Technical Information TI-F10

Locking Units

Holding in both load directions Hydraulic respectively pneumatic actuation

Function

Locking by springs / hydraulic releasing

Types KFH, KFP, u.a.

+F -F

321KL

p If the unit is pressureless - as shown in the schematic drawing- the rod is clamped by force of the springs and can hold fullnominal holding force. The proximity switch suppliers 1 is signalising „rodclamped".During every operational cycle the 3/2 way valve is actuatedelectrically and releases the Locking Unit. In all other operatio-nal conditions, as well as in cases of power failure, emergencystop, etc. the locking unit is actuated, secures the rod and stopsthe load. In case of pressure failure, the load is secured in thesame way. To avoid possible problems, the shaft should not bemoved unless the proximity switch 2 indicates „released".
clampedreleased assemblyForce-path diagramm SITEMA Locking Units clamp a shaft infinitely variable withoutchanging its position, and absorb axial forces in both directionsDepending on their type they are unclamped by hydraulic orpneumatic pressure. The clamping force is generated by springaction or by hydraulic pressure.The workholding system consists of a conical sleeve (1) and aclamping ring (2). The sleeve (1) is axially fixed in the housing (3), allowing only radial movement. The clamping ring (2) is gui-ded by the housing (3) and is forced in an axial direction overthe sleeve (1) to achieve the clamping action. The clampingforce K is generated by pressure or spring action and is inten-sified by means of conical (or inclined) surfaces. The force Lunclamps the locking unit. A well-defined clearance ensuresthat the shaft can move without any friction.SITEMA locking units absorb forces in both directions. In caseof overload, the shaft slips through the clamping unit and will normally cause no damage. Applications with recurrent over- load should be avoided. In this case, depending on force-level,slipping speed, and rod quality, seizing potential exists.

Hydraulic clamping and releasing

Types KB and KBP

p If the port K is pressurized - as shown in the schematic drawing- the rod is clamped by force of the annular hydraulic (or pneu-matic, resp.) piston and can hold a force proportional to the ap-plied pressure. Using the nominal pressure the full nominal holding force is achieved. The proximity switch 1 is signalising„rod clamped". By switching the suppliers of valve pressure is applied to port L, whichsunclamps the Locking Unit. To avoid possible problems, theshaft should not be moved before the proximity switch 2 indica-tes a „released".
SITEMA GmbH & Co.KG . Im Mittelfeld 10 . D-76135 Karlsruhe . Phone: +49(0)721/98661-0 . Fax: -11 . www.sitema.com 1/2