MTS Systems 111, 111.12, 111.11B, 111.12C, 111.11 Product Information

Series 111 Accumulator
Product Information

Model 111.11
Model 111.12

l

011-553-304 B

Copyright information

Trademark information

© 2000 MTS Systems Corporation. All rights reserved.

MTS is a registered trademark of MTS Systems Corporation.

Contact information

MTS Systems Corporation

14000 Technology Drive
Eden Prairie, Minnesota 55344-2290 USA
Toll Free Phone: [phone] (within the U.S. or Canada)
Phone: [phone] (outside the U.S. or Canada)
Fax: [phone]
E-mail: [e-mail]
http://www.mts.com

Publication information ISO 9001 Certified

M

ANUAL

P

115533-00A December 1982

115533-01A August 1983

115533-02A September 1984

115533-03A June 1987

115533-03B February 1988

115533-03C February 1989

115533-03D June 1990

115533-03E November 1991

ART

N

UMBER

P

UBLICATION

D

ATE

115533-03F July 1993

115533-03G June 1994

115533-04A June 1998

011-553-304 B June 1999

Contents

Introduction 5

Functional Description 6
Specifications 7

Installation 9

Maintenance 11

Checking the Accumulator Precharge 13
Changing the Precharge Pressure 15
Purging Fluid from the Gas Chamber 17
Removing the Accumulator 18
Replacing the Accumulator Seal 19

Series 111 Accumulators Contents

3

4

Series 111 Accumulators

Introduction

The Series 111 Accumulator stabilize the hydraulic lines in your system.
There are two models availlable:

• The Model 111.11B Accumulator is a boss port-mounted accumulator

that requires a boss adapter fitting for mounting.

• The Model 111.12C Accumulator is bolt-mounted to a flange and

typically has a larger nitrogen gas capacity than the Model 111.11B.

Contents

Functional Description 6
Specifications 7

What you need to

know

Series 111 Accumulators Introduction

MTS Systems Corporation assumes that you know how to use your
controller. See the appropriate manual for information about performing
any controller-related step in this manual’s procedures. You are expected
to know how to perform the following procedures:

• Turning hydraulic pressure on and off

• Selecting a control mode

• Manually adjusting the actuator position

5

Functional Description

The MTS Series 111 Accumulators can reduce fluctuations hydraulic lines
due to sudden changes in hydraulic flow rate. They also act a short term
energy source for high-rate tests by providing additional hydraulic flow for
short periods to meet irregular peak demands. Like a capacitor,
accumulators filter out pulses in the hydraulic fluid to provide steady
hydraulic pressure.

Accumulators are like a hydraulic
version of a capacitor. They are
hydro-pneumatic devices located at
strategic points in a hydraulic
system. They may be connected to
the pressure line and to the return
line.

Nitrogen

Side

Accumulators are precharged with
pressure. Precharge pressure is the
pressure of the compressed gas
(usually nitrogen) before hydraulic
fluid is introduced.

Inserting accumulators into the
hydraulic lines permits some fluid to
be stored under pressure a short
distance from the servovalve and
actuator. This has the effect of
keeping fluid in the lines in motion
and reducing the inertia and line
restriction considerations. When the
servovalve opens and line pressure begins to drop, the accumulator in the
hydraulic service manifold (HSM) immediately supplies part of the fluid
volume and maintains the line pressure. Then, when the servovalve closes,
the hydraulic power supply (HPS) recharges the accumulator , causing fluid
in the lines to remain in motion.

The pattern and frequency of the signal that drives the servovalve will have
considerable effect on the HSM accumulator efficiency. Square wave
signals, for example, cause a greater demand than sine wave signals or
ramp signals.

Piston

Fluid

Side

Hydraulic Fluid

Accumulator

6

Introduction

At some frequencies, fluid flow in the lines may stop completely, and
overcoming the fluid inertia may become a more significant operational
factor.

An accumulator in the return line damps the pulsing effect caused by
“slugs” of fluid being injected into the line as the actuator moves.
Movement of hoses and/or hammering of hard lines is also reduced.

Series 111 Accumulators