3943786
Twelve Point Cap Screw
Cummins®

The Cummins Twelve Point Cap Screw, part number 3943786, is a specialized fastener designed for heavy-duty truck components. This part ensures secure attachment of various components within the truck’s structure, contributing to vehicle reliability and performance ³.

Basic Concepts of Twelve Point Cap Screws

Twelve Point Cap Screws feature a hexagonal socket head with twelve sides, unlike the six sides of standard hex cap screws. This design enhances torque application and reduces the risk of cam-out during installation or removal. The design distributes force more evenly across the head, improving fastening performance ¹.

Purpose and Role in Truck Operation

This Cummins part is used in heavy-duty trucks to secure various components, ensuring structural integrity and reliable operation. It fastens critical parts subject to significant stress and vibration, contributing to the vehicle’s durability and safety ².

Key Features

The Twelve Point Cap Screw 3943786 is made from high-strength steel, providing durability for heavy-duty applications. It has a specific thread type for optimal engagement with mating components and a twelve-sided socket head that enhances torque application and reduces stripping. Corrosion-resistant coatings may be present to enhance performance in various environments ³.

Benefits

The benefits of this part include improved torque application due to its twelve-sided design, which allows for better force distribution and reduced risk of cam-out. Its material composition and design contribute to enhanced durability, resistance to wear, and corrosion, ensuring long-term reliable performance in demanding conditions ¹.

Installation Guidelines

Proper installation of the Twelve Point Cap Screw 3943786 involves using a twelve-sided socket wrench to ensure secure fastening. Follow torque specifications provided by the manufacturer to achieve the correct tension without over-tightening. Best practices include cleaning mating surfaces and using thread locker where applicable to prevent loosening due to vibration ².

Troubleshooting and Maintenance

Common issues with Twelve Point Cap Screws may include loosening due to vibration or corrosion. Troubleshooting steps involve inspecting the screw and mating surfaces for wear or damage, tightening to the specified torque, or replacing the screw if necessary. Maintenance tips include regular inspection for corrosion or wear, ensuring proper torque is maintained, and applying protective coatings or treatments as recommended by the manufacturer to prolong lifespan and ensure continued reliable performance ³.

Cummins: Manufacturer Overview

Cummins Inc. is a global power leader that designs, manufactures, and distributes a wide range of power solutions, including diesel engines and components. With a history spanning over a century, Cummins is recognized for its expertise in engine technology and commitment to quality and innovation. The company’s products are designed to meet the demanding requirements of various industries, including heavy-duty trucking, where reliability and performance are paramount ¹.

Twelve Point Cap Screw (Part 3943786) in Cummins Engines

The Twelve Point Cap Screw (Part 3943786) is a critical component in various Cummins engine models. This part provides robust fastening capabilities, ensuring secure connections in the engine assembly. Here’s how it fits into specific Cummins engine models:

ISC Series Engines

• ISC CM2150
• ISC CM554
• ISC CM850
• ISC8.3 CM2250

The Twelve Point Cap Screw is integral in securing various components within the ISC series engines. Its design allows for precise tightening and stability, which is crucial for maintaining engine integrity and performance.

ISL Series Engines

• ISL CM2150
• ISL CM554
• ISL9 CM2150 SN
• ISL9 CM2250

In the ISL series engines, the Twelve Point Cap Screw is used extensively for fastening critical parts. Its twelve-point design provides better grip and reduces the likelihood of rounding off, which is essential for the high-stress environments within these engines.

QSC and QSL Series Engines

• QSC8.3 CM554
• QSC8.3 CM850 (CM2850)
• QSC9 CM2250 / QSL9 CM2250
• QSL8.9 CM2150 L141
• QSL9 CM2250
• QSL9 CM554
• QSL9 CM850 (CM2850)
• QSK60 CM850 MCRS

For the QSC and QSL series engines, the Twelve Point Cap Screw is utilized in various applications, including securing engine blocks, cylinder heads, and other vital components. Its design ensures that these connections remain tight and secure under the demanding conditions these engines operate in.

The consistent use of the Twelve Point Cap Screw across these engine models underscores its importance in maintaining the structural and operational integrity of Cummins engines ².

Role of Part 3943786 Twelve Point Cap Screw in Engine Systems

In the intricate assembly of engine systems, the Twelve Point Cap Screw 3943786 serves as a fundamental fastening element, ensuring the secure attachment of various components. Its application spans across several key areas within the engine, contributing to the overall stability and functionality of the system.

Attachment and Mounting

The Twelve Point Cap Screw is extensively used in the attachment and mounting processes of engine components. It provides a robust connection between the starting motor and its mounting bracket. This secure fastening is essential for maintaining the alignment and operational integrity of the starting motor, which is pivotal during engine start-up sequences.

Starting Motor

In the starting motor assembly, the Twelve Point Cap Screw plays a significant role in attaching the motor to its housing. This ensures that the motor remains firmly in place, allowing for efficient transmission of mechanical force required to crank the engine. The screw’s design allows for easy installation and removal, facilitating maintenance and repair procedures.

Pump Systems

Within pump systems, particularly fuel pumps, the Twelve Point Cap Screw is utilized to secure the pump to its mounting surface. This attachment is vital for maintaining the pump’s position and ensuring consistent fuel delivery to the engine. The screw’s reliability under varying operational conditions contributes to the pump’s durability and performance.

Fuel System Components

In the fuel system, the Twelve Point Cap Screw is employed to fasten various components, such as fuel lines and filters, to their respective mounts. This secure attachment is important for preventing leaks and ensuring the smooth flow of fuel throughout the system. The screw’s ability to withstand high pressures and temperatures makes it an ideal choice for fuel system applications.

Overall, the Twelve Point Cap Screw 3943786 is an indispensable component in the assembly and maintenance of engine systems, providing the necessary fastening strength and reliability across a range of critical applications ³.

Conclusion

The Cummins Twelve Point Cap Screw, part number 3943786, is a vital component in heavy-duty truck and engine systems. Its unique design, robust material composition, and reliable performance make it essential for securing various components, ensuring the structural integrity and operational reliability of the vehicle. Proper installation, regular maintenance, and adherence to manufacturer guidelines are crucial for maximizing the lifespan and performance of this part.