Standard adapters are available in two configurations: Male-to-Male and Female-to-Male.
Male-to-Male adapters are typically designed to provide full thread engagement of the mating thread with additional thread available for the use of a lock nut. A wrench flat is also normally machined in the center of the adapter to assist in installation or removal.
Female-to-Male adapters are sold in pairs and are designed for use with tension rods and act to reduce or adapt the tension rod thread to the required male thread for the accessory.
Rigid couplings are also available for converting threaded accessories to standard Instron Pin and Clevis mounting that are standard on most Instron electromechanical frames. These couplings are normally provided with a male threaded end to a male pin end, along with matching knurled lock nuts for both ends of the adapter and the required tommy bar(s) for tightening or loosening the lock nuts.
Additional customized adapters can be engineered and manufactured to nearly any specification and dimension.
Principle of Operation
Adapters whether standard or custom, are normally threaded into the accessory and then the entire unit is threaded or pinned into the machine load cell, table, crosshead, tension rod, or other appropriate mounting point.
Lock nuts are used to maintain alignment of grips, remove slack in load train, and minimize movement of the fixture during testing.
Knurled lock nuts are used for most applications since hand tightening of lock nuts and adapters is sufficient for most testing. When additional tightening is required, most adapters have a wrench flat or tommy bar recess to allow torquing the adapter as required. These points also allow for ease of removal if the adapter becomes stuck.
Tommy bars are small rods that are extremely effective in tightening or loosening lock nuts when a little more torque than hand tight is required.