Catalogues - sitema-safety-catchers-hydraulic-for-compressive-load

Catalogue SITEMA Safety Catchers hydraulic / for compressive load

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SiTE MA

Technical Information SITEMA - Safety Catchers

Hydraulic or pneumatic actuation

English translation of German original

Technical Information TI-A10

Safety Catchers

0 High holding force by self-intensifying clamping

0 Hydraulic respectively pneumatic actuation

0 Approved for use in professional presses and lifting gear (DIN EN 693)

Expertise in Safel

TI-A10-EN-03/2008

Contents

1 Purpose....................................................................... 1

2 Function........................................................................ 1

3 Design types................................................................ 2

4 Control.......................................................................... 2

5 Choosing the right size............................................... 2

6 Rod requirements........................................................ 2

7 Service life.................................................................... 2

8 Acceptance by Safety Authorities.............................. 3

9 Own hazard analysis.................................................. 3

10 Operating conditions.................................................. 3

11 Overall documentaion and CE professional label.......................... 3

12 Regular functional checks.......................................... 3

13 Maintenance................................................................. 3

14 How to attach............................................................... 4

A detailed description of the control, assembly and operational test of the SITEMA Safety Catchers can be found in the Operating Manuals BA-A11 to BA-A14".

2Function

vice'

released

force-parth diagram

structure

Fig. 1: Design principle

The piston shaft (1) is surrounded by the housing (2) in which several wedged clamping jaws (3), each with one industrial slide lining (4) and one brake lining (5), are assembled. When pressure (p) is applied to the plungers (8), the clamping jaws are held in a raised position so that the shaft can move freely. The industrial springs (6) are compressed in this position.

The Safety Catcher becomes effective as soon as pressure is released from the plungers (8). The action of the springs causes the clamping jaws (3) to then clamp the shaft (1) firmly, thus securing the load.

The clamping force, however, is not built up until the shaft has been moved by the load. Due to the self-intensifying static friction at the shaft, the clamping jaws (3) are drawn into the clamping position at their stops (7) after having moved the distance "e" (approx. 5 to 15 mm, depending on the design). This movement is illustrated as phase A in the force-path diagram.

If the load is increased further (phase B), the shaft remains in its position, independent of the load, until the static holding force F* is reached. As soon as this limit is exceeded, the clamping device (phase C) generates a mean dynamic braking force F -- the holding force -- and thus dissipates the kinetic energy of the falling mass.

The clamping is released by an upward movement of the shaft through path "e", by applying pressure corresponding to the load being lifted. Thus the release operation is only possible if the pressure system is intact. Excess pressure (e.g. for breaking loose) is normally not required.

1Purpose

Safety Catchers are used where protection of personnel and accident prevention must be achieved in connection with raised loads or tools in case of failure of load-bearing machine parts. This may be a leakage or breakdown, for example, of a hydraulic or pneumatic pressure system. Safety Catchers catch falling masses infinitely variable at any position of the stroke, in a mechanically secure and absolutely reliable manner. The design principle of the self-reinforcing clamping ensures an extremely high safety level.

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SITEMA GmbH & Co.KG . Im Mittelfeld 10 . D-76135 Karlsruhe . Phone: +49(0)721/98661-0 . Fax: -11 . www.sitema.com