MTS Series 646 Hydraulic Collet Grips - Manual (Page 15)

Series 646 Hydraulic Collet Grips Introduction 15
Hydraulic Grip Components
I TEM D ESCRIPTION
Load unit crosshead and
base plate Provides the structure to mount the grips and other components in the force
train. It is also the reaction mass for the force train. The crosshead and base
plate are connected with columns.
Force transducer Measures the axial forces applied to the specimen. An axial-torsional version
also measures the rotational forces applied to the specimen.
The force transducer can be located in the base or the crosshead of the load
unit.
Hydraulic pressure
and return lines Ports the hydraulic fluid to and from the grips. The hydraulic fluid comes from
a dedicated hydraulic grip supply that produces 45 MPa (6500 psi). Each grip
has two hydraulic lines connected to it, a hydraulic pressure line and a
hydraulic return line.
Upper and lower grips Clamps a specimen in place. The grips house the collets and the hydraulic
components that operate the grips.
Collet Contacts and holds the specimen in place. Collets are available for flat, round,
and threaded specimens.
Actuator rod Applies axial forces to a specimen. The actuator is a hydraulically powered
device that provides linear displacement of (or forces into) a specimen. For
axial-torsional systems, the actuator applies both axial and torsional forces to
the specimen.
The actuator rod can be located in the base or the crosshead of the load unit.
Axial attachment kit Includes the required components to install the grips. Each grip model/load
unit model combination has a unique attachment kit.
Shims Allows further rotation of the grips to change the orientation of the spiral
washers so the appropriate opening is set. When axial grips are installed, the
upper and lower grips might not be aligned after being screwed onto the
mounting studs. Shims can be added so that the amount of rotation can be
changed. The shims are available in thicknesses that correspond with 1/8 to 1/2
turns of rotation.
Spiral washers Ensures preloading without inducing offsets in the force train. They provide a
backlash-free union of threaded components.
Mounting stud Mounts the grips to the other components in the force train. Connector studs
are threaded rods that connect the grips with an actuator rod or force
transducer.
Adapter plate Allows axial-torsional grips to be mounted to a force transducer. The adapter
provides the thread needed to use the couplings.
Upper and lower
couplings Clamps the grips to the to the actuator and force transducer. The couplings
have left and right handed threads that preload the grip connection and
prevents backlash in the force train.