MTS Material Test Systems - Manual (Page 21)

3.2.2.0 Servohydraulic and Mechanical Components
The following paragraphs briefly describe the servohydraulic and mechanical components that are typical
supplied with the MTS Landmark System.
Load frame
There are a variety of load frames that can be supplied with the system. The load frame is the mechanical
foundation of the test system in which the load cell transducer, specimen fixturing or grips, and hydraulic
actuator are mounted.
The load frame can be configured with hydraulic-controlled crosshead locks and lifts that allow convenient
crosshead positioning during specimen installation. (Manual crosshead locks and lifts and manual crosshead
locks and hydraulic lifts are also available on some models.)
Load frames come in a variety of configurations, but all have the same basic components described below.
Some examples are:
• Basic two-column floor-standing frames for general material testing such as the MTS Landmark Load
Frame
• Table-top frames for biomechanical and biomaterials testing such as the MTS Bionix Load Frame
• T-slot baseplate frames for general component testing such as the MTS Model 322 Load Frame
• Frames specifically designed for high cycle elastomer testing such as the MTS Model 331.02 and 331.05
Load Frames.
• Frames with high mass base designs for shock absorber testing such as the MTS Model 84X and 85x
Load Frames
Hydraulic actuator
The hydraulic actuator is typically mounted in the base of the load frame; some load frames can have crosshead
mounted actuators. It is the force-generating and/or positioning device in the system. Hydraulic fluid is applied
to either side of the actuator's piston to cause its piston rod to extend or retract.
Servovalve(s)
The servovalve converts a control signal (from the test controller) to control the direction and amount of fluid
flow to the actuator. This regulated hydraulic fluid flow controls the displacement or force being applied to
the test specimen.
Hydraulic service manifold
The hydraulic service manifold contains the required hydraulic porting to accommodate the servovalve(s),
an actuator, and the crosshead lifts. The actuator and servovalve(s) are mounted to the manifold. The manifold
includes a low hydraulic flow feature that lets you limit the velocity of the actuator for specimen installation.
Accumulators
The accumulators suppress line-pressure fluctuations. The pressure-line accumulators provide fluid storage
so a constant line pressure can be maintained at the servovalve(s) for maximum performance. The return-line
accumulator minimizes return-line pressure fluctuations.
MTS Material Test System Operation 21
3.0 Introduction