assembly, ensuring structural integrity and operational efficiency. Below is a detailed look at how this part fits into various Cummins engines.

Cummins 4B3.9 and 6B5.9 Engines

In the 4B3.9 and 6B5.9 engines, the Hexagon Head Cap Screw 3901221 is utilized to fasten components that require precise alignment and secure fastening. These engines, known for their reliability and performance, depend on this screw to maintain the structural integrity of the engine block and other critical assemblies.

Cummins 6C8.3 and B3.9 G Engines

The 6C8.3 and B3.9 G engines also incorporate the 3901221 screw in their design. This part is often used in the fastening of engine mounts, brackets, and other components that need to withstand high stress and vibration. The precision and strength of the screw ensure that these parts remain securely in place, contributing to the overall durability of the engine.

Cummins B4.5, B5.9, and B5.9 CM2670 B166C Engines

In the B4.5, B5.9, and B5.9 CM2670 B166C engines, the Hexagon Head Cap Screw 3901221 is used in several key areas. These include securing the cylinder head to the engine block, fastening various engine accessories, and ensuring the proper alignment of internal components. The screw’s design allows for easy installation and removal, which is crucial during maintenance and repair operations.

Cummins B5.9 G and B5.9 GAS PLUS CM556 Engines

For the B5.9 G and B5.9 GAS PLUS CM556 engines, the 3901221 screw plays a vital role in maintaining the alignment and stability of the engine’s internal components. This includes securing parts of the fuel injection system, turbochargers, and other critical assemblies. The screw’s robust design ensures that these components remain tightly fastened, even under the high pressures and temperatures typical of diesel engines.

Cummins B6.7S and C GAS PLUS CM556 Engines

In the B6.7S and C GAS PLUS CM556 engines, the Hexagon Head Cap Screw 3901221 is used to fasten various engine components, including those related to the exhaust system and fuel injection. The screw’s precision and strength are critical in ensuring that these parts remain securely in place, contributing to the engine’s overall performance and longevity.

Cummins G5.9 and G5.9 CM558 Engines

For the G5.9 and G5.9 CM558 engines, the 3901221 screw is used in several key areas, including the fastening of engine mounts and brackets. This ensures that the engine remains securely in place within the vehicle, reducing vibration and improving overall performance.

Cummins ISB3.9 CM2220 B107 and ISB5.9 CM2880 B127 Engines

In the ISB3.9 CM2220 B107 and ISB5.9 CM2880 B127 engines, the Hexagon Head Cap Screw 3901221 is used to secure various engine components, including those related to the fuel injection system and turbochargers. The screw’s design ensures that these parts remain tightly fastened, even under the high stresses typical of heavy-duty engines.

Cummins ISB5.9G CM2180 and ISM CM570 Engines

For the ISB5.9G CM2180 and ISM CM570 engines, the 3901221 screw is used in the fastening of engine mounts, brackets, and other critical components. This ensures that the engine remains securely in place, reducing vibration and improving overall performance.

Cummins QSB3.9 30 CM550, QSB3.9 CM2880 B138, and QSB5.9 30 CM550 Engines

In the QSB3.9 30 CM550, QSB3.9 CM2880 B138, and QSB5.9 30 CM550 engines, the Hexagon Head Cap Screw 3901221 is used to secure various engine components, including those related to the exhaust system and fuel injection. The screw’s precision and strength are critical in ensuring that these parts remain securely in place, contributing to the engine’s overall performance and longevity.

Cummins QSB5.9 CM2880 B139, QSB5.9 CM550, QSB5.9G, and QSM11 CM570 Engines

For the QSB5.9 CM2880 B139, QSB5.9 CM550, QSB5.9G, and QSM11 CM570 engines, the 3901221 screw is used in the fastening of engine mounts, brackets, and other critical components. This ensures that the engine remains securely in place, reducing vibration and improving overall performance. The screw’s robust design ensures that these components remain tightly fastened, even under the high pressures and temperatures typical of diesel engines.

Role of Part 3901221 Hexagon Head Cap Screw in Various Engine Components

Drive System

In the drive system, the 3901221 Hexagon Head Cap Screw is utilized to secure the drive belt tensioner. This ensures that the belt remains taut, providing consistent power transmission from the engine to other components such as the alternator and water pump. Proper tension is vital for efficient operation and longevity of the drive components.

Fan Assembly

Within the fan assembly, this screw plays a part in attaching the fan blades to the fan hub. This secure attachment is essential for effective airflow across the engine, aiding in the dissipation of heat and maintaining optimal operating temperatures.

Governor Mechanism

The governor, which regulates engine speed, often incorporates the 3901221 Hexagon Head Cap Screw to fasten various linkages and pivot points. This secure fastening ensures that the governor can accurately modulate fuel delivery and maintain stable engine performance under varying loads.

Air Compressor

In air compressor systems, this screw is employed to affix components such as the compressor housing or mounting brackets. Secure attachment is necessary to withstand the high pressures and vibrations inherent in compressor operation, ensuring reliable performance and safety.

Lever and Rocker Systems

For levers and rocker systems, the 3901221 Hexagon Head Cap Screw is instrumental in attaching pivot points and linkage arms. This secure connection is fundamental for the precise movement and operation of these components, which are often involved in valve actuation and other critical engine functions.

Rocker Levers

In the context of rocker levers, this screw is used to fasten the rocker arm to its pivot point on the engine block or cylinder head. This ensures that the rocker arm can transmit motion from the camshaft to the valves with minimal play, contributing to efficient valve operation and overall engine performance.

Conclusion

The 3901221 Hexagon Head Cap Screw is a vital component in the operation and maintenance of Cummins engines. Its robust design, precision, and ease of use make it an essential part in securing various engine components, ensuring structural integrity and operational efficiency. Regular maintenance and proper installation are key to maximizing the performance and longevity of this Cummins part.