What is a Place Bolt and how is it used?

Fasteners that create a “locking” action are commonly used in applications that experience high vibration or flexing to ensure that the assembly does not come loose over time. Many of our customers are aware of the choices that are available in locking nuts (All Metal Lock Nuts, Nylon Insert Lock Nuts, etc) but when it comes to the bolt or screw that is used in the assembly, the choices for a locking screw are limited. The two main styles of locking screws that are used in the industry are the Hex Serrated Flange Screw or a Hex Bolt that has a nylon or chemical patch applied to the threads.

Both options have limitations for use in some applications. For example, Hex Serrated Flange Screws can mar the surface that they are being assembled onto, causing premature rusting. Additionally, chemical patches can be adversely affected when exposed to chemicals or heat. Many of our customers are not aware of another option when it comes to a bolt that can create a locking action within your assembly. 

However, Earnest Machine offers Place Bolts which feature a special head design that provides a “locking” action between the head of the bolt and the material being clamped. The combination of the special recessed groove under the head and the slots in the top of the head cause the head to flex as it is tightened, illustrated in figure 1. This creates a spring action in the head that provides additional elastic elongation that is not achieved by standard Hex Head Cap Screws. This spring action also provides increased resistance to loosening in high vibration applications.

Typically, Place Bolts are used on the inside of engines and transmissions where a loose assembly would result in a major repair. Often, this style of fastener is chosen to assemble the flywheel to the torque converter on most transmission assemblies due to the constant speed changes and excessive vibrations that can be encountered within this application. 

Earnest Machine’s line of Place Bolts are made to the dimensional requirements of the General Motors standard for Type AA Hex Head Lock Bolts. Additionally, Earnest Machine’s line of Place Bolts are also manufactured from high-strength alloy steel and are through-hardened to the Grade 8 strength level as specified in the Society of Automotive Engineers standard SAE J429.

So, whether you are designing a new assembly or trying to improve an existing one, a Place Bolt is an excellent choice for when you want to achieve maximum resistance to vibration, preventing your assembly from loosening over time, and greatly reducing the likelihood of a major failure or repair. 

To learn more about Earnest Machine’s line of Place Bolts, download the spec sheet or speak to an Earnest Sales Representative at +44 (0) 1902 711041. 

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